Study On High-Temperature Resistance Of Drilling Fluids

Along with the rapid development of deep drilling techniques, the technical problemsdrilling fluids face become more serious. Because of the complicated geological conditionsinland, deep drilling fluids face the problems such as high temperature high density andsaturated salt, that have a great influence on properties of drilling fluids. Based on thehigh-temperature malfunction of common mud additives such as polyacrylamide, starch andCMC, the interreaction between polymers and surfactants was deeply analysed. Then theoptimum surfactant and anti-oxidant were optimized in order to restrain high-temperaturedegradation of polymers. Aimed at the high-temperature excessive cross-linking of SMP, theinfluence factors, such as salinity, temperature, pH etc, were analysed as well as the molecularstructure of SMP. The reason of high-temperature cross-linking was found andhigh-temperature stabilisers TSA and SA were developed. Results of in-house experimentsand field testings indicate that the using of Tween-80/CTAB and pml improve the resistanceof the drilling fluid temperature performance, and that TSA and SA inhibit the cross-linkingeffectively, so as to improve rheology of drilling fluids.Based on the use of additives in Tarim oilfield, the filtrate loss reducer with hightemperature resistance and salt tolerance and other additives were optimized. Experiments'result and grading analysis determine the grain composition of barites. A series of saturatedsalt water drilling fluid of high temperature(150℃, 180℃and 200℃), from 1.5 g/cm3 to 2.5g/cm3, were developed using high-temperature stabilisers, and the ability of high temperature,calcium, cuttings and salt resisted had been evaluated. Experiments'result proved that thissystem has better rheology behavior, lower HTHP filtration, contamination resistance.Organic slat can improve rheology in high density drilling fluids. The last, the relationbetween quality of mud-cake and organic matter content in mud-cake was studied, thatprovide reference for forming thin and tough mud-cake.