四川盆地川西坳陷须家河组硅质碎屑颗粒溶蚀作用及机理

Dissolution mechanism of siliciclastic particles in Xujiahe Formation, West Sichuan Depression, Sichuan Basin

林小兵 田景春 刘莉萍 李敏同

LIN Xiaobing TIAN Jingchun LIU Liping LI Mintong

1. 成都理工大学 “油气藏地质及开发工程”国家重点实验室, 成都 610059; 2. 中国石化 西南油气分公司 勘探开发研究院, 成都 610041; 3. 四川省冶金地质勘查局 水文工程大队, 成都 611700

1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China; 2. Exploration and Development Institute of Southwest Petroleum Branch Company, SINOPEC, Chengdu, Sichuan 610041, China; 3. Hydro-Engineering Team of Sichuan Metallurgical Geology & Exploration Bureau, Chengdu, Sichuan 611700, China

以四川盆地川西坳陷上三叠统煤系地层的须家河组优质储层为对象，运用普通薄片、主体薄片、阴极发光、扫描电镜和激光拉曼探针分析，对其中发育的硅质碎屑溶蚀机理进行了探讨。川西须家河组硅质碎屑存在酸性地层水条件下有氟参与发生的溶蚀。在须家河组石英包裹体中测到的F成分，是F-、HF2-、未离解的HF分子及（HF）2等含F成分的总和，并且以未离解的HF分子和（HF）2为主。硅质溶蚀过程中，活性成分（HF）2或HF2-吸附于硅质颗粒表面，H+对反应起催化作用。其他矿物组合同时发生物质的交换与变化，包括长石、岩屑的溶蚀、硅质胶结等。硅质溶蚀的识别标志主要包括：地球化学标志、硅质颗粒的部分溶解、致密砂岩背景下颗粒间接触缝的开启和矿物组合标志。

The siliceous debris dissolution event in the diagenetic series of clastic rocks of the Upper Triassic Xujiahe Formation in the West Sichuan Depression were studied to establish a theoretical dissolution model. The model may be used for recognizing dissolution by means of macroscopic observation of drill cores, profiles and testing data. Results show that the dissolution of siliciclastic particles happens under acidic formation water conditions with F participation. The F component detected in inclusions should be the sum of F-, HF2-, un-dissociated HF molecule, (HF)2, among which the un-dissociated HF molecule and (HF)2 are the main elements. The active component (HF)2 or HF2-were adsorbed on the surface of silicon particles during the dissolution under the catalysis of H+. Material exchange and transformation of other mineral assemblages occurred at the same time, including felspar and rock debris dissolution as well as siliceous cementation, etc. The keys to recognize siliceous dissolution mainly include geochemistry characteristics, partly dissolved siliceous particles, open contact fractures between siliceous grains in tight sandstones and mineral assemblages.

国家自然科学基金（41002032）、成都理工大学沉积地质学科研创新团队项目（KYTD201703）和成都理工大学中央财政支持地方高校发展专项资金（11000-13Z00701）资助。

https://doi.org/10.11781/sysydz201903404