Well Logging Evaluation Of Igneous Gas Reservoir In Yingcheng Formation Of LS1 Well Area

LS1 well area was evaluated and developed in 2012,and 5 development wells were deployed,all gas testing obtained over 10,000 cubic meters of industrial gas flow.However,limited by the geological understanding at that time,production process,gas price and other factors,the scale benefit of the well area was not realized.Up to now,LS1 well area still has great potential for development.This paper takes the igneous gas reservoir of yingcheng formation in LS1 well area as the research object,and conducts indepth research from four aspects,namely,igneous rock lithology identification,reservoir space type research,reservoir parameter calculation and comprehensive reservoir logging evaluation.According to the actual development of igneous rock in yingcheng formation of the study area,guided by the idea of sequential separation,the lithology of igneous rock was identified by crossplot method and TAS chart method successively.On the basis of fully analyzing the well logging response characteristics of each lithology,combined with logging data and microscopic identification results,a relatively systematic lithology identification standard for igneous rock is established.A comprehensive study of reservoir space types and their development was conducted by using clear casting film and intuitive imaging images.According to the different configuration relations and combination modes among the small opening,holes and fractures,the reservior can be devided into three types:cavernous reservoir,fracture-vuggy reservoir and fractured reservoir,and the well logging response characteristics of each type of reserviors are implemented.In terms of reservoir parameter calculation,the effective porosity and permeability interpretation model are established by lithology based on the NMR logging results,abundant core analysis data and well logging response characteristics,the error analysis of the model results is also carried out,and the average absolute error of porosity calculated by the model is only 0.77%.By summarizing the conventional logging response characteristics of fractures,the qualitative identification of fractures is explored by using conventional logging ratio method.It is found that the ratio method can effectively identify fractures on the premise of consistent lithology,and the related parameters of fractures are quantitatively obtained by using imaging logging data.The curve overlapping method is used to identify reservoir fluid properties,in which the neutron logging curve has obvious"excavation"effect in the gas interval,so that the neutron-density curve can be overlapped to a large extent in reverse,and the gas layer can be identified effectively.Then,the pore availability and fracture availability of the reservoir are evaluated by using the NMR logging data and dipole shear wave logging data,meanwhile,using conventional log interpretation results,combined with the oil test and production conclusion calibration the lower limit of effective reservoir:R_t?16?·m,??9%,S_w?55%.Through the above research,finally,a relatively complete well logging evaluation system of igneous gas reservoir is established.