Synthesis Of Cationic Hyperbranched Polymers And Their Application In Drilling Fluids

Hyperbranched polymers are dendrimers with highly branched topologies.Because of its unique three-dimensional spherical structure,the surface enrichment of a large number of end groups which has higli adsorption capacity and high reaction activity,high solubility,low viscosity and the simple synthetic operation,it has been wildly studied and used in the fields of coatings,biological medicine of life,science of life,cosmetics,nano materials and petroleum engineering and other fields.Howerver,in the field of petroleum engineering,hyperbranched polymers as a shale inhibitor and microporous plugging agent research has not been reported.In this paper,two kinds of cationic hyperbranched polypers,terminal-amino hyperbranched polymers(HP-NH2)and terminal-quaternary ammonium salt hyperbranched polymers are preparaed,and was applied to shale gas drulling fluid,potassium-bassed polysulfide lubricating drilling fluid,in order to strengthen the system of drilling fluid7 inhibition to the shale and plugging property to the micropore.In this paper,a cationic hyperbranched polymer(HP-NH2)with amino group was synthesized by using succinic anhydride and diethylenetriamine as raw materials and tetrahydrofuran as solvent.Then,amino of HP-NH2 end groups were modified by epoxypropytrimethyl ammonium chloride to obtain terminal-quaternary ammonium salt hyperbranched polymers(HP-HTC).The structures and properties of the monomers and hyperbranched polymers were characterized by FT-IR IR,TOF LC / MS,1H-NMR,TGA,GPC and SEM.The results show that AB2 monomer,HP-NH2 with HP-HTC is really synthesized.The inhibitory ability of HP-NH2 and HP-HTC was tested by linear expansion experiment,shale rolling recovery experiment,suppression of pulp experiment and sedimentation experiment.The experimental results proved that HP-NH2 and HP-HTC have a good inhibitory property on the hydration dispersion and the hydration swelling of the clay,and its inhibition increases with the increase of the molar mass of the terminal mass.The linear expansion rates of 3% HP-NH2(N =4.77 mol / kg)and 3% HP-HTC(C = 3.89 mol / kg)were 26.9% and 22.4%,respectively,and the recoveries of shale rolling were 71.14% and 73.03%.The plugging property of HP-NH2 and HP-HTC are tested by pressure transfer experiment,seepage test and API filtration test,and the experimental results show that HP-NH2 and HP-HTC have good plugging ability for nano-pores an low-permeability cores,and their sealing increases with the increase of the molar mass of the terminal mass.The results showed that 3% HP-NH2(N = 4.77 mol / kg)and 3% HP-HTC(C =3.89 mol / kg)could effectively reduce the filtration loss,and the filtration loss was about 50% of the original drilling fluid,while proving that the cationic hyperbranched polymer does not act as a function of increasing the viscosity of the filtrate.In this paper,the inhibition mechanism of HP-NH2 and HP-HTC on the hydration and hydration expansion of clay was analyzed by FT-IR spectroscopy,XRD test,Zeta potential test and laser particle size analysis.The results show that HP-NH2 and HP-HTC inhibit the hydration dispersion of clay by reducing or reversing the clay surface Zeta potential,compression diffusion double layer,inhibit the hydration swelling of clay by entering the clay layer,the replacement of hydrated cations,and the formation of water on the clay surface.The blocking mechanism of HP-NH2 and HP-HTC was analyzed by SEM test.The results could be used to control the formation of mud cake and block the micropores of mud cake to reduce the filtration loss.Finally,the changes of the rheological,inhibitory and blocking properties of potassium-calcium-based polysulfone lubricating shale gas drilling fluid after HP-NH2 and HP-HTC were added.The results show that the optimal dosage of HP-NH2 and HP-HTC in the drilling fluid system is 3%and the kinetic ratio is 0.36 and 0.37,respectively.The results show that the inhibition and plugging of drilling fluid has been greatly enhanced after the additon of HP-NH2 and HP-HTC,which to strengthen the inhibition of HP-NH2 is weaker than HP-HTC,the strengthening of plugging is stronger than HP-HTC.