CO₂-水-岩石相互作用对岩石孔渗参数及孔隙结构的影响——以延长油田35-3 井储层为例

Effect of CO₂-water-rock Interaction on Porosity，Permeability and Pore Structure Characters of Reservoir Rock：A Case Study of 35-3 Well in Yanchang Oilfield

肖娜 李实 林梅钦

XIAO Na LI Shi LIN Meiqin

二氧化碳注入油藏后会与储层中的地层水和岩石发生反应，导致储层的孔隙度、渗透率和孔隙结构等物性参数发生改变。以延长靖边油田特低渗油藏35-3 井储层岩心为研究对象，研究了不同反应时间和反应压力下CO2-水-岩石相互作用后，岩石孔隙度、渗透率和孔隙结构分布的变化，考察了压力对CO2-水-岩石相互作用后岩石表观形貌及溶液中Ca2+浓度的影响。结果表明，岩石孔隙结构的变化受溶蚀作用、微粒运移和新生矿物沉积的综合影响；当反应时间和反应压力改变时，岩石内小孔隙的分布发生较大的改变，大孔隙分布变化不明显。CO2-水-岩石作用6~24 h 后，岩石水测渗透率均降低；随反应时间增加，岩石孔隙度先降低后增加，岩石渗透率恢复值逐渐增加，CO2对储层渗透率变化的影响逐渐减小。CO2-水-岩石在7~15 MPa下作用后，岩石水测渗透率均降低；随压力增加，岩石孔隙度先增加后降低，岩石渗透率恢复值逐渐降低，CO2对储层渗透率变化的影响增加。反应压力增加，岩石溶蚀现象更加明显，溶液中Ca2+浓度增加。图10 表3参17

CO2 could react with formation water and reservoir rock when it was injected into reservoir. The interaction of CO2-rock-water could change the porosity，permeability and pore structure characters of the reservoir. In this paper，the changes of porosity，permeability and pore structure of the rock were measured after rock reacted with CO2 and water in different reaction times and under different reaction pressures. The apparent morphology of the rock and Ca2+ concentration in water after the interaction of CO2-rock-water under different pressures were also measured. The results showed that the change in pore structure of rock was influenced by the comprehensive effects of dissolution，particle migration and the deposition of new minerals. With the change of reaction time and reaction pressure，the distribution of small pores in rock changed greatly，while that of macropores changed little.The water permeability of rocks all decreased after CO2-water-rock reaction of 6—24 hrs. With the increase of reaction time，the porosity of rock decreased first and then increased，the permeability recovery of rock increased gradually which showed that the effect of CO2 on reservoir permeability changes decreased gradually. The water permeability of rocks all decreased after CO2-water-rock reaction under 7—15 MPa. With the increase of reaction pressure，the porosity of rock increased first and then decreased，the permeability recovery of rock decreased gradually which showed that the effect of CO2 on reservoir permeability changes increased gradually. The dissolution of rock was more obvious and the concentration of Ca2+ in solution increased with the increase of reaction pressure.

10.19346/j.cnki.1000-4092.2018.01.016