基于溶蚀模拟实验的碳酸盐岩埋藏溶蚀孔洞预测方法--以四川盆地龙王庙组储层为例  

Prediction of burial dissolved vugs in carbonates based on dissolution simulation:A case study of the Longwangmiao Formation dolostone reservoirs,Sichuan Basin

作　　者：沈安江 乔占峰 佘敏 蒙绍兴 张杰[1,2] 王鑫 Shen Anjiang;Qiao Zhanfeng;She Min;Meng Shaoxing;Zhang Jie;Wang Xin(Hangzhou Research Institute of Geology,PetroChina,Hangzhou,Zhejiang 310023 China;Key Laboratory of Carbonate reservoirs,CNPC,Hangzhou,Zhejiang 310023,China)

机构地区：[1]中国石油杭州地质研究院,浙江杭州310023 [2]中国石油天然气集团有限公司碳酸盐岩储层重点实验室,浙江杭州310023

出　　处：《石油与天然气地质》2021年第3期690-701,共12页Oil & Gas Geology

基　　金：国家科技重大专项(2016ZX05004-002);中国石油天然气股份有限公司直属院所基础研究和战略储备技术研究基金项目(2018D-5008-03);中国石油天然气股份有限公司重大科技项目(2018A-0103);中国石油天然气股份有限公司重大科技项目(2019B-0406)。

摘　　要：针对碳酸盐岩埋藏溶蚀孔洞预测的难题,以四川盆地龙王庙组白云岩储层为解剖对象,通过地层条件下的溶蚀模拟实验揭示碳酸盐岩埋藏溶蚀孔洞发育的主控因素和分布规律,为埋藏溶蚀孔洞预测提供理论依据。实验结果表明,岩石物性、酸性流体浓度和温度主控埋藏溶蚀孔洞的发育,地质界面(暴露面、层序界面、不整合面和断裂系统)和高孔渗层主控埋藏溶蚀孔洞的平面分布,垂向上存在一个“成孔高峰期”,埋藏溶孔的生成呈事件式发生,在特定深度段的温度和高浓度酸性流体的匹配下可以形成大量的溶蚀孔洞,并受埋藏史、温压史和流体演化史控制;基于埋藏溶蚀孔洞发育主控因素和分布规律认识,通过四川盆地龙王庙组埋藏前孔隙分布图、筇竹寺组烃源岩在70~100℃温度窗生烃和生酸强度图、龙王庙组经历70~100℃温度窗时古隆起和断裂分布图、龙王庙组经历70~100℃温度窗时埋藏时间(Ma)等值线图的编制,预测了龙王庙组埋藏溶蚀孔洞的分布。构建了碳酸盐岩溶蚀孔洞预测技术及流程,为碳酸盐岩储层埋藏溶蚀孔洞分布预测和评价提供了手段。The prediction of burial dissolved vug distribution in carbonate rocks has always been challenging.This study,taking the Longwangmiao Formation dolostone as an example,reveals the origin of burial dissolved vugs and their distribution in carbonates through dissolution modelling under formation conditions and may serve as a theoretical foundation for the prediction of burial porosity in carbonates.The results show that the burial dissolved vugs in carbonates are formed under the control of the physical properties of rocks,organic acid concentration and temperature.Their distribution is laterally conditioned by geological boundaries(namely,exposed interface,sequence boundary,unconformity and fault system)and high-permeability layers,and vertically showing a vug-generating peak season,during which,burial dissolved vugs occurred in great numbers because of suitable temperature and high concentration of acid fluid at some intervals with certain burial depth and then evolved along with burial,temperature-pressure and fluid changes.Based on the understanding of the origin of burial dissolved vugs and their distribution patterns,this study quantitatively predicts the burial dissolved vug distribution in the Longwangmiao Formation dolostone by mapping the pre-burial porosity distribution of the Longwangmiao Formation,the organic acid and hydrocarbon generation intensity of the Qiongzhusi Formation source rocks at the temperature window of 70-100℃,the distribution of paleo-uplifts and faults as well as the burial duration of the Longwangmiao Formation within the window(70-100℃,corresponding to a depth of 1740-2850 m).This technique and process may be a useful tool in the prediction and assessment of burial dissolved vugs in other carbonate reservoirs.

关 键 词：埋藏溶蚀孔洞 成孔高峰期 溶蚀模拟实验 白云岩储层 龙王庙组 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]