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Petroleum Geology and Engineering (Bimonthly), founded in 1987, is an academic journal supervised by Sinopec Group, sponsored by Henan Oilfield Company of China Petroleum and Chemical Corporation, and publicly issued at home and abroad.
The Petroleum Geology and Engineering has always been adhering to the "propaganda of the scientific and technological principles of the party and the state on the petroleum and petrochemical industry, geared to the needs of oilfield scientific research and production, disseminating petroleum scientific and technological information, exchanging academic ideas, promoting the transformation of scientific and technological achievements, and accelerating the development of the oil and gas industry development". The journal mainly publishes academic papers of new technology, new theoretical research results and new technology application on Geology Exploration, Oil Field Development and Petroleum Engineering. It is a platform for academic exchange and information dissemination of scientific and technological workers in oil and gas exploration and development.
Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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2020, 34(05): 1-7.
Abstract
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Abstract:
Based on the new 3D data of the east of Sandaoqiao area, the fault characteristics of pre Mesozoic buried hill in the north of Shaya uplift was analyzed. Combined with the regional tectonic background, the formation stages of faults were analyzed, and meantime the petroleum geological significance of different faults was studied. The results show that reverse faults, normal faults and strike slip faults were developed in the pre Mesozoic buried hill of northern Shaya uplift, and there were three groups of strike in plane, namely NNE, NW and EW. The strike slip fault to the south of Luntai fault was formed in the middle and late Caledonian period. The strike slip fault to the north of Luntai fault was reformed by Hercynian reverse fault. It has the characteristics of "apparent reverse and real positive" on the profile, and presents NE direction on the plane. The NNE trending reverse faults were formed in the late Caledonian and early Hercynian movements, and were shaped in the late Hercynian movement. The NW trending normal fault is related to the Permian volcanic activity in the late Hercynian. The nearly EW trending thrust fault was formed in the late Hercynian movement and Indosinian movement. The faults with different properties and stages have constructive significance for the formation of buried hill traps. The reverse fault controls the formation of fault structural belt, forming anticline, fault anticline, fault block and other structural traps. The extensional faults and strike slip faults related to volcanic rocks can effectively improve the reservoir conditions of carbonate rocks.
Based on the new 3D data of the east of Sandaoqiao area, the fault characteristics of pre Mesozoic buried hill in the north of Shaya uplift was analyzed. Combined with the regional tectonic background, the formation stages of faults were analyzed, and meantime the petroleum geological significance of different faults was studied. The results show that reverse faults, normal faults and strike slip faults were developed in the pre Mesozoic buried hill of northern Shaya uplift, and there were three groups of strike in plane, namely NNE, NW and EW. The strike slip fault to the south of Luntai fault was formed in the middle and late Caledonian period. The strike slip fault to the north of Luntai fault was reformed by Hercynian reverse fault. It has the characteristics of "apparent reverse and real positive" on the profile, and presents NE direction on the plane. The NNE trending reverse faults were formed in the late Caledonian and early Hercynian movements, and were shaped in the late Hercynian movement. The NW trending normal fault is related to the Permian volcanic activity in the late Hercynian. The nearly EW trending thrust fault was formed in the late Hercynian movement and Indosinian movement. The faults with different properties and stages have constructive significance for the formation of buried hill traps. The reverse fault controls the formation of fault structural belt, forming anticline, fault anticline, fault block and other structural traps. The extensional faults and strike slip faults related to volcanic rocks can effectively improve the reservoir conditions of carbonate rocks.
2020, 34(05): 8-11.
Abstract:
As faulting plays an important role in hydrocarbon migration and accumulation, the fine degree of fault identification affects the characterization of reservoirs and traps. In Zhangchang area of Biyang sag, the faults are characterized by complexity and the great difficulties on the plane combination and on the description of low-level sequence faults, especially the NW ones, which are difficult to identify by conventional techniques. In order to improve the accuracy of fault description and solve the rationality of fault plane combination, the seismic maximum likelihood attribute was used to study the fault distribution in Zhangchang area, including the characteristic analysis of fault seismic response, the enhancement of fault imaging technology and the calculation of maximum likelihood attribute, which solved the problem of fault description in this area. The reliability of prediction results is verified through drilling practice.
As faulting plays an important role in hydrocarbon migration and accumulation, the fine degree of fault identification affects the characterization of reservoirs and traps. In Zhangchang area of Biyang sag, the faults are characterized by complexity and the great difficulties on the plane combination and on the description of low-level sequence faults, especially the NW ones, which are difficult to identify by conventional techniques. In order to improve the accuracy of fault description and solve the rationality of fault plane combination, the seismic maximum likelihood attribute was used to study the fault distribution in Zhangchang area, including the characteristic analysis of fault seismic response, the enhancement of fault imaging technology and the calculation of maximum likelihood attribute, which solved the problem of fault description in this area. The reliability of prediction results is verified through drilling practice.
2020, 34(05): 12-18.
Abstract:
The fractured-vuggy system of Ordovician platform margin reef beach reservoirs in Tazhong I gas field is composed of hole, hole and fracture in space. In view of the complexity of the fractured-vuggy system of reef beach reservoirs, this paper puts forward the research ideas and methods of dynamic and static analysis of the fractured-vuggy connectivity of reservoir. ①Sedimentary facies, reservoir development horizons and depths are similar in the same fractured-vuggy unit. ②Formation pressure analysis is the most simple and straightforward methodology, which is the necessary and sufficient condition of connectivity study. ③The difference of fluid properties of the same fracture cavity element is small. If the difference of fluid properties is large, it cannot be connected, and the reverse recursion does not work. ④Inter-well interference test can accurately analyze the dynamic connectivity, which is the necessary and sufficient condition of connectivity study. ⑤Production dynamic data can be used to assist connectivity unit division. Through the study of static and dynamic data, the TazhongⅠ gas field is divided into 53 connected units, of which there are 3 connected fractured-vuggy systems distributed along the platform margin.
