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贵州织金地区多薄煤层水平井开发效果及产能评价

Development effect and productivity evaluation of multi-thin coal seam horizontal well in Zhijin block, Guizhou Province

  • 摘要: 煤层气水平井产能受到煤层地质条件、压裂改造程度、排采管理制度等多方面因素影响,存在同一工区不同水平井之间产能差异大的现象。以织金煤层气水平井为研究对象,深入探讨各水平井煤层地质特征、储层改造规模和排采管理等参数间的差异,基于模糊综合评价法提出了煤层气水平井产能综合评价模型,半定量的计算了织金工区各水平井的综合得分,筛选出工区产能潜力较大的ZP3、Z56井,为织金煤层气高效开发利用提供有效指导,现场排采情况验证了本研究的合理性和可靠性。研究结果表明:织金工区龙潭组煤层属于海陆过渡相环境,具有分布广、单层薄、层数多的地质特征;其中,龙潭组23号、27号煤层分布稳定、煤层含气量高,为煤层气的生成、储集提供了较好的地质基础,与水平井工艺适配性更好。水平井产能突破的关键是优选双甜点区域实施煤层气储层改造,建议煤层气水平井在开发阶段重点优化加砂量和加砂强度参数,做好高气测全烃值的水平段压裂施工,同时延长气井见气前返排液量,有助于水平井的产能突破。研究中得到了织金工区6口水平井的综合评价结果:ZP3>Z56>ZP1>Z58>Z2U1>ZP2,为织金煤层气进一步释放煤层气井产能提供了有效指导。

     

    Abstract: The productivity of coalbed methane horizontal Wells is affected by many factors such as geological conditions of coal seam, degree of fracturing transformation, drainage and production management system, and there is a phenomenon of large productivity difference among different horizontal Wells in the same working area. Taking Zhijin CBM horizontal Wells as the research object, the coal seam geological characteristics, reservoir reconstruction scale and drainage management differences of each horizontal well are deeply discussed. Based on the fuzzy comprehensive evaluation method, a comprehensive evaluation model for CBM horizontal Wells' productivity was proposed, and the comprehensive scores of each horizontal well in Zhijin working area were calculated semi-quantitatively. ZP3 and Z56 Wells with high productivity potential in the work area were selected to provide effective guidance for the efficient development and utilization of Zhijin coalbed methane. On-site discharge and production have verified its rationality and reliability. The results show that: The coal seam of Longtan Formation in Zhijin block belongs to the transitional facies environment of sea and land, and has the geological characteristics of wide distribution, thin single layer and many layers; Among them, the NO.23 and NO.27 coal seams of Longtan Formation have stable distribution and high gas content, which provides a good geological basis for the generation and storage of coalbed gas, and has better adaptability to horizontal well technology. The key to the productivity breakthrough of horizontal Wells is to realize the “geology+engineering” double dessert construction. It is suggested that the CBM horizontal Wells should focus on optimizing the parameters of sand addition and sand intensity during the development stage, do a good job in horizontal fracturing with high gas measurement of total hydrocarbon value, and extend the flowback fluid volume before gas discovery, which is conducive to the productivity breakthrough of horizontal Wells. The comprehensive evaluation results of 6 horizontal Wells in Zhijin block are as follows: ZP3>Z56>ZP1>Z58>Z2U1>ZP2, which provides effective guidance for further releasing CBM well productivity in Zhijin.

     

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