Through the study of organic matter enrichment,hydrocarbon generation and accumulation process of black shale of the Cretaceous Qingshankou Formation in the Songliao Basin,the enrichment mechanism of Gulong shale oil ...Through the study of organic matter enrichment,hydrocarbon generation and accumulation process of black shale of the Cretaceous Qingshankou Formation in the Songliao Basin,the enrichment mechanism of Gulong shale oil and the distribution of conventional–unconventional oil are revealed.The Songliao Basin is a huge interior lake basin formed in the Early Cretaceous under the control of the subduction and retreat of the western Pacific plate and the massive horizontal displacement of the Tanlu Fault Zone in Northeast China.During the deposition of the Qingshankou Formation,strong terrestrial hydrological cycle led to the lake level rise of the ancient Songliao Basin and the input of a large amount of nutrients,resulting in planktonic bacteria and algae flourish.Intermittent seawater intrusion events promoted the formation of salinization stratification and anoxic environment in the lake,which were beneficial to the enrichment of organic matters.Biomarkers analysis confirms that the biogenic organic matter of planktonic bacteria and algae modified by microorganisms plays an important role in the formation of high-quality source rocks with high oil generation capability.There are four favorable conditions for the enrichment of light shale oil in the Qingshankou Formation of the Gulong Sag,Songliao Basin:the moderate organic matter abundance and high oil potential provide sufficient material basis for oil enrichment;high degree of thermal evolution makes shale oil have high GOR and good mobility;low hydrocarbon expulsion efficiency leads to a high content of retained hydrocarbons in the source rock;and the confinement effect of intra-layer cement in the high maturity stage induces the efficient accumulation of light shale oil.The restoration of hydrocarbon accumulation process suggests that liquid hydrocarbons generated in the early(low–medium maturity)stage of the Qingshankou Formation source rocks accumulated in placanticline and slope after long-distance secondary migration,forming high-quality conventional and tight oil reservoirs.Light oil generated in the late(medium–high maturity)stage accumulated in situ,forming about 15 billion tons of Gulong shale oil resources,which finally enabled the orderly distribution of conventional–unconventional oils that are contiguous horizontally and superposed vertically within the basin,showing a complete pattern of“whole petroleum system”with conventional oil,tight oil and shale oil in sequence.展开更多
The major enrichment type of shale oil in the Chang 7_(3) shale of Upper Triassic Yanchang Formation in the Ordos Basin is unknown.This paper analyzes the organic matter transformation ratio,hydrocarbon expulsion effi...The major enrichment type of shale oil in the Chang 7_(3) shale of Upper Triassic Yanchang Formation in the Ordos Basin is unknown.This paper analyzes the organic matter transformation ratio,hydrocarbon expulsion efficiency and roof/floor sealing conditions of the Chang 7_(3) shale,and evaluates the major enrichment type of shale oil in this interval.The average organic matter transformation ratio of the Chang 7_(3) shale is about 45%;in other words,more than 50%of the organic matters have not transformed to hydrocarbons,and the lower the maturity,the greater the proportion of untransformed organic matters.The cumulative hydrocarbon expulsion efficiency of the transformed hydrocarbon is 27.5% on average,and the total proportion of untransformed organic matters plus retained hydrocarbons is greater than 70%.The relative hydrocarbon expulsion efficiency of the Chang 7_(3) shale is 60%on average,that is,about 40% of hydrocarbons retain in the shale.The Chang 7_(3) shale corresponds to Chang 7_(1+2) and Chang 8 sandstones as the roof and floor,respectively,and is further overlaid by Chang 6 shale,where extensive low porosity and low permeability–tight oil reservoirs have formed in the parts with relatively good porosity and permeability.Moreover,the Chang 7_(3) shale is tested to be in a negative pressure system(the pressure coefficient of 0.80–0.85).Therefore,the roof/floor sealing conditions of the Chang 7_(3) shale are poor.The retained hydrocarbons appear mostly in absorbed status,with low mobility.It is concluded that the medium–high mature shale oil is not the major enrichment type of shale oil in the Chang 7_(3) shale,but there may be enrichment opportunity for shale oil with good mobility in the areas where the sealing conditions are good without faults and fractures and oil reservoirs are formed off Chang 7_(1+2),Chang 6 and Chang 8.Furthermore,low–medium mature shale oil is believed to have great potential and is the major enrichment type of shale oil in the Chang 7_(3) shale.It is recommended to prepare relevant in-situ conversion technologies by pilot test and figure out the resource availability and distribution.展开更多
