彬长矿区低煤阶煤层气井的排采特征与井型优化

发布时间：2018-08-19 07:27

【摘要】：为研究我国西部侏罗纪低阶煤储层瓦斯的地面井排采特性及影响因素,以彬长矿区大佛寺井田煤层气井的地质资料、历史排采数据为基础,分析了该区块不同井型煤层气井的产水量、产气量的主要影响因素,并探讨了相关因素的主要控制机理。研究发现储层特性、水文地质条件是影响该区煤层气成藏的重要因素,在所研究的几种井型中,多分支井在该区有着良好的地面排采效果,其最高日产气量为16 582.3 m3,垂直井次之,而U型井则相对较差。排采数据显示井底流压与产气量呈指数关系,井底流压的减小,日产气量呈指数增加的趋势。在煤层气井不同排采时期,动液面高度对产气量的影响有着不同的作用规律,且对高产气阶段的影响更为显著。套压与产气量之间近似表现为线性变化的关系,但不同排采阶段二者线性关系的比例截然不同。在煤层气井的产气衰减阶段,多分支水平井的日产气量/累计产气量的比值与排采时间呈现为良好的E指数衰减关系,并以此构建了以日产量与累计产量之比和开发时间之间的关系为基础的煤层气井产能预测模型,拟合相关系数均高于0.848 2。
[Abstract]:In order to study the gas drainage characteristics and influencing factors of Jurassic low rank coal reservoir in western China, based on geological data and historical drainage data of coalbed methane wells in Dafosi coalfield in Binchang mining area. The main influencing factors of water production and gas production of coalbed methane wells of different types in this block are analyzed, and the main control mechanisms of related factors are discussed. It is found that reservoir characteristics and hydrogeological conditions are important factors affecting coalbed methane reservoir formation in this area. Among the several well types studied, multi-branch wells have good surface drainage effect in this area. The maximum daily gas production is 16 582.3 m3, followed by vertical wells, and U-shaped wells are relatively poor. The output data show that the downhole flow pressure is exponentially related to the gas production, and the downhole flow pressure decreases and the daily gas production increases exponentially. At different production stages of coalbed gas wells, the effect of moving liquid level height on gas production is different, and the effect on the stage of high production gas is more obvious. The relationship between casing pressure and gas production is approximately linear, but the proportion of linear relationship between casing pressure and gas production is very different. In the stage of gas production attenuation of coalbed gas wells, the ratio of daily gas production to cumulative gas production of multi-branch horizontal wells shows a good E exponent attenuation relationship with production discharge time. Based on the relationship between daily production and cumulative production and development time, a productivity prediction model for coalbed gas wells is constructed. The fitting correlation coefficients are all higher than 0.848 2.
【作者单位】：中国矿业大学安全工程学院;陕西彬长矿业集团有限公司;陕西彬长大佛寺矿业有限公司;
【基金】：国家重点基础研究发展计划(973)资助项目(2011CB201205) 国家自然科学基金资助项目(51204169) 江苏省自然科学基金资助项目(BK20131115)
【分类号】：TD712.6

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