Abstract:Based on abundant data of oil test, logging, borehole log and experimental results, the forming conditions of shale oil and gas in Jiyang depression were investigated. Three sets of continental shale at the formations of Paleogene Upper Es4 , Lower Es3 and Es1 were concluded. They respectively have the material foundation and reservoir conditions for shale oil and gas because of their wide distribution, great thickness and high abundance, favorable types (mainly with type I-II1 ) and medium to high mature stages of organic matter, as well as their high content of inorganic brittle minerals (high carbonate content and a certain amount of quartz in general), development of the network of various micro-pores and micro-fractures which provides a space for the storage and flow of oil and gas. Specifically, the Upper Es4 shale oil and gas mainly exists in Dongying sag, Zhanhua sag and Guojuzi sub-sag of Chezhen sag; the Lower Es3 shale oil and gas mainly in the sub-sags忆central regions of sags; and Es1 shale oil and gas mainly in the central parts of Zhanhua ssag and Chezhen sag.

Abstract:According to the exploration practices of shale oil-gas in Bonan subsag, on the foundation of systemic analysis of producing wells of cumulative oil production and characteristics of source rocks, lithofacies, burial depth, structure and abnormal over pressure, enrichment condition of shale oil-gas is summarized. The development of effective source rocks determines the essential series of strata of shale oil-gas; the development of advantageous lithofacies (laminated argillaceous limestone lithofacies) is the basis of enrichment of shale oil-gas; the development of fracture cracks is the key of enrichment of shale oil-gas; formation of abnormal overpressure and burial depth are important factors accounting for enrichment of shale oil-gas. Lower No. 12 to Upper No. 13 layers of Es3 in Bonan subsag in which laminated argillaceous limestone lithofacies highly developed are the most enriched series of strata of shale oil-gas, it忆s necessary to synthesize the matched relation of various factors, arrange and evaluate comprehensively,classify and assort to verify its capability accordingly, it will lay a foundation for large-scale development of shale oil-gas. Three horizontal wells including well BYP1 have been deployed based on the study results, and the preliminary achievement has been obtained.

Abstract:The Lower Es3 shale of Zhanhua sag is considered as good source rock and storing hydrocarbon, and its lithologic characteristics is entirely studied in this paper. On the comprehensive analysis of the core observation,thin section identification, SEM analysis and fluorescence reaction features, the lithologic type is classified and reservoir space is identified. The reservoir property is studied with reservoir space identification and core measurement of porosity & permeability. The research shows that: the shale is rich in calcite, with the depth getting deeper, the calcite content is increasing, clay minerals and quartz contents are decreasing; the laminated argillaceous limestone is the dominant lithologic type, and the first-rate type is composed of recrystalized calcite and clayey lamina; the reservoir space is consisted mostly by micro-fracture, intercrystal micropore of calcite and clay minerals; the porosity is predominantly ranged in 2% -8% and permeability 0. 1×10-3 -10×10-3 μm2 。

Abstract:The shale gas has been becoming the focus of unconventional hydrocarbon resource. In order to evaluate the shale oil and gas, it is the foundation to study the lithologic characteristics in detail, and it is necessary to compare the thin section identification results with the logging lithology. On the exploration research in Jiyang depression and analysis of collected representative data of mudstone/ shale in America and China, a multi-factors identification scheme on mudstone and shale is put forward, according to the current various classification and discrepancy of nomenclature. The color, structure, texture, organic matter, texture and mineral constitute is the requisite factors to describe and identify the lithofacies. The oil shale or oil source rock should be subdivided in view of graded evaluation. It is very helpful to unify the thin section identification results with the logging lithlogy.

Abstract:Shale oil and gas has become new energy growth area in China. In order to establish the well logging evaluation method of this kind of reservoir, taking the exploration well Luo 69 of Luojia area as example, the shale lithofacies, reservoir space type, physical properties and oiliness are systematically analyzed, and the logging parameter quantitatively models including mineral constituent of calcium, quartz, and clay content, and porosity, water saturation and total organic carbon are also established. urthermore,the shale formation is divided into four types based on the varied oil and gas quality, in which, the type I is of the best oil quality. This research provides an effective reference for the deployment of the first shale horizontal well in Shengli Oilfield, and achieves a good result. It can provide reference for todays shale oil and gas exploration.