Based on previous studies on the internal structures of fault belts, the fault belts in the Laoyemiao Oilfield of the Nanpu Sag can be divided into three units, a crushed zone, an upper induced fracture zone and a low...Based on previous studies on the internal structures of fault belts, the fault belts in the Laoyemiao Oilfield of the Nanpu Sag can be divided into three units, a crushed zone, an upper induced fracture zone and a lower induced fracture zone according to the log response characteristics. The upper induced fracture zone is characterized by the development of pervasive fractures and has a poor sealing or non-sealing capability. It therefore can act as pathways for hydrocarbon migration. The lower induced fracture zone consists of fewer fractures and has limited sealing capability. The crushed zone has a good sealing capability comparable to mudstone and can thus prevent lateral migration of fluid. Through physical modeling and comparing laboratory data with calculated data of oil column heights of traps sealed by faults, it is concluded that the fault-sealing capability for oil and gas is limited. When the oil column height reaches a threshold, oil will spill over from the top of reservoir along the lower induced fracture zone under the action of buoyancy, and the size of reservoir will remain unchanged. Analysis of the formation mechanisms of the fault-sealed reservoirs in the Nanpu Sag indicated that the charging sequence of oil and gas in the reservoir was from lower formation to upper formation, with the fault playing an important role in oil and gas accumulation. The hydrocarbon potential in reverse fault-sealed traps is much better than that in the consequent fault-sealed traps. The reverse fault-sealed traps are favorable and preferred exploration targets.展开更多
Beating chamber is one of important components that support aero-engine rotors and research on oil droplet and oil film motions is an important part of bearing chamber lubrication and heat transfer design. Consid- eri...Beating chamber is one of important components that support aero-engine rotors and research on oil droplet and oil film motions is an important part of bearing chamber lubrication and heat transfer design. Consid- ering the pressure of sealing air is an important operating condition that affects the oil droplet and oil film mo- tions, the effect of sealing air pressure on airflow in bearing chamber is investigated in this paper firstly ; and then based on the air velocity and air/wall shear force, the oil droplet moving in core air, deposition of oil droplet im- pact on wall as well as velocity and thickness of oil film are analyzed secondly; the effect of sealing air pressure on oil droplet velocity and trajectory, deposition mass and momentum, as well as oil film velocity and thickness is discussed. The work presented in this paper is conducive to expose the oil/air two phase lubrication mechanism and has certain reference value to guide design of secondary air/oil system.展开更多
AIM: To investigate the efficacy and safety of n-3 polyunsaturated fatty acids (PUFA) from seal oils for patients with nonalcoholic fatty liver disease (NAFLD) associated with hyperlipidemia. METHODS: One hundred and ...AIM: To investigate the efficacy and safety of n-3 polyunsaturated fatty acids (PUFA) from seal oils for patients with nonalcoholic fatty liver disease (NAFLD) associated with hyperlipidemia. METHODS: One hundred and forty-four patients with NAFLD associated with hyperlipidemia were included in the 24-wk, randomized, controlled trial. The patients were randomized into two groups. Group A (n = 72) received recommended diet and 2 g n-3 PUFA from seal oils, three times a day. Group B (n = 72) received recommended diet and 2 g placebo, three times a day. Primary endpoints were fatty liver assessed by symptom scores, liver alanine aminotransferase (ALT) and serum lipid levels after 8, 12, 16, and 24 wk. Hepatic fat inf iltration was detected by ultrasonography at weeks 12 and 24 after treatment. RESULTS: A total of 134 patients (66 in group A, 68 in group B) were included in the study except for 10 patients who were excluded from the study. After 24 wk of treatment, no change was observed in body weight, fasting blood glucose (FBG), renal function and blood cells of these patients. Total symptom scores, ALT and triglyceride (TG) levels decreased more significantly in group A than in group B (P < 0.05). As expected, there was a tendency toward improvement in aspartate aminotransferase (AST), γ-glutamyltranspeptidase (GGT), and total cholesterol (TCHO) and high- density lipoprotein (HDL) cholesterol levels (P < 0.05) after administration in the two groups. However, no significant differences were found between the two groups. The values of low-density lipoprotein (LDL) were significantly improved in group A (P < 0.05), but no significant change was found in group B at different time points and after a 24-wk treatment. After treatment, complete fatty liver regression was observed in 19.70% (13/66) of the patients, and an overall reduction was found in 53.03% (35/66) of the patients in group A. In contrast, in group B, only f ive patients (7.35%, 5/68) achieved complete fatty liver regression (P = 0.04), whereas 24 patients (35.29%, 24/68) had a certain improvement in fatty liver (P = 0.04). No serious adverse events occurred in all the patients who completed the treatment. CONCLUSION: Our results indicate that n-3 PUFA from seal oils is safe and effi cacious for patients with NAFLD associated with hyperlipidemia and can improve their total symptom scores, ALT, serum lipid levels and normalization of ultrasonographic evidence. Further study is needed to confi rm these results.展开更多
