High Temperature Fracturing Fluid Based on Nanofiitered Seawater

摘要

One of the most serious oil field problems is scale deposition, particularly when two incompatible waters are involved. The control of scale deposition in high-pressure, high temperature (HPHT) wells has been challenging because most scale inhibitors lose effectiveness at high temperatures as a result of molecular instability. In the context of adapting to the continuous challenges of the oil and gas industry, and needing to preserve freshwater resources in the Middle East, an in-depth study of the scaling results from mixing fracturing fluid was conducted. The use of nanofiitered (NF) seawater mixed with formation water containing high total dissolved solids (TDS) under HPHT conditions is discussed. A series of dynamic experiments was performed using a DSR-6000 dynamic scale loop at 330 °F and 3,000 psi. Additionally, static experiments were conducted at room temperature and at 330 °F for 2 and 24 hours. For both the dynamic and static tests, two mixing ratios were tested: 80:20 and 50:50 mixtures of NF seawater and formation brine. The 80:20 mixing ratio represents the worst-case scenario, according to scale advisor software results. Moreover, regained core permeability tests at 300 °F and 330 °F, and proppant pack damage tests were also performed. Results from the dynamic scale loop tests demonstrated that the lowest concentration of scale inhibitor tested (250 ppm) met the criteria for scale elimination, along with all higher concentrations, for both mixing ratios. The static tests were also successful, with no precipitation formed. Regained core permeability was in the range of 77% to 89%. Finally, the proppant pack damage test result of 56% indicated good cleanup properties for the NF seawater.