页岩油气纵向综合甜点识别新方法及定量化评价

A new identification method for the longitudinal integrated shale oil/gas sweet spot and its quantitative evaluation

页岩储层厚度一般较大,且储层物性纵向上非均质性强,长水平井多级压裂开发技术要求对水平井着陆点及轨迹进行优选。通过综合考虑页岩可压性、资源禀赋、流动性等因素,提出了页岩油气纵向综合甜点的概念,其是纵向地质因素与工程因素的综合。建立了页岩油气纵向综合甜点识别流程及方法,实现了纵向上从远景段、有利段、核心段,再到甜点段的识别过程。定义了纵向综合甜点指数,可以量化评价储层物性纵向分布的差异及非均质性。在此基础上,考虑地应力分布预估有效压裂裂缝高度,定义了纵向综合甜点系数,能够准确量化最优水平井着陆点,可以有效指导水平井靶点及轨迹设计,并且经过现场应用证明了该方法的有效性。

Shale reservoir is generally characterized by large thickness and strong longitudinal heterogeneity of reservoir physical prop- erty. The multi-stage fracturing development technology for long horizontal well requires the optimization of landing point and trajec- tory in horizontal well. This paper put forward the concept of longitudinal integrated shale oil/gas sweet spot considering shale fraca- bility, resources endowment, fluidity and other factors, which is a synthesis of longitudinal geological factors and engineering fac- tors. Then the identification process and method of longitudinal integrated sweet spot was established, thus realizing the recognition process from prospective segment to favorable segment, core segment and sweet spot segment, respectively. Meanwhile, longitudi- nal integrated sweet spot index was designed, which can quantitatively evaluate the difference and heterogeneity in longitudinal distri- bution of reservoir physical properties. On this basis, the longitudinal integrated sweet spot coefficients considering effective stress distribution were designed to predict effective hydraulic fracture height, which can accurately quantify the optimal horizontal landing point and effectively guide the target point and trajectory designs of horizontal well. Field application has proved the effectiveness of this method.