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影响煤层气开发效果的地质因素再认识
断块油气田
2020年 27卷 第3期
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Title
Re-recognition of geological factors affecting coalbed methane development effect
单位
中联煤层气国家工程研究中心有限责任公司，北京 100095
中石油煤层气有限责任公司，北京 100028
Organization
National Engineering Research Center of China United Coalbed Methane, Beijing 100095, China
PetroChina Coalbed Methane Company Limited, Beijing 100028, China
摘要
地质特征认识对煤层气开发效果起着重要作用。在资源特征相差不大的情况下，发现煤层气相邻井的产量差异仍较大。排除工程因素后，通过选取8类地质参数，细致比对了保德区块低产井与邻井的参数特征，筛查出其关键因素为煤层微幅构造与顶板封盖条件，其中以微幅构造为主。据此，重新认识并划分出区块新的次生褶皱背斜单元、向斜单元和斜坡单元，获得了不同次生褶皱构造单元的开发特征。结果表明，高、低产井分布与次生褶皱背斜、向斜相关性高达92%。其中：高产井主要分布在次生褶皱背斜变化较缓、呈隆起状的“平台”，且煤层顶板以泥岩、碳质泥岩为主，封盖性较好；低产井主要分布在次生褶皱向斜，同一井台各井开发效果差异表现为从向斜条带轴部—向斜条带内—向斜条带外的煤层气井平均单井产量不断增加，到向斜轴部的距离大于向斜曲率半径73.5%的范围为主力产气区，小于向斜曲率半径40.0%范围为产水主力区。这对煤层气新井部署、生产管理、开发调整等，具有一定的指导意义。
Abstract
Geological characteristics recognition plays an important role in the development effect of colabed methane(CBM). It is found that the productions of adjacent CBM wells are still quite different under the condition of little difference in resource characteristics. After eliminating engineering factors, 8 kinds of geological characteristics parameters were selected to carefully compare the low-yield wells and adjacent wells of Baode Block. Key factors screened out were the micro-amplitude structure of coal seam and the roof sealing condition, and the micro-amplitude structure is the main factor. On the basis of micro-amplitude structure, the new secondary fold anticline units, secondary fold syncline units and slope units in Baode Block were re-recognized and divided, and the development characteristics of different secondary fold structural units were deeply analyzed. Results show that the correlation between the distribution of high or low productivity wells and secondary fold anticline or syncline is as high as 92%. The high productivity wells are mainly distributed in the platform of secondary fold anticline with gentle change and uplift shape, and its coal seam roof is dominated by mudstone and carbonaceous mudstone with good sealing property. The low productivity wells are mainly distributed in secondary fold syncline, and the difference of development effect of each well on the same platform shows that the production of CBM wells increases in turn from the axis of syncline strip to the inside of strip to the outside of strip. The main gas producing area is located in the area where the distance from the syncline axis is more than 73.5% of the syncline curvature radius, and the main water producing area is located in the area where the distance from the syncline curvature radius is less than 40.0%. It has certain guiding significance in new CBM wells deployment, production management and development adjustment, etc.
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