TITLE:
Numerical Simulation of Oil and Gas Two-Phase Flow in Deep Condensate Gas Reservoirs in Bohai Buried Hills
AUTHORS:
Zhennan Gao, Xianbo Luo, Lei Zhang, Qi Cheng, Yingxu He
KEYWORDS:
High Temperature and High Pressure, Condensate Gas Reservoirs, Mist Flow, Characterization of Seepage Flow, History Match, Production Regulation
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.13 No.11,
November
27,
2023
ABSTRACT: The BZ19-6 gas field is characterized by high temperature and high
pressure (HTHP), high condensate content,
little difference between the formation pressure and dew point pressure, and
large amount of reverse condensate liquid. During the early stage of depletion
development, the production gas-oil ratio (GOR) and production capacity remain
relatively stable, which is inconsistent with the conventional reverse condensate
seepage law. In view of the static and dynamic conflict in development and production,
indoor high-temperature and high-pressure PVT experiment was carried out to reveal the
mist-like condensation phenomenon of fluids in the BZ19-6 formation. And the
seepage characteristics of condensate gas reservoirs with various degrees of depletion
under the condition of HTHP were analyzed based on production performance. The
change rule of fluid phase state was analyzed in response to the
characterization difficulties of the seepage mechanism. The fluid state was described using the miscible mechanism. And the
interphase permeability interpolation coefficient was introduced based on
interfacial tension. By doing so, the accurate characterization of the
“single-phase flow of condensate gas-near-miscible mist-like quasi
single-phase flow-oil-gas two-phase flow” during the development process was
achieved. Then the accurate fitting of key indicators for oilfield development
was completed, and the distribution law of formation pressure and the law of
condensate oil precipitation under different reservoir conditions are obtained.
Based on research results, the regulation
strategy of variable flow rate production was developed. Currently, the work
system has been optimized for 11 wells, achieving a “zero increase” in
the GOS of the gas field and an annual oil increase of 22,000 cubic meters.