A Novel Crude Oil Base Gelled Fracturing Fluid

A novel crude oil base gelling fracturing fluid is prepared for use in low permeable and water sensible reservoir at Huatugou, Qinghai, and consists of combinational phosphoric acid ester YJY A3 (selected from 3 bi and tricomponent combinational phosphoric acid esters), organic Al salt readily dispersible in oil as crosslinker, and an organic base as gel breaker in the crude of the same reservoir. The basic formulation is established as follows: 1.8%YJY A3+1.8%YJY B+1-2% organic base+crude. The laboratory performance evaluation shows that the gelled fluid viscosity increases with increasing temperature in range 20-55℃ and keeps practically unchanged in range 55-70℃; the gel viscosity is of 100 mPa·s when shearing at 25-60℃ and 170 s -1 in 60 min; the gelled fluid breaks down in 4-8 hrs adjustibly at 20-70℃; the permeability damage rate caused by the broken down gel for 2 reservoir core samples accounts 2.1% and 4.2% only meanwhile that by a commonly used broken down water base gel-as high as 85.4% and 91.4%.