Experimental Investigation and Performance Evaluation of a Novel High Temperature Tolerant Seawater-based Fracturing Fluid

Abstract

As an important component of the fracturing treatment, fracturing fluids act as the carrier of proppant materials in offshore fracturing and frac-pack operations, thereby playing a decisive role in enhancing the deliverability near fractures and the productivity accordingly. According to the component analysis of seawater samples, the main challenges for developing a high temperature seawater-based fluid system were identified and the technical strategies to circumvent with these challenges were also established. To this end, novel anti-salt compound plant gum was synthetized to enhance the salt tolerance and dispersion effect of thickener. Organic boron-zirconium crosslinker was compounded to improve the crosslinking density and intensity. Chelating and screening agent, gel protective agent and temperature stabilizer were adopted to chelate metal ions, protect the gum from decomposing by organic matter or bacteria, as well as boost temperature resistance of fluid system respectively. Then a novel seawater-based fluid system was developed. The seawater-based fluid system developed has strong temperature tolerance of up to 160 °C. The performance of this fluid system was also evaluated by systematic studies. Results indicate that this new fluid system has good compatibility with formation water, without the occurrence of any precipitation during the compatibility evaluation tests. Moreover, the fluid system exhibited good leakoff control ability and a higher regained permeability than HPG solution, when the gel breaking fluid was pumped though the core samples in the targeted formation. The excellent performance of this fluid system signifies potential application prospect in the future deep-sea stimulation treatment.