Synthesis Of A Damp Ionic Polymer Drilling Fluid Fluid Loss Additive

Deep Wells and ultra-deep well drilling has become an important part of petroleum industry in China. Among of them, drilling fluid technology is an important link in oil and gas drilling engineering technology. And it plays a crucial role to ensure the safety of drilling, drilling speed and drilling cost. Therefore, it is necessary to research fluid loss additive which could be used in the complex and high-temperature formation for high-temperature and deep well drilling technology.Through molecular design, feasibility analysis, choice of synthesis methods and initiator system, acrylamide (AM), acrylic acid (AA),2-acrylamide-2-methyl propane sulfonic acid (AMPS), styrene sulfonate (SSS) and dimethyl diallyl ammonium chloride (DMDAAC) were chose as monomers to synthetize a kind of zwitterionic copolymer used as fluid loss additive for drilling fluid, using ammonium persulfate-sodium bisulfite as initiator. And the copolymer was synthesized in aqueous solution. The synthetic conditions with optimal property were that m(AMPS):m(AM):m(SSS):m(AA):m(DMDAAC)=30:40:8:15:7, initiator was 0.6%, monomer concentration was 30%, reaction temperature was 50?, pH value was 7and the reaction time was 6 h. In view of the product synthesized under the condition of the optimization, the structure of copolymer was characterized by FTIR and 1HNMR. Results showed that the synthetic product was the target product.The performance evaluation of the synthetic copolymer showed that, in the fresh-water drilling fluid, the saline water drilling fluid, the saturated-brine drilling fluid and the composite-brine drilling fluid as the copolymer dosage was 2.0% in each fluid, the API filtration of system was 6.4 mL,8.0 mL,9.6 mL and 12.0 mL in the conditions of 150? and 16 h. In the fresh-water drilling fluid, when the copolymer dosage was 2.0%, the API filtration of system was 12.0 mL in the conditions of 200? and 16 h., In the saline water drilling fluid, when the copolymer dosage was 2.0%, the API filtration of system was 18.0 mL in the conditions of 200? and 16 h.. In the saturated-brine drilling fluid and the composite-brine drilling fluid, when the copolymer dosage was 2.5%, the API filtration of system was 8.4 mL and 10.0 mL in the conditions of 150? and 16 h. Under the same conditions, compared with the JT-888, SPNH and SMP, the polymer filtration effect is better.When replaced the fluid loss agent, under the same conditions and the same aging, in the polymer drilling fluid system and the compound salt water polymer drilling fluid system, the synthetic polymer fluid loss additive is more excellent. Increase the filtrate loss additive to 3.0%, the polymer drilling fluid system API filter loss was 2.2 mL, HTHP filter loss was 8.6 mL, in the conditions of 200? and 16 h. Increase the filtrate loss additive to 2.0%, the compound salt water polymer drilling fluid system API filter loss was 2.2 mL, HTHP filter loss was 8.2 mL, in the conditions of 150? and 16 h.The results of zwitterionic polymer to particle size distribution of system showed that the particle sizes of 0.1?1 ?m was increased after adding the synthetic copolymer.It indicated that the fluid loss additive of synthetic copolymer made the clay particles dispersed more finely. And it could generate filter cake effectively as well as improve the quality of filter cake. When the electrolyte is added, the number of coarse particles in the drilling fluid system is increased. When the electrolyte is added, the number of coarse particles in the drilling fluid system was increased. The result shows that the degree of dispersion of clay particles was poor, and the loss of filtration was increased.