低渗透油藏注采动态连通性评价方法

A method to evaluate dynamic connectivity of injection and production in low permeability reservoir

井间动态连通性是油藏动态分析的重要内容之一。以多元线性回归法建立的井间动态连通性模型适用对象主要为中高渗透油藏,目前对低渗透油藏井间动态连通性的研究甚少。低渗透油藏孔喉细微,孔隙结构和流体分布复杂,渗流存在启动压力梯度,渗流规律与中高渗透油藏有很大差异。文中以油藏地质参数和油水井生产动态数据为基础,将启动压力梯度引入低渗透油藏油井产量计算,同时利用非线性扩散系数对注水信号在低渗透油藏传播存在的时滞性和衰减性作了降噪处理,从而使模型反演的连通系数更符合于低渗透油藏特征。实例计算所得连通系数反映的井间动态连通性与生产动态特征吻合较好。

Inter-well dynamic connectivity is one of the important research contents in reservoir dynamic analysis. The inter-well dynamic connectivity model established with multiple linear regression method mainly applies to middle and high permeability reservoir. Unforlunately, the research for low permeability reservoir is very little at present. Because of subtle pore throat, complicated pore structure and fluid distribution, and existing starting pressure gradient in low permeability reservoirs, the seepage law obviously differs from that of middle and high permeability reservoir. Based on the geological parameters and production dynamic data, the starting pressure gradient is introduced to calculate oil well output in this paper. Meanwhile, the nonlinear diffusion coefficient solves the delay and decay characteristics of injected water signal propagation in low permeability reservoir, which makes the connectivity coefficient calculated by reg^ssion model be more conform to the characteristics of low permeability reservoirs. An example calculation shows that the inter-well dynamic connectivity reflected by connectivity coefficient is consistent with actual roduction characteristics.