The fractured-vuggy system of Ordovician platform margin reef beach reservoirs in Tazhong I gas field is composed of hole, hole and fracture in space. In view of the complexity of the fractured-vuggy system of reef beach reservoirs, this paper puts forward the research ideas and methods of dynamic and static analysis of the fractured-vuggy connectivity of reservoir. ①Sedimentary facies, reservoir development horizons and depths are similar in the same fractured-vuggy unit. ②Formation pressure analysis is the most simple and straightforward methodology, which is the necessary and sufficient condition of connectivity study. ③The difference of fluid properties of the same fracture cavity element is small. If the difference of fluid properties is large, it cannot be connected, and the reverse recursion does not work. ④Inter-well interference test can accurately analyze the dynamic connectivity, which is the necessary and sufficient condition of connectivity study. ⑤Production dynamic data can be used to assist connectivity unit division. Through the study of static and dynamic data, the TazhongⅠ gas field is divided into 53 connected units, of which there are 3 connected fractured-vuggy systems distributed along the platform margin.
2020, 34(05): 19-24.
Abstract:
Based on high-precision 3D seismic data, coherent slices, and forward modeling, and referring to the existing understanding of the“Faulted Solution” of the Ordovician in the Tarim basin, the newly discovered reservoir type of the middle Permian Maokou formation in southwestern Sichuan-columnar sag volume distribution characteristics and causes are analyzed. The results show such anomalous bodies are widely developed near the strike-slip faults of the northeastward basement in southwestern Sichuan. The seismic profile shows continuous downward sag of multiple sets of isotropic axes, extending from the top of the Maokou formation to the Sinian basement. Coherent slices are circular or ring-like features. Based on the analysis of the existing geological data, it is considered that such anomalous bodies are mainly caused by hydrothermal dissolution. The northeast strike-slip fault activated during the Emei rift during the Xingkai rift is the main controlling factor for its distribution. The study is of certain significance for expanding the exploration areas and zones in Southwest Sichuan and increasing reserves and production.
Based on high-precision 3D seismic data, coherent slices, and forward modeling, and referring to the existing understanding of the“Faulted Solution” of the Ordovician in the Tarim basin, the newly discovered reservoir type of the middle Permian Maokou formation in southwestern Sichuan-columnar sag volume distribution characteristics and causes are analyzed. The results show such anomalous bodies are widely developed near the strike-slip faults of the northeastward basement in southwestern Sichuan. The seismic profile shows continuous downward sag of multiple sets of isotropic axes, extending from the top of the Maokou formation to the Sinian basement. Coherent slices are circular or ring-like features. Based on the analysis of the existing geological data, it is considered that such anomalous bodies are mainly caused by hydrothermal dissolution. The northeast strike-slip fault activated during the Emei rift during the Xingkai rift is the main controlling factor for its distribution. The study is of certain significance for expanding the exploration areas and zones in Southwest Sichuan and increasing reserves and production.
2020, 34(05): 25-29.
Abstract:
According to the characteristics of high density and high viscosity of crude oil in Binchang block of Ordos basin, the causes of crude oil thickening were studied by analyzing the geochemical characteristics of crude oil. The results show that the high viscosity crude oil in Binchang block was formed by the combined action of primary and secondary factors: ① The crude oil in Binchang block was formed in reduction environment, and the RO of Chang 7 oil shale of source rock was 0.5%~0.8%, and the maturity was low, which led to the high heavy component of crude oil. ② Faults and fractures are widely developed in Binchang block, and the reservoir is vulnerable to late transformation. The soluble hydrocarbons in crude oil are selectively dissolved due to fault communication with formation water, and the loss of light components in crude oil during oil migration leads to crude oil thickening.
According to the characteristics of high density and high viscosity of crude oil in Binchang block of Ordos basin, the causes of crude oil thickening were studied by analyzing the geochemical characteristics of crude oil. The results show that the high viscosity crude oil in Binchang block was formed by the combined action of primary and secondary factors: ① The crude oil in Binchang block was formed in reduction environment, and the RO of Chang 7 oil shale of source rock was 0.5%~0.8%, and the maturity was low, which led to the high heavy component of crude oil. ② Faults and fractures are widely developed in Binchang block, and the reservoir is vulnerable to late transformation. The soluble hydrocarbons in crude oil are selectively dissolved due to fault communication with formation water, and the loss of light components in crude oil during oil migration leads to crude oil thickening.
2020, 34(05): 30-33.
Abstract:
The comprehensive isotropic velocity field will affect the dynamic correction effect of the wide azimuth seismic gathers, and then affect the residual static correction effect, the azimuth anisotropy correction effect and the stacking effect. In the processing of wide azimuth seismic data, the NMO (Normal Move Out) velocity changes with the change of azimuth. The multi-directional velocity field obtained by the multidirectional velocity analysis can effectively improve the quality of gathers after NMO correction, eliminate the adverse effects of isotropic velocity field on the residual static correction and azimuthal anisotropy correction in OVT (Offset Vector Title) domain seismic data processing, and improve the flatness of gathers after NMO correction and the imaging accuracy of low order faults. The method proves to be effective in seismic data processing of CY-DZ exploration area in Nanyang sag.
The comprehensive isotropic velocity field will affect the dynamic correction effect of the wide azimuth seismic gathers, and then affect the residual static correction effect, the azimuth anisotropy correction effect and the stacking effect. In the processing of wide azimuth seismic data, the NMO (Normal Move Out) velocity changes with the change of azimuth. The multi-directional velocity field obtained by the multidirectional velocity analysis can effectively improve the quality of gathers after NMO correction, eliminate the adverse effects of isotropic velocity field on the residual static correction and azimuthal anisotropy correction in OVT (Offset Vector Title) domain seismic data processing, and improve the flatness of gathers after NMO correction and the imaging accuracy of low order faults. The method proves to be effective in seismic data processing of CY-DZ exploration area in Nanyang sag.
2020, 34(05): 34-38.
