Hydraulic fracturing process using a polymer gel

#1. Technical Field

#The invention relates to a process for hydraulically fracturing a subterranean hydrocarbon-bearing formation and more particularly to a process for fracturing the formation with a crosslinked polymer gel.

#2. Background Information

#A production well is drilled to a depth of 1550 m in a Pennsylvania aged sandstone formation which has a formation temperature of 82.degree. C. and has some natural fracturing. 9.4 m of the well are perforated. The well initially produces 86 liters of oil per hour and 404 liters of water per hour.

#The well is hydraulically fractured using a gel comprising 3700 ppm acrylamide polymer, 300 ppm chromic acetate complex, and a produced water solvent at a temperature of 66.degree. C. The acrylamide polymer is a 30% hydrolyzed polyacrylamide having a molecular weight of 11,000,000. The produced water has a total dissolved solids content of 0.58 wt %.

#Thirty thousand liters of the gel is injected at 1600 liters per minute. Thereafter, three gel slugs having a volume of 7600 liters each and containing and 8 to 16 mesh sand proppant are injected at the same rate. The first slug has 0.24 kg of sand per liter of gel, the second has 0.48 kg/l, and the third has 0.72 kg/l.