Matrix shrinkage and swelling effects on economics of enhanced coalbed methane production and CO2 sequestration in coal

F. B. Gorucu, S. A. Jikich, G. S. Bromhal, W. N. Sams, T. Ertekin, D. H. Smith

Research output: Contribution to conferencePaper

10 Scopus citations

Abstract

Increases in CO2 levels in the atmosphere and their contributions to global climate change have been a major concern. It has been shown that CO2 injection can enhance the methane recovery from coal. Accordingly, sequestration costs can be partially offset by the value added product. Indeed, coal seam sequestration may be profitable, particularly with the introduction of incentives for CO2 sequestration. Hence, carbon dioxide sequestration in unmineable coals is a very attractive option, not only for environmental reasons, but also for possible economic benefits. Darcy flow through cleats is an important transport mechanism in coal. Cleat compression and permeability changes due to gas sorption desorption, changes of effective stress, and matrix swelling and shrinkage introduce a high level of complexity into the feasibility of a coal sequestration project. The economic effects of carbon dioxide-induced swelling on permeabilities and injectivities has received little (if any) detailed attention. Carbon dioxide and methane have different swelling effects on coal. In this work, the Palmer-Mansoori model for coal shrinkage and permeability increases during primary methane production was re-written to also account for coal swelling caused by carbon dioxide sorption. The generalized model was added to PSU-COALCOMP, a dual porosity reservoir simulator for primary and enhanced coalbed methane production. A standard five-spot of vertical wells and representative coal properties for Appalachian coals were used.1 Simulations and sensitivity analyses were performed with the modified simulator for nine different parameters, including coal seam and operational parameters and economic criteria. The coal properties and operating parameters that were varied included Young's modulus, Poisson's ratio, the cleat porosity, and the injection pressure. The economic variables included CH4 price, CO2 cost, CO2 credit, water disposal cost, and interest rate. Net present value analyses of the simulation results included profits due to methane production, and potential incentives for CO2 sequestered. This work shows that for some coal-property values, the compressibility and cleat porosity of coal may be more important than more purely economic criteria.

Original languageEnglish (US)
Pages137-151
Number of pages15
StatePublished - Dec 1 2005
EventSociety of Petroleum Engineers Eastern Regional Meeting 2005 - Morgantown, West VA, United States
Duration: Sep 14 2005Sep 16 2005

Other

OtherSociety of Petroleum Engineers Eastern Regional Meeting 2005
CountryUnited States
CityMorgantown, West VA
Period9/14/059/16/05

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All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

Gorucu, F. B., Jikich, S. A., Bromhal, G. S., Sams, W. N., Ertekin, T., & Smith, D. H. (2005). Matrix shrinkage and swelling effects on economics of enhanced coalbed methane production and CO2 sequestration in coal. 137-151. Paper presented at Society of Petroleum Engineers Eastern Regional Meeting 2005, Morgantown, West VA, United States.