A Mechanistic Model for CO2 Sequestration in Tiffany Coal Bed Methane Field

Conference · Thu May 01 04:00:00 EDT 2003

OSTI ID:911291

Liang, Jenn-Tai; Raterman, Kevin T; Robertson, Eric P

The objective of this project is to develop mechanistic models specific to CO2 sequestration in BP’s Tiffany coal bed methane (CBM) field. In this study, the original field model was modified to match the field performance of a 5-spot pattern in the northern part of the Tiffany Field where BP plans to perform a micro-pilot test. The modified model consists of one high-permeability fast layer sandwiched between two low-permeability slow layers. In this mechanistic model, the fast layer represents well-cleated and fractured coal from all geological layers while the slow layers represent coal with little or no fracture development from the same geological layers. The model successfully matched the performance of the 5-spot pattern during the enhanced recovery period (N2 injection). However, in order to match nitrogen breakthrough times and nitrogen cut the vertical transmissibility between layers had to be set to zero. During gas injection, nitrogen was allowed to enter all three layers, not just the high-permeability fast layer. However, because the permeabilities of the slow layers were low and there is no communication between the fast and the slow layers, most of the injected nitrogen entered the high-permeability fast layer. This suggests that the future gas injection and CO2 sequestration may be restricted to only one third of the total available pay. For future gas injections, the modified model predicted early CO2 breakthrough with high CO2 cut. This suggests that the actual CO2 sequestration capability of the Tiffany Field might not be as high as originally expected. This is a direct consequence of the reduced available pay in the modified model. The modified model also predicted early inert gas (N2 plus CO2) breakthrough and high inert gas cut during future gas injections. If this is confirmed in the pilot test, the high volume of inert gas produced could overwhelm the reprocessing capability resulting in early termination of the project.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-99ID13727
• OSTI ID: 911291
• Report Number(s): INEEL/CON-03-00136
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CO2 sequestration
COAL
COMMUNICATIONS
ENHANCED RECOVERY
FRACTURES
GAS INJECTION
METHANE
NITROGEN
PERFORMANCE
REPROCESSING
coal bed methane (CBM)
mechanistic models
micro-pilot test