从“源盖控烃”探讨四川盆地威远地区深层页岩气田富集高产地质因素  

Main geological factors of enrichment and high yield of deep shale gas reservoirs in Weiyuan area,Sichuan Basin:analyzed from the perspective of source-cap controlling hydrocarbon

作　　者：孙川翔 聂海宽 熊亮[4] 杜伟[1,2,3] 张光荣 陈清[6] 李东晖 SUN Chuanxiang;NIE Haikuan;XIONG Liang;DU Wei;ZHANG Guangrong;CHEN Qing;LI Donghui(Petroleum Exploration and Production Research Institute,Sinopec)

机构地区：[1]页岩油气富集机理与有效开发国家重点实验室 [2]中国石油化工股份有限公司石油勘探开发研究院 [3]中国石化集团页岩油气勘探开发重点实验室 [4]中国石化西南油气分公司勘探开发研究院 [5]中国地质大学(北京)能源学院 [6]中国科学院南京地质古生物研究所

出　　处：《海相油气地质》2022年第2期135-145,共11页Marine Origin Petroleum Geology

基　　金：国家自然科学基金项目“四川盆地五峰组—龙马溪组页岩气储层演化机理及评价方法”(编号:41872124);“特提斯域内大陆单向裂解—聚合过程中的油气大规模富集效应”(编号:9175520021)共同资助。

摘　　要：随着深层页岩气勘探开发的逐步深入,四川盆地威远地区页岩气井出现试采产量高,但产量递减快、单井估算的最终可采储量(EUR)低等特征。基于威远地区深层页岩气成藏条件和勘探开发实践,从“源盖控烃”角度探讨了研究区深层页岩气田富集高产的地质因素。结果表明:①威远地区五峰组—龙马溪组页岩沉积环境受川中古隆起和自流井水下高地的控制,多个笔石带页岩出现不同程度的减薄或缺失,发育于古水深相对较大、缺氧环境中的LM1—LM4笔石带页岩岩性为黑色含灰碳质页岩和含灰硅质页岩,厚度总体较小,页岩品质比焦石坝、长宁地区的稍差;②威远地区后期地层抬升剥蚀强烈,区域盖层三叠系膏盐岩部分遭受剥蚀,区域封闭性遭到一定程度的破坏,距离古隆起较远地区的保存条件较好;③威远地区深层页岩气藏由于埋深大、温度和压力高,页岩的甲烷吸附能力降低,气体赋存形式以游离气为主。提出源盖条件是威远地区五峰组—龙马溪组深层页岩气试采产量高、但稳产能力较差的重要地质原因,指出LM1—LM4笔石带页岩厚度大、中下三叠统膏盐岩盖层保存完整的区域是页岩气富集的有利区。With the deepening of shale gas exploration and development,shale gas fields in the Weiyuan area of the southwestern Sichuan Basin have shown great resource potential.However,gas wells with high test production reveal rapid decline rate and low estimated ultimate recovery(EUR)of single well.To clarify the geological reasons,the main factors affecting the enrichment and high production of deep shale gas are discussed from the perspective of source-cap controlling hydrocarbon based on the deep shale gas accumulation conditions as well as the exploration and development practices in the Weiyuan area.The results show that:(1)The sedimentary environment of Wufeng Formation-Longmaxi Formation in Weiyuan area is controlled by the central Sichuan paleo-uplift and the Ziliujing underwater highland,and multiple graptolite shale intervals is thinned or missing in varying degrees.The LM1-LM4 graptolite shale interval developed in anoxic environment with relatively large paleowater depth is generally thin(1.8-4.5 m).The lithology is black gray carbonaceous shale and gray siliceous shale with high carbonate minerals content and low siliceous minerals content.The anti-compaction ability of reservoir is weak,and the shale quality is slightly worse than that in Jiaoshiba and Changning areas.(2)The dissolution pores of carbonate minerals in shale of Wufeng Formation-Longmaxi Formation in Weiyuan area are developed and formed after the maximum oil generation period of kerogen,which is not conducive to shale gas enrichment.(3)In the later stage,the strata were uplifted and denuded strongly,part of the Triassic gypsum salt rock acting as regional cap was denuded,so the regional sealing was damaged to a certain extent,but the preservation conditions were better in the area far from the paleo-uplift.(4)The deep shale gas reservoir in Weiyuan area has large buried depth,high temperature and pressure,and the proportion of micropores,mesopores and other small pores with large specific surface area is reduced due to the influence of higher

关 键 词：古隆起 笔石带 页岩气 保存条件 龙马溪组 威远地区 四川盆地 

分 类 号：TE132.2[石油与天然气工程—油气勘探]