Study On Modified Silicone Gel Killing Fluid

Inorganic salt well killing fluid cardinally based on CaCl₂ is widely used in oil and gas field,but there are some shortcomings such as no suspension and serious filtration and corrosion,which could be solved by gel-type inorganic salt well killing fluid.Moreover,the salt factory in Sichuan Province would produce large quantity of waste brine that was rich in CaCl₂,the Ordinary Calcium Water one of them,which would reduce the cost and make the best use of it if used to prepare for gel-type inorganic salt well killing fluid.Therefore,it is of great practical significance to study the preparation of gel-type well killing fluid based on the Ordinary Calcium Water.In order to prepare gel-type well killing fluid,the modified guar gum powder selected as thickener was conducted through orthogonal test,the results showed that the raw materials and the reaction condition were sorted as follows,NaOH>CHPTAC?3-chloro-2-hydroxypropyl three methyl ammonium chloride?>anhydrous ethanol>deionized water and alkalization temperature>alkalization time>etherification temperature>etherification time,the optimal formulas based on mass fraction and condition were obtained as follows:guanidine collagen powder was 10.4%,deionized water was 28.4%,anhydrous ethanol was 56.8%,NaOH was 1.3%,CHPTAC was 3.1%and alkalization time was 60 minutes,alkalization temperature was 30?,etherification time was 3 hours and etherification temperature was 75 ?.FIR,DSC and XRD were used to confirm the modified guar gum.Two density formulations was ascertained through selecting crosslinker and testing the performance of the killing fluid,the formula based on mass fraction for the density of 1.4g/cm³ was obtained as follows:the Ordinary Calcium Water was 97.85%,modified guar gum was 1.4%,zirconium oxychloride was 0.7%and HEDP was 0.05%,the formula based on mass fraction for the density of 1.6g/cm³ was obtained as follows:zinc chloride was 53.25%,zinc chloride was 45.4%,modified guar gum was 0.9%,zirconium oxychloride was 0.4%and HEDP was 0.05%.The well killing fluid systems had the characteristics of high viscosity,low filtration,good emulsification of the crude oil,good compatibility with the reservoir and good thermal stability.Specially,the rheological test results showed that the well killing fluid was a non-Newtonian fluid and consistent with the power law equation,the shear resistance was good at 25 ? and 170 s"1 shear rate,the zero shear viscosity of the gel system decreased gradually when the temperature rised from 25 ? to 65 ?,high temperature sensitivity because of the flow activation energy of gel well killing fluid system was 34.88kJ/mol,the G' conveied elastic modulus and G" conveied viscous modulus decreased with temperature increasing,with the frequency increasing,G' and G" increased,but G' is always greater than G",tan? increased with temperature increasing within the range of the test.rheology indicated that the gel well killing fluid could also be used as fracturing fluidIn order to expand the scope of application of gel well killing fluid,the corrosion of P110 steel was studied by weightlessness and electrochemical method.,the results were as follows.In the case of no corrosion inhibitor,the corrosion rate of the two kinds of density of gel well killing fluids increased with the increasing of temperature,the two kinds of gel well killing fluids added WLD31C had a better corrosion inhibition effect than added WLD31A.After adding WLD31C inhibitor,the corrosion inhibition efficiency of 1.4g/cm³ well killing fluid increased with temperature increasing,however,the corrosion inhibitor failed and the corrosion current density increased at 90 ? the corrosion inhibition efficiency of 1.6g/cm³ well killing fluid reached to 70.3%and 40.8%at 60 ? and 70 ? and the effect of corrosion inhibition to steel was obvious and the corrosion current density decreased,the corrosion rate of the well killing fluid increased and the corrosion current density increasd at 80 ? and 90?.In the absence of a corrosion inhibitor,the gel well killing fluid had a smaller corrosion rate than conventional well killing fluids.