Challenge: Decrease costs of fracture-stimulation operations in 14 Eagle Ford Shale wells
Solution: Streamline perf-and-drop technique by using KickStart™ rupture disc valve to fracture the first fracture stage without mechanical intervention and initiate plug-and-perf operations
Results: Streamlined operations and—after operating costs were factored in—saved Cabot more than USD 1.4 million
Tight economics in many onshore North American unconventional oil and gas plays have made it critical for operators to maximize efficiencies and minimize costs of operations. This optimization is often achieved by the use of improved completion techniques.
With approximately 700 wells in the Eagle Ford Shale's Buckhorn area alone, Cabot Oil & Gas needed a way to streamline its completions and decrease costs in the horizontal, cemented, multistage wells. As with most operators in the region, Cabot used the plug-and-perf technique for treating multiple production intervals sequentially. This method is an efficient, cost-effective way to treat every stage except the first one. In this first stage, no perforating guns can be pumped down in the well to access the reservoir because after the casing is cemented, the well is a closed system and does not allow pumping. Coiled tubing (CT) or other mechanical intervention is instead used to run the perforating guns to the initial toe stage before the plug-and-perf operation begins. Coordinating the CT unit and mobilizing a workover rig adds to the expense, complicates logistics of the first stage, and adds to the inherent risk of extra operations.
Various methods were considered for stimulating the toe stage so that operational speed and economics could be optimized without affecting the fracture stimulating of this first interval. Most proved unacceptable.
Cabot chose to incorporate the SLB KickStart rupture disc valve into its plug-and-perf operations. This pressure-activated valve's run at the toe of the well as part of the casing allows the first fracture stage to be initiated easily, without mechanical intervention. The valve uses a rupture disc for precise activation and helical ports that allow hydraulic fracturing to be performed through the valve into the cement and the formation. Often the valve is activated ahead of time so that when the fracturing treatment crew arrives on location, the valve is open and ready for the treatment to be pumped. Then, once it is activated, plug-and-perf operations can begin. Because the valve's ID is nearly fullbore, when cementing is completed, a standard cement wiper plug can be pumped through it.
Cabot used the KickStart rupture disc valve to fracture stimulate the toe stage, pumping more than 250,000 lbm of proppant at 65 bbl/min in all 14 Eagle Ford wells without incident. All KickStart valves activated within the set desired pressure range of the first time. Subsequent stages were selectively stimulated using the standard pump-down technique. By eliminating the CT-conveyed first-stage perforating gun run, the cost of each well was reduced by more than USD 100,000, saving Cabot a total of USD 1.4 million. This savings took into account both the cost of the valve and the money saved by eliminating the CT run.
Cabot has found the KickStart valve highly successful and continues to use it in its Eagle Ford Shale operations. The valve has also been used successfully in hundreds of horizontal wells in most North American unconventional plays, including the Marcellus Shale, Avalon Shale, Fayetteville Shale, Barnett Shale, Montney Shale, Granite Wash, and Horn River Basin.
