Even in modest rate coal bed methane (CBM) wells, it is generally accepted that very high fracture conductivity is needed to ensure rapid dewatering, which has made 12/20 sand a common choice.
Methane gas from wells completed exclusively in coal seams has become a major energy resource in the USA, and it is being evaluated in many other countries. In all but a very few cases, stimulation by hydraulic fracturing is required for adequate production rates. The application of fracturing to improve degasification of coal beds prior to mining began in 1974, but in recent years its application has expanded such that many completions are independent of any expected future mining operations. Wells are often completed in multiple coal seams with possibly hundreds of feet between the completion zones.
The hydraulic fracturing fluids, equipment, and designs used for coalbed methane wells have seen major evolutionary changes from the early treatments when completing in seams to be mined. When fracturing became common in coal seams where mining was not being considered, roof integrity was no longer a concern and the treatment designs began to undergo more accelerated changes.
This paper will trace the historical application of hydraulic fracturing in the two major commercial coalbed methane producing areas: The Black Warrior Basin of Northern Alabama and the San Juan Basin of Northwest New Mexico/Southwest Colorado. Recent applications in the Raton and Piceance Basins of Colorado and the Central Appalachian Basin will also be addressed.
Author(s): Halliburton Services, B.W. McDaniel
Paper Number: SPE 21292