双重介质压裂直井非稳态井底压力分析

Dynamic Analysis on Bottom Pressure of Unsteady Flow in Dual-Medium Fracturing Vertical Well

精确求取压裂直井非稳态井底压力,有助于实时监控和预测油井产量。基于渗流控制方程,考虑裂缝与基质的窜流,引入双重介质流体交换系数,建立双重介质油藏非定常流的瞬时压力数学模型。通过数学变换方法、数值反演和轴对称变换解相似方法,求取了井底流压的实数域数值解,并对井底流压进行了敏感性因素分析。分析结果表明:压力曲线可以分为早期线性流、中期径向流、晚期球形流、边界控制流四个阶段;裂缝半长和渗透率比主要影响早期线性流,弹性储容比(基质)和交换系数主要影响中期径向流,表皮系数则主要影响晚期球形流。井底压力的动态分析,为油井的合理配产,提供了一定的技术支持。

Accurately obtaining the unsteady flow bottom pressure of fracturing vertical wells helps to monitor and predict oil and gas well production in oil and gas field development.From the most basic seepage control equation, considering the turbulence of the fracture and the matrix, a mathematical model of the instantaneous pressure of the unsteady flow in the dual-medium reservoir is established.Through the mathematical transformation method and numerical inversion method, the real-domain numerical solution of the bottom hole flow pressure is obtained, and the sensitivity factor analysis of the bottom hole flow pressure is carried out.The analysis results show that the pressure curve can be divided into four stages, namely early linear flow, medium radial flow, late spherical flow and boundary control flow.The fracture half-length and the permeability ratio mainly affect the early linear flow, and the elastic storage ratio(matrix)and the exchange coefficient mainly affect the medium-term radial flow, and the skin coefficient mainly affects the late spherical flow.The dynamic analysis on bottom pressure provides technical support for rational production allocation of oil well.