Volume 20,Issue 2,2013 Table of Contents
2013, 20(2):1-4.
Abstract:
All kinds of property of oil reservoir that have definite single or multiple dynamics implications reflect accumulating dynamics. The oil reservoir quantitative feature exactly exhibits the type and quantitative feature of accumulating dynamics. It has close relationship between oil column, reservoir pressure, oil saturation and dynamics. Oil reservoir type is different from trap type because of accumulating dynamics. It is the relationship between evolution of different zones and reservoir types in basin. It macroscopically displays the feature and evolution of basin. Based on the property and evolution of oil reservoir, we classified the accumulating system,and deeply analyze the manifestation of accumulation dynamics, resistance, replacement and accumulation, and then establish the oil reservoir forecasting mode base of basin accumulation dynamics environment and trap type distribution feature.
All kinds of property of oil reservoir that have definite single or multiple dynamics implications reflect accumulating dynamics. The oil reservoir quantitative feature exactly exhibits the type and quantitative feature of accumulating dynamics. It has close relationship between oil column, reservoir pressure, oil saturation and dynamics. Oil reservoir type is different from trap type because of accumulating dynamics. It is the relationship between evolution of different zones and reservoir types in basin. It macroscopically displays the feature and evolution of basin. Based on the property and evolution of oil reservoir, we classified the accumulating system,and deeply analyze the manifestation of accumulation dynamics, resistance, replacement and accumulation, and then establish the oil reservoir forecasting mode base of basin accumulation dynamics environment and trap type distribution feature.
2013, 20(2):5-10.
Abstract:
North Africa region experienced extensional and compressive tectonic movement’s reformation during the pan-African, alpine and hercynian periods, and passed through the complex basin evolution process which formed the pan-African basement, early Palaeozoic stable passive continental margin evolution, late Paleozoic Foreland evolution, Mesozoic rift evolution and Cenozoic reversal,and then caused the current western Paleozoic and east-central Mesozoic-Cenozoic petroleum system which are mutually uncorrelated in the plane. This paper systematically analyzed the geological characteristics of two big petroleum system and put forward the exploration potential targets, pointed out that, under the cover of Silurian-Carboniferous Acacus petroleum group, the Devonian Tadrart group and the Triassic thick evaporated salt, in ancient uplift and nearby unconformity trap are main exploration potential targets of west basin Paleozoic petroleum system; moreover, the fault and lithologic trap near the graben and horst and deep cretaceous sandbody are the main exploration potential targets of east-central basin Mesozoic-Cenozoic petroleum system, and the study has certain theoretical significance and practical value to know oil reservoir distribution rules so as to improve the success rate of exploration in North Africa.
North Africa region experienced extensional and compressive tectonic movement’s reformation during the pan-African, alpine and hercynian periods, and passed through the complex basin evolution process which formed the pan-African basement, early Palaeozoic stable passive continental margin evolution, late Paleozoic Foreland evolution, Mesozoic rift evolution and Cenozoic reversal,and then caused the current western Paleozoic and east-central Mesozoic-Cenozoic petroleum system which are mutually uncorrelated in the plane. This paper systematically analyzed the geological characteristics of two big petroleum system and put forward the exploration potential targets, pointed out that, under the cover of Silurian-Carboniferous Acacus petroleum group, the Devonian Tadrart group and the Triassic thick evaporated salt, in ancient uplift and nearby unconformity trap are main exploration potential targets of west basin Paleozoic petroleum system; moreover, the fault and lithologic trap near the graben and horst and deep cretaceous sandbody are the main exploration potential targets of east-central basin Mesozoic-Cenozoic petroleum system, and the study has certain theoretical significance and practical value to know oil reservoir distribution rules so as to improve the success rate of exploration in North Africa.
2013, 20(2):11-14.
Abstract:
The activation of formation water has important domination to the generation, migration, accumulation and loss of oil and gas.And, the evolution of formation water is closely related to the accumulation process of oil and gas. On the basis of analysis of the formation water distribution characteristics of Niuzhuang sag, and under the guidance of fliud dynamics, three types of enclosure correlating with fluid activation are classified through saline enclosure petrography observation. The three main formation fluid active stages which are end of Ed, deposition period of Ng and deposition period of Nm-Quaternary period are classified in respect of homogenization temperature and salinity measurement of salt-water inclusion in sand rock reservoir combined with the study of thermal evolution history of Niuzhuang sag in this paper. The palae-salinity of different formation fluid active stages is recovered by means of fluid inclusions analysis technique, and the palae-pressure of different formation fluid active stages is recovered by fluid inclusions methane content calculation. The palae-salinity of the evening of Ed period increased, and the palae-salinity of Ng period declined. The palae-pressure of the end of Ed period declined, the palae-pressure of Ng period increased. The ancient fluid evolution model and the dynamic model of formation water activation and oil accumulation are accomplished finally.
The activation of formation water has important domination to the generation, migration, accumulation and loss of oil and gas.And, the evolution of formation water is closely related to the accumulation process of oil and gas. On the basis of analysis of the formation water distribution characteristics of Niuzhuang sag, and under the guidance of fliud dynamics, three types of enclosure correlating with fluid activation are classified through saline enclosure petrography observation. The three main formation fluid active stages which are end of Ed, deposition period of Ng and deposition period of Nm-Quaternary period are classified in respect of homogenization temperature and salinity measurement of salt-water inclusion in sand rock reservoir combined with the study of thermal evolution history of Niuzhuang sag in this paper. The palae-salinity of different formation fluid active stages is recovered by means of fluid inclusions analysis technique, and the palae-pressure of different formation fluid active stages is recovered by fluid inclusions methane content calculation. The palae-salinity of the evening of Ed period increased, and the palae-salinity of Ng period declined. The palae-pressure of the end of Ed period declined, the palae-pressure of Ng period increased. The ancient fluid evolution model and the dynamic model of formation water activation and oil accumulation are accomplished finally.
2013, 20(2):15-20.
