Abstract:To ascertain the pore structure characteristics and methane adsorption capacity of organic-rich shale in the Lower Silurian Longmaxi Formation of Zhaotong Demonstration Area，southern Sichuan Basin，the low-temperature nitrogen adsorption experiments and high-temperature methane adsorption experiments were designed to obtain parameters of pore structure in organic-rich shale. And then isothermal adsorption line was fitted by using the revised Langmuir-Freundlich model to evaluate the methane adsorption of shale samples. At last，the effect of microscopic pore structure on the methane adsorption capacity of the shale was discussed. The results show that the ink-bottle-like and slit-like pores are the main pore types of the organic-rich shale in the study area. The specific surface area ranges from 9.429 to 27.742 m2/g；the pore volume ranges from 0.011 to 0.02 cm3/g；the average pore diameter ranges from 8.546 to 10.982 nm，and the fractal dimension ranges from 2.552 2 to 2.725 5. The Langmuir-Freundlich（L-F）model was used to fit the experimental data of methane adsorption of shale samples at 30 ℃，and the Langmuir volume ranges from 1.397 32 to 4.076 61 m3/t，indicating that the methane adsorption capacity of different shale samples varies obviously. With the increase of total organic carbon content，the number of organic matter pores in organic-rich shale samples increases，and the specific surface area increases too，which provides more positions for methane adsorption and thus enhances the methane adsorption capacity. On the other hand，with the increase of fractal dimension，the pore surface of the shale becomes more irregular，and thus the pore diameter of the shale becomes smaller. As a result，the adsorption potential between pore walls increases and the methane adsorption capacity of shale increases. Clay minerals in the organic-rich shale have little contribution to the adsorption capacity.

Abstract:The mechanisms and rules of hydrocarbon migration and accumulation in the Yanchang Formation of Honghe Oilfield in southwestern Ordos Basin are still unclear，which restricts the further exploration in this region. In this paper，a pressure-drop gradient model was derived in the situation of hydrocarbon migrating downward along faults and fractures in tight sandstone to investigate transport mechanisms of hydrocarbon entrapped in the Yanchang Formation of Honghe Oilfield and analyze the rules of their migration and accumulation based on the comprehensive analysis of geologic setting，gas logging，well-logging data and results obtained by quantitative grain fluorescence techniques. The results show that the pressure-drop gradient of hydrocarbon migration downward is Δp3 = (0.028±0.01) MPa/m along the faults，and 0.24 MPa/m along the fractures；in the case that the hydrocarbon migrates downward along the fractures firstly and then along the faults， the range of pressure-drop gradient is 0.14-0.18 MPa. In the late Early Cretaceous，the hydrocarbon was generated from source rock of Chang7 member mostly，and was driven by abnormal formation pressure to be transported to Chang8 member along the faults and fractures vertically. The hydrocarbon then migrated laterally along the microfractures in short distance，within small range and forming dendritic path，and accumulated in effective regions. Finally，favorable exploration targets found in Chang8 member of Honghe Oilfield are areas having open fractures and transporting layers superimposing each other，lithologic traps in“sweet spots”area with good reservoir physical property，lithology-structure traps with better regional lateral seal and layers with low residual formation pressure and relative low potential in overpressure zone.

Abstract:When the low-permeability sandstone reservoirs enter into the middle-late stage of development，the relative high-permeability zones are easy to be formed between wells and the heterogeneity of reservoirs is enhanced because of the long-term water injection，which results in serious water coning and poor development effect. After washing in the relatively high-permeability zones，the physical properties of reservoirs are improved，and the remaining oil enrichment area can be easily formed in the external reservoirs due to the low degree of production. Accurate description on the state and distribution of the relatively high-permeability zones is the key of remaining oil prediction and tapping in the low-permeability sandstone reservoirs. Based on dynamic-static development data of the production wells，the reservoir parameter model can be established combined with the stochastic simulation. Ensemble Kalman filter algorithm was applied to achieving iteration and updating of the geological attribution model and the numerical simulation. The attribution model reflecting real geological conditions at various development stages can be obtained combined with the dynamic production data. The results show that the permeability model gained by this algorithm can point out the discrepancies in physical properties in the plane and identify the position and configuration of the relatively high-permeability zone in the low-permeability sandstone reservoir. It lays a foundation for the predicting and tapping of the residual oil distribution.