Abstract:Shale gas is unconventional resource. Its characteristics of source rock and reservoir rock are different from that of conventional natural gas reservoirs. Thus, the shale gas resource calculation method should be different from that of conventional gas reservoir. Firstly, the shale gas resource evaluation method suitable to China is proposed according to the geological conditions of shale gas development in China as well as the availability of data. It mainly includes volumetric method which is suitable for the high degree exploration area and analogy method which is suitable for the low degree exploration area to calculate the amount of resources.Key parameters of the volumetric method which including the effective thickness, gas content, gas saturation and porosity, are pointed out, and the method for determining these parameters is described. Standards of analog parameter values are proposed and seven indicators including organic carbon content, kerogen type, maturity, shale monolayer thickness, brittleness index, porosity, burial depth are considered as the main parameters of the shale gas geological analogy. The volumetric method and analogy method both have advantages and disadvantages, thus, the total shale gas geological resources should be calculated taking account of the actual situation of evaluation area, and appropriate resources evaluation method should be selected.

Abstract:Isothermal adsorption tests on shale always yield abnormal maps. On the basis of summary of the abnormal types, the study to probe the abnormal reasons is carried out and corresponding strategies are proposed. When the pressure is high, the methane in reservoir conditions is in supercritical state,the Langmuir model which is based on the condensation mechanism is no longer suitable to describe the adsorption features. This problem can be solved by amending the model or revising test data. When the pressure is low, the disorder on the measurement is caused by the adsorbed gas content in shale that is far lower than coal-bed gas,while the clay mineral content is much higher than that in coal-bed. In order to eliminate the disorder, the sample weight should be more and the sample preprocessing procedures should be amended.

Abstract:In order to discuss the thermal evolution features of coal bed gas through the hydrous thermal simulation experiments of the selected Jurassic coal samples of Qiadam Basin,the authors analyzed the evolution characteristics of liquid oil and gas production.The experimental results indicated that gaseous hydrocarbons were generated in thermal evolution stages and liquid oil was produced in oil window range and had a lower yield. At the oil-generating peak, the methane relative content is lower,a little higher before, and rising rapidly after the peak. Heavy hydrocarbon gas relative content is higher at oil-generating stage and early high mature stage and decrease later. In nonhydrocarbons, the carbon dioxide relative content is clearly higher than nitrogen忆s and is mainly generated at the stage of liquid oil formation. The hydrogen gas relative content is higher, and first increases and then decreases with temperature rising and its minimum value appears after oil-generating peak. The Jurassic coal sample overall has high methane yield,much more than the measured gas content of general coal, and functions as the foundation for the coal-derived gas generation and conventional reservoir gas.

Abstract:There is a new type of diagenesis trap of conglomerate body which is sealed by root fan in northern Dongying sag. Based on core observation, grain size analysis, thin sections identification and clay mineral analysis, the lithofacies architecture and different diagenetic evolution of root fan and middle fan are studied, the genetic mechanism and controlling factors are proposed. The root fan lithology is conglomerate with complex matrix, the content of matrix is high, which disfavors the preservation of primary pores with the depth of burial. The main diagenetic types include the compaction and the recrystallization, and the porosity and permeability are persistently declined. The middle fan lithology is grain-supported pebbled sandstone or conglomeratic sandstone, the content of matrix is lower, which favors the preservation of primary pores. The main diagenetic types include the compaction, cementation,dissolution and replacement in acid environment, which formed several secondary pore zones. So, the lithofacies architecture is the foundation for the diagenesis trap, and the difference of diagenesis between root fan and middle fan is determinant for the diagenesis trap. The influences of diagenesis trap include sedimentary sequence, lithofacies architecture and diagenesis fluid.

