火山岩储层沥青发育特征与天然气富集规律——以川西凹陷带二叠系火山岩为例  

Bitumen development characteristics and gas enrichment laws in volcanic rock reservoir: A case study of the Permian volcanic rocks in the western Sichuan depression

作　　者：王尉 赵路子[2] 张本健 刘冉 李亚 赵立可 裴森奇[3] 胡涛[4] WANG Wei;ZHAO Luzi;ZHANG Benjian;LIU Ran;LI Ya;ZHAO Like;PEI Senqi;HU Tao(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China;PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China;Northwest Sichuan Division,PetroChina Southwest Oil&Gasfield Company,Jiangyou,Sichuan 621700,China;College of Geosciences,China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油西南油气田分公司勘探开发研究院,四川成都610041 [2]中国石油西南油气田分公司,四川成都610041 [3]中国石油西南油气田分公司川西北气矿,四川江油621700 [4]中国石油大学(北京)地球科学学院,北京102249

出　　处：《中国矿业大学学报》2021年第6期1169-1180,共12页Journal of China University of Mining & Technology

基　　金：国家重大科技专项课题(2016ZX05007004);中国石油西南油气田分公司重大科学研究与技术开发专项(2019ZD01)。

摘　　要：川西凹陷带二叠系火山岩的岩石类型和储集空间多样,沥青发育特征差异性较大,储层流体性质复杂,为进一步明确火山岩天然气的富集规律,基于火山岩岩石学和地球化学分析,研究了火山岩储层的成岩作用、不同类型的沥青产状以及沥青发育丰度与现今流体性质间的关系,认为不同类型火山岩储集空间的差异演化控制了古油藏的分布,影响了现今储层沥青的发育和天然气的富集.研究结果表明:川西凹陷带二叠系火山岩储层岩性为熔结火山碎屑岩和火山碎屑岩,其中熔结火山碎屑岩中塑变碎屑镜下百分比大于25%,成岩早期溶蚀形成大量的孔洞,为古油藏的形成提供了储集条件,现今溶蚀孔洞中发育大量的水洗(或降解)沥青和热变质沥青,储层含气性相对较好;火山碎屑岩以压实成岩为主,易溶的塑变碎屑镜下百分比低于25%,仅发育少量的次生孔隙,限制了早期油气大规模聚集,现今火山碎屑岩中热变质沥青镜下百分比低于1%,储层含气性相对较差.固体沥青的差异分布表明古油藏的发育规模主要受早期储层质量控制,古油藏的原位裂解导致现今熔结火山碎屑岩含气性普遍较好,为研究区最有利的勘探目标.The Permian volcanic rocks with various types in the western Sichuan depression, Sichuan Basin, are featured by different reservoir spaces, the large difference among development characteristics of bitumen, and complex property of reservoir fluid. In order to further figure out accumulation laws of gas in volcanic rocks, the diagenesis, the different bitumen occurrence, and the relationship between the development abundance of bitumen and existing fluid property in the volcanic reservoirs were analyzed on the basis of petrography and geochemistry. It is deemed that not only the distribution of paleo reservoirs but also the bitumen development and gas accumulation in current reservoirs are controlled or affected by the differential evolution on various volcanic reservoir spaces. Results show that the Permian volcanic reservoirs in the depression are composed of agglutinate and pyroclastic rocks. The percentage of plastic debris under the microscope is more than 25% in the agglutinate. A large number of vugs formed by the early diagenetic dissolution might provide reservoir conditions for the paleo reservoirs. Whereas plenty of both water-washing(degradable) and thermal metamorphic bitumen developed in current dissolution vugs can result in better gas-bearing properties in the reservoirs. Furthermore, in the pyroclastic rocks mainly generated by compaction diagenesis, the percentage of soluble plastic debris under the microscope lower than 25% and fewer secondary pores might affect an extensive oil and gas accumulation in the early stage. Thermal metamorphic bitumen under the microscope less than 1% developed in the pyroclastic rocks may lead to poor gas-bearing properties. In addition, from the perspective of differences in the distribution of solid bitumen, it is demonstrated that for the paleo reservoirs, their development scale is mainly controlled by the quality of early reservoirs and the in-situ pyrolysis may bring about better gas-bearing properties in the current agglutinate. Therefore, the agglutinate res

关 键 词：四川盆地 火山岩 古油藏 原油裂解 固体沥青 

分 类 号：TE122.1[石油与天然气工程—油气勘探]