基于地震电磁属性的页岩气储层预测与监测方法研究

The project takes shale gas that the forecast and monitoring of organic matter content, reservoir rock brittleness and fracture development as the main scientific problems. According to the petrophysical properties testing of Shale gas as research foundation and basis, we analyze that the characteristics of shale reservoir rock mechanics and microstructure change have the influence of seismic elastic properties and their response mechanism, and establish the connection with reservoir rock seismic features and shale reservoir characteristics parameters. We predict the distribution of shale gas reservoir viscoelasticity using the methods of oil seismology and microseism. Through the test with time response and frequency characteristics of rock sample electrical parameters, the relations between shale gas and total organic carbon content, we set up the geological and geophysical model with electromagnetic detection, the analysis on the electromagnetic response characteristics, and then the organic carbon content is calculated by means of the electromagnetic and induced polarization effect. Based on the technology of microseismic surface wave extraction, surface wave inversion, microseismic source location and well seismic monitoring on the ground, we do the research of shale gas well fracturing process and development characteristics. This project researches and reveals the forecasting and monitoring methods of the seismic and electromagnetic attributes about the shale gas reservoir. The research results can provides basic property parameters for shale gas exploration and exploiting, and then, which is very important scientific significance for shale gas exploration and development in our country.

项目以页岩气层有机质含量预测和页岩气储层岩石脆性与裂缝发育预测与监测为主要科学问题。以页岩气层岩石物理性质测试作为研究基础和依据，分析储层页岩岩石力学特征与微观结构特征变化对地震弹性属性的影响及其响应机理，建立储层岩石地震特征与页岩储层特征参数的联系；采用石油地震和微地震方法，预测页岩气储层粘弹性分布特征；通过岩石样品电性参数的时间特性及频率特性测试，分析其与总有机碳含量之间的关系，建立页岩气电磁探测地质地球物理模型，分析其电磁响应特征，进而利用电磁与激发极化效应预测有机碳含量；通过地面微震面波提取、面波反演及微地震震源定位技术和井中微震监测技术，研究页岩气井压裂过程裂缝发育特征。探索并揭示基于地震和电磁属性的页岩气储层预测与监测方法。研究成果对建立控制页岩气勘探与开采的基本属性参数，进而对页岩气勘探和开发都有十分重要的科学意义。

该项目在对地震和电磁属性分析的研究中，着重进行了不同学科间的交叉和渗透，通过方法的机理研究，重点解决页岩气储层岩石脆性和裂缝发育机理，页岩气层TOC含量预测两个基础科学问题。重点从四个方面开展了科学研究：页岩气岩石物理测试分析与建模；电磁与激发极化效应的TOC预测方法研究；地震页岩气储层特征（脆性、裂缝等）预测方法研究；微震页岩气层监测方法研究。并取得以下主要成果：（1）通过对页岩进行系统的地震岩石物理性质测试，认为高TOC含量的储层岩石通常表现出低泊松比、低阻抗和低杨氏模量的特征；页岩样品的各向异性受粘土含量的控制，与粘土含量存在明显的函数关系；准确的建立了龙马溪组页岩的地震岩石物理模型，实验结果和测井数据验证了模型的准确性。（2）采用岩石电学参数测试等手段，建立脆性矿物、TOC与页岩电性之间的关系。确定脆性矿物含量高于70%，过低会导致岩石电阻率升高，极化特征减弱；较高的TOC（>3%）是页岩的低阻和较高极化成因的关键因素，并且有机质本身的同构置换也会使得页岩导电性和极化增强；电阻率与黄铁矿含量呈负相关关系，极化率与黄铁矿含量呈正相关关系。（3）通过相干和曲率属性的研究，认为龙马溪组页岩储层的物源沉积区域微裂缝稍有发育；提取体积模量、剪切模量、拉梅常数、泊松比等岩石物理参数，建立页岩脆性参数预测的方法技术，认为龙马溪组页岩储层的脆性特征不明显，这与岩石物理测试结果也吻合较好；（4）开展了微震弱信号提取方法和信号分析处理方法研究，完成了一个微地震地面监测系统，当压裂段为水平井的时候，观测系统相对集中于水平井一边更有利于提高监测效果，并提出了震源位置与震源机制联合反演算法。研究成果可提供页岩气勘探与开采的基本属性参数，部分成果已得到了较好的应用和推广，进而对页岩气勘探和开发都有十分重要的地质意义。