Abstract:The hydrocarbon is mainly distributed in shallow water delta system of N1 mL in the Huanghekou sag. The hydrocarbon distribution and accumulation are analyzed according to sequence-structure herein. The lower member of Minghuazhen Formation is recognized as 3 long-term cycles and 8 middle-term cycles with high resolution sequence stratigraphy in Neogene. The early phase of ascending half cycles and middle-late phase of descending half cycles form sandbodies development favorable position are the main position of hydrocarbon distribution. Structure setting controls the direction of hydrocarbon migration, and positive structure zones are favorable areas of petroleum migration and accumulation. The faults of connecting deep and shallow strata are the main pathway of petroleum migrating to Neogene in the vertical direction. And, the late-stage faults adjust and distribute hydrocarbon. The sequence-structure controls the hydrocarbon accumulation layer and enrichment degree, and the good matching relation between faults (especially oil-migrating faults) and reservoir-seal assemblage is the main reason accounting for high hydrocarbon accumulation. The sequence-structure determine the effectiveness of the Neogene traps, and formed lithologic-structure, structure-lithologic and lithologic hydrocarbon reservoir.

Abstract:In order to study the relationship between tectonic stress field and migration and accumulation of oil and gas in Damintun depression, and based on the features of geology and tectonic stress field in the area, the three-dimensional tectonic stress field finite element model of the block is established. The contour maps of maximum principal stress, minimum principal stress and maximum shear stress of the target zone are obtained through analysis of numerical simulation. Based on that above, the oil and gas enrichment zones are forecasted by the theory of oil and gas migration. The results show that: under the effect of tectonic stress field,the direction of migration and accumulation of oil and gas is from high areas to low areas in tectonic stress field, and from high potential areas to low potential areas in fluid potential field. The favorable zones are low value areas of tectonic stress, low potential areas of fluid potential field, and the oil and gas across the trap near fracture zones. High-yielding wellblocks are consistent with low value areas of tectonic stress field and fluid potential field through the comprehensive analysis of actual capacity of drilled wells and forecast results, which provides scientific basis for the prediction of enrichment zone for oil and gas and deployment of favorable drilling wells in the area.

Abstract:The region where there are abundant magma rocks has become important exploration fields for oil and gas, but the oil-gas origin in the region is very complicated. The intense magma activities took place ever in Luojia area of Zhanhua sag where rich oilgas with abnormal chemical properties is accumulated. By cores and log interpretation, we determined the type and orientation of the magma rocks, then, studied source rock忆s petrology nearby the magma rocks, and then verified the source rock thermal metamorphism and organic carbon mineralization. By means of chemical analysis, we found that the source rocks maturity is very high and experienced abnormal change, as well as higher H2 S and CO2 in oil-gas. We may infer that the magma rocks, on the one hand, accelerated organic matter thermal evolution in the source rocks as well as the hydrocarbon generation, on the other hand, they caused the carbonate and sulfate decomposition, generating inorganic H2 S and CO2 . In the end, we indicate that the magma activities are causes of oil-gas enrichment and abnormal properties, and suggesting that the magma rocks should be accountable of the oil-gas origin and exploration and development.

Abstract:The research of overpressure prediction and detection has long been concentrated on under-compaction, the overpressure originated from hydrocarbon generation was thought difficult and even impossible to be predicted and detected. In order to predict and detect the pressure originated from hydrocarbon generation, we compared the characteristics of under-compaction strata with that of source rocks, and studied the changing of pressure caused by hydrocarbon generation with depth. The results show that the socalled under-compaction actually is the combined response of genuine under-compaction and hydrocarbon generation, the pressure generated by hydrocarbon generation could also be predicted and detected while drilling. Based on that, the method distinguishing their contribution and the predicting and detecting methods, such as exponent and neural network, are put forward. This research result renew the viewpoint that the overpressure originated from hydrocarbon generation couldnt be predicted and detected, so, it contributes to improve geology understanding about overpressure and the level of overpressure prediction and detection.

