Kinds of complex-structure wells can effectively improve production,which are widely used.However,in the process of drilling and completion,complex-structure wells with long drilling cycle and large exposed area of re...Kinds of complex-structure wells can effectively improve production,which are widely used.However,in the process of drilling and completion,complex-structure wells with long drilling cycle and large exposed area of reservoir can lead to the fact that reservoir near wellbore is more vulnerable to the working fluid invasion,resulting in more serious formation damage.In order to quantitatively describe the reservoir formation damage in the construction of complex-structure well,taking the inclined well section as the research object,the coordinate transformation method and conformal transformation method are given according to the flow characteristics of reservoir near wellbore in anisotropic reservoir.Then the local skin factor in orthogonal plane of wellbore is deduced.Considering the un-even distribution of local skin factor along the wellbore,the oscillation decreasing model and empirical equation model of damage zone radius distribution along the wellbore direction are established and then the total skin factor model of the whole well is superimposed to realize the reservoir damage evaluation of complex-structure wells.Combining the skin factor model with the production model,the production of complex-structure wells can be predicted more accurately.The two field application cases show that the accuracy of the model can be more than 90%,which can also fully reflect the invasion characteristics of drilling and completion fluid in any well section of complex-structure wells in anisotropic reservoir,so as to further provide guidance for the scientific establish-ment of reservoir production system.展开更多
The key to realize the commercial production of natural gas hydrate(NGH)is to increase theNGH productivity significantly in the scale of magnitude.Whether NGH production can be commercialized depends on two aspects.Th...The key to realize the commercial production of natural gas hydrate(NGH)is to increase theNGH productivity significantly in the scale of magnitude.Whether NGH production can be commercialized depends on two aspects.The first is whether the in-situ recoverable reserves are large enough to support the basic production period for commercial production.The second is whether the average productivity can reach the standard for commercial production.In this paper,we will analyze mainly about the potential stimulation technologies for NGH development,and discuss about the basic principles,the evaluation methods,and the technical bottlenecks for NGH production and stimulation.The results indicate that the main mechanisms for increasing theNGH productivity are in three respects,namely enlarging the drainage area,increasing the NGH dissociation efficiency,and improving the seepage conditions.With complex-structure wells and multiple-well patterns,combined with novel production methods and/or reservoir stimulation technologies,the NGH productivity can be increased greatly.Particularly,the complexstructure wells and well patterns are very important for increasing NGH productivity.With complex-structure wells and well patterns,combined with heat injection and/or reservoir stimulation,NGH productivity can be increased on a magnitude scale.Currently,in fundamental researches,there are some technical bottlenecks for the studies of NGH production,mainly in sample preparation,simulated reservoir monitoring,and mechanical coupling technologies.Therefore,it is suggested that the study focuses should be on the above technical bottlenecks during the basic research on how to increase the NGH productivity.It is concluded that the combined application of complex-structure wells(horizontal wells and multi-lateral wells),well-pattern production models(with multi-cluster/group well production),the novel production methods(mainly thermal stimulation,together with depressurization),and reservoir stimulation technologies(hydraulic fracturing)are the keys to increase NGH productivity in the scale of magnitude.展开更多
基金supported by National Natural Science Foundation of China(Grant No.52004297 and Grant No.51991361)China Postdoctoral Science Foundation(Grant No.BX20200384)。
文摘Kinds of complex-structure wells can effectively improve production,which are widely used.However,in the process of drilling and completion,complex-structure wells with long drilling cycle and large exposed area of reservoir can lead to the fact that reservoir near wellbore is more vulnerable to the working fluid invasion,resulting in more serious formation damage.In order to quantitatively describe the reservoir formation damage in the construction of complex-structure well,taking the inclined well section as the research object,the coordinate transformation method and conformal transformation method are given according to the flow characteristics of reservoir near wellbore in anisotropic reservoir.Then the local skin factor in orthogonal plane of wellbore is deduced.Considering the un-even distribution of local skin factor along the wellbore,the oscillation decreasing model and empirical equation model of damage zone radius distribution along the wellbore direction are established and then the total skin factor model of the whole well is superimposed to realize the reservoir damage evaluation of complex-structure wells.Combining the skin factor model with the production model,the production of complex-structure wells can be predicted more accurately.The two field application cases show that the accuracy of the model can be more than 90%,which can also fully reflect the invasion characteristics of drilling and completion fluid in any well section of complex-structure wells in anisotropic reservoir,so as to further provide guidance for the scientific establish-ment of reservoir production system.
基金Project supported by the National Key R&D Project“Application Demonstration of Trial Production,Environmental Monitoring and Comprehensive Evaluation of Hydrate”(No.:2017YFC0307600)Shandong Provincial Taishan Scholars Special Expert Project(No.ts201712079)Shandong Provincial Natural Science Foundation Project“Numerical Simulation of the Influence of Hydraulic Cutting on the Productivity of Depressurization Production of Silty Hydrate in the South China Sea”(No.ZR2019BD058).
文摘The key to realize the commercial production of natural gas hydrate(NGH)is to increase theNGH productivity significantly in the scale of magnitude.Whether NGH production can be commercialized depends on two aspects.The first is whether the in-situ recoverable reserves are large enough to support the basic production period for commercial production.The second is whether the average productivity can reach the standard for commercial production.In this paper,we will analyze mainly about the potential stimulation technologies for NGH development,and discuss about the basic principles,the evaluation methods,and the technical bottlenecks for NGH production and stimulation.The results indicate that the main mechanisms for increasing theNGH productivity are in three respects,namely enlarging the drainage area,increasing the NGH dissociation efficiency,and improving the seepage conditions.With complex-structure wells and multiple-well patterns,combined with novel production methods and/or reservoir stimulation technologies,the NGH productivity can be increased greatly.Particularly,the complexstructure wells and well patterns are very important for increasing NGH productivity.With complex-structure wells and well patterns,combined with heat injection and/or reservoir stimulation,NGH productivity can be increased on a magnitude scale.Currently,in fundamental researches,there are some technical bottlenecks for the studies of NGH production,mainly in sample preparation,simulated reservoir monitoring,and mechanical coupling technologies.Therefore,it is suggested that the study focuses should be on the above technical bottlenecks during the basic research on how to increase the NGH productivity.It is concluded that the combined application of complex-structure wells(horizontal wells and multi-lateral wells),well-pattern production models(with multi-cluster/group well production),the novel production methods(mainly thermal stimulation,together with depressurization),and reservoir stimulation technologies(hydraulic fracturing)are the keys to increase NGH productivity in the scale of magnitude.
