Study On Logging Evaluation Method Of Upper Paleozoic Tight Sandstone Reservoir In S Area Of Central And Eastern Henan

Coal mining and coalbed methane drainage are traditionally the main methods in Area S,but in the production process,it was found that the sandstone section of the Upper Paleozoic coal measure strata also had high gas logging display.In order to do a good job in the exploration and development of tight sandstone gas in the study area,this paper takes the Upper Paleozoic Lower Shihezi Formation,Shaguoyao sandstone and Dazhan sandstone in Shanxi Formation as the main research objects,and conducts the logging evaluation research of tight sandstone reservoirs in the target interval to serve the exploration and development.Based on a large amount of literature research,this paper combed the main methods of tight sandstone,lithology identification,physical property prediction,gas bearing evaluation,and rock mechanics parameter interpretation.Combining the collected geological,core testing,gas logging and logging data.Firstly,the pre-processing of logging curves was carried out.Secondly,the stratigraphic framework of the study area was established through stratigraphic division and correlation.Then,the models of lithology identification,physical property evaluation,gas bearing prediction,rock mechanics and in-situ stress prediction were established respectively.Finally,the horizontal and vertical plane distribution of reservoir parameters in the target interval is studied by using the optimized model.The study shows that in the tight sandstone reservoirs in Area S,the sand pot kiln sandstone at the bottom of the lower stone box and the Dazhan sandstone in the middle of Shanxi Formation are relatively stable in distribution and better in gas logging.Lithology is mainly gray Shi Ying medium-fine sandstone mixed with dark mudstone,minerals are mainly Shi Ying,containing a small amount of feldspar and debris.In this paper,this interval is taken as the main target layer,and qualitative lithologic identification based on principal component analysis intersection graph method and Fisher discriminant analysis has achieved good results.The shale content is predicted by the combination method of natural potential and natural gamma,with the average content ranging from 3% to 26%.The porosity and permeability prediction model established by multiple regression method predicts that the porosity distribution is in the range of 3.02%-5.16%,and the permeability distribution is in the range of 0.014-1.294×10-3?m2,which has good consistency with the range of porosity and permeability tested.Qualitative identification of gas layer is carried out by intersection graph method and curve overlapping method.Quantitative evaluation of gas saturation is carried out by Archie formula method based on elastic modulus constraint of gas measurement scale.The calculated gas saturation is evenly distributed between 33% and 67%,which is in good agreement with gas measurement data.Finally,the dipole shear wave data is used to fit the vertical and horizontal wave conversion model,the previous dynamic and static elastic parameter conversion model is used to complete the conversion,and the improved Newbery model is used to calculate the in-situ stress to complete the rock mechanics and in-situ stress evaluation.Finally,the single well vertical profile analysis and the plane reservoir parameter distribution evaluation of the target interval are completed by combining the above models.