A study on the carbon dioxide injection into coal seam aiming at enhancing coal bed methane (ECBM) recovery

Akash Talapatra

doi:10.1007/s13202-020-00847-y

Abstract

Coal seams, particularly deep unmineable coal reservoirs, are the most important geological desirable formations to store CO2 for mitigating the emissions of greenhouse gas. An advantage of this process is that a huge quantity of CO2 can be sequestrated and stored at relatively low pressure, which will reduce the amount of storage cost required for creating additional platform to store it. The study on CO2 storage in coal seam to enhance coal bed methane (ECBM) recovery has drawn a lot of attention for its worldwide suitability and acceptability and has been conducted since two decades in many coalmines. This article focuses on the coal seam properties related to CO2 adsorption/desorption, coal swelling/shrinkage, diffusion, porosity and permeability changes, thermodynamic/thermochemical process, flue gas injection, etc. Here, the performance analysis of both CO2 storage and ECBM recovery process in coal matrixes is investigated based on the numerical simulation. In this study, a one-dimensional mathematical model of defining mass balances is used to interpret the gas flow and the gas sorption and describe a geomechanical relationship for determining the porosity and the permeability alteration at the time of gas injection. Vital insights are inspected by considering the relevant gas flow dynamics during the displacement and the influences of coal swelling and shrinkage on the ECBM operation. In particular, pure CO2 causes more displacement that is more efficient in terms of total CH4 recovery, whereas the addition of N2 to the mixture assists to make quicker way of the initial methane recovery. However, this study will support future research aspirants working on the same topic by providing a clear conception and limitation about this study.

Highlights

Coal seams, those are unmineable and found in deep reservoir, are desirable target formations to store CO2 as a part of mitigating greenhouse gas emission process (Talapatra 2019), because coal can store a large quantity of C O2 gas via adsorption process at relatively high temperature and low pressure, compared with the other target reservoirs, which further reduces both the compression and injection expenses (Reid et al 1987)
Much endeavor has been conducted toward the enhanced coal bed methane (ECBM) recovery studies by focusing on the C O2 injection approach, which is considered as an essential area of carbon capture, utilization, and storage purposes (Talapatra et al 2019; Busch et al 2003; Fitzgerald et al 2005)
The concept of storing C O2 under coal reservoirs for enhancing the coal bed methane recovery criteria has been directed since the early 1990s, which recently have included N2 to make a mixture of flue gas with CO2 to promote the process effectively (Arri et al 1992)

Summary

Introduction

Those are unmineable and found in deep reservoir, are desirable target formations to store CO2 as a part of mitigating greenhouse gas emission process (Talapatra 2019), because coal can store a large quantity of C O2 gas via adsorption process at relatively high temperature and low pressure, compared with the other target reservoirs, which further reduces both the compression and injection expenses (Reid et al 1987). This includes the existing well infrastructure and economic benefits to the enhanced coal bed methane (ECBM) recovery operation. A number of field tests have been done to examine the suitability of C O2 storage facilities and ECBM behavior in parallel with the laboratory experiments based on the practical-field conditions

Methods

Results

Conclusion