Based on the elastoplastic model of cement sheath considering the influence of three-dimensional principal stress and the stress field model of interface crack,a mechanical performance design method of cement sheath i...Based on the elastoplastic model of cement sheath considering the influence of three-dimensional principal stress and the stress field model of interface crack,a mechanical performance design method of cement sheath is established to meet the wellbore sealing requirements during fracturing.This method takes the failure types of the cement sheath,such as tensile failure,plastic yield,interface crack propagation along interface and zigzag propagation into account.Meanwhile,the elasticity modulus and Poisson's ratio quantitative design charts of cement sheath are constructed based on this method,and the safety and risk areas of wellbores are defined,which quantify the yield strength and tensile strength indexes of cement sheath.The results show that decreasing elasticity modulus,increasing yield strength and Poisson's ratio of cement sheath can avoid plastic deformation of cement sheath;increasing the tensile strength of cement sheath can prevent its tensile failure;increasing elasticity modulus and Poisson's ratio of cement sheath is good for shortening the length of the interface crack,but will increase the risk of interface cracks zigzagging into cement sheath.The model calculation and case verification has proved that the method in this paper can give accurate calculation results and is convenient for field application.展开更多
Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has ...Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has been widely reported that the effectiveness and efficiency of water shutoff using gel is mostly dependent on the gel dynamic sealing properties in the porous media.Firstly the gelation strength and gelation time of polymer gel were evaluated.Then,core flowing experiments were conducted before and after gelation in a 32 m long sand pack.In addition,water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method.The experimental results show that moderate-strength gel can be formed at 65 °C.According to the integrated evaluation of the plugging coefficient,plugging strength and water breakthrough time,the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation.Based on sands gelation status and effluent analyses,the effective migration distance of the gel particles is 4-14 m.Through the core flooding experiments using the 80 cm heterogeneous core,it is evidenced that the gel can be formed in the deep reservoir(40.63% of total length) with the plugging strength as high as 6.33 MPa/m,which leads to extra oil recovery of 10.55% of original oil in place(OOIP) by water flooding after gel treatment.展开更多
The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been bu...The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been built in China since the 1970s, there is still a lack of experience for large-volume underground storage in complicated geological conditions. The current design concept of water curtain system and the technical instruction for system operation have limitations in maintaining the stability of surrounding rock mass during the construction of the main storage caverns, as well as the long-term stability. Although several large-scale underground oil storage projects are under construction at present in China, the design concepts and construction methods, especially for the water curtain system, are mainly based on the ideal porosity medium flow theory and the experiences gained from the similar projects overseas. The storage projects currently constructed in China have the specific features such as huge scale, large depth, multiple-level arrangement, high seepage pressure, complicated geological conditions, and high in situ stresses, which are the challenging issues for the stability of the storage caverns. Based on years’ experiences obtained from the first large-scale (millions of cubic meters) underground water-sealed oil storage project in China, some design and operation problems related to water curtain system during project construction are discussed. The drawbacks and merits of the water curtain system are also presented. As an example, the conventional concept of “filling joints with water” is widely used in many cases, as a basic concept for the design of the water curtain system, but it is immature. In this paper, the advantages and disadvantages of the conventional concept are pointed out, with respect to the long-term stability as well as the safety of construction of storage caverns. Finally, new concepts and principles for design and construction of the underground water-sealed oil storage caverns are proposed.展开更多
