FU Jin-hua1,2, LUO Shun-she3,4*, NIU Xiao-bing1,5, LV Qi-qi3,4, XU Li-ming1,5, FENG Sheng-bin1,5, LI Shi-xiang1,5
1. National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Xi'an 710018, China;
2. PetroChina Changqing Oilfield Company, Xi'an 710018, China;
3. Laboratory of Exploration Technologies for Oil and Gas Resources (Yangtze University), Ministry of Education, Wuhan 430100, China;
4. School of Geosciences of Yangtze University, Wuhan 430100, China;
5. Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi'an 710018, China
Abstract: Tight sandstone study has been an important research field in the exploration and development of oil and gas in China. In this paper, the tight sandstone sedimentary characteristics of the Member 7 of Yanchang Formation in the Longdong area, which is believed to have great potential for exploration and development, were studied. The gravity flow sedimentary characteristics in the research area was systematically studied through field profile and core observation, logging data, and deep-water gravity flow deposition theory. Three genetic types of gravity flow deposited sand body were found in this area, including sandy debris flow deposit, turbidite deposit and slump deposit. The sandy debris flow deposit, which develops massive bedding and distributes near its source, is consisted of gray, brown and gray massive fine-grained sandstones with a thickness of more than 0.5 m, mostly more than 1 m. The turbidite, which normally shows a distal distribution and possesses complete or incomplete Bouma sequences, is made up by gray, dark gray siltstones, argillaceous sandstones, the thickness of a single turbidite layer is a few centimeters to tens of centimeters. The slump deposit is the least developed sand body in the research area. The gravity flow deposit sand bodies in the Member 7 of Yanchang Formation distributes successively in the longitudinal direction and discontinuously in the horizontal direction. In summary, the gravity flow sand body in the Member 7 of the Yanchang Formation is characterized by zonal distribution and belongs to the channel type (non-fan) gravity flow sedimentary deposition system.
Keywords: Ordos Basin tight sand sandy debris flow deposits Turbidite depositional model
*Corresponding Author, E-Mail: lss@yangtzeu.edu.cn
Bulletin of Mineralogy, Petrology and Geochemistry Vol. 34, No.1, 2015, page 29-37
