东濮凹陷油田卤水地球化学特征及其指示意义

Hydrogeochemistry of Oilfield Brines from DongpuDepression and Its Indicating Significance

采集东濮凹陷内不同层位卤水样品进行水化学与同位素分析,基于卤水水化学与δD、δ18 O和δ13 C同位素特征,探讨了东濮凹陷油田卤水地球化学起源及深部地层中相关的水文地球化学过程,最终提出了东濮凹陷油田卤水的成因机制。凹陷内油田卤水水化学类型为CaCl 2型,为典型的深成陆相成因,起源于地质历史时期受到强烈蒸发作用影响的地表古盐湖,后期被封存于岩石孔隙和裂隙中,并经历了一系列深层次生改造(岩盐溶滤、脱硫酸、阳离子交换及钠长石化等作用)和浅层混合过程,形成了现今东濮凹陷赋存的油田卤水。研究成果可为东濮凹陷油田卤水资源合理开发与高效利用提供科学指导,并可为其他同类型卤水资源研究提供借鉴思路。

The brine samples from different layers were collected within the Dongpu Depression for hydrochemical and isotopic analysis.Based on the hydrochemical characteristics andδD,δ18 O,andδ13 C isotope compositions of the brine,the geochemical origin of the oilfield brine and the related hydrogeochemical processes in the deep strata of the Dongpu Depression were studied.Ultimately,the genetic mechanism of oilfield brine in the Dongpu Depression was proposed.The water chemistry of the oilfield brine in the depression is characterized as CaCl 2 type,representing a typical deep continental origin.It originated from ancient salt lakes on the surface that experienced intense evaporation in geological history.Subsequently,it was sealed in rock pores and fractures,undergoing a series of deep-seated modifications such as rock salt dissolution,desulfation,cation exchange,and albitization,as well as shallow mixing processes,forming the oilfield brine that exists in the Dongpu Depression today.The research results can provide scientific guidance for the rational development and efficient utilization of the oilfieldbrine resources in the Dongpu Depression,and can also provide reference ideas for the study of other similar brine resources.