Abstract:
Because China has some of the most water-flooded oilfield in world, stable oil production relies on controlling water injection and increasing oil recovery. The sandstone stacked styles, heterogeneity, geometry of reservoirs can be studied by high resolution sequence stratigraphy with a kind of new vision, which closely links remaining oil distribution and extends new method for studying remaining oil distribution. This paper studies base level changing laws of different cycles based on detailed research of sedimentary micro-facies of Karamay formation, then the short base level cycles of Karamay formation can be divided into 2 main classes and 12 small classes. The middle base level cycles control the development of short base level cycles, so the Karamay formation can be divided into 3 middle cycles and 14 short cycles, then the isochronous stratigraphic framework are built. The short base level cycles which are located in the middle base level cycles have different remaining oil distribution in isochronous stratigraphic framework. The result shows that the detailed sedimentary work is the base for studying sequence stratigraphy. The reservoirs that are deposited in the high accommodation can have good isochronous and low intraformational heterogeneity, so, the remaining oil distribute in thin, small, nonproducing or low degree of water flooded area. Meanwhile, the reservoir that is distributed in low accommodation can have poor isochronous and high intraformational heterogeneity, and which are composed of noncontemporaneous deposit, so, the remaining oil is distributed in low permeable reservoirs in form of lens.
Because China has some of the most water-flooded oilfield in world, stable oil production relies on controlling water injection and increasing oil recovery. The sandstone stacked styles, heterogeneity, geometry of reservoirs can be studied by high resolution sequence stratigraphy with a kind of new vision, which closely links remaining oil distribution and extends new method for studying remaining oil distribution. This paper studies base level changing laws of different cycles based on detailed research of sedimentary micro-facies of Karamay formation, then the short base level cycles of Karamay formation can be divided into 2 main classes and 12 small classes. The middle base level cycles control the development of short base level cycles, so the Karamay formation can be divided into 3 middle cycles and 14 short cycles, then the isochronous stratigraphic framework are built. The short base level cycles which are located in the middle base level cycles have different remaining oil distribution in isochronous stratigraphic framework. The result shows that the detailed sedimentary work is the base for studying sequence stratigraphy. The reservoirs that are deposited in the high accommodation can have good isochronous and low intraformational heterogeneity, so, the remaining oil distribute in thin, small, nonproducing or low degree of water flooded area. Meanwhile, the reservoir that is distributed in low accommodation can have poor isochronous and high intraformational heterogeneity, and which are composed of noncontemporaneous deposit, so, the remaining oil is distributed in low permeable reservoirs in form of lens.
2013, 20(2):21-24.
Abstract:
The petrologic characteristics，diagenesis and major controlling factors of reservoir quality of the Liushagang formation in Huachang-Bailian area, Fushan depression, Beibuwan basin are analyzed by means of physical properties analysis, casting thin-section, X-ray diffraction and SEM. This study shows that the reservoir of Liushagang formation, characterized by litharenite and lithic sandstone, is low porous and permeable with dissolved intergranular and intragranular pore as the main pore type and then the residual primary pore. The reservoir in research area is mainly affected by combined factors of depositional environment and diagenesis, whose original porosity is medium and strongly reformed by later diagenesis. Currently, the Liushagang reservoir is at late diagenetic phase A.The main diagenesis types in Liushagang reservoir are compaction, secondary enlargement of quartz and cementation of authigenic clay mineral, etc. It is the compaction that reduces the primary pore space in Liushagang reservoirs, while dissolution generated secondary porosity that improves reservoir quality. By comprehensive analysis of the structure, deposition, diagenesis, the result shows that the favorable reservoir in the Fushan depression is mainly distributed in the relatively higher parts of braided delta front sandbodies.
The petrologic characteristics，diagenesis and major controlling factors of reservoir quality of the Liushagang formation in Huachang-Bailian area, Fushan depression, Beibuwan basin are analyzed by means of physical properties analysis, casting thin-section, X-ray diffraction and SEM. This study shows that the reservoir of Liushagang formation, characterized by litharenite and lithic sandstone, is low porous and permeable with dissolved intergranular and intragranular pore as the main pore type and then the residual primary pore. The reservoir in research area is mainly affected by combined factors of depositional environment and diagenesis, whose original porosity is medium and strongly reformed by later diagenesis. Currently, the Liushagang reservoir is at late diagenetic phase A.The main diagenesis types in Liushagang reservoir are compaction, secondary enlargement of quartz and cementation of authigenic clay mineral, etc. It is the compaction that reduces the primary pore space in Liushagang reservoirs, while dissolution generated secondary porosity that improves reservoir quality. By comprehensive analysis of the structure, deposition, diagenesis, the result shows that the favorable reservoir in the Fushan depression is mainly distributed in the relatively higher parts of braided delta front sandbodies.
2013, 20(2):25-29.
Abstract:
It has been a great breakthrough of bed rock exploration in Liaohe depression that the interior reservoirs are found in the metamorphic rock of Archean Eonothem. Because the current understanding constrained that only the weathered crust of metamorphic rock can form reservoirs, and it has been changed, and that, the formation theory of hydrocarbon reservoirs of bed rock in Liaohe depression has been enriched. The interior oil pools in metamorphic rock of Archean Eonothem in Liaohe depression will be important prospective target because it has important potential capacities for exploration. With continuous exploration, the new difficulty questions will gradually appear, so, it will become more important that the formation features of interior oil pools in metamorphic rock of Archean Eonothem should be clarified. This paper discusses the known interior reservoir in metamorphic rock of Archean Eonothem. Firstly,their properties of crude oil are analyzed, then, the formation features of known interior reservoir, such as Xinggu7, Shen311, Zhaogu1 and so on, are presented, ultimately, the formation features of interior reservoir in metamorphic rock of Archean Eonothem in Liaohe depression are proposed. The theoretical knowledge in this paper will have important directive significance for the exploration of interior oil pools in metamorphic rock of Archean Eonothem in Liaohe depression and other similar exploration areas all over the world.
It has been a great breakthrough of bed rock exploration in Liaohe depression that the interior reservoirs are found in the metamorphic rock of Archean Eonothem. Because the current understanding constrained that only the weathered crust of metamorphic rock can form reservoirs, and it has been changed, and that, the formation theory of hydrocarbon reservoirs of bed rock in Liaohe depression has been enriched. The interior oil pools in metamorphic rock of Archean Eonothem in Liaohe depression will be important prospective target because it has important potential capacities for exploration. With continuous exploration, the new difficulty questions will gradually appear, so, it will become more important that the formation features of interior oil pools in metamorphic rock of Archean Eonothem should be clarified. This paper discusses the known interior reservoir in metamorphic rock of Archean Eonothem. Firstly,their properties of crude oil are analyzed, then, the formation features of known interior reservoir, such as Xinggu7, Shen311, Zhaogu1 and so on, are presented, ultimately, the formation features of interior reservoir in metamorphic rock of Archean Eonothem in Liaohe depression are proposed. The theoretical knowledge in this paper will have important directive significance for the exploration of interior oil pools in metamorphic rock of Archean Eonothem in Liaohe depression and other similar exploration areas all over the world.
