Development and performance evaluation of a novel SiO2-enhanced seawater-based temperature-resistant clean fracturing fluid

Hydraulic fracturing has been proposed as a potential technology for the development of low-permeability oil reservoirs and also has promising application prospects offshore. In this study, a novel SiO2-enhanced seawater-based temperature-resistant clean fracturing fluid was formulated. The fracturing fluid main agents, additives and reducing agents were screened. Besides, the physical and chemical properties (rheology) as well as application (i.e., sand-carrying, gel-breaking, dynamic fluid loss, dynamic damage and anti-swelling) performance of the proposed SiO2-enhanced seawater-based temperature-resistant clean fracturing fluid were systematically investigated. It was revealed that 3.2wt% AASB-17+1.92wt% NaSal+0.1wt% SC-107+0.1wt% TS3 was the optimal SiO2-enhanced seawater-based clean fracturing fluid system formula. The SiO2-enhanced seawater-based temperature-resistant clean fracturing fluid exhibited remarkable rheological characteristics, the temperature and shear resistance was increased by 28%, with a maximum temperature resistance of 90ºC. The fluid can be applied to the fracturing development of most oil reservoirs in the Bohai Bay. In addition, the presence of SiO2 nanoparticles significantly improved the sand-carrying properties of the proposed system. The experimental results also suggested that the proposed SiO2-enhanced seawater-based temperature-resistant clean fracturing fluid showed excellent performance of shear recovery (fixed shear viscosity recovery rate was 100%), gel breaking (30min,1 mPa·s), filter loss (Cw=4.75×10-4m/min1/2), anti-swelling (anti-swelling rate was 77.78%) and salt tolerance. This study provides fundamental technical support for the application of SiO2-enhanced seawater-based temperature-resistant clean fracturing fluid in offshore fracturing.