关键词: 压裂液, 有机硼锆交联剂, 耐温抗剪切, 合成

Abstract:

Fracturing is an important stimulation means for low-permeability oil reservoirs to increase their productivity. The normal operation of hydraulic fracturing largely depends on whether the fracturing fluid has excellent heat and shear resistance which in turn depends on the crosslinking agent. In this work, melamine, sodium tetraborate, and zirconium oxychloride were used as raw materials to synthesize a new W-SN crosslinking agent through “one-step method”. Under laboratory conditions, the performance of the fracturing fluid used with this crosslinking agent was evaluated. By study of the preparation process of W-SN crosslinking agent, the optimized synthesis conditions were obtained as follows: 5wt% zirconium oxychloride, 1wt% melamine, 2.5wt% sodium tetraborate, pH of 0.5, temperature of 90 ℃, and reaction time of 4 hours. The optimized conditions for gelation with partially hydrolyzed polyacrylamide （HPAM） were as follows: crosslinking time, 25 minutes; mass ratio of HPAM to W-SN, 100∶2.5. Both W-SN crosslinker and the HPAM gel show improved salt tolerance and thermal stability, satisfying the practical requirements of hydraulic fracturing operation.

Key words: fracturing fluid, organic boron zirconium crosslinking agent, thermal stability and shear resistance, synthesis