2013, 20(2):30-33.
Abstract:
Exploration in the area between Dingjiawuzi and Bamianhe tectonic zones has achieved a breakthrough in the east part of South Slope of Dongying sag. The Es4 oil and gas reservoir was found in Block Wang146. The reservoir has a burial depth of 1 462.9- 1 748.5 m, but the physical properties of crude oil shows the characteristic of high density, high viscosity and low freezing point, that is, a typical deep viscous oil reservoir. The formation mechanism of the reservoir is worth discussing. Based on the analysis of the information regarding the single well hydrocarbon and characteristics of the remarkable composition in the crude oil, it is clarified that the main source of hydrocarbon is generated in source rocks of Es4; during the process of migrating hydrocarbon outward from the oil-bearing depression, the degradation occurred; It is determined further that this area has 2 dominant hydrocarbon migration directions according to the differences in the degree of degradation of crude oil. The main migration path is along Dingjiawuzi structural trend, and another is along Bamianhe tectonic zones trend, and the degradation in the migration path of Dingjiawuzi structural trend is the strongest, therefore, it has caused the formation of the Es4 deep viscous oil reservoir in the Wang146 area. It is still of broad exploration prospects along the dominant hydrocarbon migration path.
Exploration in the area between Dingjiawuzi and Bamianhe tectonic zones has achieved a breakthrough in the east part of South Slope of Dongying sag. The Es4 oil and gas reservoir was found in Block Wang146. The reservoir has a burial depth of 1 462.9- 1 748.5 m, but the physical properties of crude oil shows the characteristic of high density, high viscosity and low freezing point, that is, a typical deep viscous oil reservoir. The formation mechanism of the reservoir is worth discussing. Based on the analysis of the information regarding the single well hydrocarbon and characteristics of the remarkable composition in the crude oil, it is clarified that the main source of hydrocarbon is generated in source rocks of Es4; during the process of migrating hydrocarbon outward from the oil-bearing depression, the degradation occurred; It is determined further that this area has 2 dominant hydrocarbon migration directions according to the differences in the degree of degradation of crude oil. The main migration path is along Dingjiawuzi structural trend, and another is along Bamianhe tectonic zones trend, and the degradation in the migration path of Dingjiawuzi structural trend is the strongest, therefore, it has caused the formation of the Es4 deep viscous oil reservoir in the Wang146 area. It is still of broad exploration prospects along the dominant hydrocarbon migration path.
2013, 20(2):34-38.
Abstract:
The structure is complicated in the block Bi123-124 of the Guchen oilfield, and the reservoir is controlled by the lithology and structure. The crossflow is very serious in the study area, and the adjustment of the injection and production is difficult. On the basis of the data of core, well log, grain size, we identify the signs of sedimentary facies, and study the micro-facies of the reservoir sedimentary facies. The result shows that the Ⅳ sandstone layer of the second member of He Formation has developed delta front subfacies deposit, which can be divided into six types of sedimentary microfacies and creeping turbidite sandbody. The sedimentary microfacies include subsea distributary channel, river flank, mouth bar, distal bar, front sheet sand and distributary inter channel. The shape and distribution and superposition of the reservoirs sand are analyzed, so we can find that the subsea distributary channel and mouth bar are the favorable facies belts of the study area. All of above proofs that the oilfield in the studied is controlled by the structure and lithology. The result of the study can provide geological basis for the next step of the adjustment of the exploration.
The structure is complicated in the block Bi123-124 of the Guchen oilfield, and the reservoir is controlled by the lithology and structure. The crossflow is very serious in the study area, and the adjustment of the injection and production is difficult. On the basis of the data of core, well log, grain size, we identify the signs of sedimentary facies, and study the micro-facies of the reservoir sedimentary facies. The result shows that the Ⅳ sandstone layer of the second member of He Formation has developed delta front subfacies deposit, which can be divided into six types of sedimentary microfacies and creeping turbidite sandbody. The sedimentary microfacies include subsea distributary channel, river flank, mouth bar, distal bar, front sheet sand and distributary inter channel. The shape and distribution and superposition of the reservoirs sand are analyzed, so we can find that the subsea distributary channel and mouth bar are the favorable facies belts of the study area. All of above proofs that the oilfield in the studied is controlled by the structure and lithology. The result of the study can provide geological basis for the next step of the adjustment of the exploration.
2013, 20(2):39-41.
Abstract:
Three-dimensional quantitative analysis of fracture is not only the comprehensive embodiment of fracture research results,but also the objective need of fractural reservoirs study and numerical reservoir simulation. With the advance of logging recognition,seismic detecting, dynamic monitoring, physical modeling and numerical simulation methods, we can get more valuable materials than before which bring even higher challenges in fracture three-dimensional modeling. Three main steps included in the fracture three-dimensional quantitative analysis, i.e., fracture intensity modeling, DFN modeling and fracture network properties modeling. It is the most important and the most difficult thing that how to unify the fracture information and research results, how to calculate fracture attributes such as aperture and permeability. This paper has proposed the related solutions and discussions, introduced a method which uses imaging or conventional logging data, dynamic analysis results, seismic detecting data and other data to build fracture intensity model, and uses core fracture data in combination with empirical formulas to build fracture properties models. Combining this method with international fracture modeling software, we can quantitatively describe the three-dimensional distribution of fracture and provide solid support for reservoir study and numerical simulation.
Three-dimensional quantitative analysis of fracture is not only the comprehensive embodiment of fracture research results,but also the objective need of fractural reservoirs study and numerical reservoir simulation. With the advance of logging recognition,seismic detecting, dynamic monitoring, physical modeling and numerical simulation methods, we can get more valuable materials than before which bring even higher challenges in fracture three-dimensional modeling. Three main steps included in the fracture three-dimensional quantitative analysis, i.e., fracture intensity modeling, DFN modeling and fracture network properties modeling. It is the most important and the most difficult thing that how to unify the fracture information and research results, how to calculate fracture attributes such as aperture and permeability. This paper has proposed the related solutions and discussions, introduced a method which uses imaging or conventional logging data, dynamic analysis results, seismic detecting data and other data to build fracture intensity model, and uses core fracture data in combination with empirical formulas to build fracture properties models. Combining this method with international fracture modeling software, we can quantitatively describe the three-dimensional distribution of fracture and provide solid support for reservoir study and numerical simulation.
