Abstract:After more than 50 years of development in Shengli Oilfield，waterflooding reservoirs have entered extra-high water cut period with 92.6% of composite water cut and 26.2% of recovery degree of reserves. The extra-high water cut and higher recovery degree require better water injection technology. The key of improving the quality of waterflood development is to improve the“triple rate”of the water injection. According to the constraints of“triple rate”and the analysis of the effects of separated layer water injection technology at early stage in the water flooding reservoirs of Shengli Oilfield，combined with the requirements of the waterflood development characteristics of different reservoirs，wells and working conditions，key technologies of improving the separated layer injection rate and the pass rate of the strata were researched to achieve the integrated support of standardized strings for different well conditions in different reservoirs. It was applied to the optimized water flooding blocks that have potential of improving“triple rate”with scale popularization. The“triple rate”indicator for the integrated oil reservoir，fault block reservoir and low-permeability reservoir was improved from the aspect of engineering，and the injection-production corresponding rate was further improved in the reservoir. The natural decline rate reduced and the waterflood development effect was improved.

Abstract:In order to reduce uncertainty in the spatial and temporal distribution of source-convergence sedimentary system with low well density, the applicability of the sedimentary forward modeling in the Junggar Basin was discussed. Based on drilling and seismic data of the research area，combined with previous knowledge on the sedimentary background，the sedimentary system of Triassic Jiucaiyuanzi Formation in Well Fu19 area of the Fudong slope，Junngar Basin was simulated forwardly by means of sedimentary forward modelling using the DionisosFlow software. Results show that the far source at Kelameili Mountain located in the northeast to the Well Fu19 area and the point source at the Beisantai uplift are the main sediments supply，the east source in the south of the uplift is the secondary source. As a result，the far-source fine-grained braided river delta front was formed and the near-source hybrid sediments with coarse grains were deposited from the point source. The overall sedimentary evolution was influenced by the frequent lake level rise and fall. Consequently，there are two mid-stage positive cycles in vertical，having the typical lithology characteristics of“sand enveloped by mud”. Good sand body deposited at the front fan delta in the second member of Jiucaiyuan Formation in the periphery of Well Fu19 area，where the effect of lake water dynamic action is weak，together with the superposed mudstone in the shore-shallow lacustrine facies，a good combination of reservoirs and cap rocks can be formed，which is a favorable area for exploration.

Abstract:The reservoir space and microscopic pore structure of Cambrian black shales in the Yichang area of western Hubei were studied through the analysis of low-temperature liquid nitrogen adsorption and scanning electron microscopy. Besides，the main control factors of pore development of shale were determined based on experiment data of total organic carbon and X-ray diffraction. The results indicate that the storage space type of shale gas reservoir in the Shuijingtuo Formation are mainly residual intergranular pore，secondary dissolution pore，mineral moldic pore，intercrystal pore，microcrack and organic pore. Micropores and small pores are the main pores in shale. For pores with a diameter less than 10 nm，the average contribution rate to specific surface area can reach 87.51%，and for pores with a diameter more than 10 nm，the average contribution rate to pore volume is 56.32%. The clay minerals can provide more adsorption sites and pore space for shale gas occurrence in the shale of the study area. Quartz are favorable for shale pore development and the pore structure will become complex due to the high content of carbonate minerals.

Abstract:In order to clarify the control of Paleogene faulting on subsag morphology，features and migration of sedimentation-subsidence center in different sedimentary period in Dongpu Sag，the structure of Dongpu Sag was interpreted and analyzed using the seismic data，drilling，logging data and heavy magnetic data. The results show that it is a universal basin in the sediment of the fourth member of Shahejie Formation in Dongpu Sag. Then the intense fault movement resulted in the division of sag during the sedimentation of the lower third member of Shahejie Formation. A framework characterized of multifaults，multiuplifts and multisubsags formed during the sedimentation of 1-4 sand group in the middle third member of Shahejie Formation. The activity of the second-level and the third-level faults formed in the early stage were gradually weakened or stopped after the sedimentation of the second member of Shahejie Formaiton. Large numbers of third-level and the fourth-level faults formed，and the framework characterized of multifaults-multiuplifts-multisubsags became more obvious. The equilibrium crustal gravity subsidence resulted in the seesaw-type differentiation of the strata and controlled the evolution of subsags combined with the fault activity. The Paleogene fault activity controlled the subsag evolution and the distribution of hydrocarbon source rocks in Dongpu Sag，and the occurrence of the fault controlled the morphology of subsag and the type of kerogen.

