In-depth Recognization Of Geological Characteristics And Evaluation Of Development Effect For XN Fault Reservoir

XN oil reservoir is a fault oil reservoir controlled by lithology and structure.The reservoir of XN oil reservoir is a medium-porosity and medium-permeability sandstone reservoir.It has strong water sensitivity characteristics.After more than 30 years of water injection development.the reservoir is currently in the development phase of high moisture content levels(82.8%).The plane contradictions and interlayer contradictions in the reservoir have gradually intensified.The degree of water drive and control in oil reservoir has reduced.The water injection of wells is serious ineffective.Therefore,this thesis adopts the static and dynamic methods to recognize the geological characteristics of XN fault reservoir and comprehensively evaluate the development effect in order to improve the development effect.Firstly,this thesis uses static and dynamic analysis means of single well to analyze the variation characteristics of reservoir parameters and the medium characteristics in the process of the reservoir development.Then,according to the existing data of reservoir,this thesis recognizes the variation characteristics of reservoir parameters such as microscopic throat size and influence of parameters changes on large properties of reservoirs.In this manner,this thesis recognizes the geological characteristics of XN fault reservoir.Afterwards,this thesis uses reservoir engineering means and fuzzy synthetic evaluation to evaluate the development effect of the reservoir.Finally,this thesis combines the geological characteristics to analyze the distribution characteristics of remaining oil in XN oil reservoir.The research shows that the connectivity of sand body is moderate and the reservoir has strong structural heterogeneity.The long-term water injection has caused a large number of particle migration in strong water-sensitive reservoirs.The drop of pressure in the later stage of reservoir development is relatively large.As a result,the microscopic throat size of the reservoir changes obviously,and finally the large properties of XN oil reservoir change significantly.The permeability of water injection wells generally shows a good trend,however,the permeability of inter-well in XN oil reservoir show a trend of deterioration at the later stage of reservoir development.Due to the influence of particle migration,the difference of permeability in interlayer also shows a weakening trend in the later stage of development,which indicates that the intensification of interlayer contradiction is mainly influenced by the structural heterogeneity and dominant channels in XN oil reservoir.XN fault reservoir is located in complex faults and has long-term water injection.The reservoir shows dual medium characteristics in some areas of the reservoir(near the main faults)during the production process.The dual medium characteristics of XN oil reservoir are not only beneficial to the water injection,but also likely to develop into dominant channels,which will aggravate the structural heterogeneity of the reservoir and result in poor water injection efficiency and water drive efficiency in some areas.The data of new well shows that the degree of water control and water drive is not high in some areas.Influenced by the sedimentary characteristics and dual medium characteristics in some areas,the effect directions are obvious,and the producing degree of water drive in horizontal and vertical distribution is imbalance,which indicate that the potential for further reservoir adjustment is large.The research of geological characteristics shows that the key to improve the effect of water injection and the producing degree of water drive is to effectively inhibit or eliminate invalid water caused by dominant channels.At present,the comprehensive evaluation of the development effect is Class ? level.The remaining oil of reserves has obvious difference in each sand layer.The remaining reserves in the main layers are still large,but the moisture content levels are high.As a result,it's difficult to make further development.The application of Advanced Production Decline Analysis methods and static analysis means can deeply analyze the physical characteristics and its changes of complex reservoirs from bottom to well.The method has some innovation,and it also can be used for reference in analyzing reservoir characteristics of similar complex fault reservoirs.