Exploration and Development Research Institute of Petro China Huabei Oilfield Company

为了解煤层气储层应力敏感损害机理,探讨高煤阶煤储层应力敏感损害程度,选择沁水盆地南部9个高煤阶煤岩样品完成应力敏感试验,并进行了系统的压敏效应评价。结果表明:沁水盆地南部高煤阶煤岩样品渗透率损害程度较大,主要表现为强压敏;煤岩渗透率随围岩增大呈负指数形式降低,渗透率随围压变化速率与最大损害率变化趋势相同;当有效应力小于9.5 MPa时,煤储层渗透率随有效应力增加快速下降,应力敏感性较强;大于有效应力9.5 MPa以后,渗透率随有效应力的增加下降速度减缓,应力敏感性减弱。依据这一规律,有效避免煤层气开发过程中煤储层渗透率应力敏感损害是实现煤层气高产、稳产开发的关键问题。

In order to realize the damage mechanism of stress sensitivity in coal reservoir, discuss the damage degree of high rank coal reservoir, 9 high- rank coal samples were collected in southern Qinshui Basin to complete the stress sensitivity measurement, and then the effect of stress sensitivity was systematic evaluated. Th e results showed that the damage degree of coal permeability of high- rank coal samples is large, main strong stress sensitivity. The permeability would decrease as a negative exponent with the surrounding stresses increase.The variation rate of coal permeability have the same trend with variation of the maximum damage rate. The permeability declined rapidly when the effective stress was lower than 9. 5 MPa, reflecting a strong stress sensitivity; while the permeability declined slowly when the ef fective stress was larger than 9. 5 MPa, reflecting a weak stress sensitivity. As a rule, how to avoid or decrease the permeability damage during the process of coalbed methane development is a key problem for achieving a high and stable gas production rate.

国家重大科技专项资助项目(2011ZX05061)；国家自然科学基金资助项目(41272175)；