Abstract:
By using the reservoir techniques of microscopy fluorescence, according to fluorescence in the distribution of pore throats and intensity of fluorescence, reservoir microscopic fluorescence can clearly reflect the pore and throat as well as connectivity conditions in the pore structure, and then reveal the reservoir quality and gas bearing. Taking the sandstone reservoir of Xujiahe formation of upper Triassic in Shunan area of Sichuan basin as an example, the fluorescence characteristics and gas bearing property of pore type reservoir and fracture pore type reservoir are expounded respectively, and the pore lower limit of the two types of reservoirs is determined by combining the measured physical property data. The results show that the microscopy fluorescence distribution and intensity in the pore throat can be divided into three types of fluorescence levels. The reservoir microscopy fluorescence method can directly and reliably reflect the reservoir oil and gas potential. The lower limit of physical property determined by this method is consistent with the intersection method of porosity and permeability, the minimum pore throat radius method and the oil testing method, which proves that the method of determining the lower limit of gas bearing property and physical property by microscopy fluorescence is effective under the condition of incomplete data.
By using the reservoir techniques of microscopy fluorescence, according to fluorescence in the distribution of pore throats and intensity of fluorescence, reservoir microscopic fluorescence can clearly reflect the pore and throat as well as connectivity conditions in the pore structure, and then reveal the reservoir quality and gas bearing. Taking the sandstone reservoir of Xujiahe formation of upper Triassic in Shunan area of Sichuan basin as an example, the fluorescence characteristics and gas bearing property of pore type reservoir and fracture pore type reservoir are expounded respectively, and the pore lower limit of the two types of reservoirs is determined by combining the measured physical property data. The results show that the microscopy fluorescence distribution and intensity in the pore throat can be divided into three types of fluorescence levels. The reservoir microscopy fluorescence method can directly and reliably reflect the reservoir oil and gas potential. The lower limit of physical property determined by this method is consistent with the intersection method of porosity and permeability, the minimum pore throat radius method and the oil testing method, which proves that the method of determining the lower limit of gas bearing property and physical property by microscopy fluorescence is effective under the condition of incomplete data.
2020, 34(05): 39-43.
Abstract:
The distribution of sedimentary facies belt in Chang-3 member of Yanchang formation is the key factor to control the distribution of tight sandstone reservoir. Based on the analysis of core, drilling, logging and seismic data, combined with the sedimentary background of Yanchang formation in Ordos basin, it is considered that the braided river delta and shore shallow lacustrine sedimentary system are mainly developed in Xun-Yi block area of Chang 3 member. The sedimentary microfacies such as underwater distributary channel, distributary bay and mouth bar are identified. Among them, the underwater distributary channel has wide development scale, large sand body thickness (single sand body thickness of 8.0～18.0 m), and good physical properties (average porosity of 11.3%, average permeability of 0.7×10–3μm2), which plays an important role in controlling the enrichment degree of oil and gas, and are favorable exploration facies zones.
The distribution of sedimentary facies belt in Chang-3 member of Yanchang formation is the key factor to control the distribution of tight sandstone reservoir. Based on the analysis of core, drilling, logging and seismic data, combined with the sedimentary background of Yanchang formation in Ordos basin, it is considered that the braided river delta and shore shallow lacustrine sedimentary system are mainly developed in Xun-Yi block area of Chang 3 member. The sedimentary microfacies such as underwater distributary channel, distributary bay and mouth bar are identified. Among them, the underwater distributary channel has wide development scale, large sand body thickness (single sand body thickness of 8.0～18.0 m), and good physical properties (average porosity of 11.3%, average permeability of 0.7×10–3μm2), which plays an important role in controlling the enrichment degree of oil and gas, and are favorable exploration facies zones.
2020, 34(05): 44-48.
Abstract:
Based on the surface soil samples of an oil and gas area in Jiangsu oilfield, a gas reservoir and reservoir simulation environment with certain oil and gas background information was constructed. The quantity change characteristics of oil and gas microorganisms under different light hydrocarbon seepage conditions were studied through simulation experiments by using surface soil samples from a certain area in Jiangsu oilfield. The results showed that the number of microorganisms using hydrocarbons as carbon source increased rapidly and finally reached a plateau stage, while the number of microorganisms without hydrocarbon supply decreased gradually. The number of microorganisms was proportional to light hydrocarbon leakage flux in a short time, however, after long-term domestication under different leakage flux, the number of microorganisms tended to be uniform. The abundance of gas indicator gene pmoA and oil indicator gene bmoX have good response and specificity to gas and oil reservoir environment respectively. Microorganisms were in a state of extinction under the simulation condition of exhausted reservoir without hydrocarbon supply. Through simulation experiments, the response of surface oil and gas microorganisms to underlying reservoirs is verified, and the quantitative variation characteristics of oil and gas microorganisms under light hydrocarbon seepage environment are preliminarily clarified．
Based on the surface soil samples of an oil and gas area in Jiangsu oilfield, a gas reservoir and reservoir simulation environment with certain oil and gas background information was constructed. The quantity change characteristics of oil and gas microorganisms under different light hydrocarbon seepage conditions were studied through simulation experiments by using surface soil samples from a certain area in Jiangsu oilfield. The results showed that the number of microorganisms using hydrocarbons as carbon source increased rapidly and finally reached a plateau stage, while the number of microorganisms without hydrocarbon supply decreased gradually. The number of microorganisms was proportional to light hydrocarbon leakage flux in a short time, however, after long-term domestication under different leakage flux, the number of microorganisms tended to be uniform. The abundance of gas indicator gene pmoA and oil indicator gene bmoX have good response and specificity to gas and oil reservoir environment respectively. Microorganisms were in a state of extinction under the simulation condition of exhausted reservoir without hydrocarbon supply. Through simulation experiments, the response of surface oil and gas microorganisms to underlying reservoirs is verified, and the quantitative variation characteristics of oil and gas microorganisms under light hydrocarbon seepage environment are preliminarily clarified．
2020, 34(05): 49-53.
