松河井田储层高压形成机制及对煤层气开发的影响

High pressure formation mechanism of reservoir in Songhe Mine Field and its impact to coalbed methane development

从生烃及储存条件2个方面分析了松河井田煤储层异常高压的形成机制,并探讨了其对煤层气开发的影响。研究表明:松河井田较高的煤变质程度有利于煤储层大量生烃;同时,高地应力造成的储层低渗透率,顶底板良好的封盖作用以及龙潭煤系较弱的水动力条件等为煤层气的储存提供了良好的条件,上述因素共同作用导致井田煤储层的异常高压。储层异常高压有利于煤层气的大量保存,增大了煤层气井排水降压的幅度,为煤层气地面开发提供了有利条件,但同时易造成煤储层较强的应力敏感性,因此建议降低煤层气井排采过程中的流压,以缓解应力敏感效应的不利影响。

From the aspects of the hydrocarbon generation and storage conditions,the paper analyzed the abnormal high pressure formation mechanism of the reservoir in Songhe Mine Field and discussed the formation mechanism affected to the coalbed methane development.The study showed that the high coal metamorphism degree of Songhe Mine Field could be favorable for the coal reservoir to have great hydrocarbon generations.Meanwhile,the low permeability of the coal reservoir caused by the high geostress,a good sealing role of roof and floor,weak water dynamic conditions of Longtan coal measures and others could provide good conditions to the storage of the coalbed methane and thus the joint roles of the above factors caused abnormal high pressure of the coal reservoir in the mine field.The abnormal high pressure of the coal reservoir would be favorable for the great storage of the coalbed methane,could highly increase the water discharging and pressure released of the coalbed methane well,would provide favorable conditions for the surface development of the coalbed methane and would cause a high stress sensitivity of the coal reservoir.Therefore,the paper proposed to highly reduce the flow pressure in the drainage process of the coalbed methane well,in order to release the unfavorable influences of the stress sensitivity effect.