煤储层流速敏感性“气液等效”评价方法

Gas/liquid equivalence evaluation method for the sensitivity of coal reservoir to flow velocity

孙晗森 徐加放 于政廉 王德桂 马洪涛 马腾飞

SUN Hansen XUN Jiafang YU Zhenglian WANG Degui MA Hongtao MA Tengfei

中联煤层气有限责任公司 中国石油大学(华东)石油工程学院

China United Coalbed Methane Co. Ltd., Beijing 100011, China College of Petroleum Engineering, China University of Petroleum (East China), Qingdao 266580, Shandong, China

油气储层的敏感性评价是合理制定钻采技术措施和储层保护原则，防止储层伤害的基础，而储层临界流速的确定又是其他敏感性评价的前提。流速敏感性评价通常采用模拟地层水进行，而对于气藏，尤其是煤层气的开采不同于常规油气储层，大多渗透率低，且存在排水和采气两个环节，因此现有的液测岩心流动实验的评价方法无法对其进行全面、有效的流速敏感性评价。为此，以动能定理为依据建立了“气液等效”的流速敏感性评价新方法，使得气测法和液测法取得的临界流速能够进行等效替代，并充分考虑气体滑脱效应，推导出了气测法确定临界流速的计算方法，从而建立了煤层气储层流速敏感性气测实验方法。实验结果表明，气测法能够应用于流速敏感性评价中，且临界流速的推导结果与液测法结果误差在20%以内，具有较强的参考性，适合于煤储层的流速敏感性评价。

The sensitivity evaluation on oil and gas reservoirs is the foundation for reasonably formulating the drilling & production technologies and measures and the reservoir protection principles to prevent reservoir damage, and the determination of the critical flow velocity in the reservoir is the prerequisite to the other sensitivity evaluations. The sensitivity to flow velocity is commonly evaluated using the simulated formation water. As for coalbed methane (CBM) especially, however, its production is different from that of conventional oil and gas reservoirs. It is mostly of low permeability and its production has two links, i.e., water drainage and gas recovery. Therefore, existing evaluation method of liquid measuring core flow experiment cannot provide comprehensive and effective evaluation on its sensitivity to flow velocity. A new method for evaluating the sensitivity to flow velocity based on gas/liquid equivalence was established according to the kinetic energy theorem. In this method, the critical flow velocity obtained from gas measuring method and that from liquid measuring method can be substituted equivalently. Then, a method for calculating the critical flow velocity based on gas measuring method was derived by taking full consideration of gas slippage effect. In this way, a gas measuring experiment method on the sensitivity of CBM reservoir to flow velocity was developed. It is experimentally indicated that gas measuring method is applicable to evaluate the sensitivity to flow velocity and the error between its derivative result of critical flow velocity and the result of liquid measuring method is within 20%, so it can provide valuable reference and is suitable for evaluating the sensitivity of coal reservoir to flow velocity.

10.13639/j.odpt.2019.04.017