Abstract:Igneous rock often causes the abnormal response of well logging due to hydrothermal alteration，especially the false appearance of high neutron logging value，which restricts the identification and quantitative evaluation of effective storage space in oil and gas exploration. Based on the principle of neutron logging，combined with microscopic observation，it is pointed out that the hydrothermal altered minerals such as chlorite and zeolite which contain a large amount of crystal water is the main cause of high neutron value. When the neutron logging value is over 30% and no obvious anomaly exists in natural potential curve，basically it is invalid reservoir. It is suggested that the porosity calculation model associated with neutron logging should be substituted by the MOSTAFA model to quantitatively characterize reservoir porosity in case of se? rious alteration. The rock acoustic in the model could be determined by the method of the cross-plot of logging curves. Taking the igneous reservoir at the upper fourth member of Shahejie Formation in Binnan Oilfield as an example，the skeleton acoustic value is 167 μs/m and the lithology index is 1.706，and the average porosity is 15% calculated by MOSTAFA model. Through comparison between the porosity calculated by the model processing and the measured porosity of cores，it is confirmed that the model of MOSTAFA，which is suitable for carbonate reservoir，is good for evaluation of the porosity of igneous rock when an appropriate rock skeleton parameter is used，and it could be used to quantitatively evaluate physical properties of altered igneous rock in Binnan Oilfield.

Abstract:Based on outcrop observation and sample collection in the field，the study of developmental patterns and characteristics of interbedded volcanic and sedimentary rocks in the Lower Permian of Zhunnan area was carried out through volcanic petrographic analysis，sample test and indoor comprehensive analysis. The result shows that the volcanic rocks in this area are mainly composed of basic volcanic rocks（basalt）and its associated acidic volcano rocks（dacite porphyry or rhyolite），which would be present as bimodal volcanic rock combination characteristics. Conglomerates and glutenite are mainly developed in the sedimentary rocks. The main components of the gravel are volcanic rocks and pyroclastic rocks，and their composition maturity and structural maturity are relatively low. The sequence of interbedded volcanic and sedimentary rock strata is characterized by alternation of basalt，dacite porphyry and volcanic breccia or sand and mudstone. Six types of lithofacies can be divided as volcanic eruption facies，subvolcanic facies，volcanic effusive facies，alluvial fan fan-root subfacies，alluvial fan fan-middle subfacies and alluvial fan margin subfacies. Four cycles can be divided as neutral cycle，neutral-acid cycle，sedimentary cycle and basic volcanic sedimentary cycle. Under the structural background of continental rift，the basaltic magma formed by the upwelling asthenosphere mantle is melted with the undercut crustal material to become mixed acidic magma，and thus the rhyolite，rhyolite porphyry and basalt were formed，interbedded with the sedimentary rocks formed during the intermittence period after the volcanic activity.

Abstract:The palaeo-subterranean river has strong heterogeneity and complex spatial structure，which bring difficulties in understanding on facture-cave structure characteristics of palaeo-subterranean river in the western Tahe Oilfield and its controlling factors. To solve these problems，the well-seismic calibration technique and the spectral decomposition technique were utilized to identify and characterize the palaeo-subterranean rivers systemically in the western Tahe Oilfield.Results show that there are four major palaeo-subterranean rivers in the Ordovician carbonate rocks in the western Tahe Oilfield，presenting as complex reticular or dendrimer structure in the plane. From the dynamic and static data of drilling wells and well-seismic calibration，there are two types of horizontal distribution pattern for the karst caves of the palaeosubterranean rivers，which are the ribbon-like cave with continuous distribution and the block-like cave with scattered distribution. In the vertical，it can be divided into three types from top to bottom：unfilled cave，sand and mud filled cave and breccia filled cave. The seismic reflection of favorable fracture-cave reservoirs in the seismic section is characterized by the first trough and peak under the reflection of middle-upper Ordovician top surface in“string”. The Palaeostructural form，fracture system and open entrances control the morphology of palaeo-subterranean rivers and the structural features of fracture-cave reservoirs. As the fault system plays a constructive role in the hydrocarbon charge，the development areas of the palaeo-subterranean river matching well with faults are favorable targets for hydrocarbon enrichment.

