煤层气井越流补给的判识方法

Identifying method of leakage recharge in CBM wells

  • 摘要: 排水降压是煤层气开发的技术依据,及时判别煤层气井是否存在越流补给,将关乎到排采工作制度的制定和产气量预测。通过煤层气井不同排采阶段的实际产水量与理论值的比较,并结合套压、井底流压、动液面和产气量的变化特征,能够快速判识越流补给。若煤层气井实际产水量明显高于理论值,且开始产气时动液面上升后不再下降,产气量和套压保持在较低水平,则认为该井存在越流补给。在此基础上,根据动液面、套压和产气量特征划分越流补给井类型,确定合理的后续排采制度。通过分析沁水盆地煤层气井的排采数据,验证了越流补给井及类型的快速识别方法。

     

    Abstract: Drainage and pressure lowering are echnical basis for coalbed methane development, and prompt leakage recharge identification is related to the drainage working system and gas production forecast. Combined with the variation of bottom hole flowing pressure, casing pressure, producing fluid level and gas production of different drainage stages in CBM wells, the existence of leakage recharge is identified by comparison between theoretical and real water production. The paper points out that there is leakage recharge when the real water production is greater than the theoretical value, and the rose fluid level no longer declines after gas production, gas production and casing pressure are maintained at a low level. On this basis, according to the characteristics of dynamic fluid level, casing pressure and gas production, leakage recharge types are classified and the subsequent drainage working system is determined reasonably. The production curves of CBM wells show that this approach is effective in southern Qinshui basin.

     

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