Accumulation conditions and key technologies for exploration and development in Sebei gas field in Qaidam Basin, NW China

• Main Author: Daowei Zhang
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2019-09-01
• Series: Petroleum Research
• Online Access: http://www.sciencedirect.com/science/article/pii/S2096249519300481

The Sebei gas field, located in the northern slope of the Sanhu depression in the eastern Qaidam Basin, is the largest inland biogas producing area in China. It is a typical Quaternary biogenetic gas reservoir composed of multiple layers of unconsolidated sandstone. Through systematic study of gas generating mechanism of source rock, reservoir-caprock combination and trap evolution, the unique biogas accumulation model characterized by “continuous hydrocarbon generation and dynamic accumulation” is established. Its uniqueness is reflected in the biogas generation mechanism under dual effect of low-temperature thermodynamics and microbial degradation, source-reservoir one body, self generation and self storage, dynamic source-reservoir-caprock assemblages and anticline trap formation mechanism of multi-factor mutual promotion. This understanding reveals the intrinsic factors for formation of large-scale biogas field under frigid climate, high salinity and low organic matter abundance. A number of exploration and development technologies have been worked out during the exploration and development of the Sebei gas field. Among them, the low-amplitude structure identification technique, multi-parameter gas-bearing detection technique, sand control and comprehensive water control technique for unconsolidated sandstone are well applied in discovering the gas field, increasing reserve, and increasing and maintaining gas production. The above understandings and key technologies have great reference significance and demonstration effect for biogas exploration and development in China and the world. Keywords: Biogas, Low-temperature thermodynamic, Continuous hydrocarbon generation, Dynamic accumulation, Sebei gas field, Qaidam basin