Abstract:An ΔlogR technique has a poor effect on predicting total organic carbon of source rocks with middle and deep burial depth. Aiming at this problem，on the basis of the normalization principle and one-to-one mapping，the ΔlogR technique was modified and natural gamma ray was introduced to build a model for total organic carbon prediction，by which the total organic carbon can be predicted not only in the middle and deep source rocks but also in the shallow. The introduced natural gamma data helps to reduce the impact of high resistivity of non-hydrocarbon source rocks on total organic carbon estimation and improve anti-interference ability of the prediction model. All data are normalized to solve the errors caused by different well logging instruments or standards，which also helps to reduce the complexity of data in the process.Combined with the exploration situation of southwest subsag in Dongpu Sag，including poor exploration，application of many well logging instruments，source rock buried deeply in the middle of the third member of Shahejie Formation and low acoustic value，the ΔlogR and the improved ΔlogR techniques were applied respectively to predict total organic carbon.Compared with the ΔlogR technique，the square of correlation coefficient is increased by 0.371 and the standard deviation is decreased by 0.139. It indicates that the improved ΔlogR technique could be well applied to predicting total organic carbon of source rocks with middle and deep burial depth. In addition，the improved ΔlogR technique was applied to predicting total organic carbon of source rocks in southwest subsag of Dongpu Sag，and the result indicates that the north is a potential area for petroleum exploration.

Abstract:The lithology trap is an important area which can contribute to the petroleum reserve in Jiyang Depression presently. Due to the influence of the limy mudstone，the accuracy of the description of lithology trap is low，which limits its exploration deployment. Based on the XRF microelement measurements of limy mudstone and various methods of micro-analysis such as XRD whole rock mineral analysis，the lithofacies of limy mudstone were divided to solve the geological problem that limy mudstone and sandstone were difficult to distinguish. Through the forward modeling research of seismic reflection characteristics of different lithology combination models，the reflection characteristics of different lithology combinations and their amplitude and frequency differences were determined in the limy mudstone development area. And multi-attribute neural network waveform classification constrained by geological models was established based on multiple seismic attributes analysis and under the guidance of internal seismic reflection structure and external geometry，which can be used to predict the favorable facies belt in the limy mudstone development zone. A new prestack geostatistical inversion method that was constrained by static model was proposed by the application of the method of weighted facies modeling，which can be used to depict the spatial distribution of sandstone reservoir in the limy mudstone development zone. And good exploration result was achieved and proved by drilling.

Abstract:Near-source shallow glutenite fan delta is developed wildly in the first member of Shawan Formation in Chepaizi Uplift. Its sedimentary characteristics are complex and the lithology，physical properties and oil-bearing properties can vary significantly. Thus，it’s difficult to carry out the oil and gas exploration in this type of glutenite. Therefore，it is necessary to study the distribution characteristics of the glutenite reservoir in the near-source fan delta in the study area. The sedimentary characteristics of the glutenite were studied by analyzing the core data. Based on the analysis of palaeogeomorphology and seismic reflection characteristics，the near-source fan deltaic facies in the first member of Shawan Formation of Chepaizi Uplift was divided into two types of sedimentary filling model-the retrogradation type and the vertical aggradation type. For the former type，the glutenite retrogrades backward obviously in space with an overall positive rhythm and ob? vious sedimentary facies transition；while for the latter type，the glutenite aggrades vertically to make its thickness great without obvious change in sedimentary sequence and sedimentary facies. According to the statistical analysis of reservoir physical properties data，the lower limits of the reservoir physical properties for the near-source shallow glutenite reservoir in the first member of Shawan Formation were determined（porosity：16%，permeability：21 mD）. The glutenite in the fan delta front is effective reservoir with good physical properties；while the glutenite in the fan delta plain is not reservoir due to its poor physical properties，which can act as lateral sealing layer. Therefore，in the retrogradation type，the effective reservoirs are superposed retrogradationally and scattered in space，while in the vertical aggradation type，the effective reservoir，which is very thick in vertical，can be found in the anterior and middle of the fan delta.