The manufacturing industry today due to worldwide competition is focused on shorter development cycle. In this situation, computer aided education (CAE) technology as a tool for simultaneous achievement of quality, ...The manufacturing industry today due to worldwide competition is focused on shorter development cycle. In this situation, computer aided education (CAE) technology as a tool for simultaneous achievement of quality, cost and delivery (QCD) plays an important role. The hardware-software environment surrounding CAE has evolved. Though technological problems have been understood and general solutions have been derived and reflected in the CAE analysis software, research findings that boost the credibility of CAE have still not been incorporated fully enough into the development of design process. The real technical mechanism issue is not precisely capture. Therefore, it is important to clarify the real cause in CAE results through CAE simulation in order to assure product reliability and assurance. It is the aim of this study to realize the prediction of design analysis process through understanding of unclear technical mechanism in abnormal occurrences with the utilization of CAE simulation. In other words, it is the aim of this study to focus on issue in automotive transaxle oil seal leakage to understand, grasp, and visualize the main cause through usage of CAE analysis process. It is understood that the point of contact and pump volume was related and this could contribute towards seals quality design. Plus, the utilization of CAE analysis in prediction phase to realized design development is also possible展开更多
The electro-hydraulic servo drive hydraulic cylinder has many unique advantages, such as fast response, high load stiffness, high control power, strong anti-eccentric load ability and so on, so it has been widely used...The electro-hydraulic servo drive hydraulic cylinder has many unique advantages, such as fast response, high load stiffness, high control power, strong anti-eccentric load ability and so on, so it has been widely used in industrial control. Based on the guide sleeve of hydrostatic seal of hydraulic cylinder, the reasonable number of oil chamber of guide sleeve is studied in this paper. ICEM CFD software and FLUENT simulation software are used to calculate and analyze the number of different oil chambers of guide sleeve of hydrostatic seal. The temperature field of piston rod with different moving speed, different initial pressure of oil chamber and oil film under different number of oil chambers is analyzed. The relationship between the pressure field and temperature field provides a better basis for optimizing the design of hydrostatic guide sleeve and helps to improve the servo drive cylinder.展开更多
基金Supported by the Heilongjiang Province S&D Project(2022-JS-1740,2022-JS-1853)China National Petroleum Corporation Scientific Research and Technological Development Project(2021DJ1808).
文摘Through the study of organic matter enrichment,hydrocarbon generation and accumulation process of black shale of the Cretaceous Qingshankou Formation in the Songliao Basin,the enrichment mechanism of Gulong shale oil and the distribution of conventional–unconventional oil are revealed.The Songliao Basin is a huge interior lake basin formed in the Early Cretaceous under the control of the subduction and retreat of the western Pacific plate and the massive horizontal displacement of the Tanlu Fault Zone in Northeast China.During the deposition of the Qingshankou Formation,strong terrestrial hydrological cycle led to the lake level rise of the ancient Songliao Basin and the input of a large amount of nutrients,resulting in planktonic bacteria and algae flourish.Intermittent seawater intrusion events promoted the formation of salinization stratification and anoxic environment in the lake,which were beneficial to the enrichment of organic matters.Biomarkers analysis confirms that the biogenic organic matter of planktonic bacteria and algae modified by microorganisms plays an important role in the formation of high-quality source rocks with high oil generation capability.There are four favorable conditions for the enrichment of light shale oil in the Qingshankou Formation of the Gulong Sag,Songliao Basin:the moderate organic matter abundance and high oil potential provide sufficient material basis for oil enrichment;high degree of thermal evolution makes shale oil have high GOR and good mobility;low hydrocarbon expulsion efficiency leads to a high content of retained hydrocarbons in the source rock;and the confinement effect of intra-layer cement in the high maturity stage induces the efficient accumulation of light shale oil.The restoration of hydrocarbon accumulation process suggests that liquid hydrocarbons generated in the early(low–medium maturity)stage of the Qingshankou Formation source rocks accumulated in placanticline and slope after long-distance secondary migration,forming high-quality conventional and tight oil reservoirs.Light oil generated in the late(medium–high maturity)stage accumulated in situ,forming about 15 billion tons of Gulong shale oil resources,which finally enabled the orderly distribution of conventional–unconventional oils that are contiguous horizontally and superposed vertically within the basin,showing a complete pattern of“whole petroleum system”with conventional oil,tight oil and shale oil in sequence.