Abstract:Hilbert-Huang transform is a new time-frequency technology of processing non-stationary signal based on empirical mode decomposition, which can get the instantaneous time-frequency property for different intrinsic mode functions. Compared with conventional time-frequency technique, Hilbert-Huang transform has its advantage in resolving and stationary of signal, and can realizes the linear instantaneous time-frequency analysis of seismic signal with physical significance, and describes the relationships among time, frequency and energy of seismic signal more delicately, by which, the sedimentary cycles of different levels can be classified. The analysis results of model data and actual seismic data show that the time-frequency analysis of seismic data processed by Hilbert-Huang transform can accurately classify different level stratigraphy sedimentary cycles. And that, it is a simple process with high precision, which provides a new feasible method and reference for sedimentary cycles classification and fine stratigraphy correlation.

Abstract:Gas-Assisted Gravity Drainage (GAGD), solving the problem of low volume sweep coefficient for continuous gas injection (CGI) or water-alternating-gas injection (WAG) and increasing the ultimate recovery to a great extent, is a recent method for enhancing oil recovery. However, no effective predicting methods of oil recovery for GAGD exists. Based on the study of producing mechanism of GAGD and dimensional analysis method, this paper analyzed three dimensionless varies, Capillary Number, Bond Number and Gravity Drainage Number, and evaluated its relative influence on oil recovery. Considering the effect of wettability, viscosity ratio, and the difference between oil density and gas density, Bond Number and Gravity Drainage Number are modified and its relationship with recovery is established by experiment and field data. Finally, a new predicting method of oil recovery for GAGD is set up. Application shows that this method is far more suitable for GAGD and its predictive result is more reasonable. Therefore, it is quite significant for determining recovery of such type of development mode.

Abstract:The Tahe karstic/ fractured carbonate reservoir is of large cavities, caverns and fractures functioning as the major reservoir spaces, its heterogeneity is very high with a variety of flow patterns. The exploration and development are highly difficult. The Tahe karstic/ fractured carbonate reservoir development process has been analyzed in this paper. In the natural energy development stage,the early water breakthrough appears in producing wells, low well controlling reserves and insufficient natural energy lead to a lower reservoir recovery rate. Low waterflooding efficiency is the main problem for low recovery efficiency in water flooding development stage. At the same time, in response to the specific reservoir conditions and development characteristic in Tahe oil reservoir, the main influencing recovery factors and the key development problems have been analyzed. And, the enhanced oil recovery technique in karstic/ fractured reservoir, which has an important guiding significance for further improving the recovery of the Tahe oil field,has been investigated. In the natural energy exploitation stage, the enhanced recovery target is “overall control water cut of wells to inhibit the water coning, improving the controlling reserves ability of producing wells冶. For the supplementary energy development stage, the enhanced recovery strategy is “optimization of water injection development, expanding sweeping volumetric methods by means of gas injection and thickened water flooding.

Abstract:The air-foam flooding technique which combines the advantage of air injection displacement and foam flooding has enhanced the sweep efficiency and oil displacement efficiency and achieved well application effect in middle-high temperature reservoirs, however, it is less applicable in shallow ultra-low permeability and low temperature reservoirs. According to the reservoir characteristics of ultra-low permeability reservoirs in Northern Shaanxi, we analyzed the suitability of the air-foam flooding technique in these reservoirs through theoretical studies, laboratory test and field test, taking Tang 114 well area in Ganguyi oil field as an example. The results show that the crude oil in low permeability layers is obvious motivated in the lab experiment, the oil displacement efficiency rises from 8. 33% to 50. 55%, the water content of the field test well group decreased from 98% to 73%, the daily fluid production rate dropped 2 m3 , and the daily oil production is 6 times of that of the original. The air-foam flooding technique has strong suitability in Ganguyi oil field and oil recovery can be greatly enhanced. It has certain reference significance for stabilizing oil output and controlling water content for the similar reservoirs.