Abstract:The evolution characteristics of different zones in the shallow sea area are obviously different due to the effect of Tanlu strike-slip fault. Based on the offshore and onshore seismic data，the strike-slip characteristics and their effects on the faults in shallow sea area were analyzed. The structural styles of the area were concluded based on the physical simulation experiments，and the division pattern of differential tectonic evolution was established. The study results show that there are NW-trending faults，NNE-trending faults and NE-trending faults. The NW-trending faults developed during Cenozoic and remained active with characteristics of left-lateral shearing in Kainozoic. The NNE-trending faults are right-lateral shear faults，and the NE-trending faults are extensional normal faults. And the strike-slip effect of NNE fault is the strongest of the three. The strike-slip effect of NW-trending fault is stronger than that of NE-trending fault. There are four types of strike-slip fault in the study area which are the bending strike-slip fault，the superimposed strike-slip fault with pressure releasing，the superimposed strike-slip fault with pressure increasing and the extensional strike-slip fault at its end in cauda equine. Finally，the differential tectonic evolution of the shallow sea area started to appear in the depositional period of Es3，which is due to transformation of Tanlu fault from sinistral to dextral. Meanwhile，the shallow sea area was divided into three evolutionary zones. The Ⅰ-area is an inherited faulted depression which is controlled by NW-trending faults. The Ⅱ-area is a coherent faulted depression which is controlled by NW-trending and NE-trending faults. The Ⅲ area is a strike-slip faulted depression and it is controlled by NNE-trending faults.

Abstract:Using the newest acquired seismic and drilling data，combined with physical analogue modeling，the differences in structural characteristics and control factors of Yingxiong Range structural belt in the western Qaidam Basin were analyzed.The results indicate that Yingxiong Range structural belt of the western Qaidam Basin is characterized by“the westeast segmentation，the north-south zonation and the vertical stratification”. The sedimentary period of the Eocene E32xg was the key period of structure deformation of Yingxiong Range structural belt of the western Qaidam Basin. As affected by the normal faults in the pre-existing paleo-structure，the uneven distribution of flexible or weak rock such as the dark mudstone and gypsum rock in that period were the main factors controlling the difference of structural characteristics of Yingxiong Range structural belt of the western Qaidam Basin. During Paleogene，the Altyn Tagh Fault began to function，normal faults developed in Yingxiong Range structural belt of the western Qaidam Basin under the weak extensional tectonic setting，which controlled the development of flexible or weak rock such as the dark mudstone and gypsum rock. During Neogene，the Eastern Kunlun Fault began to function，and the present characteristics of“positive inversion structure”were formed under the strong compressive tectonic setting in Yingxiong Range structural belt of the western Qaidam Basin.

Abstract:Shale gas is one of the unconventional natural gas resources，and shale gas reservoir is composed of extra-dense matrix and natural fracture system. Shale gas in the matrix is adsorbed gas that is self-generated，self-stored and selftraped，while that in the fracture system is free gas. Overall adsorbed gas is the main resource of shale gas，which will be desorbed at the fracture surface created by multistage fracturing in the horizontal well. The desorbed gas and free gas controlled by the horizontal wells are generally called well-controlled movable gas in-place and recoverable reserves. Volumetric method is the most common one for estimating resources of adsorbed gas in the matrix and free gas in the fracture systems in the shale gas reservoirs. However，the application of the volumetric method is greatly influenced by the validity of data including original adsorbed gas content，effective porosity in the fracture system，shale bulk density，and initial formation pressure. It should be noted that the volumetric method formula is uncorrected which was reported in the 2014 national technical standards for shale gas resources/reserves estimation. Moreover，the standards do not refer to any specific content about performance estimating methods. Therefore，considering shale gas is developed in well unit，performance method was presented as to estimate the well-controlled movable in-place and recoverable reserves of shale gas wells. The results of actual application in 3 shale horizontal gas wells indicates that the new method is practical and effective.