2013, 20(2):42-44.
Abstract:
Due to lack of sufficient data previous research mostly studied the petroleum geology character with limited 2D seismic data and logging data, so, the understanding is limited. On the basis of former understanding, and combined the 3D seismic data with core,well logging and logging data of new wells, we deeply studied the sedimentary facies and rules of distribution of down-Cretaceous in Zuunbyan sub-basin 3D work area, the author thought that, in the period of down-Cretaceous deposition, under the control of adjacent structure, the lake basin water body of study area went through shallow to deep to shallow, and relevantly formed phase sequence from stream delta front，shallow to semi-deep and deep lacustrine to delta front. Source of favorable sediments are mainly from west hog of Zuunbyan sub-basin.
Due to lack of sufficient data previous research mostly studied the petroleum geology character with limited 2D seismic data and logging data, so, the understanding is limited. On the basis of former understanding, and combined the 3D seismic data with core,well logging and logging data of new wells, we deeply studied the sedimentary facies and rules of distribution of down-Cretaceous in Zuunbyan sub-basin 3D work area, the author thought that, in the period of down-Cretaceous deposition, under the control of adjacent structure, the lake basin water body of study area went through shallow to deep to shallow, and relevantly formed phase sequence from stream delta front，shallow to semi-deep and deep lacustrine to delta front. Source of favorable sediments are mainly from west hog of Zuunbyan sub-basin.
11 Characteristics on lithosomic sand bodies of upper member of Guantao formation in Zhanhua depression
2013, 20(2):45-47.
Abstract:
Comprehensively using well drilling, well log, logging, regional geological characteristics, all kinds of dynamic and quiescent data, we obtain the conclusions that the upper member of Guantao formation in Zhanhua depression developed not only fluvial facies but also lacustrine sand bodies. The early upper member of Guantao formation developed fluvial facies of braided and meandering streams, and the middle-late developed depositional systems of shore and shallow lacustrine and shallow delta-oxidizing and fluctuated shallow lake. The lacustrine depositional model expands the exploration area, and the lacustrine depositional theory, combining with production practice of oilfield, makes stratigraphic correlation more reliable. The beach bar, channel sand, and flat sand bodies are better exploration areas of Ng1+2 in Zhanhua depression.
Comprehensively using well drilling, well log, logging, regional geological characteristics, all kinds of dynamic and quiescent data, we obtain the conclusions that the upper member of Guantao formation in Zhanhua depression developed not only fluvial facies but also lacustrine sand bodies. The early upper member of Guantao formation developed fluvial facies of braided and meandering streams, and the middle-late developed depositional systems of shore and shallow lacustrine and shallow delta-oxidizing and fluctuated shallow lake. The lacustrine depositional model expands the exploration area, and the lacustrine depositional theory, combining with production practice of oilfield, makes stratigraphic correlation more reliable. The beach bar, channel sand, and flat sand bodies are better exploration areas of Ng1+2 in Zhanhua depression.
2013, 20(2):48-51.
Abstract:
The Gbeibe oilfield is an old oilfield with 36 years development history in Syria, and the success rate of drilling and the production of old oil producer are very low before Chinese company took over it in 2004, the geologic characteristics and the oil and gas distribution in the reservoir fracture system are less clear, the reservoir fracture system identification technology itself is currently one of globe problem about the oilfield development technology, in view of this situation, the fault and fracture automatic identification technology which is based on the ant colony optimization(ACO) is successfully applied in Gbeibe oilfield, the technology has clarified that there are 2 fracture zone whose direction are the main east-west and north-south all over Gbeibe oilfield, and 3 fracture system which are not in communication with each other and relatively independent communication system, moreover, it also presents that the distribution of oil and gas well productivity and production is mainly controlled by fault system, that is, the high and middle oil producers are generally located in or near the fracture zone, and the longer the perforated section in the fault zone, the higher the yield, low production wells especially dry-wells are generally located far away from the fault zone in the region. After we use this technique accurately to predict the fault and fracture zone distribution and design of horizontal well in Gbeibe oilfield, the drilling success rate of horizontal well is greatly improved, up to 95%, and the daily oil production is greatly increased to 2 350 m3/d from 800 m3/d, the research achievements support the efficient development of Gbeibe oilfield.
The Gbeibe oilfield is an old oilfield with 36 years development history in Syria, and the success rate of drilling and the production of old oil producer are very low before Chinese company took over it in 2004, the geologic characteristics and the oil and gas distribution in the reservoir fracture system are less clear, the reservoir fracture system identification technology itself is currently one of globe problem about the oilfield development technology, in view of this situation, the fault and fracture automatic identification technology which is based on the ant colony optimization(ACO) is successfully applied in Gbeibe oilfield, the technology has clarified that there are 2 fracture zone whose direction are the main east-west and north-south all over Gbeibe oilfield, and 3 fracture system which are not in communication with each other and relatively independent communication system, moreover, it also presents that the distribution of oil and gas well productivity and production is mainly controlled by fault system, that is, the high and middle oil producers are generally located in or near the fracture zone, and the longer the perforated section in the fault zone, the higher the yield, low production wells especially dry-wells are generally located far away from the fault zone in the region. After we use this technique accurately to predict the fault and fracture zone distribution and design of horizontal well in Gbeibe oilfield, the drilling success rate of horizontal well is greatly improved, up to 95%, and the daily oil production is greatly increased to 2 350 m3/d from 800 m3/d, the research achievements support the efficient development of Gbeibe oilfield.
2013, 20(2):52-54.
Abstract:
In view of some restrictions of application of pre-stack seismic inversion to hydrocarbon detection, application of prestack seismic inversion to predicting hydrocarbon for conglomerate body in Minfeng area is suggested. Firstly, the parameters of interest interval including density, compressional wave velocity, shear wave velocity and Poisson’s ratio are calculated by means of analyzing geophysical signature. Secondly, the seismic response characteristics for gas bearing reservoir in pre-stack gather are analyzed by forward modeling. Lastly, based on intersection analysis methods, the applicability of parameters such as intercept-gradient, velocity-density,Lambda constant, velocity-Poisson’s ratio to hydrocarbon detection is correlated and Lame’s constant and Poisson’s ratio which are sensitive to hydrocarbon in interval of interest are selected as inversion parameters. The ability of sensitive parameters to locate the gas bearing reservoir is analyzed through prestack seismic inversion. The application results indicate that the research results acquired by intersection interpretation of lambda constant and shear modulus extracted from pre-stack seismic inversion coincides with drilling test results, and predicted favorable gas-bearing area of 109 km2, natural gas resource of 290×108 m3.
