基于正交各向异性介质频变AVAZ反演的裂缝含气性预测  

Prediction of fracture gas bearing based on frequency-dependent AVAZ inversion in orthotropic medium

作　　者：陈天杰 程冰洁[1] 徐天吉 钱忠平[4] 邹振 CHEN Tianjie;CHENG Bingjie;XU Tianji;QIAN Zhongping;ZOU Zhen(Key Laboratory of Earth Exploitation and Information Technology,Ministry of Education,Chengdu University of Technology,Chengdu,Sichuan 610059,China;School of Resources and Environment,University of Electronic Science and Technology of China,Chengdu,Sichuan 611731,China;Yangtze Delta Region Institute of University of Electronic Science and Technology of China(Huzhou),Huzhou,Zhejiang 313099,China;National Engineering Research Center for Oil and Gas Exploration Computer Software,Beijing 100088,China)

机构地区：[1]成都理工大学“地球勘探与信息技术”教育部重点实验室,四川成都610059 [2]电子科技大学资源与环境学院,四川成都611731 [3]电子科技大学长三角研究院(湖州),浙江湖州313099 [4]油气勘探计算机软件国家工程研究中心,北京100088

出　　处：《石油地球物理勘探》2024年第3期567-580,共14页Oil Geophysical Prospecting

基　　金：国家自然科学基金项目“基于应力诱导各向异性与岩石力学性质的深层页岩储层可压裂性评价方法研究”(42074160);四川省自然科学基金项目“深层—超深层页岩储层‘甜点’要素智能预测与一体化表征方法研究”(2023NSFSC0255);中国石油天然气集团有限公司重大科技专项“多物理场高精度油气地球物理探测技术与装备研究”(2023ZZ05)联合资助。

摘　　要：依赖频率的AVO反演方法(FDAVO)可以提取与流体有关的异常信息,但由于没有考虑实际储层中各向异性的影响,难以适用于裂缝性油气藏。另外,各向异性通常与频率相关,这一特性有利于利用OVT域叠前地震数据识别有效裂缝。为此,提出基于正交各向异性(OA)介质频率相关的AVAZ(OA-FDAVAZ)反演的裂缝含气性预测方法。首先基于Chapman模型的数值模拟分析弹性参数随频率、入射角等参数的变化特征;然后基于OA介质纵波反射系数近似式推导出OA-FDAVAZ反演的目标方程,构建了新的频散属性Iani;最后利用最小二乘法反演正交各向异性频散属性。模型试算表明:含气裂缝层的正交各向异性频散属性明显强于含水裂缝层,而不含裂缝的各向同性层频散响应微弱,验证了所提频散属性对流体的敏感性。实际OVT域叠前地震数据应用结果表明:正交各向异性频散属性的预测结果与钻探结果吻合较好。与传统方法对比,该方法受背景干扰小,可准确刻画储层中裂缝含气性的空间分布特征。The frequency-dependent AVO inversion method(FDAVO)can extract fluid-related anomaly infor-mation,but it is difficult to apply to fractured reservoirs because it fails to consider the effect of anisotropy in real reservoirs.In addition,the anisotropy is often frequency-dependent,which facilitates the identification of effective fractures using OVT domain pre-stack seismic data.Therefore,a frequency-dependent AVAZ(OA-FDAVAZ)inversion method for gas content prediction based on orthotropic(OA)media is proposed.Firstly,based on the numerical simulation of the Chapman model,the variation characteristics of elastic parameters with frequency and incidence angle are analyzed.Then,the objective equation of OA-FDAVAZ inversion is de-rived based on the approximation of the P-wave reflection coefficient of OA media,and a new dispersion attri-bute Iani is constructed.Finally,the least square method is used to invert the OA dispersion properties.The model test results show that the OA dispersion property of the gas-bearing fractured layer is obviously stronger than that of the water-bearing fractured layer,while the anisotropic layer without cracks has a weak dispersion response,which verifies the sensitivity of the proposed dispersion property to fluid.The application results of OVT domain pre-stack seismic data show that the prediction results of the OA dispersion attribute are in good agreement with the drilling results.Compared with traditional methods,the proposed method is less affected by background interference and can accurately characterize the spatial distribution characteristics of gas bearing in fractures in reservoirs.

关 键 词：正交各向异性 Chapman模型 纵波频散 OVT域地震数据 含气性预测 

分 类 号：P631[天文地球—地质矿产勘探]