Abstract:Organic matter and pyrite in shale deposited in reduction environment，which are easy to be oxidized and dissolved. Oxidation is useful to the reform of the seepage channels of shale matrix，but its influence on the stress sensitivity of permeability of shale fracture is not clear. Artificial fractured samples were imbibed in distilled water or 15% oxidation liquid for 24，48，and 72 h respectively. Samples permeability were measured after the samples were dried. The stress sensitivity of the samples that soaked for 72 h were evaluated. Meanwhile，the ion type and concentration of the solution were tested，and the change of shale composition and structure before and after oxidation were characterized by X-ray diffraction（XRD）and scan electron microscope（SEM）. Results show that the permeability of the samples soaked in distilled water is increased by 0.42-6.15 times and the stress sensitivity coefficients range from 0.514 to 0.587. The permeability of rock samples soaked in the oxidation fluid is increased by 5.53-65.45 times，while the stress sensitivity coefficients range from 0.482 to 0.517. Ion analysis and XRD test results show that the oxidation can significantly reduce the content of dolomite and calcite，and pyrite even disappears completely.But the content of clay mineral，quartz and feldspar remains unchanged.It means that selective oxidative dissolution occurs on the fracture plane. The section observation and SEM image of the sample confirm that oxidation fluid infiltrates along the crack and the lamellation，inducing and expanding cracks and improving micro-and nano porosity.It is proved that the oxidation results in the expansion of pore and crack in shale. Selective oxidative dissolution of minerals on the fracture plane and the consequent expansion of pore and crack caused by oxidation，which helps to remain relatively high flow capacity during fracture closure and reduce the stress sensitivity damage.

Abstract:In order to expand sources of surfactants used for oil displacement in oilfield，the biological oil sulfonate was synthesized from waste cooking oil by sulfonation. The influences of mass fraction of biological oil sulfonate，mass concentration of sodium chloride，total mass concentration of calcium and magnesium ions and temperature on the interfacial tension between biological oil sulfonate solution and crude oil were studied. The results show that the minimum interfacial tension between biological oil sulfonate solution and crude oil decreases with the increase of mass fraction of biological oil sulfonate. The minimum interfacial tension can be reduced to the ultra-low level when mass fraction of the biological oil sulfonate increases to 0.15%. The minimum interfacial tension between biological oil sulfonate solution and crude oil remains at ultra-low level with an increase of mass concentration of sodium chloride when the mass concentration of sodium chloride is less than 80 g/L. The minimum interfacial tension between biological oil sulfonate solution and crude oil maintains at ultra-low level with the increasing total mass concentration of calcium and magnesium ions when the total mass concentration of calcium and magnesium ions is lower than 400 mg/L. The minimum interfacial tension between biological oil sulfonate solution and crude oil decreases first and then increases with an increase of temperature. But the minimum interfacial tension keeps at ultra-low level with temperature under 70 ℃. Compared with petroleum sulfonate provided by Daqing Oilfield，the biological oil sulfonate has a better effect on reducing interfacial tension between oil and water at high mass concentration of sodium chloride，high temperature and high total mass concentration of calcium and magnesium ions.

Abstract:In order to solve the inefficient and invalid circulation between injection and production wells during waterflooding development in Bohai reservoir，channeling path should be managed，and the starch graft copolymer gel has the advantages of low initial viscosity，high gelling strength，good sealing effect and acid and alkali resistance. It plays an important role in the process of large-channel oilfields or ultra-high permeability zones in land oilfields. Experimental study and mechanism of the effect of space size on the gelling effect of the starch graft copolymer were carried out. The results show that the chemical reaction space environment has a great effect on the gelling effect of the starch graft copolymer，and when the space size is larger，the gelling effect is better. In order to ensure the cross-linking reaction of the starch graft copolymer in the core pores，the concentration of the components that obtained by taking the grinding bottle as the gelling environment needs to be increased while taking the viscosity as the evaluation index. In addition，it is necessary to inject pre-slugs and displacement slugs before and after the injection of the starch graft copolymer into the core，and it will contribute to the promotion of cross-linking reactions among the components.

