The Westerose Gas Field produces gas from the Glauconitic Formation. This formation can be subdivided into an upper permeable sand (1–10 mD) and a lower sand (normally less than 0.5 mD). The reservoir quality of the lower sand is fairly uniform throughout the area, but the upper section can contain either permeable "bar" sands or low permeability "interbar" sands. "Bar" type sands have greater thickness than the "interbar" sands and, in general, contain greater gas reserves. Nevertheless, inter-bar sands are estimated to contain up to 225.4 MMm3 (8 Bcf) original gas in place per section, which is a significant gas target. These reserves have not been extensively developed since vertical wells that penetrate the interbar sand are usually very poor producers.
An experimental pilot project was conducted to determine the feasibility of developing additional gas reserves in the tight sands located between the main bar trends. As part of this work, a study was conducted to analyze and compare fracturing and completion alternatives in the Glauconitic "bar" and "interbar" sands. For each type of sand, optimal fracture designs for vertical wells were determined and vertical fractured well performance was compared to stimulated and unstimulated horizontal wells drilled either parallel or perpendicular to the minimum in-situ stress. This paper reports the findings of the Westerose fracturing and completions study, and field results from wells drilled and completed in 1997 in accordance with the study recommendations.