Abstract:
The reservoirs from the third member of Liushagang formation in the X oilfield of Wushi sag is complex and sensitive. In this study, a variety of analytical methods, such as thin section identification of rock, X-ray diffraction of clay minerals, scanning electron microscopy, high-pressure mercury injection, are used to carry out the reservoir sensitivity test, so as to analyze the reservoir sensitivity regularity and sensitivity damage mechanism, and provide a basis for efficient development of the oilfield. The experimental results show that the water sensitivity of Glutenite reservoir is very strong, and the water sensitivity of fine sandstone reservoir is medium to strong; the velocity sensitivity of Glutenite reservoir in single-phase brine is medium, the critical velocity is 0.965 m/d, the velocity sensitivity is weak in single-phase neutral oil, there is no critical velocity, and the fine sandstone reservoir has no speed sensitivity; the overall acid sensitivity of the reservoir is medium to weak, and the alkali sensitivity is weak. The content, type, occurrence and pore structure of clay minerals and cements are important factors that cause strong sensitivity of reservoir. It is suggested that the compatibility between working fluid and formation fluid should be done well in drilling and completion, and the injection production flow rate should be controlled under formation conditions to avoid reservoir damage.
The reservoirs from the third member of Liushagang formation in the X oilfield of Wushi sag is complex and sensitive. In this study, a variety of analytical methods, such as thin section identification of rock, X-ray diffraction of clay minerals, scanning electron microscopy, high-pressure mercury injection, are used to carry out the reservoir sensitivity test, so as to analyze the reservoir sensitivity regularity and sensitivity damage mechanism, and provide a basis for efficient development of the oilfield. The experimental results show that the water sensitivity of Glutenite reservoir is very strong, and the water sensitivity of fine sandstone reservoir is medium to strong; the velocity sensitivity of Glutenite reservoir in single-phase brine is medium, the critical velocity is 0.965 m/d, the velocity sensitivity is weak in single-phase neutral oil, there is no critical velocity, and the fine sandstone reservoir has no speed sensitivity; the overall acid sensitivity of the reservoir is medium to weak, and the alkali sensitivity is weak. The content, type, occurrence and pore structure of clay minerals and cements are important factors that cause strong sensitivity of reservoir. It is suggested that the compatibility between working fluid and formation fluid should be done well in drilling and completion, and the injection production flow rate should be controlled under formation conditions to avoid reservoir damage.
2020, 34(05): 54-58.
Abstract:
Due to the fact that the variation law of oil and gas in near critical state reservoirs is more complex than that in conventional reservoirs, the deviation of oil and gas recovery degree and production gas oil ratio predicted by conventional reservoir engineering method is large, and dynamic prediction is difficult. Based on the generalized material balance equation and oil-gas two-phase permeability curve under low interfacial tension, a new dynamic prediction method for near critical reservoir is established by analyzing the factors affecting the fluid characteristics and development law of near critical reservoir. The results show that the oil recovery degree and instantaneous gas oil ratio calculated by the improved new method are more in line with the actual production performance, and the prediction of oil-gas recovery law and recovery rate is more accurate because of the dual effects of dissolved gas oil ratio and volatile oil gas ratio, as well as the change characteristics of oil-gas phase permeability under low interfacial tension. The research results have certain guiding significance for the development of similar reservoirs.
Due to the fact that the variation law of oil and gas in near critical state reservoirs is more complex than that in conventional reservoirs, the deviation of oil and gas recovery degree and production gas oil ratio predicted by conventional reservoir engineering method is large, and dynamic prediction is difficult. Based on the generalized material balance equation and oil-gas two-phase permeability curve under low interfacial tension, a new dynamic prediction method for near critical reservoir is established by analyzing the factors affecting the fluid characteristics and development law of near critical reservoir. The results show that the oil recovery degree and instantaneous gas oil ratio calculated by the improved new method are more in line with the actual production performance, and the prediction of oil-gas recovery law and recovery rate is more accurate because of the dual effects of dissolved gas oil ratio and volatile oil gas ratio, as well as the change characteristics of oil-gas phase permeability under low interfacial tension. The research results have certain guiding significance for the development of similar reservoirs.
2020, 34(05): 59-62.
Abstract:
The micro pore structure of tight sandstone reservoir is complex, and bound water exists generally. Its distribution, occurrence and flow mechanism have great influence on gas bearing property and micro seepage. By selecting rock samples of different types of gas reservoirs in western Sichuan depression, the experimental analysis of semi permeable partition method is carried out to reveal the internal relationship between micro pore structure and occurrence state and production mechanism of bound water. The results show that: ①Different types of reservoirs have different distribution characteristics of irreducible water saturation, and the micro pore structure is the internal factor affecting the irreducible water saturation. When the pore radius is large, but the flaky or necked throat is developed, the pore throat separation is poor and there are many micro pores and throats. The original formation water is easy to be trapped in the places where the pore throat size changes rapidly or in the micro pore throat, resulting in high irreducible water saturation. While, as for the shrinkage pores, the tube bundle throats are relatively developed, the pore throat separation is good, the micro pore throat is less or the pore throat volume ratio is small, and the irreducible water saturation is relatively low. ②Under the action of large pressure gradient or the induction of movable water, part of high value bound water can be transformed into critical water, and finally become movable water to participate in the flow and produce with natural gas. It is concluded that the production pressure difference should be controlled in the initial stage of development. Once the original bound water begins to participate in the flow, the water production and wellbore effusion in the middle and later stages of development will be intensified.
