Study On Tight Sandstone Gas Reservoirs With Logging Evaluation To Upper Paleozoic In Shilijiahan Zone,Hangjinqi Area

Tight sandstone gas has become an important field for increasing natural,It has become the main support China recent natural gas production increased rapidly.The buried depth of the sandstone reservoir in the Shilijiahan zone is very shallow,the gas source condition is sufficient,and the multi-layer gas system is developed,which has great exploration potential.Based on the detailed understanding of the geological characteristics and distribution characteristics of the tight sandstone gas reservoirs of the Shilijiahan zone in the Hangjinqi area,this paper uses well-logging,Geological-logging and laboratory analysis to carry out the study on the characteristics of the tight sandstone gas reservoirs in the study area.This paper analyzes the low resistance genesis of gas reservoirs in tight sandstone,studies the distribution law of formation water,and points out the influencing factors of gas and water distribution.The appropriate physical model of rock is established,(Formation water resistivity,porosity,permeability,saturation,etc.).The method of identifying the fluid properties was established by using a variety of logging data and mathematical methods,and the main factors of the production capacity The analysis system is divided into the favorable zone of gas-bearing,forming a suitable evaluation system of tight sandstone gas,laying the foundation for energy substitution and unconventional resource development.The main research process and achievements of this paper are as follows:(1)Based on the analysis of the core test data,the rock types of the Shiligakhan zone in the Hangjinqi area are mainly coarse and medium-grained quartz sandstone,clastic sandstone and silty mudstone,gas well log of electrical characteristics is not obvious,the physical properties of quartz sandstone are better than that of clastic sandstone,double pore structure obviously,the existence of large pores and micro pores,but still dominated by micropores.(2)To study and summarize the low resistance genesis of Upper Paleozoic gas reservoirs.The main factors affecting are the high water saturation and the developed of micropores.The secondary factors are the salinity of formation water,the mineral content of clay and the intrusion of drilling fluid.(3)The salinity distribution of formation water in the study area increases with depth in the vertical direction,and the resistivity of formation water decreases with increasing depth.In the horizontal direction,the salinity and resistivity of formation water distribution is not obvious;formation water is mainly calcium chloride,formation water to bound water,interlayer water and free water in the form of reservoirs,the production of water is mainly free water and after the transformation of the output of the inter-layer water.The distribution of formation water is mainly controlled by the physical properties and hydrocarbon generation intensity of the reservoir,and the local reservoir is affected by microstructure.(4)According to the existing data of the study area,the formation water resistivity is calculated by using the method of formation water salinity conversion method,natural potential calculation method,radial ratio method and apparent formation water resistivity calculation method.Through comparative analysis of the calculating results that the formation water resistivity is calculated by radial ratio method and formation water salinity conversion method.(5)The porosity was calculated by logging curve fitting method,formation component analysis method and multi-porous logging method.After comparison with the calculated results,the porosity was calculated by formation component analysis and establishment of the work area of the permeability calculation model by using the relationship between porosity and permeability.(6)Based on the lithology,pore structure and rock electrical parameters of the area,the optimal saturation model and the muddy correction saturation model are established.The two models can be used as the model of saturation in the study area and the shale content is high(more than 10%),the mudstone resistivity is relatively large,the shale correction saturation model is better.When the shale content is low(below 10%),the optimized saturation model is better.(7)Study on identification methods of gas reservoirs,including visual identification and pattern recognition.The identification parameters of the gas-water layer logging response are obtained by intuitively identifying the gas-water layer through the test data.The volume compression coefficient-Poisson's ratio envelope method has a good recognition effect in the intuitive identification.Using Fisher discriminant analysis method,singular value decomposition(SVD)method was used to identify the reservoir fluid identification.The comparison between the recognition results and the test gas-water data shows that the Fisher method is better and the SVD effect is the second.(8)The main factors affecting the production capacity in the study area are: shale content,porosity,permeability,water saturation,irreducible water saturation.Using the porosity,permeability,water saturation and sand body thickness map for favorable zone division.