Non-Crosslinking Vegetable Gum Fracturing Fluid XG-1 Technology

A non-crosslinking vegetable gum fracturing fluid XG-1 was developed based on the concept that xanthan gum (XG) forms rod-shaped double helix polymer in water solution. The fracturing fluid treated with 0.5% XG-1 had apparent viscosity (AV) over 70 mPa·s, and over 40 mPa·s at 50-100 ℃ because the AV of the fracturing fluid decreased with temperature. When pH of the fracturing fluid was maintained between 2 and 12, the AV would be maintained at about 60 mPa·s. Fracturing fluids prepared with 20% KCl and 20% CaCl₂ both had AV greater than 40 mPa·s, and both had good salt tolerance. When the AV of the fracturing fluids were greater than 40 mPa·s, settling velocity of the proppant would be greater than 0.014 mm/s, and the gel-broken fluid had viscosity greater than 5 mPa·s, with its surface tension similar to that of guar gum fracturing fluids. Fracturing fluid treated with 0.5% XG-1 had residue content of 90 mg/L after gel-breaking, far less than that of the guar gum fracturing fluids at the same viscosifier concentration. This fracturing fluid can be used in the fracturing operation of medium- to low-permeability reservoirs with few natural fractures.