Synthesis Of New Clay Stabilizer And Its Application In Oil Fields

Foreign water and chemical additives are injected into the reservoir by water injection development and acid fracturing.A large number of clay minerals in the reservoir will undergo hydration expansion and dispersion migration after contacting with water,blocking pore throat,reducing reservoir permeability and causing reservoir damage.Clay stabilizer can effectively prevent hydration expansion and dispersion migration of clay minerals.With the development of oil exploration and development technology,the current clay stabilizer has been unable to meet the development requirements of some low permeability,high temperature and high salinity reservoirs.In this paper,two new cationic polymer clay stabilizers have been synthesized.Through a series of performance evaluation and oilfield application tests,it has been verified that they can meet the development requirements of low permeability,high temperature and high salinity reservoirs.(1)The homopolymer PDMC is synthesized by aqueous solution polymerization with DMC as reactant and[(NH4)2S2O8]as initiator.The intrinsic viscosity of the product is studied in terms of polymerization temperature,reaction time,solid content and initiator dosage.The experimental results show that the product is PDMC,which is proved by Infrared spectrum and Nuclear magnetic resonance hydrogen spectrum.When the solid content is 21%,the initiator content is 1.86%,the reaction temperature is 80?,the reaction time is 6h,and the intrinsic viscosity of PDMC reaches the maximum value of 108.9mL/g.(2)Using AM and DMC as monomers and[(NH4)2S2O8]/(NaHSO3)as composite initiators,the copolymers P(AM-DMC)are synthesized by free radical copolymerization.The effects of monomer molar ratio,solid content,initiator dosage and reaction temperature on the conversion rate of monomers and the intrinsic viscosity of products are studied.The experimental results show that the structure of the product is basically consistent with the expected structure.When n(AM):n(DMC)=2:1,solid content is 35%,mass fraction of initiator[(NH4)2S2O8]/(NaHSO3)is 1.0%,m[(NH4)2S2O8]:m(NaHSO3)=1:1,reaction temperature is 70?,the monomer conversion rate and product P(AM-DMC)characteristic viscosity are the best,among which monomer conversion rate is 83.1%,viscosity is 152.7mL/g.(3)When PDMC and P(AM-DMC)are diluted to a certain concentration with water,they are clay stabilizers JSH and JSHA.The performances of JSH and JSHA are evaluated by the experiments of anti swelling rate,water washing and temperature resistance,cuttings recovery rate,core permeability and compatibility.Considering the effect of anti swelling and the cost of raw materials,the optimal concentration of JSH and JSHA is 1.0%,the anti swelling rate is 91.32%and 93.69%respectively.The combination of JSH and JSHA with inorganic salt shows good compatibility and anti swelling effect.The anti swelling effect of the combination of JSH and JSHA with KCl is better than that of NH4Cl,the anti swelling rate of the combination of JSH and JSHA with KC1 is 95.52%and 96.13%respectively.JSH and JSHA have long-term and good anti swelling effect temperature resistance.(4)By analyzing the geological characteristics of C8 reservoir in the construction block,it is concluded that the reservoir in C8 member belongs to the reservoir with low porosity,ultra-low permeability and high salinity.The application test of JSH and JSHA in the acidizing and fracturing process of well Y73 shows that the compatibility of JSH and JSHA with formation water and fracturing fluid base fluid of well Y73 is good,the clay stability effect is more than 80%when the dosage of JSH and JSHA is 1.0%,which shows that JSH and JSHA can meet the application and development requirements of low permeability and high salinity reservoir.