低渗透油藏流体渗流再认识

为了正确认识低渗透储集层渗流规律,针对目前低渗透油藏流体渗流理论中具有代表性的低渗透油藏流体非线性渗流模型,从模型建立所采用的假设条件、推导过程及使用实验数据的合理性等方面进行深入研究与分析,厘清低渗透油藏开发中长期存在的一些模糊认识。该模型建立过程中存在3方面问题:一是假设条件本身不能被科学所证实,所得结果不能被测量;二是公式推导过程中基本方程及导出过程均存在错误,导致其最终表达式错误;三是低渗透储集层岩石渗流实验中得到的压力梯度实验数值过高,不具有合理性。首次指出,不是所有低渗致密储集层流体渗流都具有启动压力梯度,只有当储集层压力系数低于1,渗流才需要启动压力梯度;低渗透油田开发中,储集层已建立了较高的驱动压力体系,低渗透油藏数值模拟、产能预测和试井都不应再考虑启动压力梯度。揭示低渗透储集层流体渗流规律、创建中国低渗透油田开发理论,需要发展数字岩心技术、创新现代油层物理实验技术等。

Further understanding on fluid flow through multi-porous media in low permeability reservoirs

This paper studies typical nonlinear models of fluid flow through multi-porous media in low-permeability reservoirs,analyzes hypothesis conditions,derivation process and the experimental data rationality,and clarifies some confusions in order to understand the fluid flow rules through multi-porous medium in low permeability reservoirs.There are three problems in establishing the models: first,hypothesis conditions cannot be proved,calculation values cannot be measured;second,wrong basic equation not only was used,but also wrong of derivation process,and derived equation is also a wrong equation;third,the threshold pressure gradients obtained from rock samples of low permeability reservoirs at the laboratory are too high,without rationality.The threshold pressure gradient does not exist in all of the low-permeability reservoirs,only when pressure coefficient of low-permeability reservoir is less than one,fluid flow through multi-porous media should need the threshold pressure gradient,threshold pressure gradient should not be considered in reservoir numerical simulation,productivity prediction and well testing in low permeability reservoirs development.To reveal flow rules of low permeability reservoirs and establish theory of low-permeability oilfield development it’s necessary to develop the digital rock technology,innovate experimental skills of modern petrophysics and so on.