Abstract:Coalbed Methane (CBM) gas has a complex process of desorption-diffusion-seepage in the stage of development, causing the changes of pore structure and impaction on production to some extent. Therefore, it is necessary to take the self-regulating effect on pore changes into consideration when studying the material balance of CBM reservoirs. On the basis of the establishment of the model, we infer the CBM reservoir material balance equation. Combined with gas, aquatic energy equation and the relative permeability curves as well as the deviation factor with increasing pressure, we conduct dynamic predict of CBM reservoir production. It is of high reliability by matching the predicted results and the actual production data. Based on the parameter sensitivity analysis,we obtain that in the late production of CBM wells, on the condition of different sensitivity, reservoir pressure and time exhibit an exponential correlation, and the impaction of reservoir pressure on gas well production. Comprehensive analysis of the results shows that the CBM reservoir production of good self-regulating effect, high permeability, high Langerhans pressure and big seam thickness is relatively high.

Abstract:On the basis of static theory and fluid mechanics in porous medium, this paper derives the relationship between the height and radius of water cone in bottom water reservoir with no interlayer using analytic methods, considering radial fluid flow of oil far from the wellbore and the hemispherical centripetal flow of water in immediate vicinity of wellbore respectively. With the analysis of factors affecting water cone, the typical bottom water reservoir numerical conceptual model is established and the water cone shape with a variety of factors is calculated. Using multivariate nonlinear regression method, the relationship between water cone affecting factors and coefficients a1 , a2 , a3 is determined, the quantitative formula of water coning is set up, and the height and volume of water cone is calculated. The validity of analytical methods and quantitative description formula are confirmed with an example of Z1 reservoir. The results indicate that quantitative description formula can satisfy the needs of oilfield.

Abstract:The Pai2 reservoir of Chunguang oilfield is characterized by high porosity, high permeability, low formation oil viscosity,large and active edge water, and has the performance of high water-free oil recovery, stable reservoir pressure, rapid rising water cut of edge wells and uneven displacing front. Statistical result of performance data shows that the water advance velocity has a linear relationship with production rate and the producer s production life after water breakthrough is inversely proportional to equal liquid rate. According to the reservoir performance features, an optimization study of reservoir develop method was conducted by numerical simulation. The result show that higher oil production and lower water production can be guaranteed if the well is shut off when its water cut reaches 90%. Keeping the producing pressure drop at 0. 3-0. 4 MPa can maintain a reasonable oil production rate at the premise of high oil recovery. Well arrays located at lower structure of the reservoir should be allocated with lower production rate while those in upper structure with high production rate, which can reduce the edge water fingering and enhance the ultimate recovery.

Abstract:The profile imbalance is an important problem demanding prompt solution during the production of horizontal wells. Based on source function method and superposition principles, a profile model for horizontal wells in anisotropic box-shaped reservoirs is presented according to the coupling between reservoir flow and wellbore flow. Under uniform recovery, the inflow rates at the two ends of the horizontal well are higher than that in the middle. The ideal profile exhibits U-shaped distribution. Under uniform perforation, the inflow rate at the heel is higher than that at the toe due to the pressure drop in the wellbore. The profile imbalance increases with the increase of perforation density and depth. A profile control method for horizontal wells is developed with the aim of uniform recovery. This method is characterized by simplicity, efficiency, and can be applied to anisotropic box-shaped reservoirs.Uniform recovery requires that the perforation density decreases step by step from the toe to the heel. The higher the perforation density at the toe, the bigger the decrease of perforation density at the heel, and the better the performance of profile control.

Abstract:Horizontal well is of capacity to improve the well production, reduce the development cost, increase economic benefits and other significant advantages, and it has become one of the advanced technique for field development, but with the development of oilfield, it has gradually exposed the problems such as the channeling along the dominant channel, and leading to high water cut and production decline rapidly, as well as the poor understanding on remaining oil distribution. Taking the bottom water reservoir of Nanpu onshore as example, the integrated use of physical simulation, numerical simulation method and data combined with the water exploration to find the approaches to study the reservoir properties, horizontal well trajectory and different development policies with respect to horizontal well water cut change, and the fluidity rule is also studied as well. Herein, we also introduce the new concept to reveal the fluidity rule for different types of bottom water reservoir. For the homogeneous reservoir, we also indicate the water channeling distribution for the horizontal wells with or without dog leg, and for the heterogeneous reservoir, the bottom water is inclined to form the conning in the high permeable zone, and is apron to accumulate the remaining oil in the low permeable area.

