The ultimate goal of increased production has led to exploring new techniques to stimulate unconventional reservoirs in an efficient and economical manner. Globally, the trend towards horizontal drilling is increasing to enhance production by increasing the contact area with the producing interval. Likewise, operators are looking to maximize the volume of reservoir rock that is fracture stimulated, using horizontal drilling to create lateral sections and combining this with the efficient placement of propped fracturing treatment. Nevertheless, individual fracturing of numerous zones with bridge plug isolation or the conventional perf-and-plug method poses several concerns regarding cost and operational efficiency in horizontal wells. A new multistage stimulation technique has been successfully deployed in the Western Desert, Egypt, for the first time allowing for multiple stages to be fracture stimulated in one continuous operation.
The technique using cemented fracturing sliding sleeves and degradable-ball drop was successfully implemented. This technique utilizes valves with preset seats and matching degradable balls to achieve zonal isolation. The balls are dropped from the surface, to isolate the stimulated interval. Once the ball lands on the seat, applying surface pressure activates the sleeve and opens up the fracturing port at the next target zone of the formation to be stimulated.
This completion system allows for maximum operational efficiency because it eliminates the need for and risks associated with the use of wireline for perforations or coiled tubing services to mill out a bridge plug or clean up a sand plug. Fewer needed services and personnel allows for reduced operating time and lower cost. In one well, implementation of the cemented sliding sleeves with degradable ball technique was successful in efficiently completing seven hydraulic fracturing stages efficiently. The subject well, 3H Pinot was drilled to a measured depth of 10,330 ft with a lateral length of over 3,300 ft. This well provides a model for the completion strategy, operational procedures, adeptness of the isolation, and time frame. Another benefit that was demonstrated during the execution was precise fracture placement in utilizing the innovative fracturing ports. Implementation of the fracturing sliding sleeves system resulted in achievement of completions and stimulation goals while significantly increasing operational efficiency by means of reduced time between fracture stages and effective isolation. Enumeration of operational setbacks encountered during the execution of the multistage fracturing treatment provides areas for future improvement and recommendations for future field operations. In the subject well, the technique impacted production because immediate and simultaneous flowback of all the stages was possible.