微区原位碳氧同位素分析技术对碳酸盐岩成岩流体性质的约束——以塔里木盆地寒武系—奥陶系为例

Constraints on carbonate diagenetic fluid properties by microzone in situ analysis of carbon and oxygen isotopes: a case study of Cambrian-Ordovician, Tarim Basin

韩俊 尤东华 钱一雄 董少峰 彭守涛

HAN Jun YOU Donghua QIAN Yixiong DONG Shaofeng PENG Shoutao

中国石化 西北油田分公司 勘探开发研究院，乌鲁木齐 830011 中国石化 石油勘探开发研究院 无锡石油地质研究所，江苏 无锡 214126 西南石油大学 地球科学与技术学院，成都 610500 中国石化 石油勘探开发研究院，北京 100083

Exploration and Development Research Institute, Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China School of Geo-Science & Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China

随着分析测试水平的提高，微区原位地球化学分析作为揭示复杂沉积—成岩过程的重要技术手段，越来越受到广泛重视。通过微区原位碳氧同位素分析，结合常规分样方法获取的碳氧同位素数据，对比讨论了同生期—埋藏期海水胶结作用、表生期大气淡水的溶蚀—充填作用与多阶段白云石化流体交代—胶结充填作用。结果显示，微区原位取样碳氧同位素分析有利于揭示胶结物形成过程的多期、多阶段的流体性质演化。常规分样获取的此类胶结物碳氧同位素值可能是多期次产物的混合值。对于相对单一的产物，如碳酸盐岩基质组分、大气淡水成因方解石等，常规分样进行碳氧同位素分析基本可以满足研究需要。微区原位取样碳氧同位素分析提供了一种相对“低成本、高精度”的分析手段，对精确示踪碳酸盐岩成岩演化过程具有重要意义。

As an important technological measure to uncover complex sedimentary-diagenetic process, microzone in situ geochemical analysis has drawn more and more attention along with improving analytical and test levels. According to the analysis of microzone in situ carbon and oxygen isotopes in combination with the data about carbon and oxygen isotopes acquired by conventional sample splitting methods, seawater cementation in syngenetic-burial stages, dissolution-infill by meteoric water in hypergenetic stage, and dolomitization fluid alternation-cementation infill in multiple stages were compared and discussed. The results demonstrated that the analysis of carbon and oxygen isotopes by microzone in situ sampling was favorable for revealing multi-stage and multi-period fluid property evolution in the process of cement formation. Carbon and oxygen isotopes of this cement type acquired by conventional sample splitting analysis might be mix values of multi-stage products. With respect to relatively single product (i.e. matrix components in carbonate rocks and calcite with meteoric water genesis), the analysis of carbon and oxygen isotopes by conventional sample splitting could basically meet study requirements. Microzone in situ sampling analysis on carbon and oxygen isotopes could provide a relatively "low cost and high accuracy" analytical measures, which has important meanings for precisely tracing diagenetic evolution of carbonate rocks.

国家自然科学基金项目 U19B6003;国家自然科学基金企业创新发展联合基金项目 U21B2063;中国石化科技部项目 P21033-1

https://doi.org/10.11781/sysydz202301135