延川南深部煤层气开发关键技术与地质工程一体化实践

Critical technologies and geology-engineering integration practices for deep CBM production in the Yanchuannan CBM field

  • 摘要:
    目的和方法 针对深部煤层气储层非均质性强、开发井网部署模式单一、常规水力压裂适用性较差、传统排采周期过长以及低效井占比大等难题,以国内首个深部煤层气田−延川南煤层气效益开发实践为例,力图通过深部煤层气地质工程一体化技术的深度融合,形成延川南深部煤层气的高效开发建产模式。
    结果和结论 结果表明:(1) 延川南深部煤层气田规模化产能建设历经规模建产、技术攻关、创新推广3个开发阶段,形成了“四元耦合”地质工程“双甜点”优选和高效开发地质认识,创立了“有效支撑”压裂理念及储层改造关键配套技术,提出了“四段三稳三控”优快上产排采等针对性技术,平均见气周期由240 d缩短至30 d,单井产量实现大幅提升,定向井单井日产气量达2.0万m3,水平井单井日产气量达6.5万m3。(2) 深部煤层气非均质性强、效益开发难度大,产能建设按照“整体部署、分批实施、评建一体、滚动建产”的思路,不断评价调整地质工程“双甜点”区,及时优化开发方案,有效规避低效井成批出现,产能到位率由最初84%提升至100%,经济效益明显提高。(3) 立足井位部署−钻完井−储层改造−试气排采−集输处理等气藏全生命周期,遵循地质工程一体化理念,形成了“储量−井网−缝网”相匹配的合理井距,单井动用储量提高30%~50%;建立了“提速+降本”为核心的优快钻完井技术,钻进速度较早期提速34%;提出了“高低压分输+三级增压+站间互通”为内涵的低压集输工艺技术,平台投资降低10.8%、节约用地20%。延川南煤层气田地质工程一体化实践,为深部煤层气产业发展提供了技术支持,具有较好的示范和带动意义。

     

    Abstract:
    Objective and Methods  This study introduces the adjustments for coalbed methane (CBM) production in the Yanchuannan CBM field‒the first deep CBM field in China. Deep CBM production in this CBM field faces challenges including strong heterogeneity of reservoirs, single arrangement mode of production well patterns, low applicability of conventional hydraulic fracturing, excessively long conventional production cycles, and a high proportion of inefficient wells. To address these challenges, a production capacity construction model for efficient deep CBM production of the field was developed through in-depth geology-engineering integration.
    Results and Conclusions The results indicate that the production capacity construction process of the Yanchuannan CBM field has undergone three stages: large-scale production capacity construction, addressing technological challenges, and technological innovations and their popularization. Results and Conclusions The following achievements were obtained: (1) The geological understanding of four critical indicators for the selection of optimal geological-engineering “sweet spots” and efficient CBM production. (2) The concept of fracturing through effective propping and key supporting technologies for reservoir stimulation. (3) The optimal and fast production technologies characterized by four stages, three pressures, and three aspects of control. Based on these achievements, the average cycle for acquiring gas shows was shortened from 240 d to 30 d, and the single-well production was significantly enhanced, with the daily gas production of directional and horizontal wells reaching 2.0×104 m3 and 6.5×104 m3, respectively. The deep CBM reservoirs in the Yanchuannan CBM field exhibit strong heterogeneity, causing difficulties with effective production. Given this, the work philosophy that consolidates overall deployment, implementation in batches, integrated assessment and construction, and rolling production capacity construction was developed for production capacity construction. Adhering to this work philosophy, the production capacity construction was performed through continuous assessment and adjustment of geological-engineering sweet spots and timely optimization of production schemes to effectively avoid the co-occurrence of a substantial number of inefficient wells. This increased the fulfillment rate of production capacity from the initial 84% to 100%, suggesting significantly enhanced economic effects. Based on the concept of geology-engineering integration and the full life cycle of gas reservoir development that consists of well emplacement, well drilling and completion, reservoir stimulation, well tests and production, and gathering, transportation, and processing, the following outcomes were obtained: (1) Rational well spacing that matches reserves, well patterns, and fracture networks, increasing single-well producing reserves by 30% to 50%. (2) The optimal well drilling and completion technology focusing on speed increase and cost reduction, improving the drilling speed by 34%. (3) The low-pressure gathering and transportation technology involving high- and low-pressure gathering and transportation, three-stage pressurization, and inter-station connection, reducing the platform investment by 10.8% and the land use by 20%. The geology-engineering integration practices in the Yanchuannan CBM field provide technical support for the deep CBM industry, holding great demonstration and promotion significance.

     

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