Coalbed methane (CBM) drilling has been occurring in the Mount Pleasant, Westmoreland County, Pennsylvania area for about a decade, with various fracturing techniques applied in these CBM wells using conventional gas well fracture methods. However, production has been response-limited either due to incomplete placement of fracturing designs and/or because these older conventional gas well fracturing designs were not effective for these CBM wells.
Due to the poor nature of the production in these coal seams, it was determined to look more closely at the fracturing techniques and apply newer technologies designed specifically for CBM well fracturing. The objective of this review was to make future drilling of the CBM wells in this area economically feasible. This paper will discuss specifics of the coalbed field, fracture designs applied in the past and in the present, fracturing job design considerations, and chemical attributes for the fracturing job.
Most of the historic fracs placed on these wells used a linear gel guar system, low sand concentrations, low sand volumes, larger proppant size, and relied on high pump rates to put the sand away. More recent frac designs were developed to utilize a hybrid crosslinked fluid system, higher sand concentrations, higher sand volumes, and a lower pump rate. Also, chemicals designed more specifically for CBM wells are included in the redesigned test wells.
Finally, we will discuss gas production with the historic fractures that were placed on these wells in the past along with several current wells in the field that used a different design. We will then compare the gas production from these data sets to the gas production for the wells in the field that were fractured by applying the new fracturing technologies. By comparison of the data sets, this paper will demonstrate that the new fracturing technologies applied to this CBM field have resulted in significantly improved gas production for the operator.
Author(s): SPE, SPE, L.L.C., S.G. Snyder, and D.W. Jockel, Halliburton; and A.W. Lopez, EnerVest Operating
Paper Number: SPE 111206