Research Of The Shale Gas Flow Lows In The Porous Medium

As an important kind of unconventional natural gas resources, shale gas has theadvantages of low carbon and clean, Countries around the world pay more and more attentionto it.Now the United States is the earliest country for the shale gas resources development inthe world,and the technology is the most mature, China is still in the early stage of the shalegas exploration and development, so for the research of flowing mechanism and explorationabout the shale gas,many problems need to solve.Shale gas reservoir has the characteristics oflow porosity, low permeability, there are many influence factors for shale gas seepage, flowcharacteristics are complex. Many scholars discussed on the seepage of the shale gas, butmost of these models contained only part of the mechanisms of the shale gas seepage. Basedon the complex pore structure and slippage on nanometer pore surface of the shale gas, andthe diffusion from the matrix system to the fracture system, through the establishment ofsingle phase flow model of natural gas, this paper more comprehensive elaborates shale gasflow mechanism and slippage and diffusion characteristics of shale gas flow. Analysis showsthat: Darcy flow rate is proportional to the pressure gradient and permeability, formationpressure does not affect the darcy flow volume flow. Slippage and diffusion effect is obviousin low pressure, the proportion of diffusion flow is larger, darcy flow is given priority to theseepage in high pressure; gas slippage effect weakened with the increase of pressure.Diffusion is similar to slippage on effects to shale gas flow: With the increase of formationpressure, the diffusion decreased significantly, the percentage is small in high pressure. Thesensitivity to the pressure of the diffusion is greater than the slippage, this is because that theslippage is inversely proportional with the pressure,and the diffusion is inversely proportionalwith the square of the pressure. Based on the study of the characteristics and seepagemechanism of the shale gas reservoir, we establish a flow model which incorporated diffusionand slippage effect, further analysis on the influencing factors of shale gas production.Thesisresearch results provides the basic theory basis for the shale gas exploration and development,and evaluation of reserves.