低渗油藏注水井试井压力响应机理及解释模型

针对低渗透油藏注水开发特点，在考虑启动压力梯度方向性和时效性的情况下，提出了低渗储层注水井井下关井试井压力响应机理。据此，综合考虑启动压力梯度、井筒储集效应、表皮效应、储层非均质性等因素，建立了低渗储层井下关井奢件下泣水井的试井解释数学模型，应用Bessel函数、Green函数和Stehfest数值反演算法对模型进行求解。利用该模型对长度油田注水井进行试井解释实例分析，解释结果与实际资料相吻合，较真实地反映了低渗储层的参数和渗流特征，可为制订注水开发方案提供依据。

Response mechanism and interpretation model of water injection well testing pressure in low permeability reservoir

In view of the features of waterflooding development in low permeability reservoir, a testing pressure response mechanism was presented for water injection well which is shut down at downhole under the conditions of considering the directivity and time efficiency of threshold pressure gradient.On the basis of this meehanism, the mathematical model of well test interpretation was established under the conditions of shutting down downhole with considerations of the threshold pressure gradient, wellbore storage effect, skin and reservoir heterogeneity. The model solution was gained with the application of Bessel function, Green function and Stehfest inversion methods. The model was used to analyze the pressure testing data of water injection wells in Changqing oilfield. The interpretation resuhs match the practice data very well, and it can actually reflect the parameters and percolation characteristics of low permeability reservoirs, and can supply a reference for making the development program.