Logging Evaluation Method Research Of Shale Reservoir On The Lower Cambrian Niutitang Formation In Cengong Block,Guizhou Province

The target layer of shale gas exploration in the Zhigong block of Guizhou is the Lower Cambrian Niutitang Formation,which is one of the very few shale gas blocks that have been successfully fractured and fired in this layer,and has great exploration potential.At present,the overall exploration and development of this layer is still in the beginning and exploration stage.Because of the complex lithology and pore structure of shale reservoirs and the influencing factors of compressibility,it is difficult to comprehensively evaluate shale gas reservoirs.Therefore,the comprehensive reservoir evaluation of target reservoirs in the study area was conducted in this paper.Shale gas reservoirs provide basis and guidance for fracturing construction.In this paper,using geology data,analysis and analysis data,logging data,and well logging data,we first established a lithology identification map,and adopted a combination of an improved BP neural network model and electrical imaging logging to identify lithology.Then,using the empirical formula method,improved?1gR method and multi-log curve regression method,a reservoir parameter calculation model was established.Fracture development sections were identified by wavelet transform,and fracture parameters were counted.The high-pressure mercury injection experiment data was used to calibrate the nuclear magnetic T₂ spectrum,and the pore structure parameters and pore structure classification were calculated.The grey correlation analysis method was used to complete the reservoir classification evaluation,and the fracturing index calculation model was established using the analytic hierarchy process.Finally,the fracturing intervals are preferably combined with the reservoir classification evaluation and compressibility evaluation results to complete the comprehensive evaluation of reservoir logging.The study finds that the intersection chart can better distinguish the four major types of lithology:shale,mudstone,sandstone,and limestone,but the distinction between siliceous mudstone,silty mudstone,siliceous shale,and shale is not obvious.The improvement of BP neural network lithology recognition accuracy rate reached 80%.By comparing the reservoir parameters and core analysis data calculated by logging between TX1 well and TM1 well Niutitang group,the correlation is between 0.61 and 0.86,and the average relative error is between 0.07%and 0.28%,which proves that the calculation model is reliable.High sex.By counting the conventional logging response characteristics of fractures,using wavelet threshold denoising and extracting wavelet high-frequency properties,it is possible to better identify the fracture development zones of shales.The porosity of the Niutitang shale is between 1%and 5%,the microscopic pore size is mainly distributed between 0.01 and 10?m,and the organic pores and mineral intergranular pores are mainly developed.The shale reservoirs with the microfracture development section generally larger than 1.0?m The layer can be better fracturing.The total gas content,porosity,total organic carbon content,effective thickness,brittle mineral content,permeability,and maximum throat throat radius were used as evaluation parameters for shale gas reservoir classification,while rock brittleness,brittle mineral content,organic carbon content,and clay Mineral content,fracture toughness,and horizontal in-situ stress are used as evaluation parameters for fractureability to complete the evaluation of compressibility of shale gas reservoirs.Micro-seismic monitoring results show that the fractures are developed near the wellbore after fracturing,indicating that the fractures can be fractured.The results of sexual assessment are more accurate.