常压页岩气立体开发特征及缝网干扰规律研究

Three-Dimensional Development Characteristics and Fracture Network Interference of Atmospheric Shale Gas Reservoir

  • 摘要: 为明确页岩气藏立体开发井的压裂施工特征和生产规律,以南川常压页岩气藏为研究对象,分析了压裂干扰现象、缝网沟通机理以及对老井生产的影响。分析结果表明,立体开发井施工压力纵向上与地质静态参数具有一致性,平面上与井距正相关,与井间采出程度负相关;受储层物性和保存条件的影响,下部气层井产能优于中部气层井,优于上部气层井;同开发层系加密井压裂时,根据老井套压变化特征,可将新老井缝网干扰划分为高导流缝间沟通、高导流缝与低导流缝的沟通和低导流缝间沟通等多种方式。结合试井解释结果,明确压裂干扰对同开发层系试采井EUR、典型曲线的影响分为4类,对不同开发层系井日产水平影响较小。其中,当空间距离小于200 m的不同层系页岩气井进行拉链压裂时,新井施工压力会大幅升高。研究结果为常压页岩气田方案部署、压裂设计和压裂过程中动态优化调整提供了理论依据。

     

    Abstract: In order to clarify the characteristics of fracturing operation and the production dynamics of three-dimensional developing wells in shale gas reservoir, the Nanchuan atmospheric shale gas reservoir served as the subject for analyzing fracture interference phenomena, fracture network connectivity mechanisms, and their impact on the production of old wells. The statistics showed that the fracturing pressure of three-dimensional developing wells aligned vertically with geological static parameters, and exhibited a positive correlation with well spacing horizontally, while showing a negative correlation with the production degree. Affected by the reservoir’s physical properties and preservation conditions, wells in the lower gas layer exhibited better productivity compared to those in the middle and upper gas layers. When infill wells in the same development layer were fractured, based on the characteristics of casing pressure changes in old wells, the fracture network interference between old and new wells could be classified into high-conductivity fracture connection, high-low conductivity fracture connection, and low- conductivity fracture connection. Based on the interpretation results of well tests, the influence on estimated ultimate recovery (EUR) and typical curves of old wells caused by fracturing interference were classified into 4 types, while minimal impact were caused on the daily production levels of wells in different development layers. However, when zipper fracturing was conducted on shale gas wells in different layers with a spatial distance of less than 200 m, the fracturing pressure of new wells significantly increased. These research results have provided a theoretical basis for the plan deployment, fracturing design, and dynamic optimization and adjustment during the fracturing process in atmospheric shale gas fields.

     

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