Research and Field Tests of Weighted Fracturing Fluids with Industrial Calcium Chloride and Guar Gum

To solve the problem of high cost and low weighting density in existing weighted fracturing fluid systems, a low-cost technology for weighting the fracturing fluid with industrial calcium chloride was developed. After analyzing the blocking mechanism of boron crosslinking agent in calcium chloride and guar gum base solution, a high-concentration calcium chloride-resistant crosslinker solution was developed. It has the advantage of being able to form crosslinked gel at low pH with high-concentration calcium chloride solution and guar gum base fluid. The industrial calcium chloride weighted guar gum fracturing fluid is characterized by its high weighting density, low base fluid viscosity, strong temperature and shear resistance. After the shearing at 140 °C and with a shearing rate of 100 s^–1 for two hours, the gel viscosity was greater than 100 mPa·s. Field tests indicated that the operating pressure can be reduced by 10–15 MPa in ultra-deep wells by using the weighted fracturing fluid with calcium chloride and guar gum. The results showed that fracturing fluid has reliable performance, and could reduce the operational pressure in ultra deep and high stress reservoir reconstructions, and thereby improve the fracturing effect, which has the value of field popularization and application.