基金Supported by the National Natural Science Foundation of China(U22B6004).
文摘The major enrichment type of shale oil in the Chang 7_(3) shale of Upper Triassic Yanchang Formation in the Ordos Basin is unknown.This paper analyzes the organic matter transformation ratio,hydrocarbon expulsion efficiency and roof/floor sealing conditions of the Chang 7_(3) shale,and evaluates the major enrichment type of shale oil in this interval.The average organic matter transformation ratio of the Chang 7_(3) shale is about 45%;in other words,more than 50%of the organic matters have not transformed to hydrocarbons,and the lower the maturity,the greater the proportion of untransformed organic matters.The cumulative hydrocarbon expulsion efficiency of the transformed hydrocarbon is 27.5% on average,and the total proportion of untransformed organic matters plus retained hydrocarbons is greater than 70%.The relative hydrocarbon expulsion efficiency of the Chang 7_(3) shale is 60%on average,that is,about 40% of hydrocarbons retain in the shale.The Chang 7_(3) shale corresponds to Chang 7_(1+2) and Chang 8 sandstones as the roof and floor,respectively,and is further overlaid by Chang 6 shale,where extensive low porosity and low permeability–tight oil reservoirs have formed in the parts with relatively good porosity and permeability.Moreover,the Chang 7_(3) shale is tested to be in a negative pressure system(the pressure coefficient of 0.80–0.85).Therefore,the roof/floor sealing conditions of the Chang 7_(3) shale are poor.The retained hydrocarbons appear mostly in absorbed status,with low mobility.It is concluded that the medium–high mature shale oil is not the major enrichment type of shale oil in the Chang 7_(3) shale,but there may be enrichment opportunity for shale oil with good mobility in the areas where the sealing conditions are good without faults and fractures and oil reservoirs are formed off Chang 7_(1+2),Chang 6 and Chang 8.Furthermore,low–medium mature shale oil is believed to have great potential and is the major enrichment type of shale oil in the Chang 7_(3) shale.It is recommended to prepare relevant in-situ conversion technologies by pilot test and figure out the resource availability and distribution.
基金the Key Project of Chinese National Programs for Fundamental Research and Development (973 Program, No. 2006CB202308)the National Natural Science Foundation of China (Grant No. 40472078)
文摘Based on previous studies on the internal structures of fault belts, the fault belts in the Laoyemiao Oilfield of the Nanpu Sag can be divided into three units, a crushed zone, an upper induced fracture zone and a lower induced fracture zone according to the log response characteristics. The upper induced fracture zone is characterized by the development of pervasive fractures and has a poor sealing or non-sealing capability. It therefore can act as pathways for hydrocarbon migration. The lower induced fracture zone consists of fewer fractures and has limited sealing capability. The crushed zone has a good sealing capability comparable to mudstone and can thus prevent lateral migration of fluid. Through physical modeling and comparing laboratory data with calculated data of oil column heights of traps sealed by faults, it is concluded that the fault-sealing capability for oil and gas is limited. When the oil column height reaches a threshold, oil will spill over from the top of reservoir along the lower induced fracture zone under the action of buoyancy, and the size of reservoir will remain unchanged. Analysis of the formation mechanisms of the fault-sealed reservoirs in the Nanpu Sag indicated that the charging sequence of oil and gas in the reservoir was from lower formation to upper formation, with the fault playing an important role in oil and gas accumulation. The hydrocarbon potential in reverse fault-sealed traps is much better than that in the consequent fault-sealed traps. The reverse fault-sealed traps are favorable and preferred exploration targets.