In view of some restrictions of application of pre-stack seismic inversion to hydrocarbon detection, application of prestack seismic inversion to predicting hydrocarbon for conglomerate body in Minfeng area is suggested. Firstly, the parameters of interest interval including density, compressional wave velocity, shear wave velocity and Poisson’s ratio are calculated by means of analyzing geophysical signature. Secondly, the seismic response characteristics for gas bearing reservoir in pre-stack gather are analyzed by forward modeling. Lastly, based on intersection analysis methods, the applicability of parameters such as intercept-gradient, velocity-density,Lambda constant, velocity-Poisson’s ratio to hydrocarbon detection is correlated and Lame’s constant and Poisson’s ratio which are sensitive to hydrocarbon in interval of interest are selected as inversion parameters. The ability of sensitive parameters to locate the gas bearing reservoir is analyzed through prestack seismic inversion. The application results indicate that the research results acquired by intersection interpretation of lambda constant and shear modulus extracted from pre-stack seismic inversion coincides with drilling test results, and predicted favorable gas-bearing area of 109 km2, natural gas resource of 290×108 m3.
2013, 20(2):55-57.
Abstract:
In the case of the sharply declining of well production caused by water blockage, which was caused by maintenance operation due to the difference between layers in Shuanghe oilfield. A new type of waterlock-proof treatment agent is developed through laboratory experiments (0.5%SATRO+0.05%alkyl sodium sulfonate+0.03%FX-02). This paper mainly introduces the formulation screening of the waterlock-proof treatment agent and the performance evaluation.The results show that:this product can effectively reduce the interfacial tension between oil and water, causing the interfacial tension to reach ultra low（10-3 mN/m）; at the same time, the product with a good demulsification performance can make the demulsification rate up to 90% in 3 h; the laboratory core physical model experiment indicates that : when the injection rate of the waterlock-proof treatment agent is 10 PV, temperature of 70 ℃, displacement pressure of 0.3 MPa, reaction time up to 8 h, the remaining ratio of the core permeability reaches up to over 85%, which can effectively prevent emulsification blocking and the formation permeability damage caused by water lock effect. The waterlock-proof treatment agent has been applied in field for 12 wells, whose effective rate is 100%, remarkable results are achieved.
In the case of the sharply declining of well production caused by water blockage, which was caused by maintenance operation due to the difference between layers in Shuanghe oilfield. A new type of waterlock-proof treatment agent is developed through laboratory experiments (0.5%SATRO+0.05%alkyl sodium sulfonate+0.03%FX-02). This paper mainly introduces the formulation screening of the waterlock-proof treatment agent and the performance evaluation.The results show that:this product can effectively reduce the interfacial tension between oil and water, causing the interfacial tension to reach ultra low（10-3 mN/m）; at the same time, the product with a good demulsification performance can make the demulsification rate up to 90% in 3 h; the laboratory core physical model experiment indicates that : when the injection rate of the waterlock-proof treatment agent is 10 PV, temperature of 70 ℃, displacement pressure of 0.3 MPa, reaction time up to 8 h, the remaining ratio of the core permeability reaches up to over 85%, which can effectively prevent emulsification blocking and the formation permeability damage caused by water lock effect. The waterlock-proof treatment agent has been applied in field for 12 wells, whose effective rate is 100%, remarkable results are achieved.
2013, 20(2):58-61.
Abstract:
During the early stage of the test of water flooding development of multi-well fracture-cavity units in carbonate fracture-cavity reservoir in Tahe oilfield, it emerged some problems such as few efficient well groups, short efficient period and very fast water cut.In accordance with these problems, based on the systematic analysis of the water flooding test early stage and laboratory research, this paper puts forward the pattern of water flooding development of multi-well fracture-cavity units of carbonate fracture-cavity reservoir,which is intended to keep pressure, multi-stage and stereoscopic water flooding. The development of keeping pressure refers to keep the pressure of reservoir to slow down the decline rate caused by the energy decline and to restrain the bottom water coning. The multi-stage development refers to adopt different waterflood pattern, injection-production parameter and matching technology at different stage of water flooding development, it should increase the water injection rate to test the connectivity and construct the injection-production relation before water flooding effect appears, and it should adopt moderate waterflood until the water flood effect become serious, and increase water injection rate for cyclic water flooding and adopt reversing the direction of water injection well and profile control at the later stage. The development of stereoscopic water flooding refers to set up stereoscopic injection-production pattern according to development rule of fracture and cavity, the condition of distribution of residual oil and connectivity, it should adopt the water flooding ways and matching technologies of bidirectional or more directional injection, separated layer water injection, low injection and high production and fracture injecting and cavity production.
During the early stage of the test of water flooding development of multi-well fracture-cavity units in carbonate fracture-cavity reservoir in Tahe oilfield, it emerged some problems such as few efficient well groups, short efficient period and very fast water cut.In accordance with these problems, based on the systematic analysis of the water flooding test early stage and laboratory research, this paper puts forward the pattern of water flooding development of multi-well fracture-cavity units of carbonate fracture-cavity reservoir,which is intended to keep pressure, multi-stage and stereoscopic water flooding. The development of keeping pressure refers to keep the pressure of reservoir to slow down the decline rate caused by the energy decline and to restrain the bottom water coning. The multi-stage development refers to adopt different waterflood pattern, injection-production parameter and matching technology at different stage of water flooding development, it should increase the water injection rate to test the connectivity and construct the injection-production relation before water flooding effect appears, and it should adopt moderate waterflood until the water flood effect become serious, and increase water injection rate for cyclic water flooding and adopt reversing the direction of water injection well and profile control at the later stage. The development of stereoscopic water flooding refers to set up stereoscopic injection-production pattern according to development rule of fracture and cavity, the condition of distribution of residual oil and connectivity, it should adopt the water flooding ways and matching technologies of bidirectional or more directional injection, separated layer water injection, low injection and high production and fracture injecting and cavity production.
2013, 20(2):62-66.
