基于叠前岩石力学参数反演的三维地应力预测研究——以长宁区块页岩气为例  

Three-dimensional in-situ stress prediction based on pre-stack rock mechanics parameter inversion:A case study of shale gas in Changning block

作　　者：金文辉 井翠 文冉 宋修艳 陈珂磷 李雪松 张奎 JIN Wenhui;JING Cui;WEN Ran;SONG Xiuyan;CHEN Kelin;LI Xuesong;ZHANG Kui(Sichuan Changning Natural Gas Development Co.Ltd,Chengdu 610051,China;Precise-energy Group,Beijing 100085,China)

机构地区：[1]四川长宁天然气开发有限责任公司,成都610051 [2]北京普瑞斯安能源科技有限公司,北京100085

出　　处：《物探化探计算技术》2024年第1期11-25,共15页Computing Techniques For Geophysical and Geochemical Exploration

摘　　要：与常规油气藏相比,页岩气藏的物性条件极差,孔渗性超低,其实现大规模开采的关键在于水平井体积压裂改造技术的应用。近年来,大量页岩气开发实践证明,水平井压裂效果受地应力作用较为明显。研究表明:当水平井沿着最大水平主应力近垂直的方向钻进,且应力差异系数较小时,有利于形成网状压裂缝。笔者选择长宁页岩气区块,对基于地震方法的三维地应力预测技术在水平井开发中的应用进行研究。利用一系列地震方法,诸如地震构造解释得到的构造信息(地震解释层位与断层)、叠前统计学反演得到的地层信息(速度与密度)、地质力学信息(杨氏模量与泊松比),优选适当的模型方法,并刻度模型参数(比奥特系数、构造应力系数a和b、局部应变系数A和B等),对三维最大和最小水平主应力大小、应力差异系数及地应力方向进行预测;研究了长宁区块页岩气的区域应力机制以及对3口水平井的微地震监测结果进行分析,验证了本文三维地应力预测结果的可靠性。在水平井设计时应综合考虑地应力方向、非均质性和应力差异系数,以获得良好的压裂效果。Compared with conventional oil and gas reservoirs,shale gas reservoirs have inferior physical properties and ultra-low porosity and permeability.The key to large-scale exploitation lies in applying horizontal well volume fracturing technology.In recent years,many development practices have proved that the fracturing effect of horizontal wells is obviously affected by In-situ stress.The study shows that when the horizontal wells are drilled along the perpendicular direction of the maximum horizontal principal stress or oblique at an angle greater than 60°,and the stress difference coefficient is small,it generates complex induced fractures.In this paper,the Changning shale gas block is selected to study the application of 3D in-situ stress prediction technology based on seismic method in horizontal well development.Based on the structural information(seismic interpretation of horizon and fault),rock mechanics information(velocity,density,Young’s modulus and Poisson's ratio)predicted by seismic method,the appropriate model method is optimized,and the model parameters(Biot coefficient,tectonic stress coefficient a and b,local strain coefficient A and B,etc.)are calibrated to predict the maximum and minimum horizontal principal stress,stress difference coefficient and in-situ stress direction.Through studying the regional stress mechanism of the shale gas in Changning block and analyzing the micro-seismicity monitoring results of three horizontal wells,the reliability of the 3D in-situ stress prediction results in this paper is verified.In the design of horizontal wells,the stress direction,heterogeneity and stress difference coefficient should be comprehensively considered to obtain favorable fracturing effect.

关 键 词：页岩气 地应力 长宁区块 水平主应力 

分 类 号：P624[天文地球—地质矿产勘探]