Abstract:The typical lateral accretion packages develop in the second member of Yinggehai Formation. There are large unexploited reserves with large risks in development in such areas. Based on the analysis of the seismic，well logging and mud logging data，the distribution characteristics and formation mechanism of the lateral accretion packages were studied. The study result shows that the lateral accretion packages in gas groupⅢa formed when the water flowed to the south of gas formation along the low position area and migrated laterally due to the underwater terrain highland in the period of deposition.The lateral accretion packages in gas groupⅡa formed due to the lateral migration of muddy channel，which can be classified into low bending packages and high bending packages in the depositional period. The high bending lateral accretion packages distribute in the terminal channel and the low bending packages distribute in the upstream channel. Combined with the analysis of drilling and seismic data，it is found that inner sandbodies in the packages has poor gas bearing property，and the top sand bodies are connected to some extent. The top of the lateral accretion packages should be considered when a well is deployed.

Abstract:To clarify the indicative significance of fluid inclusions and hydrocarbons in Ordovician carbonate reservoirs in the South of Yan’an，southeast of Ordos，a comprehensive analysis of the petrology，homogenization temperature，salinity and compositional characteristics of fluid inclusions was carried out. Combined with the burial history and thermal evolution of the study area，the hydrocarbon charging history of the reservoir was discussed. According to the phase characteristics，components and hydrocarbon occurrence distribution of fluid inclusions at room temperature，the fluid inclusions of carbonate reservoirs in the study area can be divided into five categories：aqueous inclusions，gaseous hydrocarbon inclusions，liquid hydrocarbon inclusions，bituminous inclusions，hydrocarbon-bearing aqueous two-phrase fluid inclusions，and there are still local residual free liquid hydrocarbons and migrabitumen which do not form fluid inclusions. The results show that the fluid inclusions and hydrocarbons in the study area are mainly distributed in authigenic minerals such as calcite and quartz that fill the pores，the cavities and the fractures of the reservoir. The homogenization temperature gradually increases with the increasing salinity，and the captured fluid inclusions are mainly the products of the source rocks in the high maturity stage. The Ordovician carbonate reservoirs were charged in two stages，the end of the middle Jurassic and the late of the early Cretaceous，and the latter is the main stage.

Abstract:The development of fractures results in azimuthal anisotropy of reservoirs，while the pre-stack seismic data of different orientations show differences in amplitude and other properties. Therefore，pre-stack seismic synchronous inversion method based on azimuthal seismic data can be used to get the relevant parameters of reservoir fractures and then predict reservoir fractures. For this reason，starting from the basic theory of azimuthal anisotropic medium，rock physical parameters describing fractured medium were introduced，and the relation between anisotropic parameters and fracture parameters was given. Aiming at the disadvantage that the stepwise inversion method may generate accumulated error，combined with Bayesian theory，the pre-stack seismic synchronous inversion method for fractured media was proposed. The results of both model test and real data test show that the new method has good reliability and stability.

Abstract:The strike-slip structure characteristics of Yidong fault zone and its influence on the hydrocarbon accumulation is unclear in Zhanche area of Jiyang Depression，which restricts the oil and gas exploration in this area. To solve this problem，the strike-slip structure characteristics of Yidong fault zone in Zhanche area were analyzed based on data of seismic，logging and drilling，and the effect of strike-slip faults on hydrocarbon accumulation was evaluated. The result shows that the faults in Yidong fault zone have typical strike-slip characteristics as follows：①in the plane，the main fault（F1）is intersected by its associated secondary faults（NWW）with acute or right angle，presenting the shape of“入”；while the main fault and its parallel faults in the two sides distribute in NEE-NE direction，presenting an en-echelon form；②in the vertical，the main fault has steep fault plane and the associated secondary faults are broken up to showing minus flower structure figure in seismic section，which leads to the formation of narrow and steep half grabens. The Yidong fault zone controls the development of multi-stage and multi-type sandy conglomerate fans and NE-direction distributed fault block，fault nose and fault-related anticline traps. The Yidong fault seals the hydrocarbon laterally but acts as paths for hydrocarbon vertical migration，which results in the belt-like hydrocarbon distribution characteristic along the fault zone.