Abstract:
This paper summarizes the implication and characteristics of tight oil from different domestic and foreign tight oil definitions and criteria, and statistically analyzes foreign tight oil resources and their distribution. It selects tight oil-gas fields of large development scale or mature technology as the research subject, and analyzes them from different perspectives such as geological properties,development history and status, development status technology, cost of discovery and development, development effect and laws, etc. It concludes the major development technology and policies aiming at different geological conditions, and the variation law of key development indexes including initial production and decline rate. Combined with the tight oil development status and geological characteristics of Sinopec, this paper draws inspirations in terms of geology, technology, basic research, and cost, etc. All these recognitions will be of great reference and guiding significance to the development orientation, technology policy making, recognition of development law, scheme optimization, organization and operation, and management mode of domestic tight oil development technology.
This paper summarizes the implication and characteristics of tight oil from different domestic and foreign tight oil definitions and criteria, and statistically analyzes foreign tight oil resources and their distribution. It selects tight oil-gas fields of large development scale or mature technology as the research subject, and analyzes them from different perspectives such as geological properties,development history and status, development status technology, cost of discovery and development, development effect and laws, etc. It concludes the major development technology and policies aiming at different geological conditions, and the variation law of key development indexes including initial production and decline rate. Combined with the tight oil development status and geological characteristics of Sinopec, this paper draws inspirations in terms of geology, technology, basic research, and cost, etc. All these recognitions will be of great reference and guiding significance to the development orientation, technology policy making, recognition of development law, scheme optimization, organization and operation, and management mode of domestic tight oil development technology.
2013, 20(2):67-70.
Abstract:
The small oil sand of Gudong oilfield mostly belongs to meander fluvial sedimentation, which is limited area, poor reservoir property, dispersed distribution, low flood and development performance. Digital technique is used to optimize the development project after small oil sand reservoir is described, and at the same time, the integrated technique of drilling and production is implemented.Economic benefit is enhanced through field practice, reservoir availability and recovery ratio is respectively enhanced by 59.1% and 14.8%.
The small oil sand of Gudong oilfield mostly belongs to meander fluvial sedimentation, which is limited area, poor reservoir property, dispersed distribution, low flood and development performance. Digital technique is used to optimize the development project after small oil sand reservoir is described, and at the same time, the integrated technique of drilling and production is implemented.Economic benefit is enhanced through field practice, reservoir availability and recovery ratio is respectively enhanced by 59.1% and 14.8%.
2013, 20(2):71-73.
Abstract:
The oil water contact (OWC) is very important to determine reserves at place and early development plan of the reservoir. In the early stage of exploration with less well data, the precision of oil water contact (OWC), which is determined by mud logging, well logging, oil test, etc, will be affected, especially for heterogeneous carbonate reservoir. The capillary pressure data can provide lots of information, which can be used to study oil water contact (OWC). In this paper, 8 capillary pressure (mercury injection) curves from the first developmental well-X of carbonate reservoir in Middle East were applied to regressively fit the saturation height function through multiple non-linear methods with the software of Interactive Petrophysics (IP). The optimized function was combined with the conventional log interpretation result to best fit the free water level (FWL) depth. The oil water contact (OWC) was further determined. Confirmed by the adjacent exploration well test result of oil and water zone, the method above is effective and practical. So, it can be a useful supplement for the methods of determining oil water contact.
The oil water contact (OWC) is very important to determine reserves at place and early development plan of the reservoir. In the early stage of exploration with less well data, the precision of oil water contact (OWC), which is determined by mud logging, well logging, oil test, etc, will be affected, especially for heterogeneous carbonate reservoir. The capillary pressure data can provide lots of information, which can be used to study oil water contact (OWC). In this paper, 8 capillary pressure (mercury injection) curves from the first developmental well-X of carbonate reservoir in Middle East were applied to regressively fit the saturation height function through multiple non-linear methods with the software of Interactive Petrophysics (IP). The optimized function was combined with the conventional log interpretation result to best fit the free water level (FWL) depth. The oil water contact (OWC) was further determined. Confirmed by the adjacent exploration well test result of oil and water zone, the method above is effective and practical. So, it can be a useful supplement for the methods of determining oil water contact.
2013, 20(2):74-76.
Abstract:
Difference of physical property of each stratum can cause different advancing velocity of water-oil frontal edge during the waterflooding stage in ultra-low permeability multilayer reservoir. Using seepage theory of ultra-low permeability multilayer reservoir,considering threshold pressure gradient for oil and water, a theoretical model is established and the formula of water-oil frontal edge is deduced. In addition, the influence of permeability differential, injection-production differential pressure, injection-production well spacing and oil viscosity on the water-oil frontal edge is also analyzed. Considering the influence of injection-production well spacing,the dimensionless water-oil frontal edge is first proposed. The result shows that: The greater the permeability differential, the slower the advancing velocity of water-oil frontal edge for the lower stratum; with the increase of the injection-production differential pressure, the advancing velocity of water-oil frontal edge for the lower stratum is becoming faster, but the amplitude increment is becoming smaller; with the increase of the injection-production well spacing, the distance of water-oil frontal edge for the lower stratum is becoming longer, but the dimensionless water-oil frontal edge is becoming smaller; with the decrease of oil viscosity, the advancing velocity of water-oil frontal edge for the lower stratum is becoming faster, and the amplitude increment is becoming larger.
Difference of physical property of each stratum can cause different advancing velocity of water-oil frontal edge during the waterflooding stage in ultra-low permeability multilayer reservoir. Using seepage theory of ultra-low permeability multilayer reservoir,considering threshold pressure gradient for oil and water, a theoretical model is established and the formula of water-oil frontal edge is deduced. In addition, the influence of permeability differential, injection-production differential pressure, injection-production well spacing and oil viscosity on the water-oil frontal edge is also analyzed. Considering the influence of injection-production well spacing,the dimensionless water-oil frontal edge is first proposed. The result shows that: The greater the permeability differential, the slower the advancing velocity of water-oil frontal edge for the lower stratum; with the increase of the injection-production differential pressure, the advancing velocity of water-oil frontal edge for the lower stratum is becoming faster, but the amplitude increment is becoming smaller; with the increase of the injection-production well spacing, the distance of water-oil frontal edge for the lower stratum is becoming longer, but the dimensionless water-oil frontal edge is becoming smaller; with the decrease of oil viscosity, the advancing velocity of water-oil frontal edge for the lower stratum is becoming faster, and the amplitude increment is becoming larger.
2013, 20(2):77-82.
