WELLOG             COAL BED METHANE

 

 

 

WHAT IS COAL BED METHANE?

 

Most coal beds produce methane gas. In many regions, the combination of thickness of the coal, gas content and permeability add up to profitable methane gas production.

 

HOW IS IT PRODUCED?

 

Coal Bed Methane field development is done according to well-designed plans in order to optimize gas production, field life, and profitability. A well is drilled to the top of the producing coal formation and cased with cement. The well is then under-reamed into and thru the coal formation. When formation water is pumped out of the well, reducing hydrostatic pressure, the methane gas desorbs (comes out of solution in the coal bed) and is produced in gaseous form.

 

WHERE ARE THE MAJOR LOCATIONS?

 

The main plays are in New Mexico, Wyoming, Kansas, Iowa, Alabama and along the Appalachian mountains from Pennsylvania to Virginia.

 

ALASKA has become a new CBM player with exploration and development West of Cook Inlet, Beaufort Sea, North Slope and Alaska Peninsula.

 

 

WHAT ARE THE TOOLS?

 

Because coal beds contain very low levels of natural gamma radiation, scintillation gamma logging tools offer the best choice for logging a CBM well. Often times, if the drill string has sufficient inside diameter, a slim-hole (1 1/4 inch) gamma ray logging tool is lowered into the drill string without removal from the well and a log is obtained thru the drill steel. Otherwise, open hole / cased hole gamma ray logging is performed. Perforation position within the most desired coal seam is critical in CBM well production. Casing collar Locator (CCL) is usually ran with natural gamma ray logging.

 

OLD WELLS:

 

Old wells drilled in coal producing regions offer the potential for CBM gas production. Gamma ray logging of these old wells will reveal the location of coal seams. Perforation and production of CBM gas becomes possible.

 

Revised 11-07-2016

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