Chapter Thirteen - Formation Damage in Coalbed Methane Recovery

Abstract

Coal is an unconventional hydrocarbon reservoir which is both the source and reservoir for the formed methane. Extraction of methane involves altering the existing conditions and these changes can lead to damage of the reservoir. For sustained production of coalbed methane (CBM), damage of coal needs to be minimized. Formation damage refers to the changes in the producing formation that leads to decline in coal permeability which eventually leads to the decline in production. This chapter discusses the various mechanisms in the reservoir that lead to formation damage. It describes and discusses the major types of formation damage that commonly occur when drilling CBM reservoirs. The emphasis is on the most common types of formation damage, that are those associated with drilling, completion, and specifically hydraulic fracturing. Further, damage due to volumetric deformation of coal matrix and production-related reservoir failure are also discussed.