Research On Synthesis And Mechanism Of High Temperature Resistent And Sodium/ Calcium Tolerant Filtrate Reducer

With the gradual increase in demand for oil and natural gas in our country and the depletion of shallow oil and gas resources,the exploration target is gradually expanding to a deep complex formation with high temperature and high salinity.Complex geological conditions lead to more difficult control of water loss and rheological properties of drilling fluid.As a key treatment agent to control fluid loss and rheology,fluid filtrate reducer is facing higher requirements and challenges in temperature and salt resistanceBased on the investigation and analysis of domestic and foreign high temperature salt treatment agent,combined with the molecular structure design,a multicomponent copolymer filtrate reducer called DAADS was synthesized by free radical polymerization in aqueous solution in laboratory with acrylamide(AM),2-acrylamido-2-methylpropane sulfonic acid(AMPS),diallyl dimethyl ammonium chloride(DMDAAC),N,N-Dimethylacrylamide(DMAM)and Sodium allylsulfonate(SAS).The best synthetic condition is optimized by analyzing the effect of synthetic conditions such as hydrogen ion concentration,initiator type and concentration,total concentration of monomer,ratio of different monomer,temperature of reaction and reaction timeProperties of DAADS which is synthesized under the best synthetic condition are characterized,such as:molecular structure,chemical composition,viscosity-average molecular weight,molecular weight distribution and thermal stability Characterization shows that molecular structure and chemical composition of the polymer is match with the design,viscosity-average molecular weight and molecular weight distribution of polymer is appropriate,and the polymer has excellent thermal stabilityDAADS's performance was evaluated by rheological and filtration experiments,the results showed that the synthesized polymer has good filtration performance at high temperature and high salinity:When the copolymer addition was 2.0%,the API filtrate volume of fresh water base drilling fluid,saturated brine base drilling fluid and 1.0%CaCl2 base drilling fluid were 6.4,15.6 and 6.8 mL.Compared with the additive Driscal,experimental results showed that the salt and calcium resistance property of the filter was better than that of DriscalFunction mechanism of DAADS was respectively analyzed by comprehensive application of environmental scanning electron microscopy,laser particle size distribution instrument,zeta potentiometric analyzer.The results show that DAADS copolymer,which is a kind of fluid loss reducer,can be fully adsorbed on clay,so that the clay particles are stacked more tightly and the quality of the formed mud cake is effectively improved.Strong adsorption capacity of clay particles,effectively inhibit the coalescence of clay particles,clay particle size becomes smaller.The polymer effectively adsorbs the clay particles and thickens the diffusion double layer of the clay particles,resulting in the increase of the potential(absolute value)of the drilling fluid to improve the stability of the systemThrough the optimization of the fluid loss control,inhibitor and lubricant treatment,the formula of drilling fluid system is determined:Water+4.0%bentonite+0.3%Na2CO3+2.0%DAADS+3.0%0 SMP-?+3.0%SPNH+3.0%SMC+1.0%SDJA+2.0%RH-3.The drilling fluid system temperature up to 220?,salt to saturation,anti-calcium up to 1.0%,and has good inhibitory and lubricating properties.