Publication Date:
2015-12-22
Description:
The discovery of natural gas reservoirs with high and varying CO 2 content (5% to 98%) in China has attracted worldwide attention. In this paper, the phase diagram of natural gas with different CO 2 content was calculated and drawn by PVT Sim 100 which was fitted by experimental data based on the Ruska PVT 2730 apparatus. Both the real critical parameters and the pseudo-critical parameters were calculated and compared. Also, the phase state of natural gas along the wellbore in a representative well under both shut-in and flowing conditions was analyzed. In addition, to clarifying the phase transition process, videos of a gas sample showed variation between supercritical state to gas-liquid state with isobaric cooling and heating up between 35°C and 25°C. Moreover, the compressibility factor (Z-factor) of the natural gas with different CO 2 content was chosen as one of the key physical parameters of natural gas to measure at pressures ranging from atmospheric pressure to 45 MPa and temperatures ranging from 40°C to 140°C experimentally. Results show that the Z factor decreases with the increase of CO 2 content in natural gas at isothermal conditions, and increases with the increase of temperature. Furthermore, a new model is proposed to predict pressure and Z factor. The varying CO 2 -CH 4 concentrations of this reservoir are relevant to gas compositions which may arise in depleted natural gas reservoirs used for geologic carbon sequestration. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd
Electronic ISSN:
2152-3878
Topics:
Energy, Environment Protection, Nuclear Power Engineering
,
Geosciences
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