Abstract:This paper introduced a numerical simulation study on disturbance of stress/ strain induced by mudstone soaking during injection and production activities in the Xingshugang area of the Daqing Anticline, Songliao Basin, China. The variations of stress and strain in different water contents of mudstone layers are researched in this paper. The relationships between formation pressure and stress and strain pre and post mudstone soaking are also investigated, so as to offer an evidence for a reasonable design of injection and production technique. Results indicate that different horizons have different stress responses to the soaking of mudstone. Besides, the different stress responses of different horizons, weakening of mechanical property of rocks due to the mudstone soaking, difference of pore pressure in a layer or between layers, difference of property and permeability between mudstone and sandstone,and reducing of effective stress as a result of high pressure injection giving rise to the concentration of shear strain along SI-SII mudstone layer. And, then it results in shearing casing damage of mudstone layers. Shear strain is rising with the increase of water contents of mudstone layers, and its shear strain rising rate is proportional to the increase of water contents. So, reducing the water injection pressure and formation pressure of reservoirs close to mudstone layers is needed to relieve shearing casing damage after mudstone soaking.

Abstract:Because of difference of physical property, alternation of deviation angle, friction loss in horizontal bore hole,the development within the horizontal interval is not balanced. According to the fluid mechanics in porous medium and reservoir engineering,the model of horizontal well fluid mechanics, turbulent flow model of eyehole and hole model of horizontal well are built in different reservoir. Meanwhile, the damage factor during drilling and damage factor during perforating are introduced into the new model. According to the mass conservation equation, flow couple model of reservoir and horizontal well hole are built. The effect of deviation angle, permeability, distance to bottom water, and viscosity to liquid producing balancing profile of horizontal well is analyzed by the model. By optimizing the perforation model of horizontal well, variable density perforation can achieve the liquid balancing producing for horizontal well hole. It was demonstrated that, compared to the previous horizontal well, the water cut rising is slow, and the production performance become better. Thus, variable density perforation of horizontal well is the new technique for enhance the reservoir balancing production.

Abstract:Huge reserves of shale gas reservoir, is usually of no natural capacity, is often needed to be fractured in order to produce effectively. The slick-water which has low viscosity and proppant carrying capacity is used in shale gas reservoir fracturing. Nowadays, most of the studies about the settlement and transport rule of proppant are theoretical, and the field application always relies on the former experience or software simulation with only few experimental studies. The experimental method is implemented through the fracture physical model to study the impact of the pumping rate, the fracture width, the proppant types and the sand concentration on the proppant settling velocity and horizontal displacement velocity. The correction coefficient of various parameters on the settling and transport velocity is obtained through experiments. Theoretical models of proppant settlement and transport rule in shale gas reservoir fracture are established. It is of instructive significance to the shale gas fracturing design and construction.

Abstract:Due to characteristics of high temperature, high pressure, dense lithology, strong heterogeneity and natural fractures in carbonate reservoir of Feixianguan formation and Changxing formation in Puguang gas field, the adoption of conventional acid operation may result in quick acid rock reaction and large amount of fluid leak off, therefore, it is difficult to achieve the performance of acid fracturing. Based on Puguang gas field reservoir characteristics, we establish a calculating model of multistage alternating injection acid fracturing acid etching fracture conductivity and an evaluation model for the degree of acid fingering, and we carry out the experimental study of multistage alternating injection closed acid fracturing technique influencing factors. After application this technology in Puguang 9 well, gas production before acid fracturing is 10. 32×104 m3 / d and now increased to 123. 86×104 m3 / d, stimulating effect is significant.