基金supported by the Natural Science Foundation of China under Grant No.51275411
文摘Beating chamber is one of important components that support aero-engine rotors and research on oil droplet and oil film motions is an important part of bearing chamber lubrication and heat transfer design. Consid- ering the pressure of sealing air is an important operating condition that affects the oil droplet and oil film mo- tions, the effect of sealing air pressure on airflow in bearing chamber is investigated in this paper firstly ; and then based on the air velocity and air/wall shear force, the oil droplet moving in core air, deposition of oil droplet im- pact on wall as well as velocity and thickness of oil film are analyzed secondly; the effect of sealing air pressure on oil droplet velocity and trajectory, deposition mass and momentum, as well as oil film velocity and thickness is discussed. The work presented in this paper is conducive to expose the oil/air two phase lubrication mechanism and has certain reference value to guide design of secondary air/oil system.
基金Supported by Shanghai Natural Science Fund of China, 05ZR14156
文摘AIM: To investigate the efficacy and safety of n-3 polyunsaturated fatty acids (PUFA) from seal oils for patients with nonalcoholic fatty liver disease (NAFLD) associated with hyperlipidemia. METHODS: One hundred and forty-four patients with NAFLD associated with hyperlipidemia were included in the 24-wk, randomized, controlled trial. The patients were randomized into two groups. Group A (n = 72) received recommended diet and 2 g n-3 PUFA from seal oils, three times a day. Group B (n = 72) received recommended diet and 2 g placebo, three times a day. Primary endpoints were fatty liver assessed by symptom scores, liver alanine aminotransferase (ALT) and serum lipid levels after 8, 12, 16, and 24 wk. Hepatic fat inf iltration was detected by ultrasonography at weeks 12 and 24 after treatment. RESULTS: A total of 134 patients (66 in group A, 68 in group B) were included in the study except for 10 patients who were excluded from the study. After 24 wk of treatment, no change was observed in body weight, fasting blood glucose (FBG), renal function and blood cells of these patients. Total symptom scores, ALT and triglyceride (TG) levels decreased more significantly in group A than in group B (P < 0.05). As expected, there was a tendency toward improvement in aspartate aminotransferase (AST), γ-glutamyltranspeptidase (GGT), and total cholesterol (TCHO) and high- density lipoprotein (HDL) cholesterol levels (P < 0.05) after administration in the two groups. However, no significant differences were found between the two groups. The values of low-density lipoprotein (LDL) were significantly improved in group A (P < 0.05), but no significant change was found in group B at different time points and after a 24-wk treatment. After treatment, complete fatty liver regression was observed in 19.70% (13/66) of the patients, and an overall reduction was found in 53.03% (35/66) of the patients in group A. In contrast, in group B, only f ive patients (7.35%, 5/68) achieved complete fatty liver regression (P = 0.04), whereas 24 patients (35.29%, 24/68) had a certain improvement in fatty liver (P = 0.04). No serious adverse events occurred in all the patients who completed the treatment. CONCLUSION: Our results indicate that n-3 PUFA from seal oils is safe and effi cacious for patients with NAFLD associated with hyperlipidemia and can improve their total symptom scores, ALT, serum lipid levels and normalization of ultrasonographic evidence. Further study is needed to confi rm these results.
基金Supported by Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(2020CX040000)Sichuan Science and Technology Program(2020JDTD0019)+1 种基金National Natural Science Foundation of China(52004231)Research Project of Dagang Oilfield(NO.DGYT-2018-JS-244).
文摘Based on the elastoplastic model of cement sheath considering the influence of three-dimensional principal stress and the stress field model of interface crack,a mechanical performance design method of cement sheath is established to meet the wellbore sealing requirements during fracturing.This method takes the failure types of the cement sheath,such as tensile failure,plastic yield,interface crack propagation along interface and zigzag propagation into account.Meanwhile,the elasticity modulus and Poisson's ratio quantitative design charts of cement sheath are constructed based on this method,and the safety and risk areas of wellbores are defined,which quantify the yield strength and tensile strength indexes of cement sheath.The results show that decreasing elasticity modulus,increasing yield strength and Poisson's ratio of cement sheath can avoid plastic deformation of cement sheath;increasing the tensile strength of cement sheath can prevent its tensile failure;increasing elasticity modulus and Poisson's ratio of cement sheath is good for shortening the length of the interface crack,but will increase the risk of interface cracks zigzagging into cement sheath.The model calculation and case verification has proved that the method in this paper can give accurate calculation results and is convenient for field application.