Abstract:In order to achieve water control and oil increment in the highly heterogeneous reservoirs，the micromorphology and size distribution of polymer microspheres PM1 prepared in the laboratory were firstly evaluated. Then the pore throat size distribution of cores was tested via mercury intrusion method and a series of core flooding experiments were carried out coupled with matching coefficients（the ratio of particle diameter corresponding to 25%，50% and 75% in the cumulative size distribution curve to average pore throat size）to investigate the matching between the size of polymer microspheres and pore throat. The results show that polymer microspheres PM1 were micron-sized spherical gel particles. Discrepancies exsist in the average pore throat size obtained from Kozeny theory equation and mercury intrusion method. The migration and plugging modes of polymer microspheres under varying matching coefficients can be divided into complete plugging，high-efficiency plugging，low-efficiency plugging and smooth pass. For reservoirs aiming at near-wellbore profile control，the matching coefficient range corresponding to the high-efficiency plugging mode should be taken into account at first. For reservoirs aiming at depth profile control and oil displacement，the matching coefficient range corresponding to the low-efficiency plugging mode should be used to determine the optimal microspheres size. Compared with the computed results based on Kozeny theory equation，the measurements based on mercury intrusion method can reflect the pore throat size distribution more accurately. Therefore，in the actual application，we suggest that more focus should be put on the matching coefficient range based on mercury intrusion method.

Abstract:From the aspect o“f artificial reservoir development”，the whole-fracture simulation method and fine geologic modeling were applied to the study of the dynamic extension process and the characteristics of the combination of proppant and in-situ low-permeability reservoir formed in hydraulic fracturing process. A new index named“dynamic asymmetric index of hydraulic fracture”could be used to characterize the characteristics of hydraulic fracturing dynamics，which is the evaluation parameter of the combination of in-situ reservoir and proppant. The dynamic response characteristics of this index in conventional logging curve was explored，and the evaluation system of dynamic asymmetric extension characteristics based on conventional logging data was established. The research results show that the whole-fracture simulation method is better than the semi-fracture asymmetric simulation method based on the conventional logging data，which is helpful to reservoir heterogeneity research. The dynamic asymmetric index of hydraulic fracture can reflect the asymmetric extension scale of hydraulic fracturing in a certain fracturing time. Combined with reservoir physical properties and current development state，it can provide guidance for the full utilization of reservoirs. The analysis of dynamic asymmetric extension characteristics of hydraulic fracture is an important research direction for EOR.

Abstract:In order to explore spontaneous imbibition mechanism of different pore structures and its influence on the imbibition process in the low-permeability tight reservoir，the pore structure of the low-permeability tight sandstone reservoirs in Chang6 member in X study area of eastern Ordos Basin was classified. On this basis，the influence of various pore structures on the imbibition characteristics and efficiency of oil displacement was researched through mercury intrusion，SEM and NMR and other analysis methods taking Bond index and imbibition efficiency in dimensionless time as the evaluation index. The experiment results show that there are two types of pore combination：mid-large pore and micro-pore and fracture. The proportion of the mid-large pore throat decides oil displacement effect of the imbibition in cores having different pore structure combinations，and the residual oil mainly remains in the micro-pore throat. The core having mid-large pore is characterized by high proportion of large pore throat，higher oil displacement efficiency of the imbibition in formation water and surfactant，weak effect from capillary pressure during the imbibition process and an evident change in oil displacement efficiency and the way of imbibition by surfactant. The core with micro-pore and fracture is characterized by low proportion of large pore throat，strong effect from capillary pressure and relatively poor imbibition efficiency in formation water and surfactant. Though the surfactant can significantly change the way of imbibition and improve oil displacement efficiency，a part of the residual oil still remains in the micro-pore throat.

Abstract:In order to research the effect of temperature on oil-water relative permeability in the heavy oil reservoir，the heavy oil from a block in Venezuela was prepared as gas-bearing oil under simulated reservoir conditions. Oil-water relative permeability curves at different temperatures were determined through the unsteady-state method based on one-dimensional core flow simulation experiment. Research results show that the relative permeability of the heavy oil for the oilphase is high and very low for the water-phase，and the flow capacity between oil and water is extremely imbalanced. Along with the rise of temperature，the irreducible water saturation increases linearly and the residual oil saturation decreases nonlinearly，while the saturation corresponding to the equal-permeability point increases exponentially. The overall relative permeability curve shifts to right with increasing temperature. Furthermore，the imbibition area is enlarged and the oil and water relative permeability increases，but the rising amplitude of water was less than that of oil.