Xinjiang Petroleum Geology ›› 2025, Vol. 46 ›› Issue (1): 88-96.doi: 10.7657/XJPG20250111

• RESERVOIR ENGINEERING • Previous Articles     Next Articles

Occurrence State of Water in Ultra-Low Permeability Gas Reservoirs and Its Impact on Development of A Gas Field

LIAO Hengjie(), LOU Min(), HE Xianke, DUAN Dongping, WANG Wenji, LI Yuansheng, LIU Binbin   

  1. Research Institute, Shanghai Branch, CNOOC (China) Co., Ltd., Shanghai 200335, China
  • Received:2024-08-20 Revised:2024-09-04 Online:2025-02-01 Published:2025-01-24

Abstract:

Ultra-low permeability gas reservoirs are complex in gas-water contact, and differ significantly in formation water occurrence state from conventional gas reservoirs. The occurrence state of formation water and the water saturation in such reservoirs were determined through mercury intrusion experiments and relative permeability tests, and the gas-water segregation was analyzed using the trap closure height method. Logging curves were used to predict the distribution of formation water saturation in different states for a single well, and the impact of formation water on productivity was assessed. The results show that the formation water in the study area mainly consists of strongly bound water and weakly bound water, with a small amount of movable water. No distinct gas-water segregation was observed. The clay water film is a key component of strongly bound water. In fine sandstone and the sandstone with high content of carbonate cements, the saturation of weakly bound water is higher. The movable water saturation in the study area is generally less than 6%, and the initial water production is low, exerting slight impact on productivity.

Key words: ultra-low permeability gas reservoir, formation water, occurrence state, gas field development, productivity, water saturation

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