The Application of Oil Based Fracturing Fluids to Reservoir Stimulation at Qigequan Oil Field

Two series diesel oil based and crude oil based fracturing fluids are developed for stimulating low permeable (0.001-0.03 μm 2), low temperature (25-30℃) and water sensible reservoir of Qigequan, Qinghai. In chemical structure the alkyls in phosphoric acid esters TH and XK fit to catalytic diesel oil and a crude oil taken as base oil, respectively; the crosslinker is sodium meta aluminate and is mixed all at once; the gel breaker sodium acetate is effective at low temperatures. The fluids are composed of 1.6-1.7% of phosphate TH or XK, 0.4 - 0.5% of crosslinker and 0.7-1.0% of gel breaker. The gelled fluids has viscosity 68-110 mPa·s at 30℃ (some properly formulated fluids maintain viscosity100 mPa·s after shearing at 35℃ in 30 min), break down in 12-24 hrs and give degelatinated fluids of viscosity 1.8-9.0 mPa·s, leaving a little amount of residue, and have filtrate loss coefficient C 3 ranged 1.83×10 4-6.87×10 4 m/(min) 1/2 . For hydrofracturing at Qigequan particulated pottery of density 1.56 g/cm 3 in diameter 0.45-0.90 mm is chosen as proppant. The technologic parameters of fracturing are established. The successfulness of 14 jobs performed in 2001 accounts 85.7% and the effectiveness of successful jobs-100%. The technologic parameters, designed and real, are presented for fracturing jobs in 4 wells.