Study and Field Application of an UltraHigh Temperature Fracturing Fluid

Long fracturing in high temperature(200 ℃) reservoirs was in the past achieved by cooling down of fracturing fluid of 160 ℃ and optimization of relevant techniques. This technology was expensive and needed plenty of fluid. Aterpolymer thickening agent was developed using acrylamide as the major raw material, and a fracturing fluid was prepared with the newly developed terpolymer. This fracturing fluid is stable at high temperature of 200 ℃, and the gel formed is transparent and has good elasticity. After shearing 2 hours under 200 ℃ and 170 s-1, the viscosity of the fracturing fluid is still 170 mPa·s, meaning that the fracturing fluid has good suspending capacity and filtration property. The fracturing fluid after gel-breaking has low surface tension and the residue content is only 41mg/L, characteristic of low impairment to pay zones and low friction. This fracturing fluid was used in Well Niudong-101, in which daily production of 63 m3 oil and 10.2×104 m3 natural gas was obtained at half fluid consumption of the Well Niudong-1, and the cost spent in stimulating was reduced by 45.6%. This new fracturing fluid can be used in improving the production of ultra high temperature reservoirs.