东营凹陷中央隆起带沙河街组碳酸盐胶结物发育特征及其形成机制  

Characteristics and Origin of Carbonate Cements of Shahejie Formation of Central Uplift Belt in Dongying Depression

作　　者：郭佳[1,2] 曾溅辉[1,2] 宋国奇[3] 张永旺[1,2] 王学军[4] 孟伟[1,2] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中国石油大学地球科学学院,北京102249 [3]中石化胜利油田分公司,山东东营257001 [4]中石化胜利油田地质科学研究院,山东东营257015

出　　处：《地球科学（中国地质大学学报）》2014年第5期565-576,共12页Earth Science-Journal of China University of Geosciences

基　　金：国家油气重大专项(No.2011ZX05006-001);国家自然科学基金项目(No.41172128)

摘　　要：碳酸盐胶结物是东营凹陷中央隆起带砂岩储层中重要的自生矿物,但其形成机制目前尚无深入研究.首先在岩相观察下针对东营凹陷中央隆起带沙河街组的碳酸盐胶结物进行期次划分并归纳其发育特征,再依据各期碳酸盐胶结物的共生矿物、碳氧同位素组成、流体包裹体温度、元素化学成分等信息对其形成机制进行研究.研究结果表明:研究区碳酸盐胶结物的碳不仅受到有机质成熟过程中排放的有机酸的影响,还受到沙四段沉积的湖相碳酸盐岩溶解的影响.研究区沙河街组主要发育四期碳酸盐胶结物:第一期碳酸盐胶结物以白云石为主,其形成过程与甲烷细菌对有机质的分解作用有关;第二期碳酸盐胶结物以方解石为主,与第一期碳酸盐胶结物之间夹有一层绿泥石薄膜,胶结物的形成与孔隙流体的浓缩导致的Ca、HCO3-过饱和现象相关;第三期碳酸盐胶结物主要为方解石、白云石和铁白云石,以充填长石溶孔和原生孔隙为特征,其物质来源于长石的溶蚀及泥岩的脱水作用;第四期碳酸盐胶结物多为铁方解石和铁白云石,以充填早期碳酸盐溶蚀后形成的次生孔隙为特征,物质来源于粘土矿物的转化,多与黄铁矿颗粒共生,其形成过程受到烃类流体活动的影响.Carbonate cement is an important authigenic mineral in sandstone reservoirs of the central uplift belt in the Dongying depression, but no in-depth study has been conducted on its formation mechanisms currently. In this article, carbonate cements of Shahejie Formation of the central uplift belt in the Dongying depression are divided into four periods using petrologic records and their development characteristics are concluded. And then, according to the paragenetic mineral assemblages, carbon and oxygen isotope ratios, chemical elemental composition and other information of carbonate cements, their formation mechanisms were studied. Study results show that carbonates in the study area are mainly affected by the organic acids generated during the process of maturation of organic matter and the dissolution of the carbonate debris during deposition of Es4. In the study area, four periods of carbonate cements developed mostly. The first related to decomposition effects of methane bacteria on organic of calcite and there is a layer of chlorite film locating between period of carbonate cements is mainly dolomite. Its formation is matter; the second period of carbonate cements is mainly formed the second period and the first period of carbonate cements. The formation of cements is related to Ca and HCO3 oversaturation caused by pore fluid condensation; the third period of carbonate cements mainly include calcite, dolomite and ankerite, being characterized by filling dissolution pore of feldspar and primary pore, with their substance derived from the dissolution pore of feldspar and dehydration of mudstone; the fourth period of carbonate cements is characterized by filling the early-stage carbonate-corroded pores. Their substances are derived from the conversion of clay minerals and are usually symbiotic with pyrite particles, and their formation is affected by the hydrocarbon fluid flow.

关 键 词：碳酸盐 胶结物 发育特征 形成机制 沙河街组 东营凹陷中央隆起带 

分 类 号：TE122[石油与天然气工程—油气勘探]