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从潮湿的煤层生产甲烷经常伴随着大量水的产出。从煤层释放甲烷产水是必然的,由于钻井后数周到数月才能产气,所以钻井液导致的伤害很难评价。文章描述了一种独特的煤层气井钻井液的开发,并特别强调了在水平井中的应用。流体设计综合了与煤的精细表面化学特性相匹配的各种产品,一种既提供了井眼稳定性又降低了流体漏进割理的垫层体系,及一种钻井完成后清除垫层体系的BREAKER方法。3口水平井中的2口井使用了新型钻井液体系,其结果证明,1000m长的煤层具有特殊的稳定性,可控制钻井速度并较容易下入割缝衬管。
Methane production from wet coal seams is often accompanied by large volumes of water. It is inevitable to release methane from the coal seam to produce water, which can be difficult to assess as the gas can be produced from weeks to months after drilling. The article describes the development of a unique drilling fluid for coalbed methane wells, with special emphasis on horizontal well applications. The fluid design incorporates a variety of products that match the fine surface chemistry of coal, a cushioning system that provides both borehole stability and reduced fluid leakage and a cushioning system after completion of the well BREAKER method. The new drilling fluid system was used in 2 of the 3 horizontal wells and the results demonstrate that the 1000m long coal seam is exceptionally stable, controls the drilling speed and is easier to insert into the slotted liner.