Study On Synthesis Of Sulfonated Melamine-Formaldehyde Resin And Its Drilling Fluid Loss Properties

In the petroleum well drilling process, the control of drilling fluid loss has the vital significance to protect the mud shale, wall as well as the production protection. The use of drilling fluid loss additive is the most effective method to control drilling fluid loss and protect the wall.In this paper, sulfonated melamine-formaldehyde resin(SMF), a novel kind of water-soluble polymer drilling fluid loss agent , was prepared from melamine, formaldehyde and sulfonated agents. The structure and thermal stability were studied using FTIR and TGA analyses, respectively. Not only the efflux time and salt tolerance of the polymer solution was measured, but also its performance as drilling mud fluid loss reducer was studied by measuring the API and HTHP fluid loss of fresh-water, brine and complex-brine mud respectively, so that the sulfonated agents types and optimum proportion of formaldehyde, melamine and sodium bisulfite were confirmed. The properties of fresh-water, brine and complex-brine mud treated by SMF condensate respectively are investigated with respect to zeta potential. Meanwhile, the SMF mechanism was discussed as drilling fluid loss agent. Based on the above investigation results, the following conclusions could be drawn:(1) The sodium bisulfite was sulfonated agent, SMF condensate was the object production possessing best abiity of heat resistance and salt tolerance. SMF condensate achieved best property of fluid loss control in all kinds of muds when the molar ratios of formaldehyde, melamine and sodium bisulfite were 4.5: 1.0: 1.2.(2) The optimum mix amount of SMF was 5%. SMF had an effective function as fuild loss additive when the concentration of salt not exceeded 16%, and the temperature was lower than 150℃.(3) No matter in fresh-water mud or in brine mud, The adsorptive SMF on the clay particles surface was more and more with the increase of mix amount, which resulted in the rising of zeta potential absolute value, the improving the electrostatic repulsion between clay particles, the higher electrostatic stability of mud and the smaller of mud fuild loss. In addition, SMF condensate is an excellent drilling fuild loss additive not only provide better property of fluid loss control, but also possess stronger resistance to the action of high temperature and salt. No matter in fresh-water mud or in brine mud, the fluid loss of mud is controlled effectively by SMF condensate, even under high pressure and high temperature, the condensate possesses the ability of fluid loss control.