The micro pore structure of tight sandstone reservoir is complex, and bound water exists generally. Its distribution, occurrence and flow mechanism have great influence on gas bearing property and micro seepage. By selecting rock samples of different types of gas reservoirs in western Sichuan depression, the experimental analysis of semi permeable partition method is carried out to reveal the internal relationship between micro pore structure and occurrence state and production mechanism of bound water. The results show that: ①Different types of reservoirs have different distribution characteristics of irreducible water saturation, and the micro pore structure is the internal factor affecting the irreducible water saturation. When the pore radius is large, but the flaky or necked throat is developed, the pore throat separation is poor and there are many micro pores and throats. The original formation water is easy to be trapped in the places where the pore throat size changes rapidly or in the micro pore throat, resulting in high irreducible water saturation. While, as for the shrinkage pores, the tube bundle throats are relatively developed, the pore throat separation is good, the micro pore throat is less or the pore throat volume ratio is small, and the irreducible water saturation is relatively low. ②Under the action of large pressure gradient or the induction of movable water, part of high value bound water can be transformed into critical water, and finally become movable water to participate in the flow and produce with natural gas. It is concluded that the production pressure difference should be controlled in the initial stage of development. Once the original bound water begins to participate in the flow, the water production and wellbore effusion in the middle and later stages of development will be intensified.
2020, 34(05): 63-68.
Abstract:
For the reservoir with subsequent water drive after polymer flooding, the key step to further producing remaining oil after polymer flooding and enhancing oil recovery is to find out the starting mode and mechanism of micro remaining oil. Based on the micro lithography simulation model, the micro flooding experiments are carried out in three ways: periodic water injection, increasing displacement pressure gradient and liquid flow steering. It is clear that the cluster and blind end remaining oil can be produced by the liquid flow steering and the increasing displacement pressure gradient, so as to improve the development effect after polymer flooding. After polymer flooding, it has been implemented in the upper layer of V oil formation and Ⅲ oil formation of Hetaoyuan formation of Paleogene in Shuanghe oilfield, which has achieved good results and provided a basis and direction for further EOR after polymer flooding.
For the reservoir with subsequent water drive after polymer flooding, the key step to further producing remaining oil after polymer flooding and enhancing oil recovery is to find out the starting mode and mechanism of micro remaining oil. Based on the micro lithography simulation model, the micro flooding experiments are carried out in three ways: periodic water injection, increasing displacement pressure gradient and liquid flow steering. It is clear that the cluster and blind end remaining oil can be produced by the liquid flow steering and the increasing displacement pressure gradient, so as to improve the development effect after polymer flooding. After polymer flooding, it has been implemented in the upper layer of V oil formation and Ⅲ oil formation of Hetaoyuan formation of Paleogene in Shuanghe oilfield, which has achieved good results and provided a basis and direction for further EOR after polymer flooding.
2020, 34(05): 69-73.
Abstract:
Chunguang oilfield is characterized by high porosity, high permeability, strong edge water and smallscale sandstone reservoir, the natural edge water drive development mode is adopted. In the late stage of high water cut development, under the condition of the existing well pattern, aiming at the problems such as the remaining oil at the top and flank cannot be effectively produced, by using numerical simulation technology, the study on the reservoir adaptation conditions and injection production scheme design optimization of nitrogen artificial gas cap oil displacement is carried out. This technology has been tested in Chun22 well block and achieved good development results. It can be used as reference and guidance in the later stage of high water cut development of similar small-scale sandstone reservoirs with high porosity, high permeability and strong edge water at home and abroad.
Chunguang oilfield is characterized by high porosity, high permeability, strong edge water and smallscale sandstone reservoir, the natural edge water drive development mode is adopted. In the late stage of high water cut development, under the condition of the existing well pattern, aiming at the problems such as the remaining oil at the top and flank cannot be effectively produced, by using numerical simulation technology, the study on the reservoir adaptation conditions and injection production scheme design optimization of nitrogen artificial gas cap oil displacement is carried out. This technology has been tested in Chun22 well block and achieved good development results. It can be used as reference and guidance in the later stage of high water cut development of similar small-scale sandstone reservoirs with high porosity, high permeability and strong edge water at home and abroad.
2020, 34(05): 74-78.
Abstract:
In order to solve the problems of complex water invasion, low recovery degree and difficult to greatly enhance oil recovery at the end of huff and puff development, by taking block J91 of Liaohe oilfield as an example, the feasibility of fire flooding development of heavy oil reservoir with edge and bottom water was verified from the perspective of heat and fuel by TG-DSC and indoor physical simulation, and the optimization of operation parameters was studied experimentally. The results show that the stable high temperature oxidation combustion can be achieved by fire flooding development of heavy oil reservoir with edge and bottom water, and the lower limit of fuel oil saturation is 35%. Electric ignition is recommended for the ignition of heavy oil reservoir with edge and bottom water by increasing the ignition temperature and prolonging the ignition time. In the process of displacement, variable speed gas injection is used to increase the temperature of the front edge of the fire line to ensure the stable advancement of the fire line. The study can provide a good technical guidance for the implementation of fire flooding development technology in similar reservoirs.
In order to solve the problems of complex water invasion, low recovery degree and difficult to greatly enhance oil recovery at the end of huff and puff development, by taking block J91 of Liaohe oilfield as an example, the feasibility of fire flooding development of heavy oil reservoir with edge and bottom water was verified from the perspective of heat and fuel by TG-DSC and indoor physical simulation, and the optimization of operation parameters was studied experimentally. The results show that the stable high temperature oxidation combustion can be achieved by fire flooding development of heavy oil reservoir with edge and bottom water, and the lower limit of fuel oil saturation is 35%. Electric ignition is recommended for the ignition of heavy oil reservoir with edge and bottom water by increasing the ignition temperature and prolonging the ignition time. In the process of displacement, variable speed gas injection is used to increase the temperature of the front edge of the fire line to ensure the stable advancement of the fire line. The study can provide a good technical guidance for the implementation of fire flooding development technology in similar reservoirs.
2020, 34(05): 79-82.
Abstract:
In order to solve the problem that rock deformation will affect the development effect in the process of steam flooding in heavy oil reservoir, the rock stress sensitivity experiment is proposed for the first time in unconsolidated sandstone heavy oil reservoir, and the physical simulation experiment research on the influence of rock stress sensitivity on steam displacement efficiency was carried out. The results of the study show that: whether it is a high-permeability reservoir or a low-permeability reservoir, the permeability gradually decreases with the increase of effective overburden, the sensitivity of the high-permeability reservoir is weaker than that of the low-permeability reservoir, and the change in permeability is irreversible. The higher the effective overburden pressure, the heavier the core is subjected to compression, the more serious the porestructure changes, and the lower the oil displacement efficiency. The stress sensitivity of rock has a great influence on the development effect of steam flooding. The research results have a certain guiding role for steam flooding development and strategy formulation in later heavy oil reservoirs.
