我国煤层气藏特征及提高地面抽采效果的方法

煤层气藏与常规天然气藏相比,其赋存状态、成藏过程、气藏边界以及开采规律存在着本质差别,根据近年来我国煤层气开发的探索与实践,提出了依"势"布井的理念,应利用煤层中水的"重力势能",根据煤层重力场、地应力场、压力场的分布特征,合理选择井型,部署井网,提高地面抽排煤层气效果;认为对于煤层气多分支水平井,高的煤层钻遇率未必能够带来高的煤层气产量,实钻中的井眼轨迹控制应以井眼光滑、总体上倾为原则,避免出现"波浪状"井眼。分析认为,通过提高储层温度来提高煤层气产气量,以及开展构造煤的钻井技术研究,是今后煤层气开发的重要研究方向之一。

Research on coalbed methane reservoir characteristics and the methods of improving surface extraction effect

Compared to conventional gas reservoirs, the coalbed methane (CBM) reservoirs are essential different from the former in its occurrence state, accumulation process, gas reservoir boundary and production law. According to the practice and exploration of CBM development in China in recent years, the idea of wells distribution in accordance with “the potential” was proposed, which means using “gravity potential energy” of water in coalbed as well location principle. Based on the distribution characteristics of coalbed gravitational field, in-situ stress field and pressure field, reasonable well type and well network were selected to improve ground CBM drainage effect. For CBM multi-branch horizontal wells, high coalbed drilling rates may not be able to bring high coalbed gas production. So the actual drilling of borehole trajectory control should follow the principle of smooth wellbore and overall angled up, to avoid "wavy" well eye. Analysis figures out that by increasing the temperature to rise CBM reservoir gas production, as well as to carry out drilling technology research for tectonic coal are main research direction of CBM development for future.