Dr Hongwu Lei undertook a six-month exchange from October 2017 to April 2018 at CSIRO Energy in Melbourne and worked closely with Dr Meng Lu, who is an expert in wellbore flow simulation. During the exchange they developed a wellbore simulator called “CO2Well” and applied it effectively to simulate the wellbore flow with phase transition in the Shanxi field trial of CO2 enhanced coalbed methane recovery. Dr Lei also established modules within TOUGH2 framework, such as TOUGH2Biot and TOUGH2/EOS7Cm, to simulate the THMC coupling and to understand impure CO2 injection problems.
Based on Dr Lu’s previous work, Dr Lei has extended the capability of CO2Well for simulating the impure CO2 injection in the wellbore-reservoir systems including phase transition. There are two important improvements. The first is the flash calculation for the gas-liquid equilibrium. Different from the method (e.g., global minimum) used by the original CO2Well, the fugacity-fugacity method with the check of phase stability is used in the phase flash calculation. The new method can accommodate more compounds including H2O, N2, O2 and oil components which are not considered in the original CO2Well, and is robust in algorithm. The second improvement is to couple it with TOUGH2. The coupled simulator can solve the rate-controlled, pressure-controlled and wellhead-known problems. The new simulator was also compared with T2Well, a fully coupled wellbore-reservoir simulator but not considering phase transition in the wellbore. Finally, the new developed simulator was used to model the coupled thermal and hydrodynamic processes of CO2 injection in wellbore-reservoir systems at the Ordos CCS demonstration project, based on the observed results.
Dr Lei visited the CO2CRC Otway Project during its open day on 18 November 2017 and Geoscience Australia on 21 and 22 November, 2017. Under the support of the CAGS3 exchange program, Dr Lei has completed a paper on the coupled wellbore-reservoir modelling for CO2 injection. He will continue his collaboration with CSIRO on modelling of CO2 leakage with phase transition by the developed simulator.