Study On Micro-pore Structure And Seepage Characteristics Of Chang 6₁ Reservoir In Ganguyi Region

Chang 6 reservoir in Ganguyi block has been highly developed.Distribution as well as relationship between oil and water is complex and changeable.Based on reasons above,rules for development and flooding properties both have changed,which leads to a serious contradiction in injection-production and a low recovery efficiency in production.Little research has been done on micro-pore structure and seepage characteristics of Chang 6₁ reservoir until now.To deal with these problems,this thesis conducts study on microscopic pore structure and seepage mechanism of Chang 6₁ sandstone reservoir by making a comprehensive comparison and analysis of T80 and T157 well areas in Ganguyi block.Based on experiments such as casting thin slice,SEM,high pressure mercury injection and constant-speed mercury injection,etc.,this dissertation analyzed the characteristic of micro-pore structure quantitatively and qualitatively.Further experiments including nuclear magnetic resonance,oil-water relative permeability and real sandstone water-oil displacement have also been carried out to characterize micro-seepage mechanism.This thesis also conducts a study on the influence of different pore structure and seepage characteristics on production by combining dynamics and statics data.Several achievements which have been acquired during study process are presented as follows:?1?Chang 6₁ reservoir has a poor physical property generally?the average porosity is 8.45%and the average permeability is 1.1×10-3?m2?.The rock is mainly consist of arkose and serious heterogeneity has been found in target reservoir.The diagenesis are serious,the compaction and pressure-solution?dissolution?and cementation influence the physical property and the micro-pore structure significantly.?2?Chang 6₁ reservoir has various pore types.The main types are intergranular pore and secondary dissolution pore and they are always formed mixed pore types.The major pore combination type is dissolution-intergranular pore which makes the largest contribution to reservoir pore space.Facial porosity in T80 block is relatively higher than T157 with an average value of 3.12%and 2.85%respectively.The main throat types are punctiform and punctiform-schistose in Chang 6₁ reservoir.?3?Different pore and throat types have similar pore radius,but their throat and pore throat ratio are significantly different;the results show that the development degree of the throat and the configuration relationship between pore and throat are the main reason for the difference of pore structure.Through comparison and analysis of data,we can conclude that T80 block has a better pore type than T157.?4?Through the analysis of experimental data,The saturation of movable fluid in Chang 6₁ reservoir is low with an average value of 34.27%,the range of the two phase of oil-water seepage zone is also small,the interference degree is serious and the seepage capacity is poor,and the oil displacement efficiency is low which has an average of 25.76%.The characteristics and distribution of microscopic pore structure have controlled the seepage ability of the reservoir,and the corresponding movable fluid is mainly distributed in the large pore throat which has good connectivity.Through analyzing the dynamic data of single well with different pore structure indicate that the characteristics of microscopic pore structure are the key factors to influence the development and production.