For subsequent wells, the operator asked Schlumberger to change three aspects of the stimulation design: minimize polymer gels to decrease formation damage, include a retarded acid system to increase penetration, and reduce acid viscosity to improve fracture face etching. Because the wellsite was 155 miles [250 km] from the nearest supply base, the operator also asked for acid efficiency improvements that would reduce fluid or chemical volumes, logistics, and HSE risks of transporting materials.
Adding to the challenge, the next completion was designed with 3 ½-in tubing, raising concerns about fluid friction limiting the ability to achieve the pump rates required to maintain open fractures as the acid reacted. This concern precluded the use of emulsified acid, a conventional retarded acid option, because it is incompatible with friction reducers. Emulsified acid also did not suit the customer’s logistics request because it increases environmental footprint and requires complicated batch mixing and transport.