An Ultra-High Temperature Coordinate Bond Oligomer Thinner

An ultra-high temperature coordinate bonding oligomer thinner AA-AMPS-TA (named PAAT) is synthesized as a way of dealing with the problems encountered in using high density water-based drilling fluids at elevated temperatures. These problems involve high filtration rate, high ECD and internal friction, poor mobility or even complete loss of the mobility of the drilling fluids. The thinner PAAT is synthesized through radical polymerization by introducing the molecules of tanning acids (TA) which are rich in catechol groups into the poly organic acid thinner AA-AMPS. The optimal synthesis condition of the thinner PAAT is determined through orthogonal experiment, and the thinning performance of the thinner is evaluated. The evaluation results show that after introducing TA into the molecules of the AA-AMPS, the IR spectrum of the product PAAT shows an intra-molecule hydrogen bond absorption peak, and the thermal stability of the PAAT molecules is greatly improved because of the introduction of large number of phenol groups; the decomposition temperature of the PAAT molecules is close to 500 ℃. PAAT has the ability to reduce the viscosity of low-concentration bentonite slurry and high clay concentration slurry such as one formulated with 7% bentonite and 8% kaolinite. Using PAAT, the viscosity of a high density water-based drilling fluid can be reduced by 26.5%, and after hot-rolling the water-based drilling fluid at 240 ℃, its viscosity can be reduced by 44.4%. The PAAT thinner reduces viscosity by molecule adsorption, as is verified by Zeta-potential measurement and particle size analysis. This thinner has been used in drilling the well Pengshen-101, and the viscosity and gel strengths of the drilling fluid were both satisfactorily under control at elevated temperatures.