Abstract:
The current situation of reservoirs with high water cut or low permeability in China has provided a vast space for development of CO2-EOR technique. Reservoir numerical simulation has occupied a key status in CO2-EOR technique. Therefore, it is necessary to make analysis for mathematical models of the CO2-EOR process and describe these models according to their types. This paper,on the base of references home and abroad, classifies the CO2-EOR mathematical models into five categories and summarizes the characteristic of each type. This aims to recognize the pros and cons of these models to provide references and supports in models modification and numerical simulation application in CO2-EOR. Furthermore, the new viewpoints of developing directions in CO2 flooding models are also presented.
The current situation of reservoirs with high water cut or low permeability in China has provided a vast space for development of CO2-EOR technique. Reservoir numerical simulation has occupied a key status in CO2-EOR technique. Therefore, it is necessary to make analysis for mathematical models of the CO2-EOR process and describe these models according to their types. This paper,on the base of references home and abroad, classifies the CO2-EOR mathematical models into five categories and summarizes the characteristic of each type. This aims to recognize the pros and cons of these models to provide references and supports in models modification and numerical simulation application in CO2-EOR. Furthermore, the new viewpoints of developing directions in CO2 flooding models are also presented.
2013, 20(2):83-86.
Abstract:
The effects of various factors on viscosity loss of polymer solution are investigated to highlight the main issue of serious loss for viscosity during foam flooding as well as to find the effective preserving measurements. The results showed that the reducing substances in the wastewater such as sulfides, Fe2+, SRB, and COD are the main reasons affecting the viscosity loss of polymer solution. On this basis, one kind of preserving method for viscosity loss of polymer solution in Chengdong foam flooding is pointed out by aerobic biological oxidation. The viscosity of polymer solution prepared with the wastewater which is aerobically treated by sulfur-oxidizing bacteria SOB and denitrifying bacteria DNB can reach more than 30 mPa?s.
The effects of various factors on viscosity loss of polymer solution are investigated to highlight the main issue of serious loss for viscosity during foam flooding as well as to find the effective preserving measurements. The results showed that the reducing substances in the wastewater such as sulfides, Fe2+, SRB, and COD are the main reasons affecting the viscosity loss of polymer solution. On this basis, one kind of preserving method for viscosity loss of polymer solution in Chengdong foam flooding is pointed out by aerobic biological oxidation. The viscosity of polymer solution prepared with the wastewater which is aerobically treated by sulfur-oxidizing bacteria SOB and denitrifying bacteria DNB can reach more than 30 mPa?s.
2013, 20(2):87-90.
Abstract:
To understand the waterflooding mechanism in low-permeability cores, the CT scanning has been applied to monitor the in-situ water saturation profiles along the core at different time points. The new method improves the accuracy of measurement with CT values correction. The influence of injection rates (or capillary numbers), presence of connate water and heterogeneity of core samples on displacement characteristics of waterflood has been further studied. The saturation profiles show convective straight displacement at high flow rate (high capillary number) that is, the piston-like transport mechanism is favorable. While at low flow rate (low capillary number), the capillary forces broaden the saturation distribution and water breakthrough occurs at the outlet very quickly which makes the snap-off and crawling mechanism predominant. The presence of connate water lessens the steepness of imbibition fronts. It could be attributed to the pre-existing water phase in the small pores which supplies wetting fluid and forms the stable collars of water before the connected front catches up. Therefore, the presence of connate water promotes snap-off events. The advance of saturation front proceeds in a hyper-dispersive manner and the saturation profiles are almost uniformly distributed along the heterogeneous core samples.The microscopic heterogeneity increases the difference of capillary forces generated in the displacing process, which causes the bypassing and fingering to be the dominant oil entrapment mechanism.
To understand the waterflooding mechanism in low-permeability cores, the CT scanning has been applied to monitor the in-situ water saturation profiles along the core at different time points. The new method improves the accuracy of measurement with CT values correction. The influence of injection rates (or capillary numbers), presence of connate water and heterogeneity of core samples on displacement characteristics of waterflood has been further studied. The saturation profiles show convective straight displacement at high flow rate (high capillary number) that is, the piston-like transport mechanism is favorable. While at low flow rate (low capillary number), the capillary forces broaden the saturation distribution and water breakthrough occurs at the outlet very quickly which makes the snap-off and crawling mechanism predominant. The presence of connate water lessens the steepness of imbibition fronts. It could be attributed to the pre-existing water phase in the small pores which supplies wetting fluid and forms the stable collars of water before the connected front catches up. Therefore, the presence of connate water promotes snap-off events. The advance of saturation front proceeds in a hyper-dispersive manner and the saturation profiles are almost uniformly distributed along the heterogeneous core samples.The microscopic heterogeneity increases the difference of capillary forces generated in the displacing process, which causes the bypassing and fingering to be the dominant oil entrapment mechanism.
2013, 20(2):91-94.
Abstract:
Since the start of“Eleventh Five-Year Plan”, the polymer flooding units in Henan oilfield have been in ultra-high water cut stage before injecting polymer, which has resulted in longer responding time. It is the key to maximize the proportion of effective corresponding wells, effective thickness and effective multiples in dynamically adjustment of polymer flooding. With methods of reservoir engineering, numerical simulation and field test, policy limits of polymer flooding dynamic adjustment are studied in this paper. Also, according to different stages of responding of polymer flooding and different factors that affect the performance of corresponding wells, the process control technology of improving the effect of polymer flooding is studied, including reasonable production and injection rate allocation technology, edge water control technology, polymer concentration differences adjustment technology, polymer channeling control technology, long term closure layer with high water cut evaluation and utilization technology and polymer flooding moderate extracting technology. The effect of application of the six process control technology in Shuangbei H3Ⅳ1-3 series of strata is significant and the effect of actual oil increase is better than numerical simulation forecast. When 0.56 PV polymer is injected into the reservoir, it can improve recovery by 2.83%.
Since the start of“Eleventh Five-Year Plan”, the polymer flooding units in Henan oilfield have been in ultra-high water cut stage before injecting polymer, which has resulted in longer responding time. It is the key to maximize the proportion of effective corresponding wells, effective thickness and effective multiples in dynamically adjustment of polymer flooding. With methods of reservoir engineering, numerical simulation and field test, policy limits of polymer flooding dynamic adjustment are studied in this paper. Also, according to different stages of responding of polymer flooding and different factors that affect the performance of corresponding wells, the process control technology of improving the effect of polymer flooding is studied, including reasonable production and injection rate allocation technology, edge water control technology, polymer concentration differences adjustment technology, polymer channeling control technology, long term closure layer with high water cut evaluation and utilization technology and polymer flooding moderate extracting technology. The effect of application of the six process control technology in Shuangbei H3Ⅳ1-3 series of strata is significant and the effect of actual oil increase is better than numerical simulation forecast. When 0.56 PV polymer is injected into the reservoir, it can improve recovery by 2.83%.
