煤层气低产井低产原因及增产改造技术

沁水煤层气田的煤层气开发已初具规模,但部分煤层气开发井由于地质、工程或排采因素的影响而产量低,亟需查明原因。为此,从地质因素(构造位置、陷落柱、断层等)、工程因素(钻完井及水力压裂过程中储层污染等)和排采因素(套压控制、排液速度、停电停抽等)3个方面对煤层气单井产气量的影响进行了详细的分析,阐述了嵌套钻井、短半径水力喷射钻井、小井眼侧钻、二次(重复)水力压裂等增产改造技术的特点及优势,并结合对煤层气低产井原因的分析,给出了不同增产改造技术的适用特性。对煤层气规模开发过程中老井、低产井的后期改造提供了技术支撑。

Reason analysis and stimulation measures of low coalbed methane gas production wells

At present, the scale CBM development in the Qinshui Basin has taken its shape, but the production of some CBM exploratory wells is still low due to the influence by geological reason, engineering results and drainage gas recovery control. Moreover, an in depth analysis is made on how a single CBM well's production is influenced by the above mentioned three factors: ①Geological reason, such as structural location, collapse column and faults, ②Engineering results, such as coal bed damage in drilling and completion, and bad fracturing effect; ③Drainage gas recovery control, such as casing pressure control, liquid drainage velocity, and other reasons like power off or pump stopping, etc. Hereby, the characteristics and the advantages of the stimulation measures, such as pinnate horizontal multilateral well and vertical well nested drilling technology, ultra short radius hydraulic jet drilling technology, slim hole sidetrack drilling technology, and re fracturing stimulation technology, have been introduced. In combination with reason analysis, the applicable conditions for the different stimulation technologies have been presented. This provides technical support for the post stimulations of the old and low production wells during the scale CBM development in this basin.