Abstract:Isothermal adsorption equation and isothermal cumulative adsorption equation are two important theoretical equation that describe the adsorption rule of shale gas or coal bed methane. The former describes isothermal adsorption rate at different transient pressures，and the latter describes the cumulative isothermal adsorption rate curves at different pressures. It should be pointed out that the different data points on the isothermal adsorption curve are not directly obtained through experimental tests，but are obtained by theoretical calculation formulas. Although some methods for calculating the isotherm adsorption rate have been published at home and abroad，especially in China，incorrectness and uncertainty during the theoretical derivation process lead to errors in calculation formulas and calculation results，and the concept of excess adsorption was not correct，which make it impossible to provide reliable saturated cumulative adsorption data for the evaluation of adsorption gas resources of shale and coal bed. According to the gas state equation，using the principle of material conservation of gas，three methods for calculating isothermal adsorption rate were obtained after strict derivation. The judgment factor for determining whether the state of saturated adsorption rate is reached was proposed. The application of shale and coal bed adsorption experimental data shows that the new calculation method and judgment factor are correct and effective.

Abstract:In order to provide a theoretical basis for the development of CO2 flooding in horizontal wells in oil reservoirs，a three-zone composite horizontal well model for CO2 flooding was proposed. A series of mathematical and physical methods such as Laplace transformation，orthogonal transformation，and numerical inversion were adopted to solve this model. According to the pressure response characteristics，the well testing curves were divided into nine stages including the wellbore storage stage，skin effect stage，early radial flow stage，linear flow stage，plane radial flow of CO2 zone，transfer stage of CO2 zone to transition zone，the radial flow in transition zone，the transfer stage from the transition zone to the crude oil zone and the radial flow in the crude oil zone. Sensitivity analysis was conducted on several influential factors，and results show that when the radius of the CO2 zone and transition zone become larger，the dimensionless bottomhole pressure difference will decrease，which is favorable for CO2 injection；the larger the storability ratio is，the shorter the flow time in the transition zone will be；the decrease of the wellbore storage coefficient and skin factor is more favorable for the displacement process；the greater the mobility ratio is，the longer the flow time in the transition zone will last.

Abstract:The surfactants with good CO2 foam performance were screened out by high-pressure and high-temperature visualized foam device. The solubility of the systems in supercritical CO2 were evaluated by using alcohols as co-solvents. The ability of EOR of CO2-soluble surfactant foam was tested by high-temperature and high-pressure core displacement experimental device. The results show that the selected nonionic surfactants N-P-12 have good CO2 foam stability at high-temperature condition of 125 ℃，and the addition of alcohol as co-solvents could significantly increase the solubility of the surfactants in the CO2. During the CO2 foam flooding，the resistance factor may increase first and then decrease，and the generated foam may play the role of mobility control in the system. Moreover，CO2 foam based on CO2-soluble surfactant is more efficient on enhancing oil recovery than the conventional CO2 foam，and the ultimate oil recovery is raised up to 92.50%.

Abstract:The conventional hydrolyzed polyacrylamide（HPAM）flooding agent has very low viscosity in high temperature and high salinity reservoir. By introducing 2-acrylamido-2-methylpropane sulfonic acid（AMPS）monomer to the PAM backbone，the ultra-high molecular weight（UHMW）terpolymer was synthesized. This is an effective way to improve the temperature resistance and the salt tolerance performance of the polymer. The basic physicochemical properties，rheological properties and oil displacement effect of conventional HPAM and UHMW terpolymer with AMPS monomer were studied.Compared with the conventional HPAM，the effective diameter of UHMW terpolymer was increased by more than 30% at 32 868 mg/L salinity of the simulated water. The molecular chain was more stretched and the network structure were more complete，and the viscosity was more than doubled. Rheological studies show that the thickening coefficient of the UHMW terpolymer shear rheological equation increased by 2 times，and the power-law index decreased by 22%. Therefore，the UHMW terpolymer has higher viscoelasticity，and the tensile viscosity caused by its migration in the formation was more than doubled. The double-sand-filling-tube model experiment shows that the conventional HPAM can only enhance oil recovery by 15.7%，while the UHMW terpolymer can enhance oil recovery by 24.1%. The UHMW terpolymer has better oil displacement effect and has good prospect of application.

