东海西湖凹陷B区宝石组地层岩性的新认识

New Cognitions of Stratigraphic Lithology of Baoshi Formation in B Area of Xihu Sag, East China Sea

郑华 白玉洪 孟元真 王豪 黄海龙

ZHENG Hua BAI Yuhong MENG Yuanzhen WANG Hao HUANG Hailong

中石化海洋石油工程有限公司上海特殊作业分公司，上海　200137

SINOPEC Offshore Oilfield Services Company Shanghai Oilfield Services Division, Shanghai 200137, China

东海西湖凹陷钻至宝石组的探井数量少，获取的有关地质资料有限，对宝石组的研究程度低。依据前人研究，宝石组地层以泥岩、砂岩、凝灰岩等为主。B区部署的B7井钻穿宝石组进入基底，并在宝石组进行取心。依据岩屑、岩心、测井等资料，对该区宝石组地层有了新的认识：（1）宝石组顶部局部地层发育高岭石黏土岩，岩屑与凝灰岩相似，可以通过镜下观察岩屑断面进行区分，测井曲线特征差异也较明显；（2）宝石组下部靠近基底的部分地层发生花岗岩侵入，泥岩受热接触变质作用形成角岩。目前，新岩性只在B7一口井中出现，其分布范围仍需后期更多的钻井提供实物资料，以获得更全面的认识。B7井的钻探，获得了对宝石组地层岩性的新认识，为后续的钻井、录井、地质研究等提供了新的资料。

A limited number of exploration wells have been drilled into Baoshi Formation in Xihu Sag, East China Sea, and the relevant geological data obtained is so limited that there has been few studies on Baoshi Formation. According to previous studies, the lithology of Baoshi Formation is mainly composed of mudstone, sandstone and tuff. Well B7 deployed in Area B was drilled through Baoshi Formation into the basement and cored in Baoshi Formation. Based on the data of cuttings, cores, logging data, etc., the following new understandings on the lithology of Baoshi Formation in this area have been made: (1) The local lithology at the top of Baoshi Formation develops kaolinite clay rock, and the cuttings are similar to tuff, which can be distinguished by microscope, and the logging characteristics are also different. (2) Granite intrusion occurred in some strata near the basement in the lower part of Baoshi Formation, and the mudstone was subjected to thermal contact metamorphism to form the hornstone. At present, the new lithology only appears in the well B7, and the study on its distribution range still needs more drilling to provide physical data in the later stage. The drilling of Well B7 has obtained a new understanding of the lithology of Baoshi Formation, and provided new data for subsequent drilling, mud logging, and geological research.

https://doi.org/10.3969/j.issn.1008-2336.2022.03.011