It is very difficult to evaluate the productivity of horizontal wells in fault block reservoirs due to the influence of fault sealing.On the basis of the method of images and source-sink theory,a semianalytical model ...It is very difficult to evaluate the productivity of horizontal wells in fault block reservoirs due to the influence of fault sealing.On the basis of the method of images and source-sink theory,a semianalytical model coupling reservoir and finite conductivity horizontal wellbore flow dynamics was built,in which the influence of fault sealing was taken into account.The distribution of wellbore flow and radial inflow profiles along the horizontal interval were also obtained.The impact of the distance between the horizontal well and the fault on the well productivity was quantitatively analyzed.Based on this analysis,the optimal distance between the horizontal well and the fault in banded fault block reservoirs could be determined.According to the field application,the relative error calculated by the model proposed in this paper is within ±15%.It is an effective evaluation method for the productivity of horizontal wells in fault block reservoirs.The productivity of the horizontal well increases logarithmically as the distance between the horizontal well and the fault increases.The optimal distance between the horizontal well and the fault is 0.25-0.3 times the horizontal well length.展开更多
In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir typ...In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir type, the comparability and practicality of quantitative assessment will be emerging. The evaluation system should include three parts: data verification, geological understanding and process check. Data verification mainly involves testing the accuracy of local prediction with actual data, and geological understanding is to examine whether the global estimation honors geological principles and prior insights. Process check is also indispensable to avoid occasionality. To this end, we produced a set of assessment criteria, taking complex fault-block sandstone oil reservoir as an example. To be specific, thirteen characteristic parameters were totally selected, setting weights according to their rated importance, formulating three-level evaluation standards in a centesimal system for each characteristic parameter, and obtaining the final assessment based on the cumulative score. The results indicate that such evaluation can not only access the quality of the model objectively and comprehensively, but also identify the aspects in need of improvement through the deduction items.展开更多
This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development pr...This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development process of fault block reservoirs. Considering the heterogeneity of reservoir, the Buckley-Leverett water flooding theory was applied to establish the relationship between the recovery and cumulative water injection. In order to achieve the goal of vertically balanced recovery of each section, the calculation method of vertical sectional injection allocation was proposed. The planar triangular seepage unit was assumed and sweep coefficients of different oil-water distribution patterns were characterized using multi-flow tube method. In order to balance and maximize the plane sweep coefficient, the calculation method of plane production system optimization was obtained. Then the injection-production system stereoscopic adjustment method based on equilibrium displacement was proposed with vertical sectional injection allocation and plane production system optimization. This method was applied to injection and production adjustment of BZ oilfield in southern Bohai. The effect of water control and oil increase was obvious. This method can greatly improve the effect of water flooding of offshore fault block reservoirs with the adjustment of injection-production system.展开更多
Bozhong A Oilfield is located in the northeast of Huanghekou Sag in the Bohai Bay Basin, and is a complex fault block oilfield. The main oil bearing horizon is the lower Minghuazhen Member, belonging to shallow water ...Bozhong A Oilfield is located in the northeast of Huanghekou Sag in the Bohai Bay Basin, and is a complex fault block oilfield. The main oil bearing horizon is the lower Minghuazhen Member, belonging to shallow water delta sedimentation. For the rolling exploration and evaluation of adjacent fault blocks, this paper uses the mudstone smear method to analyze and accurately characterize the lithological contact relationship between the two walls of the fault. Based on the establishment of different reservoir docking modes on the two walls of the fault, the sealing parameters are calculated to evaluate the sealing ability of the fault, thereby evaluating its reservoir formation characteristics, and predicting the height of the oil column. The above methods provide geological basis for further rolling expansion and potential tapping in the study area and surrounding areas, and have guiding significance for exploration and rolling potential tapping in similar blocks in the Bohai Sea.展开更多
Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechani...Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechanical experiments,logging interpretation,and seismic data,a 3 D geological model and heterogeneous rock mechanics field of the reservoir were constructed.Finite element simulation techniques were then used for the detailed prediction of the 3 D stress field.The results indicated that the maximum horizontal stress orientation in the study area was generally NEE-SWW trending,with significant changes in the in situ stress orientation within and between fault blocks.Along surfaces and profiles,stress magnitudes were discrete and the in situ stress belonged to theⅠa-type.Observed inter-strata differences were characterized as five different types of in situ stress profile.Faults were the most important factor causing large distributional differences in the stress field of reservoirs within the complex fault blocks.The next important influence on the stress field was the reservoir’s rock mechanics parameters,which impacted on the magnitudes of in situ stress magnitudes.This technique provided a theoretical basis for more efficient exploration and development of low-permeability reservoirs within complex fault blocks.展开更多
Fault block reservoirs are one of the main types of hydrocarbon reservoirs found in offshore basins,and they are widely distributed within the Mesozoic and Cenozoic basins of the northern South China Sea.Conventional ...Fault block reservoirs are one of the main types of hydrocarbon reservoirs found in offshore basins,and they are widely distributed within the Mesozoic and Cenozoic basins of the northern South China Sea.Conventional seismic profiles of complex fault areas often contain obvious fragmentation and distortion of seismic events that is corresponding to geological structure under the fault.This phenomenon is known as a fault shadow;it occurs in relation to rapid changes in velocity near the fault that deviate the ray path of waves,and it seriously affects the ability to determine the geological structure and subsequently evaluate the reserves of fault reservoirs.In the current conventional tomography inversion method,the velocity model is over-smoothed,which results in distortion of the reflection layer under the fault.Based on the velocity tomography inversion of imaging gathers method and the concept of regularization,this paper first introduces the anisotropy Gauss regularization operator.A high-resolution tomography inversion method is then developed,and the fault-controlled geological guidance is constrained.This technology is then applied to a complex fault block reservoir basin in the South China Sea,and the results show that it can significantly solve the problem of fault shadow imaging and determine the geological structures in the target area.The newly developed method thus has very good application prospects.展开更多
基金support from the National Science & Technology Major Project of China (No. 2009ZX05009-006)the China National Offshore Oil Corporation (CNOOC)
文摘It is very difficult to evaluate the productivity of horizontal wells in fault block reservoirs due to the influence of fault sealing.On the basis of the method of images and source-sink theory,a semianalytical model coupling reservoir and finite conductivity horizontal wellbore flow dynamics was built,in which the influence of fault sealing was taken into account.The distribution of wellbore flow and radial inflow profiles along the horizontal interval were also obtained.The impact of the distance between the horizontal well and the fault on the well productivity was quantitatively analyzed.Based on this analysis,the optimal distance between the horizontal well and the fault in banded fault block reservoirs could be determined.According to the field application,the relative error calculated by the model proposed in this paper is within ±15%.It is an effective evaluation method for the productivity of horizontal wells in fault block reservoirs.The productivity of the horizontal well increases logarithmically as the distance between the horizontal well and the fault increases.The optimal distance between the horizontal well and the fault is 0.25-0.3 times the horizontal well length.
基金Supported by the Sinopec Science and Technology Major Project(G5800-17-ZS-KJB009)
文摘In the field of 3 D geologic modeling, researchers often pay more attention to modeling methods and workflows, but neglect the quantitative evaluation of models. If the evaluation is narrowed to the same reservoir type, the comparability and practicality of quantitative assessment will be emerging. The evaluation system should include three parts: data verification, geological understanding and process check. Data verification mainly involves testing the accuracy of local prediction with actual data, and geological understanding is to examine whether the global estimation honors geological principles and prior insights. Process check is also indispensable to avoid occasionality. To this end, we produced a set of assessment criteria, taking complex fault-block sandstone oil reservoir as an example. To be specific, thirteen characteristic parameters were totally selected, setting weights according to their rated importance, formulating three-level evaluation standards in a centesimal system for each characteristic parameter, and obtaining the final assessment based on the cumulative score. The results indicate that such evaluation can not only access the quality of the model objectively and comprehensively, but also identify the aspects in need of improvement through the deduction items.
