不同碎屑矿物CO_2参与的水-岩作用效应数值模拟  

Numerical simulation for the water-rock interaction with the participation of CO_2 in different clastic minerals

作　　者：李凤昱 许天福[1] 杨磊磊[1] 封官宏[1] 杨志杰[1] 袁益龙 赵宁宁[1] 田海龙[1] 

机构地区：[1]吉林大学地下水资源与环境教育部重点实验室,吉林长春130021

出　　处：《石油学报》2016年第9期1116-1128,共13页Acta Petrolei Sinica

基　　金：国家重大科技专项(2016ZX05016-005-002);中国石油天然气股份有限公司科学研究与技术开发项目(2011A-0207)资助

摘　　要：鄂尔多斯盆地地质历史上的2次烃源充注使得以CO2为主的气体进入砂岩储层,导致储层内发生了以水-岩反应为主的成岩作用,最终使储层发生高度致密化。鉴于储层致密化过程研究对有利储层的评价和预测极其重要,以鄂尔多斯盆地东北部下石盒子组8段致密储层为例,在实测水化学、矿物等数据的基础上,运用岩石学测试分析及数值模拟方法,利用简化的二维地质模型,采用多相、多组分反应溶质运移程序TOUGHREACT,研究不同碎屑矿物条件下,CO2进入储层后所发生的水-岩反应及其对储层孔隙度的影响,确定了最有利于储层致密化形成的碎屑矿物条件。结果表明,长石类矿物溶解所产生的自生高岭石、伊利石及铁白云石是造成储层孔隙度和渗透率减小的主要矿物。绿泥石在CO2-水-岩作用的过程中,极易发生溶蚀,主要产物为铁白云石。碎屑组成中较高含量的含钙矿物对于储层的致密化有重要意义。含钙矿物总体积分数为0.315时,在CO2参与下发生的水-岩反应中,孔隙度最大降幅可达40.0%。The Ordos Basin has experienced two times of oil and gas charging in the geological history,for which the gases dominated by CO2 enter the sandstone reservoir,causing diagenesis dominated by water-rock reaction and finally resulting in high densification.Considering the significance of reservoir densification to the evaluation and prediction of reservoirs,the 8th Member of Lower Shihezi Formation in the northern Ordos Basin will be taken as an example to study the effect of water-rock reaction on the reservoir porosity after CO2 enters the reservoirs with different clastic minerals,so as to determine the most favorable clastic mineral base for reservoir densification.The study is conducted on the basis of measured chemical and mineral data,with a combination of petrological test and analysis,numerical simulation,simplified 2D geological model,and the multi-phase multi-component reactive solute transport code TOUGHREACT.The results indicate that authigenic kaolinite,illite and ankerite are the main minerals which reduce the porosity and permeability of reservoir.In CO2-water-rock reaction,chlorite can be easily eroded by CO2 acid fluid and mainly produces ankerite.The high content of calcium mineral in the clastic minerals is of great importance to the reservoir densification.When the volume fraction of calcium minerals reaches 0.315,the porosity can be reduced by as much as 40.0% during the interaction.

关 键 词：鄂尔多斯盆地 含油气盆地 CO2-水-岩反应 储层孔隙度 致密化 

分 类 号：TE123[石油与天然气工程—油气勘探]