Paleotectonic Stress Field and Fracture Prediction of Silurian Longmaxi Formation in Jingmen Area,Western Hubei
The Silurian Longmaxi Formation shale reservoir in western Hubei is developed.Owing to the low porosity and low permeability of shale,tectonic fractures have become the main controlling factors of shale gas transport and accumulation.Taking the Silurian Longmaxi Formation shale in Jingmen area of western Hubei as an example,based on seismic data,rock mechanics experiment and field measurement data,finite element numerical simulations and rock fracture criteria are used to analyze the distribution law of the paleotectonic stress field and predict the distribution characteristics of tectonic fractures.The results show that the structural fractures developed in the Jingmen area are mainly NNW-trending and NE-trending conjugate shear fractures formed in late Middle Yanshan,followed by NNE-trending and Nee-trending conjugate shear fractures formed in early Middle Yanshan.The distribution of tectonic fractures is significantly affected by faults,petrophysical parameters,and tectonic stress.The fracture coefficients of grade Ⅲ fracture and fault zones are both greater than 1.1,indicating that the structural fractures are highly developed and that the shale gas preservation effect is minimal.The comprehensive fracture coefficient of grade Ⅱ fracture development area is between 1.0-1.1,indicating good shale gas preservation.The comprehensive fracture coefficient of the grade Ⅰ fracture development area is within 0.85-1.0,which is in the state of"fractured but not fractured"and is the best shale gas preservation area.
万方数据
维普