文摘This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development process of fault block reservoirs. Considering the heterogeneity of reservoir, the Buckley-Leverett water flooding theory was applied to establish the relationship between the recovery and cumulative water injection. In order to achieve the goal of vertically balanced recovery of each section, the calculation method of vertical sectional injection allocation was proposed. The planar triangular seepage unit was assumed and sweep coefficients of different oil-water distribution patterns were characterized using multi-flow tube method. In order to balance and maximize the plane sweep coefficient, the calculation method of plane production system optimization was obtained. Then the injection-production system stereoscopic adjustment method based on equilibrium displacement was proposed with vertical sectional injection allocation and plane production system optimization. This method was applied to injection and production adjustment of BZ oilfield in southern Bohai. The effect of water control and oil increase was obvious. This method can greatly improve the effect of water flooding of offshore fault block reservoirs with the adjustment of injection-production system.
文摘Bozhong A Oilfield is located in the northeast of Huanghekou Sag in the Bohai Bay Basin, and is a complex fault block oilfield. The main oil bearing horizon is the lower Minghuazhen Member, belonging to shallow water delta sedimentation. For the rolling exploration and evaluation of adjacent fault blocks, this paper uses the mudstone smear method to analyze and accurately characterize the lithological contact relationship between the two walls of the fault. Based on the establishment of different reservoir docking modes on the two walls of the fault, the sealing parameters are calculated to evaluate the sealing ability of the fault, thereby evaluating its reservoir formation characteristics, and predicting the height of the oil column. The above methods provide geological basis for further rolling expansion and potential tapping in the study area and surrounding areas, and have guiding significance for exploration and rolling potential tapping in similar blocks in the Bohai Sea.
基金financially supported by the National Oil and Gas Major Project(2016ZX05047-003,2016ZX05014002-006)the National Natural Science Foundation of China(41572124)the Fundamental Research Funds for the Central Universities(17CX05010)
文摘Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechanical experiments,logging interpretation,and seismic data,a 3 D geological model and heterogeneous rock mechanics field of the reservoir were constructed.Finite element simulation techniques were then used for the detailed prediction of the 3 D stress field.The results indicated that the maximum horizontal stress orientation in the study area was generally NEE-SWW trending,with significant changes in the in situ stress orientation within and between fault blocks.Along surfaces and profiles,stress magnitudes were discrete and the in situ stress belonged to theⅠa-type.Observed inter-strata differences were characterized as five different types of in situ stress profile.Faults were the most important factor causing large distributional differences in the stress field of reservoirs within the complex fault blocks.The next important influence on the stress field was the reservoir’s rock mechanics parameters,which impacted on the magnitudes of in situ stress magnitudes.This technique provided a theoretical basis for more efficient exploration and development of low-permeability reservoirs within complex fault blocks.
基金the National Science and Technology Major Project of China(No.2016ZX05026-002)the National Natural Science Founda-tion of China(Nos.42106072,42074138)+4 种基金the Shandong Provincial Natural Science Foundation(No.ZR2020QD071)the Major Scientific and Technological Innovation Project of Shandong Province(No.2019JZZY010803)the Fundamental Research Funds for the Central Universities(No.201964016)the Shandong Province post-doctoral in-novation projects of special funds(No.201903079)the China Scholarship Council(No.201906335010).
文摘Fault block reservoirs are one of the main types of hydrocarbon reservoirs found in offshore basins,and they are widely distributed within the Mesozoic and Cenozoic basins of the northern South China Sea.Conventional seismic profiles of complex fault areas often contain obvious fragmentation and distortion of seismic events that is corresponding to geological structure under the fault.This phenomenon is known as a fault shadow;it occurs in relation to rapid changes in velocity near the fault that deviate the ray path of waves,and it seriously affects the ability to determine the geological structure and subsequently evaluate the reserves of fault reservoirs.In the current conventional tomography inversion method,the velocity model is over-smoothed,which results in distortion of the reflection layer under the fault.Based on the velocity tomography inversion of imaging gathers method and the concept of regularization,this paper first introduces the anisotropy Gauss regularization operator.A high-resolution tomography inversion method is then developed,and the fault-controlled geological guidance is constrained.This technology is then applied to a complex fault block reservoir basin in the South China Sea,and the results show that it can significantly solve the problem of fault shadow imaging and determine the geological structures in the target area.The newly developed method thus has very good application prospects.