In order to solve the problem that rock deformation will affect the development effect in the process of steam flooding in heavy oil reservoir, the rock stress sensitivity experiment is proposed for the first time in unconsolidated sandstone heavy oil reservoir, and the physical simulation experiment research on the influence of rock stress sensitivity on steam displacement efficiency was carried out. The results of the study show that: whether it is a high-permeability reservoir or a low-permeability reservoir, the permeability gradually decreases with the increase of effective overburden, the sensitivity of the high-permeability reservoir is weaker than that of the low-permeability reservoir, and the change in permeability is irreversible. The higher the effective overburden pressure, the heavier the core is subjected to compression, the more serious the porestructure changes, and the lower the oil displacement efficiency. The stress sensitivity of rock has a great influence on the development effect of steam flooding. The research results have a certain guiding role for steam flooding development and strategy formulation in later heavy oil reservoirs.
2020, 34(05): 83-88.
Abstract:
Due to the early polymer flooding time and short water flooding stage in offshore oil fields, traditional hall curve cannot evaluate the effectiveness of early polymer flooding. According to the seepage mechanism, considering the non-Newtonian behavior of polymer solution and the additional seepage resistance, an improved Hall Curve suitable for evaluating the early polymer injection effect is established. According to the slope and intercept of improved Hall curve which was drawn up using practical data of an injection well, the flow behavior index, the average effective viscosity within polymer-swept portion, the flow coefficient and the resistant coefficient of underground polymer solution at any time could be calculated. It can be used to evaluate the underground fluid changes and the effectiveness of early polymer flooding. The theoretical calculation results are verified by experiments, and the results are reliable, which provides a basis for the evaluation of early polymer injection effect in offshore oil fields.
Due to the early polymer flooding time and short water flooding stage in offshore oil fields, traditional hall curve cannot evaluate the effectiveness of early polymer flooding. According to the seepage mechanism, considering the non-Newtonian behavior of polymer solution and the additional seepage resistance, an improved Hall Curve suitable for evaluating the early polymer injection effect is established. According to the slope and intercept of improved Hall curve which was drawn up using practical data of an injection well, the flow behavior index, the average effective viscosity within polymer-swept portion, the flow coefficient and the resistant coefficient of underground polymer solution at any time could be calculated. It can be used to evaluate the underground fluid changes and the effectiveness of early polymer flooding. The theoretical calculation results are verified by experiments, and the results are reliable, which provides a basis for the evaluation of early polymer injection effect in offshore oil fields.
2020, 34(05): 89-92.
Abstract:
Water injection pressure is one of the key parameters of offshore water injection development. It is of great significance for the safe and efficient development of offshore oilfields to determine the reasonable pressure according to the characteristics of faults. In order to analyze the safety of water injection wells near faults in Bohai S oilfield, based on the superposition principle of potential and the mirror reflection principle of boundary, the pressure distribution of water injection wells acting on faults is deduced for the injection-production well pattern of one injection and three production near the closed faults. Through the calculation of the actual water injection well pressure in Bohai S oilfield, it is proved that the well is safe at present, and the pressure distribution system has a certain popularization value for the study of the safety of water injection wells near faults.
Water injection pressure is one of the key parameters of offshore water injection development. It is of great significance for the safe and efficient development of offshore oilfields to determine the reasonable pressure according to the characteristics of faults. In order to analyze the safety of water injection wells near faults in Bohai S oilfield, based on the superposition principle of potential and the mirror reflection principle of boundary, the pressure distribution of water injection wells acting on faults is deduced for the injection-production well pattern of one injection and three production near the closed faults. Through the calculation of the actual water injection well pressure in Bohai S oilfield, it is proved that the well is safe at present, and the pressure distribution system has a certain popularization value for the study of the safety of water injection wells near faults.
2020, 34(05): 93-97.
Abstract:
The long drilling period and insufficient reservoir reconstruction scale are the main factors restricting the economic and effective development of natural gas in Fuxian block. By simplifying the casing program of horizontal wells, the drilling period can be greatly shortened and the large-scale reservoir reconstruction can be realized. Based on the actual drilling formation data, through theoretical analysis and numerical simulation, it is clear that mudstone is easy to lose stability, there exists difficulty on long open hole cementing, and there is the problem of salt water invasion and poor reservoir protection. It is necessary to optimize the design of secondary casing program scheme of horizontal wells, support the well wall stability technology, and formulate the casing program transformation plan, etc. The application results show that the design scheme can ensure the smooth implementation of the secondary casing program of the horizontal wells in Fuxian block, shorten the drilling cycle, and provide more safe and effective borehole conditions for the later transformation.
The long drilling period and insufficient reservoir reconstruction scale are the main factors restricting the economic and effective development of natural gas in Fuxian block. By simplifying the casing program of horizontal wells, the drilling period can be greatly shortened and the large-scale reservoir reconstruction can be realized. Based on the actual drilling formation data, through theoretical analysis and numerical simulation, it is clear that mudstone is easy to lose stability, there exists difficulty on long open hole cementing, and there is the problem of salt water invasion and poor reservoir protection. It is necessary to optimize the design of secondary casing program scheme of horizontal wells, support the well wall stability technology, and formulate the casing program transformation plan, etc. The application results show that the design scheme can ensure the smooth implementation of the secondary casing program of the horizontal wells in Fuxian block, shorten the drilling cycle, and provide more safe and effective borehole conditions for the later transformation.
2020, 34(05): 98-101.
