低渗透油藏压裂时机的确定方法及应用

Confirming means and application of fracturing opportunity in low permeability reservoirs

针对非均质低渗透油藏压裂时机难以确定的实际,应用渗流力学原理,提出同一注采井网存在建立有效驱替系统的临界渗透率概念,建立储层临界渗透率求解模型,包括低于临界渗透率储层压裂的最小裂缝半长计算模型,以及高于临界渗透率储层有效驱替系统时间和见水时间模型;基于测井曲线反映储层特征参数变量,建立压裂时机优选图版.结果表明:对低于临界渗透率的储层,应采取不同缝长压裂投产,从而建立有效的驱替体系;对高于临界渗透率的储层,合理的压裂时机应大于储层建立有效驱动系统的时间,且不超过水驱前缘达到裂缝半长时间.敖南油田注水开发实践表明,该方法具有可靠性.

In view of the practical situation that it is hard to confirm fracturing opportunity in low permeability heterogeneity reservoirs,it is defined that the interface permeability to establish effective displacement system occurs in the same flood pattern by using fluid mechanics in porous medium.The formation interface permeability resolution model,the minimum half fracture length model of the formation fracturing whose permeability is lower than the interface permeability and the effective displacement system time and breakthrough time model are established.According to the logging trace which indicates reservoir characteristic parameter,the fracturing opportunity optimum charts are established.The research result is as follows: The reservoirs whose permeability is lower than the interface permeability should be fractured with different kinds of fracture length.Consequently,the effective displacement system will generate.The reservoirs whose permeability is higher than the interface permeability should be fractured at the correct time which is later than the one when the effective displacement system generates,and also be earlier than the one when waterflooding front reaches half fracture length.It is demonstrated that this method is dependable in Aonan oil field waterflooding development.