大宁−吉县区块深层煤层气生产特征与开发技术对策

Production characteristics of deep coalbed methane gas reservoirs in Daning-Jixian Block and its development technology countermeasures

  • 摘要: 鄂尔多斯盆地埋深超过2 000 m的深层煤层气资源丰富,是煤层气勘探开发重要领域,鄂尔多斯盆地东缘大宁−吉县区块开展了一批深层煤层气工艺试验,初步取得一定效果,但规模效益开发主体技术亟待攻关。基于实验分析、生产数据和裂缝监测等资料,通过对大宁−吉县区块深层煤层气储层特征、生产动态和压裂改造效果开展评价,分析了深层煤层气生产特征并提出开发技术对策。研究认为:(1) 深层煤储层具有“低渗、高含气、高含气饱和度、富含游离气”的特征;(2) 深层煤层气产能主要受资源富集、微构造和有效改造规模控制,在正向微构造发育区,资源越富集、加液强度越大、加砂强度越大,越有利于扩大供气能力和提高单井产量;(3) 深层煤层气生产井呈现出以游离气产出为主的高产期、游离气和吸附气共同产出的稳产及递减期和以吸附气产出为主的低产期三段式产出特征。基于上述认识,提出了深层煤层气开发技术对策,实施的D6-7P1井取得较好生产效果,证实在有利区实施超大规模加砂压裂可有效提高深层煤层气产能。

     

    Abstract: The Ordos Basin is rich in deep coalbed methane resources with a depth of more than 2 000 m, which is an important coalbed methane exploration and development area. A number of tests on deep coalbed methane have been carried out in Daning-Jixian Block, and preliminary results have been achieved, but the main technology of scale-efficient development needs to be studied. On the basis of the analysis of experimental data, production data and fracture monitoring data, and by the evaluation of the characteristics, production performance and fracturing effect of deep coalbed methane reservoirs in Daning-Jixian Block, the production characteristics of deep coalbed methane are analyzed and development countermeasures are proposed. The research indicates that ① Deep coal reservoirs have the characteristics of low permeability, high gas content, high gas saturation and rich free gas. ② The productivity of deep coalbed methane is mainly controlled by resource enrichment, micro-structure and effective fracturing scale. In the positive micro-structure development area, the richer the resources, the greater the fluid strength, and the greater the sand strength, the more conducive to expand the gas supply capacity and improve the single well production. ③ The production wells of deep coalbed methane are characterized by three-stage production: the high production period dominated by free gas production, the stable and decline period where free gas and adsorbed gas are produced together, and the low production period dominated by adsorbed gas production. The technology countermeasures for deep coalbed methane development are put forward based on the above, and the implementation of D6-7P1 well has achieved good production effect, which confirms that the implementation of super large-scale sand fracturing in favorable areas can effectively improve the production capacity of deep coalbed methane.

     

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