Study On Seepage Mechanism And Production Dynamic Characteristics Of Low Permeability Reservoir In Jingbian Gas Field

The low porosity and permeability of low permeability gas reservoir induce the percolation characteric is different from the conventional gas reservoir, which has the feater of nonlinearity percolation. This paper does some researches on the low permeability reservoir seepage characteristics and low permeability gas well production dynamic characteristics from the characteristics of the reservoir, filtration experiment and theory, production performance and other aspects, which are based on the research object of Jingbian gas field low permeability area, some conclusions are obtained as follows through this study:(1) Low velocity non-Darcy percolation characteristics and start-up pressure gradient exist in the Jingbian gas field reservoir rock, the later is related with irreducible water saturation, permeability and porosity. Start-up pressure gradient and reservoir rock permeability has good correlation, along with the increase of permeability, start-up pressure gradient in the way of natural logarithm of decline.(2) Jingbian gas reservoir has strong stress sensitivity, permeability stress sensitivity is strongger than the porosity stress sensitivity. Porosity, permeability and effective stress changes are shown to the power form.(3) Jingbian gas field low permeability gas wells producing water productivity decline is mainly affectec by the decline of formation pressure, reservoir stress sensitivity and reservoir formation water water invasion, reservoir formation water invasion and stress sensitive have great influence on the gas well productivity.(4) This paper establishes the low-permeability gas reservoir steady seepage flow models which are accord with the non-Darcy percolation law, and under the considering of start-up pressure gradient, stress sensitivity effect and gas slippage effect, what’s more, reduces productivity equations and the formation pressure distribution equations, draws and analyzes the corresponding influencing factors’stratum pressure distribution curves and IPR curves through some examples.(5) This paper establishes and solves the low-permeability gas reservoir unsteady seepage flow models unde the considering of threshold pressure gradient, stress-sensitive effects and gas slippage effect, in addition, draws corresponding pressure dynamic curves under the method of Stehfest numerical inversion algorithm, analyzes pressure dynamic curves of the influencing factors and feathers.(6) From the7layers group (Mawu1, Mawu2, Mawu3, Mawu4, Shihezi group, Benxi group and Shanxi group) in south two area of Jingbian gas field, Mawul is the main production gas reservoir, other strata group contribution in the gas production all maintained relatively low.The research of this paper offers some theoretical foundation and technical support to enhance the development effect of low-permeability gas reservoir in Jingbian gas field, also means much significant sense to the development of the other similar reservoir.