摘要
鄂尔多斯盆地东南部下二叠统山西组2~3亚段(以下简称山2~3亚段)为该盆地重要的天然气勘探目的层,但该亚段储层薄、厚度变化快、非均质性强,储层预测和勘探目标优选难度大。为了准确预测该亚段煤系地层致密砂岩气甜点区、提高天然气勘探成功率,针对该套储层的特征和预测难点,提出了90°相移技术识别河道外形、模型约束波阻抗反演刻画砂体厚度和子波衰减梯度属性识别含气砂体的地震逐级预测技术。研究结果表明:①山2~3亚段上覆5号煤地震强反射层,下伏储层地震反射能量弱,加之为稀疏二维地震测网、井控程度低,致使致密砂岩气甜点区预测难度大;②所提出的技术方法通过地震逐级预测约束,可以有效地刻画河道砂体分布并识别有效含气储层,提高了对勘探开发目标预测的精度;③基于该技术方法指导部署的勘探开发目标实钻效果好,地震预测结果横向分辨率高,真实地反映了河道及河道砂体的变化特征。结论认为,采用该方法可以有效地解决二维地震勘探区煤系地层强非均质性、薄储层致密砂岩气甜点区预测的地质难题。
The Submember 2~3 of the Lower Permian Shanxi Formation(hereinafter,"Shan 2~3 Submember"for short)in the southeastern Ordos Basin is an important target of natural gas exploration in this basin.However,the reservoir of Shan 2~3 Submember is characterized by small thickness,fast thickness variation and strong heterogeneity,and its reservoir prediction and exploration target selection is difficult.In order to accurately predict the sweet spots of tight sandstone gas in the coal measure strata and improve its success rate of exploration,this paper proposed a seismic stepped prediction technology based on the characteristics and prediction difficulties of this reservoir,including the 90°phase-shifting technology to determine channel outline,the model constrained wave impedance inversion to characterize sandbody thickness,and the wavelet attenuation gradient attribute to identify gas-bearing sand bodies.And the following research results were obtained.First,Shan 2~3 Submember is overlain by No.5 coal bed of strong seismic reflection and its underlying formation has weak seismic reflection energy.In addition,there is a sparse 2 D seismic grid and a low well control degree.Therefore,tight sandstone gas sweet spot prediction is high difficulty.Second,under the constraint of seismic stepped prediction,the proposed technology can be used to efficiently characterize the distribution of channel sand bodies and identify effective gas-bearing reservoirs,so as to increase the prediction accuracy of exploration and development targets.Third,the exploration and development targets deployed on the basis of this technology present a good drilling effect,the seismic prediction result has high lateral resolution,and the variation characteristics of channels and channel sand bodies are reflected truly.In conclusion,the application of this method can solve the geological difficulties of predicting tight sandstone gas sweet spots in strong-heterogeneity thin reservoirs of coal measure strata in a 2 D seismic exploration area.
作者
李国斌
张亚军
谢天峰
石小茜
王荣华
李星涛
刘雄志
景紫岩
LI Guobin;ZHANG Yajun;XIE Tianfeng;SHI Xiaoqian;WANG Ronghua;LI Xingtao;LIU Xiongzhi;JING Ziyan(Research Institute of Petroleum Exploration&Development-Northwest,PetroChina,Lanzhou,Gansu 730020,China;PetroChina Coalbed Methane Company Limited,Beijing 100028,China)
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2020年第5期34-42,共9页
Natural Gas Industry
基金
中石油煤层气有限责任公司科研项目“鄂尔多斯盆地东南缘致密气储层综合预测研究与目标优选”(编号:KKC-004-2018-017-DT)。
关键词
煤系地层
致密砂岩气
90°相移
波阻抗反演
子波衰减梯度
储集层预测
早二叠世
鄂尔多斯盆地
Coal measure strata
Tight sandstone gas
90°phase-shifting
Wave impedance inversion
Wavelet attenuation gradient
Reservoir prediction
Early Permian
Ordos Basin
作者简介
李国斌,1967年生,高级工程师,博士,主要从事沉积学、油气地质和油气成藏等方面的研究工作。地址:(730020)甘肃省兰州市城关区雁儿湾路535号。ORCID:0000-0001-9453-0130。E-mail:lgb@petrochina.com.cn。
