致密砂岩油藏CO_(2)驱固相沉积规律及其储层伤害特征  

Characteristics of solid deposition and reservoir damage of CO_(2) flooding in tight sandstone reservoirs

作　　者：郭永伟 闫方平[1] 王晶[1] 褚会丽[1] 杨建雷[1] 陈颖超[1] 张笑洋 GUO Yongwei;YAN Fangping;WANG Jing;CHU Huili;YANG Jianlei;CHEN Yingchao;ZHANG Xiaoyang(Chengde Petroleum College,Chengde 066700,Hebei,China;Chengde Field Artificial Intelligence Engineering Technology Research Center,Chengde 066700,Hebei,China)

机构地区：[1]承德石油高等专科学校,河北承德066700 [2]承德市油气田人工智能工程技术研究中心,河北承德066700

出　　处：《岩性油气藏》2021年第3期153-161,共9页Lithologic Reservoirs

基　　金：国家科技重大专项专题“超深层及中新元古界油气资源形成保持机制与分布预测”(编号:2011ZX05004)资助。

摘　　要：沥青质及金属无机沉淀对致密储层的伤害是注CO_(2)驱替中不可避免的问题。为探究沥青质及无机沉淀对储层的伤害机理,以鄂尔多斯盆地延长组长7储层为例,在明确(非)混相压力下原油中CO_(2)含量与沥青质沉淀量关系的基础上,通过开展CO_(2)驱替长岩心实验,研究了CO_(2)非混相和混相驱过程中沥青质和无机沉淀对储层的伤害特征,评价了有机和无机沉淀对储层渗透率和孔隙度的伤害程度。结果表明:当原油中CO_(2)含量达到临界值时,沥青质开始沉淀,沉淀量随CO_(2)含量的增加先快速上升后趋于稳定。混相压力下沥青质沉淀对渗透率和孔隙度的伤害程度均大于非混相。沥青质在混相压力下大量沉积部位为长岩心中后部,而在非混相压力下主要在长岩心前中部。当岩心中沥青质沉淀量达到最大时,后续岩心中的沥青质沉淀量将会逐渐降低,对渗透率造成的伤害也会逐渐减小。无机沉淀在非混相压力下对前中部岩心的渗透率伤害程度大,而在混相压力下则对中后部岩心的渗透率伤害程度大;无机沉淀对孔隙度的影响规律与对渗透率存在差异,主要与溶蚀作用及无机沉淀产生的位置有密切关系。若目标油藏采用非混相驱开发,预防重点为无机沉淀,预防沉淀部位为注入端附近储层;若采用混相驱开发,则预防重点为有机沉淀,预防沉淀部位为产出端附近储层。The damage of asphaltene and metal inorganic precipitation to tight reservoir is an inevitable problem in CO_(2) flooding.In order to explore the damage mechanism of asphaltene and inorganic precipitation to reservoir,taking Chang 7 reservoir of Yanchang Formation in Ordos Basin as an example,on the basis of clarifying the relationship between CO_(2) content and asphaltene precipitation in crude oil under(non)miscible pressure,the damage characteristics of asphaltene and inorganic precipitation on reservoir during CO_(2) immiscible and miscible flooding were studied by long core experiment,and the damage degree of organic and inorganic precipitation on reservoir permeability and porosity was evaluated.The results show that when the CO_(2) content in crude oil reaches the critical value,asphaltene begins to precipitate,and the precipitation increases rapidly at first and then tends to be stable with the increase of CO_(2) content.The damage degree of asphaltene precipitation to permeability and porosity under miscible pressure is greater than that under immiscible pressure.Under miscible pressure,a large number of asphaltenes are deposited in the back of long cores,while under non miscible pressure,they are mainly in the front and middle of long cores.When the asphaltene precipitation in the core reaches the maximum,the subsequent asphaltene precipitation in the core will gradually decrease,and the damage to permeability will also gradually reduce.The damage degree of inorganic precipitation to the permeability of the front and middle cores is greater under immiscible pressure,while the damage degree of inorganic precipitation to the permeability of the middle and rear cores is greater under miscible pressure.The effect of inorganic precipitation on porosity is different from that on permeability,which is closely related to dissolution and the location of inorganic precipitation.If the target reservoir is developed by immiscible flooding,the prevention focus is on inorganic precipitation,and the prevention positio

关 键 词：致密砂岩 CO_(2)驱替 沥青质沉积 无机沉淀 注入压力 

分 类 号：TE31[石油与天然气工程—油气田开发工程]