鄂尔多斯盆地低渗透砂岩气藏压裂模型的建立

近几年针对低渗透油藏的压裂提出了一整套优化方法，而对低渗透气藏压裂还没有进行系统的研究，导致气层改造强度不够或者过大，从而影响气藏的开采效果。根据低渗透气藏的生产特点和人工裂缝的渗流特征，建立气藏与裂缝数学模型。对气藏与裂缝方程进行两维差分得到差分方程，用IMPES方法求解。为研究水力裂缝参数对气藏开采动态的影响，将裂缝、气藏看作两个相对独立的渗流系统建立了气藏数值模拟模型，选取裂缝壁面的渗流量和压力相等来建立连接条件，研究了鄂尔多斯盆地低渗透气藏压裂裂缝条数、裂缝位置和裂缝半长对压裂井产能的影响，得出压裂井产量随裂缝条数增加而增加及裂缝长度对特定地层存在一个最佳值等认识，所建立的气井压裂优化数学模型对提高低渗透气藏单井压裂产量具有一定的指导意义。

A fracturing model for low permeability sandstone gas reservoir in the Ordos basin

In recent years, a series of optimistic method has been put forward in view of low permeability oil reservoir fracture while the comprehensive research for gas reservoir has not been done yet, which results in not strong enough or big enough reformation in gas reservoir, thus to influence the development effect of gas reservoir. The mathematical models on gas reservoir and fracture are built up in accordance with production characteristics of low permeability gas reservoir and percolation feature of artificial fracture. The gas reservoir and percolation equations are calculated by two dimension differential method to get differential equation which is solved by the IMPES method. In order to study the effect of hydraulic fracture parameter on gas reservoir development, fracture and gas reservoirs are regarded as two relatively independent percolation systems to build up a numerical simulation model on gas reservoir and under the condition of equal relationship between percolation volume and pressure on surface wall, which provides theoretical foundation for study on the influence of fracture number, fracture location and its half length on fractured well's deliverability in low permeability gas reservoir in the Orodos basin. The conclusion is obtained that with the increase of fracture number, the fracture well's deliverability will increase and there is an optimum value for fracture length to specific formation. The established optimized numerical model can be a guide to raise the production of a single well in low permeability gas reservoir after fracturing.