Process Analyses for Multiphase Flow and Phase Change in a CO2-ECBM Engineering System
Abstract
Injection of CO2 into deep unminable coal seam (CO2-ECBM), achieving the goals of carbon dioxide geological sequestration and increasing coalbed methane recovery attracts more and more people's attention. Previous studies mostly focused on the competitive adsorption of gases, relative permeability, porosity and permeability change, etc. There is not so much research on multiphase flow and phase change behavior in the wellbore. As a fact, the depth of coal seam is usually relatively shallow, mostly within 1 km, where phase change of CO2 could occur.
From 2011 to 2012, CSIRO performed a CO2-ECBM field trial in Shanxi, China in collaboration with China United Coalbed Methane (CUCBM). One vertical well was drilled for injection and production. A multi-lateral horizontal well with 2.3 km in seam length was used for CO2 injection. A U-tube sampling system was installed in a monitoring well for observing the migration of CO2 and tracer. This investigation is on the basis of field trial. By comparing simulation results to measured data, to get a deeper understanding of multiphase flow and phase change in both wellbore and adsorption/desorption in reservoir. The wellbore-reservoir coupling model is built on framework of the TOUGH program; different governing equations are applied for different sub-domains. ECO2M module is incorporated into ECBM to consider the fluid property and phase change over a wide range of pressure and temperature conditions. At the condition of low temperature, two phases of CO2 co-existing, ECO2M is applied, The ECBM is used for high temperature and only gas phase. Extended Langmuir model, Parker model, Shi and Durucan model were introduced to take into account the competitive adsorption of gases, three-phase relative permeability, and adsorption induced porosity and permeability change. Multiple interacting continua method was adopted to describe microscopic matrix and cleat in coal seam. Results shows that the decline of wellhead pressure during shut-in period is caused by leakage and give the reason for blowout phenomenon after shut-in in actual CO2 injection field. A complicated phase change process occur along wellbore. Because the downstream of the wellbore is shallower, CO2 flows up under the buoyancy effect, making downstream recover more slowly (the hysteresis phenomenon).- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMMR53A0109F
- Keywords:
-
- 1822 Geomechanics;
- HYDROLOGYDE: 1858 Rocks: chemical properties;
- HYDROLOGYDE: 5114 Permeability and porosity;
- PHYSICAL PROPERTIES OF ROCKSDE: 5139 Transport properties;
- PHYSICAL PROPERTIES OF ROCKS