煤矿区煤层气井甲烷漏失特征及漏失量模型

    Methane emission characteristics and model of coalbed methane wells in coal mining area

    • 摘要: 煤矿区煤层气开发具有良好的安全、经济和能源效益,然而地面井场甲烷漏失现象较为普遍;鉴于此,以山西沁水县煤层气排采井为研究对象,通过现场调查和多元回归分析,获取了煤层气井甲烷漏失部位和漏失量,并建立了甲烷漏失量的预测模型。结果表明:81%的煤层气井存在甲烷漏失现象,井口与排水口是甲烷漏失的2个主要部位,漏失量在0~10 m3/d的井占到59%,且整体上漏失量占气井产量的1.53%;单相水流阶段几乎不存在甲烷漏失,气液两相流阶段甲烷漏失量与井底流压、冲次、日产气量呈正相关,与泵埋没度和日产水量呈负相关,其中井底流压和泵埋没度对甲烷漏失量的影响最大;在单相气流阶段,甲烷漏失量与日产气量和套管压力呈正相关,与冲次、日产水量呈负相关,其中套管压力和日产水量对甲烷漏失的影响最大。

       

      Abstract: Coalbed methane (CBM) development in coal mining area has good safety, economic and energy benefits, but methane emission is common in surface well sites. In view of this, taking the CBM wells in Qinshui County of Shanxi Province as an example, the methane emission location and emission volume of CBM wells are obtained, and the prediction model of methane emission volume is established through field investigation and multiple regression analysis. The results show that 81% of CBM wells have methane emission. Wellhead and drainage outlet are the two main positions of methane emission. The proportion of wells with emission volume between 0-10 m3/d is 59%. On the whole, the emission accounts for 1.53% of the gas well production. There is almost no methane emission in the single liquid phase flow stage. The methane emission in the gas-liquid two-phase flow stage is positively correlated with the bottom hole flow pressure, times of stroke and gas production, and negatively correlated with the pump embedment and water production. The bottom hole flow pressure and the pump embedment have the greatest impact on the methane emission. In the single-phase gas flow stage, methane emission is positively correlated with gas production and casing pressure, and negatively correlated with stroke frequency and water production.

       

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