Shallow coalbed methane (CBM) projects can have multiple pay zones available for completion. Cased-hole completions allow zonal isolation to direct treatments, but re-establishing a connection to a coalseam through drilling and cementing damage may require high breakdown pressures even with an acid spearhead. Isolating individual zones to help ensure completion effectiveness is paramount to a successful completion.
This paper details the use of composite epoxy-glass fracturing plugs to reduce time to complete, drill out, and clean up wells drilled in the Southern Illinois Basin (SIB) project. Over 80 wells have been completed in multiple stages using as many as three composite frac plugs to isolate four coals. Accurate placement of plugs by electric line to allow staging as close as 10 ft was accomplished without communication. These four-stage frac completions were accomplished in less than 8 hours before flowing back frac fluids from all zones. Less than a single day was required to drill out all the plugs, go to bottom, circulate clean, and prepare the wells to begin pumping. The authors compare this technique with the cost and time required to do completions with alternative isolation methods.