煤层气井压后返排工艺

Flowback technology after fracturing of CBM wells

  • 摘要: 煤层气井压后返排,是关井待压力扩散一段时间后放喷,还是及时放喷,一直未能形成统一的认识。从压裂液、压力、关井时间等3个方面进行分析,认为煤层气井压裂后应及时放喷返排,建议时间控制在30 min内。同时根据煤层气井压裂后支撑剂立即沉降、颗粒之间出现胶结的特点,建立了压裂液返排模型。计算结果表明:压后返排时先用小油嘴控制放喷,然后逐步更换较大的油嘴放喷或者敞喷,及时返排压裂液,缩短返排时间。在煤层气井压后返排设计时,为定量选择放喷油嘴直径提供了重要的理论依据。

     

    Abstract: There is no unified understanding on fracturing fluid flowback of CBM wells: either shut-in for pressure diffusion after a period of time to discharge or discharge in time. By means of analyzing the fracturing fluid, pressure and shut-in time, the CBM wells should be discharged in time after fracturing and suggested time control within 30 min. At the same time, according to the fracturing characteristics of CBM wells, such as the immediate settlement of proppants and the cementation between particles, the fracturing fluid flowback model is established. The calculation results show that in order to discharge the fracturing fluid timely and shorten the flowback time, it must begin with small choke and change a bigger choke or open flow latter during fracturing fluid flowback. The results provide an important theoretical basis for the quantitative selection of choke diameter in the fracturing fluid flowback design of CBM wells.

     

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