Identification and Significance of the Middle Upper Ordovician marine Source Rocks in Transitional Zone between Awati and Manjia’er Depressions, Tarim Basin
详细信息
- 责任者：Gao Zhiyong(Laboratory Center of Petroleum Exploration and Development Research Institute ; PetroChina ; Beijing 100083 ; China) ; Li Jianjun
- 刊名：Natural Gas Industry
- 出版年：2012
- 卷期：32(5)
- 页码：p.5-10
- issnNo：ISSN1000-0976
- isbnNo：CN51-1179/TE
摘要
No Ordovician marine source rocks have been found in the transitional zone between Awati and Manjia’er depressions, Tarim Basin. However, a large amount of geochemical data indicates that the oil/gas in the middle and northern Tarim Basin (hereafter referred to as Tazhong and Tabei) are possibly sourced from this area. In view of this, we reviewed and analyzed the TOC contents of the MiddleUpper Ordovician mudstone samples from several wells on the structural high in this area. A set of marine hydrocarbon source rocks with the TOC content up to 1.30% was preliminarily recognized in an interval with a bulk thickness of 95.0 m. On this basis, we performed wellseismic data correlation of the source rocks and tracing of the horizon with source rocks on seismic section. A set of marine source rocks was finally identified in the interval from the top Middle Ordovician Yijianfang Formation to the Upper Ordovician Tumuxiuk Formation in the transitional zone between Awati and Manjia’er depressions. This set of source rocks pinches out eastwards on the western side of the eastern margin of the Gucheng Lungudong platform, overlaps and pinches out southwards near the Manjia1 well in the footwall of Tazhong Ⅰfault, overlaps and pinches out on the western platform margin in the transitional zone, and pinches out northwards in the southern part of the Yangwu2 well on the Tabei uplift. It has a maximum burial depth of up to 8500 m and a thickness of less than 150 m which was possibly deposited in an intraplatform depression within the transitional zone. It may be one of the major source rocks contributing hydrocarbons to the Tazhong and Tabei oil fields. This study is of great significance to hydrocarbon resource assessment and exploration potential evaluation.