基金Project(2011ZX05009-004)supported by the National Significant Science and Technology Program of China
文摘Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs,aiming at stabilizing oil production.It has been widely reported that the effectiveness and efficiency of water shutoff using gel is mostly dependent on the gel dynamic sealing properties in the porous media.Firstly the gelation strength and gelation time of polymer gel were evaluated.Then,core flowing experiments were conducted before and after gelation in a 32 m long sand pack.In addition,water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method.The experimental results show that moderate-strength gel can be formed at 65 °C.According to the integrated evaluation of the plugging coefficient,plugging strength and water breakthrough time,the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation.Based on sands gelation status and effluent analyses,the effective migration distance of the gel particles is 4-14 m.Through the core flooding experiments using the 80 cm heterogeneous core,it is evidenced that the gel can be formed in the deep reservoir(40.63% of total length) with the plugging strength as high as 6.33 MPa/m,which leads to extra oil recovery of 10.55% of original oil in place(OOIP) by water flooding after gel treatment.
文摘The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been built in China since the 1970s, there is still a lack of experience for large-volume underground storage in complicated geological conditions. The current design concept of water curtain system and the technical instruction for system operation have limitations in maintaining the stability of surrounding rock mass during the construction of the main storage caverns, as well as the long-term stability. Although several large-scale underground oil storage projects are under construction at present in China, the design concepts and construction methods, especially for the water curtain system, are mainly based on the ideal porosity medium flow theory and the experiences gained from the similar projects overseas. The storage projects currently constructed in China have the specific features such as huge scale, large depth, multiple-level arrangement, high seepage pressure, complicated geological conditions, and high in situ stresses, which are the challenging issues for the stability of the storage caverns. Based on years’ experiences obtained from the first large-scale (millions of cubic meters) underground water-sealed oil storage project in China, some design and operation problems related to water curtain system during project construction are discussed. The drawbacks and merits of the water curtain system are also presented. As an example, the conventional concept of “filling joints with water” is widely used in many cases, as a basic concept for the design of the water curtain system, but it is immature. In this paper, the advantages and disadvantages of the conventional concept are pointed out, with respect to the long-term stability as well as the safety of construction of storage caverns. Finally, new concepts and principles for design and construction of the underground water-sealed oil storage caverns are proposed.
文摘The manufacturing industry today due to worldwide competition is focused on shorter development cycle. In this situation, computer aided education (CAE) technology as a tool for simultaneous achievement of quality, cost and delivery (QCD) plays an important role. The hardware-software environment surrounding CAE has evolved. Though technological problems have been understood and general solutions have been derived and reflected in the CAE analysis software, research findings that boost the credibility of CAE have still not been incorporated fully enough into the development of design process. The real technical mechanism issue is not precisely capture. Therefore, it is important to clarify the real cause in CAE results through CAE simulation in order to assure product reliability and assurance. It is the aim of this study to realize the prediction of design analysis process through understanding of unclear technical mechanism in abnormal occurrences with the utilization of CAE simulation. In other words, it is the aim of this study to focus on issue in automotive transaxle oil seal leakage to understand, grasp, and visualize the main cause through usage of CAE analysis process. It is understood that the point of contact and pump volume was related and this could contribute towards seals quality design. Plus, the utilization of CAE analysis in prediction phase to realized design development is also possible
基金supported by the National 863 Project(2011AA040701)
文摘The electro-hydraulic servo drive hydraulic cylinder has many unique advantages, such as fast response, high load stiffness, high control power, strong anti-eccentric load ability and so on, so it has been widely used in industrial control. Based on the guide sleeve of hydrostatic seal of hydraulic cylinder, the reasonable number of oil chamber of guide sleeve is studied in this paper. ICEM CFD software and FLUENT simulation software are used to calculate and analyze the number of different oil chambers of guide sleeve of hydrostatic seal. The temperature field of piston rod with different moving speed, different initial pressure of oil chamber and oil film under different number of oil chambers is analyzed. The relationship between the pressure field and temperature field provides a better basis for optimizing the design of hydrostatic guide sleeve and helps to improve the servo drive cylinder.