Stimulate infill wells without harming an older primary oil producer
Infill drilling accounts for more than 60% of the new wells drilled in North America, where operators have learned through experience that stimulating infill wells sometimes causes fluid and/or proppant communication into older wells due to pressure depletion also known as frac hits. This communication can be beneficial or detrimental to production. In the most severe cases, the older wells can be sanded up, requiring expensive and time-consuming cleanout operations to restore production.
For an operator in North Dakota, detrimental frac hits occurred in about half of the operator’s new completions. To avoid the problem, operator engineers tried pumping fluid into older wells while stimulating the infill wells. The technique reduced the risk of sand flow and cleanouts in the older wells but cost up to USD 300,000 per well.
The operator wanted a more efficient solution for multistage stimulation of two infill wells near a well that had been producing hydrocarbons for 7 years. The older well had a damaged liner and a fish behind the liner, so any frac hit requiring a sand cleanout would be extremely costly in terms of deferred production and intervention expenses to restore production.
Limit fracture growth and monitor pressure response
Schlumberger recommended the BroadBand Shield service for two infill wells on either side of the older primary well. BroadBand Shield delivers far-field diversion pills to limit frac hits or fracture propagation into existing producing wells.
Rather than commit to using it for both wells, the operator engineers agreed to test the efficacy of the service in several stages of one infill well, Well 2. In Well 3, all of the stages would be stimulated with conventional fracturing designs optimized for the area. In Well 2, five stages were stimulated with BroadBand Shield service and the next five stages without BroadBand Shield service, just conventional fracturing designs. This sequence was repeated until the last stage.
To analyze fluid and proppant communication between both wells, the WellWatcher Stim service was used to monitor pressure response at high frequency in both infill wells and the older well during all stages, enabling a combined analysis to clearly confirm pressure communication or lack of communication.