玛湖砾岩油藏水平井压裂井间窜扰特征与机制分析

Characteristics and mechanism of inter-well interference in horizontal well fracturing in Mahu conglomerate reservoirs

玛湖砾岩油藏油气资源丰富,以地质工程一体化思想为指导形成的“大井丛、多层系、小井距、长井段、交错式、密切割、拉链式、工厂化”系列开发技术,已实现了百万吨级以上的年生产能力。但在实施小井距水平井、水平井体积压裂立体开发的过程中出现了不同程度的压裂井间窜扰现象,较大程度影响了钻/完井工程作业及稳定生产。为此,以理论研究与数值模拟相结合,开展了压裂窜扰机制研究及主控因素分析。研究结果表明:①根据水平井压裂井间窜扰的连通方式及窜扰特征,将玛湖砾岩油藏水平井压裂井间窜扰分为天然软弱结构发育导致的压裂窜扰、压裂缝沟通导致的窜扰和压裂扰动压力/应力扰动区连通诱发的邻井干扰3种类型。②水平井井距是影响水平井压裂井间窜扰以及井间窜扰程度的关键因素。当水平井井距小于300m时,研究区井间压裂窜扰发生几率大幅增大。综合考虑压裂窜扰对油藏开采的积极作用以及压裂窜扰对钻/完井工程作业、采油作业的不利影响,合理优化设计水平井井距,对砾岩油藏的安全、高效开发具有积极且重要的意义。

The annual production capacity of more than one million tons has been realized because Mahu conglomerate reservoirs are rich in oil and gas resources and a series of development technologies featuring"large well cluster,multi-layer system,small well spacing,long well section,staggered type,dense cutting,zippered type,and industrialization"have been formed under the guidance of the idea of geological engineering integration.However,the drilling and completion engineering and stable production are significantly affected due to the different degrees of inter-well interference in the process of three-dimensional development of horizontal wells with small well spacing and volume fracturing of horizontal wells.Therefore,theoretical research and numerical simulation are combined to study the fracturing interference mechanism and analyze the main control factors.The results show that ①according to the connection modes and characteristics of inter-well interference in horizontal well fracturing,the inter-well interference in horizontal well fracturing in Mahu conglomerate reservoirs can be divided into three types:fracturing interference caused by the development of natural weak structure,interference caused by fracture communication,and adjacent well interference induced by the connectivity of the pressure/stress interference zones due to the fracturing interference;②the horizontal well spacing is the key factor affecting the inter-well interference and the inter-well interference degree in horizontal well fracturing,the the probability of inter-well interference in the study area increases greatly when the spacing between horizontal wells is less than 300 m.Therefore,it is necessary to comprehensively consider the positive effect of fracturing interference on reservoir production and the adverse impact of fracturing interference on the drilling and completion engineering/the oil production and reasonably optimize the design of horizontal well spacing,which are of positive significance to the safe and efficient development of conglomerate reservoirs.