深层煤岩气开发地面工程面临的挑战及对策建议

Surface engineering of deep coal-rock gas development:Challenges and solutions

深层煤岩气指埋藏深度大于1500 m的煤层气资源,具有储层压力大、含气量高、游离气丰富等特点,开采难度大。近年来,中国在鄂尔多斯盆地大吉区块、沁水盆地晋中区块等深层煤岩气勘探开发取得重要新进展,深层煤岩气勘探开发展现了良好的潜力,但压裂用液量高、地面工艺配套复杂、整体投资较高等因素仍是制约此类非常规天然气高效开发的核心问题。为促进深层煤岩气的高效开发,根据目前已开发深层煤岩气试采取得的认识,充分结合已有试采井静态、动态资料,系统梳理了开发过程中地面工程面临的问题与挑战,并提出了针对深层煤岩气开发地面工程的对策与建议。研究结果表明:①深层煤岩气地面工程面临低成本水资源循环利用难度大、地面配套工艺复杂、建设投资高等方面的挑战。②根据深层煤岩气地面工程配套复杂、建设周期长、系统布局要求高等特点,创造性提出“五网同建、地面先行”的建设新模式;并构建差异化集输网、循环回用水网、绿色低碳配电网、安全高效数据网及统筹优化道路网,满足了深层煤岩气高效开发需求。③提出“前端功能模块化、后端功能集成化”设计新模式,井场按照撬装集成、组合拼接,下游站场按照立体布置、高度集成,充分适应了不同阶段煤岩气生产特征差异大的特点。结论认为,深层煤岩气开发需深入落实地上地下一体化建设模式,最大程度降低地面工程整体投资;新的地面工程建设模式体现了“高效、节能、安全、环保、智能”的理念,满足了深层煤岩气产业高质量发展的目标。

Deep coal-rock gas refers to the natural gas resources buried in coal bed deeper than 1500 m,so it is difficult to produce it due to the characteristics of high reservoir pressure,large gas content and rich free gas.In recent years,great progress has been made in the exploration and development of deep coal-rock gas in the Daji Block of the Ordos Basin and the Jinzhong Block of the Qinshui Basin,suggesting a promising potential.However,the efficient development of such unconventional gas is significantly restricted by high fracturing liquid volume,complex surface processes,high overall investment,and other factors.In order to promote the efficient development of deep coal-rock gas,this paper systematically reviews the problems and challenges in surface engineering of deep coal-rock gas development,based on the insights obtained from the production test of the developed deep coal-rock gas,together with available static and dynamic data of production test wells,and then proposes the solutions.The following results are obtained.First,the surface engineering of deep coal-rock gas faces the challenges such as difficult water recycling at a low cost,complex surface processes,and a high construction investment.Second,depending on the characteristics of surface engineering of deep coal-rock gas developing such as complex supporting facilities,long construction periods and high system layout requirements,a new construction mode of"simultaneous construction of five networks,with priority to surface infrastructures"is proposed.The five networks include a differentiated gathering and transportation pipeline network,a water recycling network,a green and low-carbon power distribution network,a safe and efficient data network,and a coordinated and optimized road network,which will be constructed to meet the needs of efficient development of deep coal-rock gas.Third,a new design mode of"modularization of front-end functions and integration of back-end functions"is put forward.The well site follows the mode of skid mounted integration and combined assembly,and the downstream stations are arranged in a three-dimensional and highly integrated manner,so as to fully adapt to the significant differences in production characteristics of deep coal-rock gas at different stages.In conclusion,the development of deep coal-rock gas requires a surface-underground integrated construction mode to minimize the overall investment in surface engineering.The proposed new surface engineering mode reflects the concepts of"efficiency,energy,safety,environment,and intelligence",and meets the goal of high-quality development of the deep coal-rock gas industry.