隐蔽河道砂体地震识别关键技术——以四川盆地中江气田中侏罗统沙溪庙组为例  

Key technologies for seismic identification of hidden channel sandbodies: A case study of Middle Jurassic Shaximiao Formation in the Zhongjiang Gas Field of the Sichuan Basin

作　　者：郑公营[1] 吕其彪[1] 赵爽[1] 彭鑫 徐守成[1] ZHENG Gongying;LYU Qibiao;ZHAO Shuang;PENG Xin;XU Shoucheng(Exploration and Development Research Institute,Sinopec Southwest Oil&Gas Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石化西南油气分公司勘探开发研究院,四川成都610041

出　　处：《天然气工业》2022年第9期35-46,共12页Natural Gas Industry

基　　金：国家科技重大专项“川西凹陷斜坡带复杂致密砂岩气藏开发关键技术”(编号:2016ZX05048-004);中国石化西南油气分公司科研项目“隐蔽性河道识别基础研究”(编号:KJ-539-1915)。

摘　　要：四川盆地川西坳陷中侏罗统沙溪庙组属于三角洲平原—三角洲前缘水上/水下分流河道沉积,河道砂体非常发育。近年来,该气藏部署实施的部分井钻遇了钻前地震资料未有效识别的河道砂体(笔者称之为隐蔽河道砂体),油气显示活跃,测试效果较好,如何有效识别该类河道、落实砂体平面展布范围、评价气藏增储上产潜力是急需解决的关键问题。为此,基于隐蔽河道砂体地质特征,从地球物理辨识机理上剖析该类砂体的响应特征,明确了隐蔽河道砂体的地震识别模式,优化了隐蔽河道砂体地震识别技术,实现了隐蔽河道砂体的精细刻画。研究结果表明:(1)隐蔽河道砂体属于中高波阻抗、以Ⅰ类和Ⅱ类AVO特征为主的砂体,地震上主要表现为“暗点型”中弱振幅,平面上主要表现为局部隐形、点状或段状不连续,具有物性和厚度隐蔽特征,常规手段难以有效识别;(2)基于高保真道集优化处理的优势道集叠加数据体可突出隐蔽河道砂体异常特征;(3)谱反演拓频处理、波形指示高分辨反演及岩性指示因子技术可有效地实现隐蔽河道砂体刻画。结论认为:(1)提出优势道集叠加、谱反演高分辨处理、波形指示高分辨反演及岩性指示因子构建等关键技术可有效地识别隐蔽河道砂体;(2)该技术已应用于川西坳陷中江气田沙溪庙组隐蔽河道识别,有效地指导了气藏开发井位的部署,有力支撑了中江气田千亿立方米探明储量的高效开发。Middle Jurassic Shaximiao Formation in the West Sichuan Depression of the Sichuan Basin is a delta plain-delta front overwater/underwater distributary channel deposit, where channel sandbodies are very developed. In recent years, some wells deployed and implemented in this gas reservoir encountered channel sandbodies that were not effectively identified by predrilling seismic data(named as hidden channel sandbodies), but have active oil and gas shows and better test results. The key problems which need urgent solution include how to effectively identify hidden channels, define the plane distribution range of sandbodies, and evaluate the reserves and production increase potential of gas reservoir. Therefore, based on the geological characteristics of hidden channel sandbodies,this paper analyzes the response characteristics of hidden channel sandbodies from the aspect of geophysical identification mechanism,establishes the seismic identification modes of hidden channel sandbodies, and optimizes the seismic identification technology for hidden channel sandbodies, so as to realize the fine characterization of hidden channel sandbodies. And the following research results are obtained. First, hidden channel sandbodies are mainly medium and high impedance sandbodies with class I and class II AVO characteristics. In the seismic, it is mainly manifested as "dark dot" medium weak amplitude, and in the plane, it is mainly manifested as local invisibility, dot or segmental discontinuity, which has the hidden characteristics in physical properties and thickness, so its effective identification can be hardly realized using conventional technologies. Second, the dominant gather stacking data volume based on the optimization of high fidelity gathers can highlight the abnormal characteristics of hidden channel sandbodies. Third, spectral inversion and frequency-extension processing, high-resolution waveform indication inversion and lithology indicator construction technologies can effectively depict hidden channel sandbodies. In

关 键 词：四川盆地 中江气田 中侏罗统 沙溪庙组 隐蔽河道砂体 优势道集 地震识别关键技术 

分 类 号：P618.13[天文地球—矿床学]