Using Well Logging Data To Study The Evolution Of Clay Minerals

Clay minerals are the most abundant minerals in strata.They are an important component of mud and shale,as well as an important cement and part of skeleton composition in sandstone.Other types of rocks also contain different types and contents of clay minerals,which can be seen everywhere in strata.The composition,content and physical and chemical properties of clay minerals in rocks are closely related to the physical properties of sandstone reservoirs,and also closely related to the quality of mudstone cap.The study of clay minerals in strata is of great significance for the protection,exploration and development of oil and gas resources.Firstly,the effects of various clay minerals on well logging curves and their well logging response characteristics were summarized,and the clay minerals were qualitatively identified in several Wells in the study area by using the crossplot method.Secondly,the multi-regression mathematical model and the multi-mineral inversion optimization processing calculation model of Quanti.Elan module based on well logging interpretation and processing software are obtained by crossfitting the well logging response values of uranium,thorium and potassium in the logging data and clay mineral core analysis data.Thus,the specific content of clay minerals in multiple wells in the study area is calculated.Both mathematical calculation models are in good agreement with the core analysis data.The result of calculation is good.Finally,the evolution characteristics of clay minerals from several wells in the study area were analyzed,and it was found that the content of clay minerals in the normal compaction section of the study area was relatively stable without significant change.At a certain depth,montmorillonite was transformed into illite,and the depth of montmorillonite transformation was about 1500 meters in the deep water area.In shallow water area,the well of transformation from montmorillonite to illite conversion depth ranges from about 1900 to 2800 meters.In the subsequent depth section,the content of kaolinite also begins to decrease,while the content of illite continues to increase.In this case,illite is the main component of clay minerals.The longitudinal variation of clay mineral content in depth profile in the study area accords with the general rule of clay mineral alteration in strata.Using well logging information to study the type and content of clay minerals and their diagenetic evolution characteristics in mudstone can provide some basic parameters and certain reference significance for further reservoir prediction and well logging interpretation in the study area.