Analysis of Structural Fracture Characteristics and Formation Stages of Carbonate Rocks:A Case Study from the Eastern Right Bank of the Amu Darya Basin
Carbonate fractures are of great significance to the exploration and development of oil and gas,but the description,for-mation and influencing factors of carbonate structural fractures have always been the focus of oil and gas reservoir research.Based on the data of core,logging interpretation and analysis of test data,the characteristics of structural fractures in the Jurassic Callovian-Ox-fordian carbonate reservoirs in the eastern part of the right bank of the Amu Darya Basin were studied.The types and development sta-ges of structural fractures were divided,the influencing factors affecting the development of structural fractures were clarified,and the influence of multi-stage fractures on natural gas accumulation was analyzed.The results show these as follows.Structural fractures are the main types of fractures developed in the Jurassic Callovian-Oxfordian reservoirs on the eastern right bank of the Amu Darya Basin.According to the occurrence,the structural fractures are divided into horizontal fractures,low-angle fractures,high-angle fractures and vertical fractures.In general,the structural fractures of the Callovian-Oxfordian reservoir are mainly NW-SE trending,but the strikes of different fractures are quite different,reflecting the characteristics of multi-stage development of fractures.There are differences in the occurrence,density and scale of different types of structural fractures.The middle and lower Jurassic XVa1 layer is the most developed,with an average fracture density of 1.48/m.The scale of structural fractures is generally large.The fracture width and frac-ture height are the largest in the XVhp layer of the Upper Jurassic,with an average fracture width of about 0.08 mm and an average fracture height of 67.1 cm.The dip angle of structural fractures is mostly between 40° and 70°.There are great differences in the de-velopment degree of structural fractures in the Jurassic Callovian-Oxfordian reservoirs in the eastern right bank of the Amu Darya Basin.The development of fractures is not only controlled by lithology,but also influenced by multi-stage tectonic movement.Bright crystal sand limestone and reef limestone are the dominant lithology for the development of structural fractures.The strong compression in the Neogene formed interlaced network fractures in the Jurassic Callovian-Oxfordian cores,which provided favorable evidence for the divi-sion of fracture stages.The structural fractures of the Jurassic Callovian-Oxfordian Stage in the eastern part of the right bank of the Amu Darya Basin were formed from the late Yanshanian to the middle Himalayan.The formation of late fractures not only improves reservoir physical properties,but also promotes natural gas accumulation.
Amu Darya Basinstructural fractureperiod analysisnatural gas accumulation
万方数据
维普
