Abstract

This paper reviews the fracture stimulation improvement achieved over the well stimulation experience to attempt a field redevelopment through a well revitalization after workover and recompletion with a multistage hydraulic fracturing string using energized fluids, notwithstanding the limited background of fracture technology applications in Italy. The objectives were concentrated on the reserves final recovery of the principal layers and assessment of potential thin layers that has never produce before, which entail the use of technologies state-of-the-art for drilling, completions, stimulation and development plans.

The hydraulic fracturing stimulation technique pumping energized fluids introduced in the Roseto-Montestillo field has proved to be very successful recovering well productivity, however some associated problems have required a process optimization during the intervention. The problems ranged from in situ stress variation, that lead to very high pumping pressure (even in presence of very depleted reservoir), plastic or soft formation with potential proppant embedment issues, effective vertical coverage of the target pays intervals and gel residue with the consequent damage to fracture conductivity.

Here significant gains in production have been observed following the successful fracture treatment optimization moving from conventional borate crosslinked guar polymer to an optimized zirconate fracturing fluid energized with CO2. The use of energized fracturing fluids, expedite the fracture clean up process and dramatically reduce the amount of fluids to be recovered, while aid the lifting process on the other layers where conventional treatments were pumped. All this lead to a higher well productivity sustained along the time while minimize post fracturing problems compare to the jobs with conventional fracture treatment.

This paper summarize the fracture stimulation treatment best practices and review the design along with the operational considerations for the area, including treatment volumes, pump rates, surface equipment, completion selection and fluid chemistry.

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