Abstract:In order to know the main controlling factors of mechanical degradation of partially hydrolyzed polyacrylamide （HPAM）in pore-throat model，the mechanical degradation experiments of partially hydrolyzed polyacrylamide（HPAM）for polymer flooding in the pore-throat model were carried out，and the effect of flow rate，concentration，pore-throat ratio and other factors on the mechanical degradation was studied. The experimental results show that the main factors of mechanical degradation of HPAM in the pore-throat model are flow rate and pore-throat ratio，and the concentration and total salinity of formation water have little influence on the mechanical degradation of HPAM. The apparent viscosity loss caused by the mechanical degradation of HPAM in the pore throat increases with the flow rate，and there is a“critical flow rate”that the polymer molecules begin to degrade rapidly，and a“limit flow rate”at which the degradation reaches the limit. When the HPAM passes through the tandem pore-throat model，the mechanical degradation occurs mainly in the first four porethroat models，which indicates that the key position of the mechanical degradation of HPAM in the reservoirs is the near bolehole zone.

Abstract:It is always hard to meet the requirement of injection allocation rate of the injector in the Shengli Oilfield due to high viscosity of crude oil and polymer/viscosity reducer solution，and the wells are forced to produce intermittently. There is no specific way to determine the maximum injection speed of the polymer/viscosity reducer combination flooding，which restricts the chemical flooding development in the heavy oil reservoirs. Based on statistics principle，reservoir numerical simulation and other methods，the typical numerical simulation model of the combination flooding was established for the Ng41-51 unit of eastern area in Gudao Oilfield，and the main control factors were screened out by Plackett-Burman experimental design. A prediction model for dimensionless water injectivity index of the polymer/viscosity reducer combination flooding was established finally by multiple regression analysis. On this basis，a method for calculating the injection rate limit of the polymer/viscosity reducer combination flooding was formed. The results show that the calculated value and predicted value of the dimensionless water injectivity index gained by the numerical simulation plan agrees well with that from the verification plan with an average error of 1.71%，which verifies the reliability of the prediction model. When the polymer concentration was 2 000 mg/L，the viscosity reducer concentration was 0.4%，the viscosity reduction rate was 90% and the injected slug size was 0.4 PV，the calculated limited injection rate of the target area was 0.106 4 PV/a. It is very close to the injection data（0.11 PV/a）in the actual situation in the field.

Abstract:Polymer/viscosity reducer combination flooding has been widely used in many oil fields and has obtained very good performance. However，as the increase of oil viscosity，the incremental oil production decreases. By far，there is no determination method of the upper limit of oil viscosity suitable for the polymer/viscosity reducer combination flooding，which severely restricts the wide application of this chemical flooding. Taking the oil increment value for a ton of agent as the standard，a determination method of the upper limit of the oil viscosity for the polymer/viscosity reducer combination flooding was built based on the financial net present value. Taking the Ng41-51 unit in eastern area of Gudao Oilfield for example，a chart was obtained to determine the upper limit of oil viscosity. The results show that the upper limit of oil viscosity increases along with the increase of oil price. If the oil price is 40 $/bbl，the upper limit of oil viscosity is only 854 mPa?s. Howev? er，if the oil price is 70 $/bbl，the upper limit of oil viscosity increases to 4 471 mPa?s.

