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PublisherAmerican Rock Mechanics AssociationLanguageEnglish
Document ID 11-538
Content TypeConference Paper
TitleA Hydromechanical Testing Facility For Tight Reservoirs
AuthorsDeisman N., University of Alberta, Edmonton, AB, Canada; Chalaturnyk R.J., University of Alberta, Edmonton, AB, Canada; Lang P., Opsens Solutions Inc., Edmonton, AB, Canada
Source45th U.S. Rock Mechanics / Geomechanics Symposium, June 26 - 29, 2011 , San Francisco, California
Copyright2011. American Rock Mechanics Association
PreviewCoal and coal seam reservoirs have unique properties and therefore pose unique reservoir engineering challenges. Coal reservoir permeability is due primarily to fracturing where gas is stored primarily through sorption in the intact matrix. Coal permeability is stress dependent and changes in gas contents and composition induce volumetric strain. Coal strength and deformation behavior is a function of fracture spacing (cleating) and is anisotropic and nonlinear. An integrated laboratory testing facility capable of observing these effects at reservoir conditions is presented. The facility is designed to capture expected coal seam reservoir conditions under primary CBM production and ECBM/CO2 storage operations. The facility is designed to measure multi-component gas and liquid permeability at independent axial and radial stress conditions. Two types of testing cells are used in the facility: one with isotropic stress control and one with triaxial stress control. The isotropic cell is designed to measure diffusion and swelling characteristics of coal. The triaxial cell is designed to measuring axial strain and radial strain as well as axial P and S waves. Both cells are capable of measuring permeability. The cells are enclosed in an isothermal air bath with a medium temperature fluid pump and time controlled gas sampling system.

1.    INTRODUCTION

 Canada’s Clean Coal and CO2 Capture and Storage Strategic Plan formulated in 2005 identified key knowledge gaps that need to be addressed for post capture injection, long term reliability, and monitoring of sequestered CO2 in coalseam, or more commonly, coalbed methane (CBM) reservoirs. For each of these issues, understanding the unique geomechanical responses of the CBM formation under CO2 storage conditions have been labeled as high priorities by Canada as well the international community [1]. Therefore there is a need not only to identify the controlling hydromechanical processes in coalseams during the sequestration life cycle, including preinjection CBM production, but there is a critical need to characterize and link these processes for use in simulations and field monitoring for performance and risk assessment. An important component to address these needs is the development of a robust experimental facility encompassing in situ CO2 injection and storage, as well CBM production, conditions found in Canada, specifically in the Alberta Basin (Figure 1). This work presents a flexible facility design enabling measurement of the unique hydromechanical properties of coal including deformation, strength, acoustic velocity, permeability and relative permeability all at variable stress and temperature conditions.

2. BACKGROUND

 CBM production operations in the Alberta Basin have been capricious with success in shallower (<600m) Horseshoe Canyon formations, using a single vertical well to complete and production multiple low gas content coal seams. However, in the deeper Upper Manville formation (>900m) high gas content seams, limited production success has been achieved using vertical or horizontal wells. One approach to increase production in the Upper Manville formation may be to use enhanced coalbed methane (ECBM) recovery techniques. ECBM involves injecting a secondary gas, such as CO2 or a gas mixture (flue gas), into the formation to displace the methane [3].
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