Genesis of lacustrine carbonate breccia and its significance for hydrocarbon exploration in Yingxi region, Qaidam Basin, NW China

• 作者: LI Senming LIU Zhanguo SONG Guangyong TANG Pengcheng WANG Peng WANG Yanqing ZHANG Yongshu ZHU Chao
• 来源期刊: 石油勘探与开发:英文版
• 学科: 地球科学
• 关键词: Qaidam Basin Yingxi REGION LACUSTRINE CARBONATE CARBONATE BRECCIA reservoir origin PALEOGENE
• 年，卷（期）: 2019,（1）
• 页码范围: 104-112
• 页数: 9页
• 分类号: P618.13

摘要

To examine the reservoir type and distribution regularity of high-and stable-yield lacustrine carbonates in the upper Member of Paleogene Xiaganchaigou Formation of Yingxi region and to determine the high-efficiency hydrocarbon exploration direction, the origin and significance of carbonate breccia in this area were investigated based on comprehensive analysis of a large number of well cores, thin sections, rock and mineral testing and log-seismic data. The study reveals that the carbonate breccia has three origins:(1) Sedimentary breccia, formed by the event-related collapse, fragmentation and re-deposition of the early weakly consolidated carbonate rock in the steep slope of underwater paleohighs due to short-term high-energy water body reformation and other geological processes.(2) Diagenetic breccia, with breccia-like structure, formed by deformation or breaking of host rock due to growth of idiomorphic and coarse crystalline gypsum-salt minerals in the weakly consolidated argillaceous carbonate rock of the penecontemporaneous period.(3) Tectonic breccia, can be further divided into fault breccia and interlayer slip breccia according to their occurrence characteristics, both of which are closely related to activity of the Shizigou thrust Fault. With a large number of partially filled pores, vugs and fractures between breccia, the two types of tectonic breccia are high-and stable-yield reservoirs in deep Yingxi region, and may occur extensively under gypsum-salt detachment layers of adjacent areas, so they are the exploration targets in the next step. Sedimentary breccia and diagenetic breccia are of great significance in searching for large-scale carbonate reservoirs.