火山岩高含CO2气藏渗透率应力敏感性研究

Permeability stress sensitivity of volcanic gas reservoir with high CO2 content

范照伟1 杨胜来1 王玉霞 邓 惠

中国石油大学石油工程教育部重点实验室，北京 102249 西南油气田分公司勘探开发研究院，四川 成都 610051

Key Laboratory for Petroleum Engineering, Ministry of Education, China University of Petroleum, Beijing 102249, China Research Institute of Exploration and Development, Southwest Oil and Gas Field Company, CNPC, Chengdu 610051, China)

从火山岩高含CO2气藏渗透率应力敏感性实验出发，对比了不同气体对渗透率应力敏感性的影响，认为天然气中CO2含量对应力敏感性有较大影响，得出了岩石渗透率随有效覆压的变化规律。对比火山岩气藏渗透率应力敏感性与一般低渗透气藏应力敏感性的规律是否相同，同时采用多种方法评价气藏的应力敏感性程度。长深气藏应力敏感性属于中等强度，在开发初期就要制定合理的气井工作制度避免伤害地层。该类气藏渗透率随有效覆压的变化符合幂函数关系。岩心与二氧化碳的作用力要强于与氮气和天然气的作用力，由于该气藏CO2含量高，因此CO2的存在会加剧了该类气藏的应力敏感性。火山岩孔隙结构复杂是该类气藏应力敏感的主要因素。

Based on the experiments of permeability stress sensitivity of volcanic gas reservoir with high CO2 content, the influence of different gas on permeability stress sensitivity was compared. It is considered that CO2 content has a major effect on permeability stress sensitivity and the variation rule of rock permeability with effective overburden pressure was obtained. It compared the permeability stress sensitivity of volcanic gas reservoir with that of generally low permeability gas reservoirs to find out whether they have same rules. It also uses several methods to evaluate the degree of stress sensitivity of gas reservoir. The results are as follows: Changshen gas reservoir has a moderate permeability stress sensitivity; the permeability changes with effective overburden pressure according to the power function. Due to the high content of CO2, the acting force of core and carbon dioxide is stronger than that of nitrogen and gas. CO2 can aggravate the permeability stress sensitivity of the reservoir; the rock′s complex pore structure is the main factor to cause the permeability stress sensitivity.