致密油藏水平井分段多簇压裂产能预测方法

摘要

由于致密油藏在水平井分段压裂后形成复杂多簇缝网,为了正确表征缝网,更准确地预测产能,根据等效渗流理论,基于Warren-Root模型,将压裂后形成的分段多簇缝网等效为高渗透带,并推导出等效渗透率及高渗透带宽度的关系式.在此基础上,应用复位势理论和势的叠加原理,运用解析法建立了致密油藏分段多簇压裂水平井考虑裂缝间干扰的非稳态产能预测模型.研究表明:致密油藏水平井日产量呈"L"型递减,产量初期递减快,后期趋于平稳;实例计算结果与实际产量接近,相对误差较小;高渗透带渗透率越大,长度越长,压裂水平井产能越大,但基于经济技术等条件,各自存在最优值.该产能预测方法对致密油藏开发具有指导意义.%As a complex multi-cluster fracture network is formed after multi-stage fracturing of horizontal wells in tight oil reservoirs,the multi-stage multi-cluster fracture network is equivalent to a high permeability zone and the formula between effective permeability and height of the high permeability zone is derived,based on equivalent per-colation theory and Warren-Root model,so as to accurately characterize fracture network and predict productivity. Based on this result,complex potential theory and theory of potential superimposition,a model is built to predict transient productivity of multi-stage multi-cluster fractured horizontal wells in tight oil reservoirs considering inter-fracture interference using analytical method. The research shows that the daily production of horizontal wells de-clines in"L"shape and production declines quickly in initial period and is stable in later period. Results of field calculation are very close to actual production data,with only a little discrepancy. Larger permeability in high per-meability zone and larger length results in larger productivity of fractured-horizontal wells. However,the parameter has an optimum value as being limited by economics and technology. The productivity prediction method provides guidance for the development of tight oil reservoirs.