Thermo-hydro-mechanical-chemical couplings controlling CH4 production and CO2 sequestration in enhanced coalbed methane recovery

Modelling and optimization of enhanced coalbed methane recovery using Co2/N2 mixtures

Study of the enhanced geothermal system (EGS) heat mining from variably fractured hot dry rock under thermal stress

Investigation of the influence of gas fracturing on fracturing characteristics of coal mass and gas extraction efficiency based on a multi-physical field model

https://escholarship.org/content/qt4qg689j1/qt4qg689j1.pdf?t=ovprfp

Fully coupled two-phase flow and poromechanics modeling of coalbed methane recovery: Impact of geomechanics on production rate

https://escholarship.org/content/qt759284bt/qt759284bt.pdf?t=ovprz0

Coupled thermal–hydrological–mechanical modeling of CO2-enhanced coalbed methane recovery

An effective and safe operation for sequestration of CO2 in coal seams requires a clear understanding of injection-induced coupled hydromechanical processes such as the evolution of pore pressure, permeability, and induced caprock deformation. In this study, CO2 injection into coal seams was studied using a coupled flow-deformation model with a new stress-dependent porosity and permeability model that considers CO2-induced coal softening. Based on triaxial compression tests of coal samples extracted from the site of the first series of enhanced coalbed methane field tests in China, a softening phenomenon that a substantial (one-order-of-magnitude) decrease of Young's modulus and an increase of Poisson's ratio with adsorbed CO2 content was observed. Such softening was considered in the numerical simulation through an exponential relation between elastic properties (Young's modulus and Poisson's ratio) and CO2 pressure considering that CO2 content is proportional to the CO2 pressure. The results of the numerical simulation show that the softening of the coal strongly affects the CO2 sequestration performance, first by impeding injectivity and stored volume (cumulative injection) during the first week of injection, and thereafter by softening mediated rebound in permeability that tends to increase injectivity and storage over the longer term. A sensitivity study shows that stronger CO2-induced coal softening and higher CO2 injection pressure contribute synergistically to increase a significant increase of CO2 injectivity and adsorption, but also result in larger caprock deformations and uplift. Overall, the study demonstrates the importance of considering the CO2-induced softening when analyzing the performance and environmental impact of CO2-sequestration operations in unminable coal seams. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

/pdf/modeling-of-co2-sequestration-in-coal-seams-role-of-co2-o90knx7oy9.pdf

Modeling of CO2 sequestration in coal seams: Role of CO2-induced coal softening on injectivity, storage efficiency and caprock deformation

The invention relates to a portable multifunctional rock-soil body seepage experiment table which mainly comprises an experiment table body, a water supply system and an experiment data measuring device, wherein multiple rows of water inlet and outlet seepage channels which are parallel to each other are arranged on the experiment table base of the experiment table body and are intersected and communicated in the middle of the experiment table base; prefabricated crack blocks are arranged in the water inlet and outlet seepage channels; water pipes forming circulation paths with a water pump are respectively arranged at the water joints of the two sides of each of the flowing water seepage channels; and a pressure sensor, a liquid filter valve, a flow sensor and a control valve are respectively arranged on each of the water pipes at the two sides of each of the flowing water seepage channels in turn. The migration condition of fluid and grains in the fluid in an experiment can be observed in real time; the change of infiltration capacity of a crack or pore medium under a vibrating condition can be measured in real time by placing the experiment table on a vibrating platform; and the portable multifunctional rock-soil body seepage experiment table has the advantages of simple structure, small size and good experiment effect, is portable, is convenient to operate and can be placed at random.

Tianran Ma

Papers

Fully coupled two-phase flow and poromechanics modeling of coalbed methane recovery: Impact of geomechanics on production rate

Coupled thermal–hydrological–mechanical modeling of CO2-enhanced coalbed methane recovery

Modeling of CO2 sequestration in coal seams: Role of CO2-induced coal softening on injectivity, storage efficiency and caprock deformation

Portable multifunctional rock-soil body seepage experiment table