Abstract
Friction reducers are commonly used in slickwater fracturing operations to minimize energy loss due to tremendous amount of friction between tubular goods and water or brine solutions during the pumping of very high rate of fluids. Currently almost all friction reducers used are high molecular weight polyacrylamide emulsions. Large amount of polymers is injected into the formation even at very low concentrations (typically 0.5 − 2 gpt) due to the large volume of a typical slickwater frac treatment. Concerns have persistently been raised over possible fracture and formation damages caused by the friction reducers. All current friction reducers, including copolymers, are polymers with C-C backbones, which are difficult to break. Tests show that these polymers, even in the presence of oxidizer breakers, cause formation damage.
A novel friction reducer featuring easily breakable chemistry has been developed to offer clean, non-damaging slickwater stimulations. This new non-damaging friction reducer, delivered also in liquid form for the ease of transportation and field operation, is very effective as a friction reducer, compatible with common chemical additives (scale inhibitors, biocides, clay stabilizers, surfactants, brines, etc) and stable towards mechanical shearing. This paper will present the product development details and lab tests on the effectiveness of the new friction reducer in water and various brines and its hydration profile at different temperatures, chemical compatibility and breaking profiles. Formation damage studies on tight sandstone and shale formation on this new friction reducer in comparison with the conventional ones have been conducted and will be discussed in the paper. Results show the non-damaging friction reducer degrades easily with conventional breakers and leave no damage to the formation. Several successful multi-stage slickwater frac completions have been performed with the new friction reducer and these field trials will also be reviewed.
