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许江, 李奇贤, 彭守建, 韩恩德. 不同层间压差条件下叠置含气系统的定产合采试验研究[J]. 煤炭科学技术, 2020, 48(1).
引用本文: 许江, 李奇贤, 彭守建, 韩恩德. 不同层间压差条件下叠置含气系统的定产合采试验研究[J]. 煤炭科学技术, 2020, 48(1).
XU Jiang, LI Qixian, PENG Shoujian, HAN Ende. Experimental study on commingled production with constant-rate of a multi-superimposed gas system under different interlayer pressure difference[J]. COAL SCIENCE AND TECHNOLOGY, 2020, 48(1).
Citation: XU Jiang, LI Qixian, PENG Shoujian, HAN Ende. Experimental study on commingled production with constant-rate of a multi-superimposed gas system under different interlayer pressure difference[J]. COAL SCIENCE AND TECHNOLOGY, 2020, 48(1).

不同层间压差条件下叠置含气系统的定产合采试验研究

Experimental study on commingled production with constant-rate of a multi-superimposed gas system under different interlayer pressure difference

  • 摘要: 为了研究滇东—黔西地区的多层叠置含气系统煤层气合采的产气特征,以4层合采方式为研究背景,利用大型多场耦合煤层气开采物理模拟试验系统展开3组不同层间压差条件下的定产煤层气合采物理模拟试验,研究了4个煤层在煤层气合采过程中的储层压力、瞬时产量、产能贡献率等参数动态演化规律。研究结果表明:在合采过程中,1号煤层的储层压力在11.5 min上升至1.1 MPa,出现明显的压力上升,这是由于煤层之间的储层压力差过大会形成层间干扰现象,使低气压煤层的储层压力上升,但该现象主要发生在合采初期,并随着合采时间的延长而减弱;在11.25 L/min的定产生产条件下,1—4号煤层的初始瞬时产量分别为-23.4、-1.6、9.3、18.3 L/min,因此当单层产气能力高于定产值时,高气压煤层的部分产气量通过井筒汇入低气压煤层,形成倒灌现象,且层间压差越大,倒灌的气量越大;在0.2、0.3和0.5 MPa的3种层间压差条件下,1号煤层在第10 min的产气贡献率分别为-3.2%、-10.4%、-16.9%,所以在合采初期,层间压差越大,对低气压煤层的产气的抑制作用越大;在稳产期内,不同储层压力的煤层产气呈现为一种“动态平衡”的产气特征,即当相对高气压煤层的产气能力不足时,相对低气压煤层的产气能力开始增加,从而维持稳定产气。

     

    Abstract: This paper presents results of an experimental study on gas production characteristics of commingled production of multi-superimposed gas system in eastern Yunnan and western Guizhou. The large-scale multi-field coupling test system was utilized to simulate commingled production with constant rate and three different pressure difference on four coal seams. The coalbed methane exploitation, reservoir pressure, instantaneous production, and productivity contribution rate of the four coal seams were analyzed. The experimental results show that No.1 coal seam shows obvious reservoir pressure rise which increased to 1.1 MPa in 11.5 minutes. The reason is that the excessive interlayer pressure difference causes interlayer interference, resulting in increase of the reservoir pressure of coal seam with low-pressure. However, the pressure increases at the early stage of commingled production and then decreases with time. When the production rate is 11.25 L/min, the initial instantaneous production rate of the four coal seams are -23.4、-1.6、9.3 and 18.3 L/min, respectively. When the gas production capacity of a single coal seam is higher than the constant production rate, part of the gas production of coal seam with high pressure enters into coal seam with low-pressure through gas well. The larger interlayer pressure difference is associated with larger gas volume of reversed gas. When the pressure differences were 0.2、0.3 and 0.5 MPa, the gas production contribution rate of No.1 seam at the 10 min was -3.2%、-10.4% and -16.9%, respectively. The result indicates that, at the early stage of commingled production, greater interlayer pressure difference has greater inhibitory effect on the gas production in low pressure coal seam. The gas production of coal seams with different reservoir pressure presents a "dynamic equilibrium" gas production feature during the stable production period. When the gas production capacity of high pressure coal seam is insufficient, the gas production capacity of low pressure coal seam begins to increase, maintaining stable gas production.

     

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