煤层气开采井组合方案设计与分析

我国煤层气地面开发目前大多以直井为主,分支水平井和U形井为辅,但是单井产量普遍较低。国外针对煤层地质特点,开发了V形井、多向羽状分支井、多层开采等新型开采模式,提高了煤层气单井产量,降低了采气成本。借鉴国外经验,详细设计了新型煤层气开采井组合方案:2口工程井成90°、共用1口抽排直井,2口工程井V形布置、共用1口抽排直井,锚形水平井和组合式锚形水平井等。以鄂尔多斯保德地区某煤层气区块的地质参数为依据,利用Eclipse气藏模拟软件,模拟分析了各方案的单井产气量、单井建井成本以及经济效益。与传统直井、分支水平开发模式对比发现,新方案能大大提高煤层气的单井产量,降低单位体积采气成本,提高经济效益。其中组合式锚形水平井的产气量最高,单位体积采气成本最低;V形井的经济效益最高。最后,针对新型煤层气开采井组合的研究现状,提出了发展建议。 

The Design and Analysis of the Scheme for Well Patterns to Produce Coal Bed Methane

Vertical well is the main ways for developing coal bed methane(CBM) in China,multi-lateral horizontal well and U-shaped wells are the subsidiary.But the gas rate per well in China is low constantly.In the view of characteristic of coal geology abroad,there have been developed some new recovery patterns,such as V-shaped wells,multi-lateral herringbone wells,and multi-layer development wells,which can not only increase gas rate but also reduce production cost.Learning from foreign experience,the new CBM patterns of well for produce CBM have been designed in detail,including:two engineering wells are vertical distributed,shared with one vertical well for extracting fluids,two engineering wells are arranged in V shape,shared with one vertical well for extracting fluids,anchored horizontal well and integral anchored wells,etc.According to geologic parameters of Baode district in Erdos Basin,with 16 km2 of CBM resource,single well construction cost and overall economic benefit of each scheme have been analyzed and simulated by using Eclipse software.Through comparison of traditional vertical well and multi-lateral horizontal well,it is found that new pattern of recovery scheme can increase gas rate significantly,reduce gas production cost and boost cumulative economic benefits.Integrated anchor wells have the best gas rate per well and lowest gas production cost,while V-shaped wells have the highest cumulative economic benefits.Finally,the suggestion for producing CBM is presented by considering the present status of well patterns.