方解石和白云石胶结物识别方法厘定——以鄂尔多斯盆地延长组砂岩为例  

New Ideas on Identification Method of Calcite and Dolomite Cements: Taking Yanchang Formation Sandstones in Ordos Basin as an Example

作　　者：周晓峰[1,2,3] 李昱东 王巍 桑廷元 于均民 ZHOU Xiaofeng;LI Yudong;WANG Wei;SANG Tingyuan;YU Junmin(College of Petroleum Engineering,China University of Petroleum (Beijing),Beijing 102249,China;Key Laboratory of MOE for Petroleum Engineering,China University of Petroleum (Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,Beijing 102249,China;Research Institute of Exploration and Development,PetroChina Yumen Oilfield Company,Jiuquan 735019,Gansu,China)

机构地区：[1]中国石油大学(北京)石油工程学院,北京102249 [2]中国石油大学(北京)石油工程教育部重点实验室,北京102249 [3]油气资源与探测国家重点实验室,北京102249 [4]中国石油玉门油田勘探开发研究院,甘肃酒泉735019

出　　处：《西安石油大学学报（自然科学版）》2019年第4期15-20,共6页Journal of Xi’an Shiyou University（Natural Science Edition）

基　　金：中国石油天然气股份有限公司重大专项“成熟探区精细勘探关键技术”(2018D-0704);国家级矿产资源综合利用示范基地项目“长庆姬塬油田特低渗透油藏综合利用示范基地”(国土资厅发[2011]88号文件)

摘　　要：目前流行的岩石薄片染色方法识别砂岩中方解石和白云石胶结物经常出现混乱,究其根源主要是由于方解石或白云石胶结物中MnO质量分数偏高导致的。鄂尔多斯盆地延长组砂岩中方解石胶结物的有效识别结果表明,岩石薄片染色方法将MnO质量分数偏高的浸染状铁Ⅰ方解石错误地识别为含铁白云石或铁白云石,将MnO质量分数偏高的斑块状无铁方解石错误地识别为铁Ⅲ方解石或含铁白云石。鉴于此,把方解石和白云石胶结物的识别方法厘定为“岩心观察大致推断碳酸盐胶结物的类型及岩石体积分数→岩石薄片染色观察碳酸盐胶结物的颜色变化及赋存状态→电子探针原位测试定量识别不同赋存状态碳酸盐胶结物”,从而有效地识别方解石和白云石胶结物,为砂岩储层研究提供更加可信的地质依据。Confusion often occurs inidentifying calcite and dolomite cements in sandstone using thin section dyeing,whose main reason is high mass fraction of MnO in calcite or dolomite cement.The effective identification results of calcite cements in Yanchang Formation sandstones in Ordos Basin show that by thin section dyeing method,the disseminated iron I calcite with high MnO content is misidentified as iron-bearing dolomite or iron dolomite,and the plaquelike iron-free calcite with high MnO content is misidentified as iron Ⅲ calcite or iron dolomite.In view of this,the recognition of calcite and dolomite cements in sandstone is divided into three steps.Firstly,the type and volume fraction of carbonate cements are roughly inferred from core observation,then,the color change and occurrence state of carbonate cements are observed by rock slice dyeing,and finally,the carbonate cements in different occurrence states are quantitatively identified using in-situ test of electron probe to effectively identify the calcite and dolomite cements and provide more credible geological basis for research of sandstone reservoirs.

关 键 词：方解石胶结物 白云石胶结物 MNO 胶结物识别 

分 类 号：TE122.1[石油与天然气工程—油气勘探]