Xinjiang Petroleum Geology ›› 2023, Vol. 44 ›› Issue (5): 562-571.doi: 10.7657/XJPG20230507

• RESERVOIR ENGINEERING • Previous Articles     Next Articles

Establishment and Application of Generalized Characteristic Curves of Gas-Water Miscible Flooding

JIA Rui1(), YUAN Quan2a, TANG Xin2a, LYU Qiqi1, GAO Wenjun2b()   

  1. 1. School of Geosciences, Yangtze University, Wuhan, Hubei 430100, China
    2. PetroChina Tuha Oilfield Company, a.Shanshan Oil Production Management Area; b.Research Institute of Exploration and Development, Hami, Xinjiang 839009, China
  • Received:2022-07-20 Revised:2023-05-06 Online:2023-10-01 Published:2023-09-25

Abstract:

Considering the limited methods for evaluating reservoir development performance using gas-water miscible flooding characteristic curves, a concept of underground water-gas cut was introduced. By analogy with the generalized mathematical model of water cut variation in water flooding reservoirs, generalized gas-water miscible flooding characteristic curves and the corresponding generalized mathematical models of underground gas-water cut variation were established. The generalized gas-water miscible flooding characteristic curve is a Type A water-alternating-gas (WAG) injection characteristic curve when n=0 and m=0, and a Type B WAG injection characteristic curve when n=1 and m=0. By varying the values of n and m, the generalized gas-water miscible flooding characteristic curve can be transformed into S-shaped, convex, S-convex, S-concave, and concave gas-water miscible flooding characteristic curves. For purpose of field application, a general formula for the generalized gas-water miscible flooding characteristic curve and solution method for the corresponding mathematical model combining underground gas-water cut variation were provided. The application to the evaluation of the development performance of WAG injection in the reservoir of Sanjianfang formation in Pubei oilfield, and of gas cap gas + edge water displacement in S31 reservoir in Jinzhou oilfield shows a high fitting accuracy. This method can be a reference for other reservoirs.

Key words: Pubei oilfield, Jinzhou oilfield, reservoir with gas-water miscible flooding, generalized gas-water miscible flooding characteris-tic curve, underground gas-water cut, gas-water cut variation, mathematical model

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