Study On Synthesis And Properties Of Cement Retarder For High Temperature And Multi - Effect Oil Well

An oil cement retarder BH was synthesized by copolymerizing Acrylic Acid(AA),Sodium p-Styrene Sulfonate(SSS) and a vinyl monomer APO(containing hydrophilic long chain).The optimum reaction conditions was determined by the single factor method. Specific conditions: monomer ratio of n(AA):n(SSS):n(APO)=1:1:0.1, monomer concentration 30 wt%,4 wt% initiator(Ammonium persulfate),pH=5,reaction temperature 80℃ and reaction timel4 h. The structure of the copolymer was characterized by FT-IR and EDS. The results showed that: All functional groups are present in the BH. Thermal gravimetric analysis demonstrated that the thermal stability of BH is excellent BH can be used in a wide temperature range.The synthetic retarder BH under optimal conditions added to the well cement. Studied the retarder BH retarding performance of the slurry, dosage sensitivity,temperature sensitivity and compatibility etc. Results indicate that:BH can be used in high temperature of 170℃,Dosage 2.5% thickening time can reach 300 min, thickening time is adjustable in 90-170℃, dosage and thickening time have good linear relationship, temperature sensitivity coefficient is less than 20%, dosage sensitivity coefficient meet the industry standards(0.1-0.3),BH has little effect on cement strength and has good salt resistance. Other properties of the slurry on the findings added with retarder BH:retarder BH has a good dispersion in the conventional density cement slurry system, can significantly improve the slurry rheology.BH’s application performance on different density slurry system was studied. 2.01,2.15,2.30 g/cm3 density of three kinds of high-density slurry system adjusted by iron ore, 120℃ thickening time can be adjusted in 160～270 min,90 ℃ curing 48 hours the strength of cement reached 10.8 MPa.1.35,1.43,1.52 g/cm3 density of three kinds of low-density slurry system adjusted by cenosphere,105℃ thickening time can be adjusted in 140-240 min, with the increase retarder BH, the strength of cement increased,90℃ curing 24 hours the strength of cement reached 9.0 MPa.The mechanism of oil well cement retarder BH was explored. Retarder BH can delay the hydration rate of cement and extended the time to produce calcium hydroxide obtained by XRD and EDS analysis Meanwhile, retarder BH adsorbed on the surface of cement particles to hinder the entry of water molecules, slow down the rate of cement hydration. Through complexometric titration and SEM studies have shown that BH can be increased saturation solubility of calcium hydroxide, inhibiting the generation of calcium hydroxide precipitate, extend the induction period and to change the crystal morphology of calcium hydroxide When adding low dosage of BH, calcium hydroxide crystals become loose from dense; Adding high dosage of BH, crystalline polymorph of calcium hydroxide from hexagonal columnar to spherical. Conclusion can be drawn, Mechanism of retarder BH effect the oil well cement mainly through adsorption theory and complex theories.