Abstract:
In order to further reduce costs and increase efficiency, the tests on secondary casing program of horizontal wells and the optimization of casing cementing and completion were carried out in Dongsheng gas field. Based on the construction difficulties, combined with the theoretical analysis of mechanics, and the key technologies such as physical-chemical compound leakproof and collapse prevention, PDC bit with high efficiency selection techniques, and long open hole cementing techniques were optimized formed by laboratory experiment and mechanics analysis. The field application shows that the construction of six wells is smooth and no complex situation occurs. Compared with the three-stage casing program of horizontal wells in the same period, the drilling cycle is shortened by 34.98 d, the mechanical drilling rate is increased by 1.78 m/h, and the cost of drilling and completion of a single well is saved by more than 357,000 yuan.
In order to further reduce costs and increase efficiency, the tests on secondary casing program of horizontal wells and the optimization of casing cementing and completion were carried out in Dongsheng gas field. Based on the construction difficulties, combined with the theoretical analysis of mechanics, and the key technologies such as physical-chemical compound leakproof and collapse prevention, PDC bit with high efficiency selection techniques, and long open hole cementing techniques were optimized formed by laboratory experiment and mechanics analysis. The field application shows that the construction of six wells is smooth and no complex situation occurs. Compared with the three-stage casing program of horizontal wells in the same period, the drilling cycle is shortened by 34.98 d, the mechanical drilling rate is increased by 1.78 m/h, and the cost of drilling and completion of a single well is saved by more than 357,000 yuan.
2020, 34(05): 102-105.
Abstract:
Under the influence of geological factors, the same bottom hole assembly (BHA) and drilling parameters are applied in different areas, and the effect of deviation prevention and correction is quite different. According to the characteristics of different blocks, the existing well deviation control theory is synthetically used to achieve the purpose of fast single well deviation control, cost reduction and efficiency increase. Yishen-1 well is a key pre-exploration vertical well of Sinopec. In the drilling process, the techniques such as the conventional pendulum drilling tool anti-deviation, straight screw composite drilling anti-deviation technology, curved screw combined with under size centralizer anti-deviation, single bending and double stable drilling tool anti deviation are successively used, together with electronic multi-point inclinometer technique, the mechanical while drilling inclinometer technique and the measurement while drilling (MWD) inclinometer technique, so as to achieve well trajectory trace control. Based on the comparative analysis of the application of various anti deviation and correction techniques and the principles of various anti deviation and correction technology, this paper puts forward the drilling assembly of each opening in the block, which can be used for reference for the same type of wells in Dayi area.
Under the influence of geological factors, the same bottom hole assembly (BHA) and drilling parameters are applied in different areas, and the effect of deviation prevention and correction is quite different. According to the characteristics of different blocks, the existing well deviation control theory is synthetically used to achieve the purpose of fast single well deviation control, cost reduction and efficiency increase. Yishen-1 well is a key pre-exploration vertical well of Sinopec. In the drilling process, the techniques such as the conventional pendulum drilling tool anti-deviation, straight screw composite drilling anti-deviation technology, curved screw combined with under size centralizer anti-deviation, single bending and double stable drilling tool anti deviation are successively used, together with electronic multi-point inclinometer technique, the mechanical while drilling inclinometer technique and the measurement while drilling (MWD) inclinometer technique, so as to achieve well trajectory trace control. Based on the comparative analysis of the application of various anti deviation and correction techniques and the principles of various anti deviation and correction technology, this paper puts forward the drilling assembly of each opening in the block, which can be used for reference for the same type of wells in Dayi area.
2020, 34(05): 106-108.
Abstract:
The continuous high-speed exploitation in Henan oilfield for many years has resulted in serious sand production, formation deficit, too much casing pressure, worse wellbore conditions, serious casing damage, and more channeling wells outside the tube year by year. In view of the problem of channeling out of oil-water wells, the technology of channeling sealing agent with high-strength and low-density was studied and the density of channeling sealing agent was 1.28 g/cm3. The results show that the salinity of water sample has little effect on the initial setting time and breakthrough pressure gradient strength of the channeling sealer. The interface bonding strength between channeling sealer and steel body is high and the temperature resistance is excellent. The field application shows an obvious effect, and that the daily liquid output is 8.5 m3, the daily oil output is 1.2 t.
The continuous high-speed exploitation in Henan oilfield for many years has resulted in serious sand production, formation deficit, too much casing pressure, worse wellbore conditions, serious casing damage, and more channeling wells outside the tube year by year. In view of the problem of channeling out of oil-water wells, the technology of channeling sealing agent with high-strength and low-density was studied and the density of channeling sealing agent was 1.28 g/cm3. The results show that the salinity of water sample has little effect on the initial setting time and breakthrough pressure gradient strength of the channeling sealer. The interface bonding strength between channeling sealer and steel body is high and the temperature resistance is excellent. The field application shows an obvious effect, and that the daily liquid output is 8.5 m3, the daily oil output is 1.2 t.
2020, 34(05): 109-113.
Abstract:
The non-stop intermittent pumping wells are good to improve the pumping efficiency and reduce the energy consumption, while in the process of determining the working system, there are many problems, such as the low operability of the actual determination method, the great influence of subjective factors, and the weak individualization of single well design. By analyzing the influencing factors of the working system, based on the optimization of 9 relatively independent factors, by using big data mining technology, taking the normal running time and running period as the analysis mining object, the adaptability of common data mining algorithms is compared and analyzed, and the algorithm with the strongest adaptability is selected. The results show that BPNN algorithm is better than R-SVM and MRA algorithm in regression calculation, C-SVM algorithm is better than BAYSD and NBAY algorithm in classification algorithm, and C-SVM-BPNN algorithm is better than BAYSD and NBAY algorithm in system efficiency and pump efficiency. The research results have a good guiding role in determining the optimal working system of non-stop intermittent pumping wells.