2013, 20(2):95-98.
Abstract:
The heterogeneity of oil reservoir is the major internal factors affecting the oil-water seepage and oil and gas recovery of the reservoirs. The injection and production parameters have a great influence on recovery of heterogeneous reservoirs，and visualization study of microcosmic model is an effective method of determining the reasonable injection and production parameters of heterogeneous reservoirs. In this paper, seven experimental schemes are designed according to different injection-production methods and injection-production rate. Conducting water-driving-oil displacement experiments using visual dynamic simulation displacement experiment device, we study the influence on water flooding degree by physical property difference, well-pattern type and injection and production parameters of heterogeneous reservoirs. The results show that the change of water injection mode and injection and production parameters in high and low permeability areas have a great influence on recovery of heterogeneous reservoirs. The high recovery can be obtained by flooding according to certain ratio and surrounding equilibrium flooding in high and low permeability areas.
The heterogeneity of oil reservoir is the major internal factors affecting the oil-water seepage and oil and gas recovery of the reservoirs. The injection and production parameters have a great influence on recovery of heterogeneous reservoirs，and visualization study of microcosmic model is an effective method of determining the reasonable injection and production parameters of heterogeneous reservoirs. In this paper, seven experimental schemes are designed according to different injection-production methods and injection-production rate. Conducting water-driving-oil displacement experiments using visual dynamic simulation displacement experiment device, we study the influence on water flooding degree by physical property difference, well-pattern type and injection and production parameters of heterogeneous reservoirs. The results show that the change of water injection mode and injection and production parameters in high and low permeability areas have a great influence on recovery of heterogeneous reservoirs. The high recovery can be obtained by flooding according to certain ratio and surrounding equilibrium flooding in high and low permeability areas.
2013, 20(2):99-102.
Abstract:
The addition of CS2 into oil solvent can enhance its efficiency to dissolve paraffin, but it will result in the problem of metal corrosion. So, a method to determine the content of CS2 in oil based paraffin remover is suggested in this paper. In this method, the content of CS2 can be determined after it is swept from the oil based paraffin remover and absorbed by absorbents. So, the key to this method is to improve the efficiency and analysis accuracy of absorbing CS2. In this paper, for absorbing CS2, we designed a new type of units in the base of air sampler，and compared the standard absorbing curve and efficiency of different absorbers by spectrophotometric method. The results confirm that the alcohol solution of diethyl amine-copper acetate shouldn’t be selected to absorb CS2 due to the disturbance of redundant Cu2+；compared to alcohol-thylenediamine solution, a higher rate of CS2 absorption is obtained by using the system of methanol-potassium hydroxide and the corresponding product of absorbing is chemically stable in 2 hours. Moreover, with the self-designed setup and methanol-potassium hydroxide solution as absorbents, the adsorption efficiency of CS2 is as high as 98% and the result has good repeatability.
The addition of CS2 into oil solvent can enhance its efficiency to dissolve paraffin, but it will result in the problem of metal corrosion. So, a method to determine the content of CS2 in oil based paraffin remover is suggested in this paper. In this method, the content of CS2 can be determined after it is swept from the oil based paraffin remover and absorbed by absorbents. So, the key to this method is to improve the efficiency and analysis accuracy of absorbing CS2. In this paper, for absorbing CS2, we designed a new type of units in the base of air sampler，and compared the standard absorbing curve and efficiency of different absorbers by spectrophotometric method. The results confirm that the alcohol solution of diethyl amine-copper acetate shouldn’t be selected to absorb CS2 due to the disturbance of redundant Cu2+；compared to alcohol-thylenediamine solution, a higher rate of CS2 absorption is obtained by using the system of methanol-potassium hydroxide and the corresponding product of absorbing is chemically stable in 2 hours. Moreover, with the self-designed setup and methanol-potassium hydroxide solution as absorbents, the adsorption efficiency of CS2 is as high as 98% and the result has good repeatability.
2013, 20(2):103-107.
Abstract:
Stimulation technology is the key technology in unconventional gas exploitation, the unconventional gas geological condition is complicated and special, and seriously restricts the development and utilization of unconventional gas, and challenge the backward technology. Chinese unconventional gas stimulation technology development and history is studied in this paper, so far, the study of tight gas sandstone stimulation has formed relatively perfect technology system; the coal bed methane stimulation has conducted a series of experiments and research; and the shale oil and gas stimulation technology is still in the experimental stage, and this technology is not perfect. Through the analysis of the research present situation of unconventional gas stimulation technology home and abroad, we propose the problem and research direction in the unconventional gas stimulation.
Stimulation technology is the key technology in unconventional gas exploitation, the unconventional gas geological condition is complicated and special, and seriously restricts the development and utilization of unconventional gas, and challenge the backward technology. Chinese unconventional gas stimulation technology development and history is studied in this paper, so far, the study of tight gas sandstone stimulation has formed relatively perfect technology system; the coal bed methane stimulation has conducted a series of experiments and research; and the shale oil and gas stimulation technology is still in the experimental stage, and this technology is not perfect. Through the analysis of the research present situation of unconventional gas stimulation technology home and abroad, we propose the problem and research direction in the unconventional gas stimulation.
2013, 20(2):108-110.
Abstract:
There are cracks and karst caves development in carbonate formations. If we still follow the security pressure of drilling fluid density in accordance with the conventional formation fracture pressure, the leakage is susceptible to be formed. Based on the different mechanisms, the leakage pressure considering the burst leakage pressure and natural leakage pressure is proposed, and then we put forward the calculation model of the two type leakage pressures. According to the model predictions of Halahatang sag X1 well’s leakage pressure, we can ascertain that the model can meet the requirement of engineering.
There are cracks and karst caves development in carbonate formations. If we still follow the security pressure of drilling fluid density in accordance with the conventional formation fracture pressure, the leakage is susceptible to be formed. Based on the different mechanisms, the leakage pressure considering the burst leakage pressure and natural leakage pressure is proposed, and then we put forward the calculation model of the two type leakage pressures. According to the model predictions of Halahatang sag X1 well’s leakage pressure, we can ascertain that the model can meet the requirement of engineering.
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