High temperature and high density sealing fluid is one of the key technologies for high temperature and high pressure well completion.At present,there are only bromine salt,zinc salt or cesium formate solution in the solid-free brine sealing fluid with a density of more than 1.60 g/cm3.The toxicity of bromine salt is great,and the high temperature corrosion of zinc salt is difficult to control.The high price of cesium formate is difficult to meet the technical requirements of high temperature and high pressure well completion.It is imperative to develop a new solid-free high density clean brine sealing fluid for high temperature and high pressure wells.A new potassium-based phosphate solid-free high-density packer fluid was developed by optimizing the soluble salt SW4 with tripotassium phosphate TKP as the main agent and adding other treatment agents.Its density adjustment ability,theological and theological model of aqueous solution,metal corrosion,high temperature stability,biological toxicity and other properties were tested.The results show that the maximum density of SW4 packer fluid can reach 1.90 g/cm3 at room temperature.With the increase of density,the viscosity of its aqueous solution increases,and its rheological model is Newtonian fluid.The corrosion rates of A3 steel,N80 steel,TN110Cr13S and TN110Cr13M steel in 1.85 g/cm3 SW4 packer fluid at 150 ℃ for 7 d were less than 0.076 mm/a.The corrosion of N80 steel in 1.80 g/cm3 SW4 packer fluid was significantly lower than that of calcium bromide and zinc bromide under the same conditions,which was comparable to that of cesium formate.Under the same dosage,SW4 can provide more K+and has better anti-swelling property.High temperature stability,can meet the needs of high temperature and high pressure well completion conditions;low biological toxicity and environmental acceptability.SW4 can meet the technical requirements as a solid-free high-density packer weighting agent.
potassium-based phosphatehigh density packer fluidsolid-free packer fluidcorrosionHTHP well
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