The non-stop intermittent pumping wells are good to improve the pumping efficiency and reduce the energy consumption, while in the process of determining the working system, there are many problems, such as the low operability of the actual determination method, the great influence of subjective factors, and the weak individualization of single well design. By analyzing the influencing factors of the working system, based on the optimization of 9 relatively independent factors, by using big data mining technology, taking the normal running time and running period as the analysis mining object, the adaptability of common data mining algorithms is compared and analyzed, and the algorithm with the strongest adaptability is selected. The results show that BPNN algorithm is better than R-SVM and MRA algorithm in regression calculation, C-SVM algorithm is better than BAYSD and NBAY algorithm in classification algorithm, and C-SVM-BPNN algorithm is better than BAYSD and NBAY algorithm in system efficiency and pump efficiency. The research results have a good guiding role in determining the optimal working system of non-stop intermittent pumping wells.
2020, 34(05): 114-117.
Abstract:
In the process of drilling and completion, in order to prevent wellbore collapse or control overflow, the pressure in the wellbore is generally greater than the formation pressure, which will lead to drilling mud invasion into the reservoir and mud pollution. In view of the problem that the reservoir with high content of argillaceous sandstone is easy to be blocked by mud pollution, resulting in poor effect of new production wells and serious impact on normal production, indoor dissolution experiment of mud filter cake and rock debris is carried out. Through core flow experiment, the acid solution formula suitable for removing mud pollution and plugging in sandstone reservoir with high shale content is selected, so as to recover or improve the permeability of reservoir. The experimental results show that the fluoroborate acid system not only has good corrosion ability to drilling mud, but also has good sand stabilization performance, which can effectively reduce the excessive corrosion of acid to reservoirs.
In the process of drilling and completion, in order to prevent wellbore collapse or control overflow, the pressure in the wellbore is generally greater than the formation pressure, which will lead to drilling mud invasion into the reservoir and mud pollution. In view of the problem that the reservoir with high content of argillaceous sandstone is easy to be blocked by mud pollution, resulting in poor effect of new production wells and serious impact on normal production, indoor dissolution experiment of mud filter cake and rock debris is carried out. Through core flow experiment, the acid solution formula suitable for removing mud pollution and plugging in sandstone reservoir with high shale content is selected, so as to recover or improve the permeability of reservoir. The experimental results show that the fluoroborate acid system not only has good corrosion ability to drilling mud, but also has good sand stabilization performance, which can effectively reduce the excessive corrosion of acid to reservoirs.
2020, 34(05): 118-122.
Abstract:
In Chunguang oilfield, the reservoir from Neogene Shawan formation is easy to produce sand due to the unconsolidated sandstone. With the increase of reservoir water content, the sand production is intensified. By continuously tracking the sand production in different time and under different water cut stages, the dynamic reasons of sand production are analyzed. The comprehensive loose index is used to subdivide the cementation types of reservoir rocks, and the mechanism and regularity of sand production in different units of Shawan formation are clarified. At the same time, according to two kinds of micro sand production mechanism of the sandstone reservoir, by taking the reservoir heterogeneity into consideration, the stress model and micro dynamic model of sand production process of Shawan formation are established. It is clear that the main sand production mechanism is like earthworm holes, showing obvious vertical and horizontal heterogeneity, which provides basis for the optimization of sand control process parameters.
In Chunguang oilfield, the reservoir from Neogene Shawan formation is easy to produce sand due to the unconsolidated sandstone. With the increase of reservoir water content, the sand production is intensified. By continuously tracking the sand production in different time and under different water cut stages, the dynamic reasons of sand production are analyzed. The comprehensive loose index is used to subdivide the cementation types of reservoir rocks, and the mechanism and regularity of sand production in different units of Shawan formation are clarified. At the same time, according to two kinds of micro sand production mechanism of the sandstone reservoir, by taking the reservoir heterogeneity into consideration, the stress model and micro dynamic model of sand production process of Shawan formation are established. It is clear that the main sand production mechanism is like earthworm holes, showing obvious vertical and horizontal heterogeneity, which provides basis for the optimization of sand control process parameters.
2020, 34(05): 123-126.
Abstract:
The reservoir of Zhuang 75 block in Wuhaozhuang oilfield is characterized by high formation temperature, serious reservoir heterogeneity, high permeability zone development, and rapid water increase after water injection. For such a high temperature reservoir, the commonly used polymer gel profile control agent has low strength and is easy to dehydrate at high temperature, resulting in poor adaptability. Therefore, a profile control agent of silicone resin with high temperature resistance and high strength is developed. The formulation of profile control agent was optimized in laboratory experiment, and the dissolution time, gel forming time, curing strength, temperature resistance and salt resistance of profile control agent were evaluated. Through the core plugging experiment, the injection ability, plugging ability and water erosion resistance of profile control agent in the core were evaluated. The experimental results show that the silicone resin solution has low viscosity and is easy to be injected into the formation, the temperature resistance is 150℃, the salinity resistance is 200 000 mg / L, and the strength is more than 200 kPa. The silicone resin has a strong sealing performance and good water erosion resistance, after flushed 100 PV by the injected water, the core plugging rate is still above 92%, which meets the requirements of profile control in Zhuang 75 block and can effectively improve the development effect.
The reservoir of Zhuang 75 block in Wuhaozhuang oilfield is characterized by high formation temperature, serious reservoir heterogeneity, high permeability zone development, and rapid water increase after water injection. For such a high temperature reservoir, the commonly used polymer gel profile control agent has low strength and is easy to dehydrate at high temperature, resulting in poor adaptability. Therefore, a profile control agent of silicone resin with high temperature resistance and high strength is developed. The formulation of profile control agent was optimized in laboratory experiment, and the dissolution time, gel forming time, curing strength, temperature resistance and salt resistance of profile control agent were evaluated. Through the core plugging experiment, the injection ability, plugging ability and water erosion resistance of profile control agent in the core were evaluated. The experimental results show that the silicone resin solution has low viscosity and is easy to be injected into the formation, the temperature resistance is 150℃, the salinity resistance is 200 000 mg / L, and the strength is more than 200 kPa. The silicone resin has a strong sealing performance and good water erosion resistance, after flushed 100 PV by the injected water, the core plugging rate is still above 92%, which meets the requirements of profile control in Zhuang 75 block and can effectively improve the development effect.
