Stress-sensitive Gas Reservoir Seepage Theory And Well Test Analysis Research

Nowadays,the development and utilization of natural gas for reducing greenhouse gas emissions,improving energy structure in our country,promoting the development of green economy is of great significance.Traditional seepage theory is based on the assumption of rigid media,namely porous media is micro compressible,and pressure has no effect on the physical properties of the rocks.With the development of various types of oil and gas fields and the use of complex structure wells,classical percolation theory and well test model has been the challenge of a variety of abnormal curves.A variety of numerical simulation technology based on the traditional percolation theory is not available in the development of the stress-sensitive gas reservoirs.Due to the gas reservoir formation pressure changing in the mining process,the changes of effective stress caused the changes of formation structure,reservoir properties changing.In this paper,firstly,considering deformation theory,reservoir seepage theory of stress sensitivity,and the solving methods about nonlinear flow model,the research status at home and abroad is summarized,and discussing the principle of effective stress in porous media,the deformation mechanism and influencing factors of porous media,and the mechanism of permeability reduction.Then,appling the exponential modulus to characterize the stress sensitive permeability,the stress sensitive testing models(single porous and radial composite single porous media,fractured and radial composite fractured media,multi-layer without crossflow and radial composite multi-layer media)are established.The type curves are drawed,and the effect of acting factors on these curves is analyzed.The applicability of the stress sensitive model is verified by examples.Finally the research achievement of well testing on stress sensitivity is obtained.