Research On Synthesis, Performance Of High Temperature Resistent And Sodium Tolerant Filtrate Reducer And Inhibitor

To get the oil and gas resources in deep formation leads to the increasing of well depth, and makes stringent requirements to water based drilling fluid. The treating agents, as a key component of drilling fluid, faced the baptism from hith temperature, salt and calcium. Based on this fact, developing fluid treating agent, which is also suitable for water based drilling fluid, with excellent resistance to heat and and salt is the major topics in oilfield chemistry.According to theories of molecular structure design and structure features of existing treating agent with resistance to heat and salt, chosing N,N-dimethylacrylamide(DMAA),2-acrylamido-2-methyl-l-propyl(AMPS), dimethyl diallyl ammonium chloride(DMDAAC) and N-vinylpyrrolidone(NVP), as reactive monomers, using ammonium persul and sodium hydrogen sulfite fate as initiators and pure water as solvent, zwitterionic copolymer fliud loss additive called PDADS was synthesized by radical polymerization. Chosing N,N-dimethylacrylamide(DMAA), γ-methacryloxypropyl trimethoxy silane(KH-570) and N-vinylpyrrolidone (NVP) as reactive monomers, using2,2’-Azobisisobutyronitrile (AIBN) as initiators and N,N-dimethytformamide(DMF)as solvent, Organosilicone-polyamine inhibitor called PKDAS was synthesized by radical polymerization. The best synthetic conditions of two polymer treating agents were optimized by analyzing the effect of synthetic conditions such as hydrogen ion concentration, initiator concentation, total concentration of monomer, ratio of different monomer, temperature and time of reaction.After the best synthetic conditions of PDADS and PKDAS were ensured, these copolymers were characterized and analysised by comprehensive applicating with FITR, TGA and GPC. Results showed that molecular structures and chemical compositions of PDADS and PKDAS matched with the design, their viscosity-average molecular weight and molecular weight distribution of polymer were appropriate, and the polymer has excellent thermal stability.PDADS’s performance was evaluated by rheological and filtration experiments, the results showed that the filter loss of drilling fluid was decreased from28.0mL to6.0mL after adding2.0%of PDADS, and it’s rheological property was improved. After adding2.0%PDADS, the filter loss of drilling fluid, which was thermal aged at220℃for16h, with5.0%NaCl and0.8%CaCl2was effectively controlled, showed that the PDADS has excellent filtrate reduction property with resistance of heat, salt and calium, the results of contrast test among PDADS, JT-888and SPNC also proved this conclusion.PKDAS’s inhibition behavior was evaluated by inhibity experiments of bentonite and drilling cutting, the results showed that the mud making of bentonite and drilling cutting was strongly controlled after adding1.0%PDADS. After themal aging at220℃for16h, PKDAS maintained strong inhibition behavior to bentonite and drilling cutting, and it was also proved by contrast test among PKDAS, NH-1and FA-367.Function mechanism of PDADS and PKDAS was respectively analyzed by comprehensive applicating of environmental scanning electron microscopy(ESEM), laser particle size distribution instrument, Zeta potentiometric analyzer and X ray diffracmeter, including microstructures of PDADS and PKDAS in pure water, salt water and drilling fluid, microscopic appearance of filter cakes formed by these drilling systems, particle size distribution and Zeta potential of clay particles in these systems. The results showed that dispersing property of clay particles was significantly improved and ratio of tiny particles was increased after adding PDADS, thus the coalescence probability of tiny particles polymer was significant reduced, and density of filter cake was increased, so the filter loss of drilling fluid could be effectively controlled. After adding PKDAS, the Zeta potential of clay particles was dramatically reduced, so the coalescing probability was increased, and macromolecules of PKDAS formed enveloping layer outside clay particles under the effect of absorption, thus the invasion of hydrones into lattice spacing was prevented, at the same time, the supramolecular system, which was formed by bridging of copolymer macromolecules, could stabilize clay particles, thus dispersion and migrartion of clay particles was effectively restrained.Based on the fliud loss additive of PDADS and inhibitor of PKDAS, determining a recipe of water based drilling fluid with excellent resistance to heat, salt and calcium, which is suitable for deep and extradeep well drilling operation by laboratory experiment.