The Research On The Logging Rock Mechanics Analysis And Application In Anisotropic Shale Reservoir

With the demand of oil and gas increasing,people gradually explore from conventional sandstone reservoir to unconventional shale reservoir.Usually,shale formation has obvious stratification structure and anisotropic characteristics,especially the transverse isotropic(TI)characteristics.In shale gas mining process,we need drilling and fracturing in shale formation.Therefore,studying the mechanical properties of shale formation is the certain basis for borehole wall stability analysis and fracturing design.Often learning the shale formation mechanics characteristic can’t ignore the anisotropy.According to the above mentioned,this paper theoretically analyzes the transverse isotropic formation of the monopole dipole flexural wave and the stoneley wave of dispersion and sensitivity characteristics,then,using the two kinds of the guided wave inversion of the TI formation parameters,and comparing the inversion results of two methods.On this basis,TI parameter is used to calculate the rock mechanics and strength parameters.Also we studied the horizontal stress,formation fracture pressure and collapse pressure,finally investigated the stability of borehole wall and predicted the safety window of drilling mud slurry.Results show that,in the transversely fast isotropic formation,TI parameters and the size of anisotropy obtained from the dipole flexural wave inversion is more accurate,so that the horizontal in-situ stress is more reliable.The greater the anisotropy of formation,the difference of horizontal in-situ stress,between anisotropic medium and isotropic medium,is more obvious.When the equivalent density of drilling fluid density is lower than the collapse pressure,sidewall instability,collapse,hole enlargement and formation serious sand production,so that the overburden pressure is lower than the minimum horizontal stress.