Abstract:Smart water flooding is a new technology for oilfield development with low-cost，environmental protection and huge potential. Based on the research results of many scholars at home and abroad，the main mechanisms of the smart water flooding for enhanced oil recovery were analyzed and summarized as：alkali-like flooding，particulate migration，multicomponent ion exchange and reservoir wettability transition. EOR mechanism by the smart water flooding was verified by physical simulation experiments. The results show that the pH value of the produced water in the core flow experiment with the smart water flooding is significantly higher than that with the high-salinity water flooding；and the maximum pH value can reach 8.23，which indicates that the smart water flooding can exert the effect similar to the alkali flooding and improve the recovery factor. The smart water was used to displace the uncalcined and calcined cores at 650 ℃，and the ultimate recovery efficiency were 56.48% and 53.45%，respectively. The clay in the calcined cores no longer migrated，and the recovery efficiency was significantly lower than that of the uncalcined ones. It shows that the migration of the particulates in the process of smart water flooding can improve the recovery efficiency. By examining the concentration of each ion in the produced liquid during the smart water flooding，it is found that the Ca2+ concentration increases first and then decreases gradually，and the concentration of Mg2+ increases slightly and then decreases gradually and finally becomes stable. It shows that a small amount of Ca2+ ions was exchanged by Mg2+ and a large amount of Ca2+ on the clay surface was exchanged by H+ in the smart water during the water flooding. It shows that there are multicomponent ion exchange processes during the smart water flooding and the recovery efficiency is improved. After 70 hours，the smart water was applied around the oil droplet1.The contact angle between the oil droplet and the core gradually decreased from the initial value 124° to 67°. The wettability changes from lipophilic to hydrophilic. It indicates that the smart water flooding can change the wettability of the core surface and then enhance oil recovery.

Abstract:Pore-fracture media with different scales are formed after volume fracturing of horizontal wells in tight reservoirs. The flow law of fluid in different scale media is different. It is difficult to predict the production. Based on summary of the previous understanding of the flow law of fluid in different scale media，the production prediction model of the volume fractured horizontal well in the tight reservoir was established，and its accuracy was proved by actual oilfield data. The influencing factors on production of the volume fractured horizontal well in the tight reservoir were analyzed. The stress sensitivity coefficients of different media was sorted based on their influence on production. From great to small，they are stress sensitivity coefficient of the secondary fracture，stress sensitivity coefficient of the main artificial fracture and stress sensitivity coefficient of the matrix. The high-speed nonlinear coefficient has great influence on the production，while the start-up pressure gradient has little influence on the production.

Abstract:Due to the high permeability and the development of high-capacity channels in offshore oilfields，it is difficult for the conventional plugging agents to meet the technical and economic requirements of plugging. In order to solve this problem and plug the highly permeable layers effectively，the composition of plugging agent was optimized and its influencing factors were studied through experiments under the reservoir temperature condition based on the reservoir characteristics and fluid properties of Bohai Oilfield. Physical simulation and instrument testing was done theoretically guided by inorganic chemistry and reservoir engineering. Considering the curing time，the acid solubility and the compressive strength of the plugging agent，NaOH，inorganic tackifier and compound retarder were recommended as the best choice for the curing agent，the tackifier and the retarder. The influence of retarder on the curing time of the plugging agent is the most obvious compared with the components of tackifier，curing agent，retarder and main agent. When the concentration of retarder is from 0.1% to 0.5%，the curing time ranges from 5.5 hours to 480 hours.

Abstract:In order to quickly classify and distinguish carbonate reservoir types，the fractured-vuggy combination pattern of the fractured-vuggy carbonate units was determined based on the data of typical well. Typical cores were selected for holemaking and was applied to physical simulation experiment，and the flow characteristics of the fractured-vuggy type unit，isolated cave type unit and cave type unit with fluid supply by matrix were analyzed. Noise processing and integrated compressibility coefficient analysis was done to correct the flow characteristics curves at flush stage. Based on the oil-pressure curve，cumulative pressure drop vs. cumulative liquid production curve，dynamic data of leakage and venting and static data of sculpture of fractured-vuggy unit at the flush stage in the Yingmai2 block，Tarim Oilfield，the fractured-vuggy units in 40 wells of Yingmai2 block can be classified into 4 types combined with pressure buildup well test data. The cave type units with fluid supply by matrix，fractured-vuggy type units and isolated cave type units and other type units. This method can be applied to the quick recognition of the fractured-vuggy units in the future development of reservoir.