Study On Preparation And Properties Of Water - Based Drilling Fluid For Anti - High Temperature Loss - Reducing Agent

With the shallow formation of oil and gas resources increasingly exhausted, oil exploitation has gradually turned to deep formation. Drilling fluid is an important part of petroleum drilling and its high temperature stability directly determines the success or failure of drilling engineering. However, the additives of drilling fluid resistant to high temperature and salt become the biggest technical problem in current years. So it has important theoretical and practical significance to develop the novel additives of water based drilling fluid resistant to high temperature.According to the molecular structure design requirements of the fluid loss additive resistant to high temperature,2-acrylamide-2-methyl propane sulfonic acid (AMPS), Acrylamide (AM), dimethyl diallyl ammonium chloride (DMDAAC) and Sodium styrene sulfonate (SSS) are selected as the structure monomers. Using Ammonium persulfate as initiator, a new quadripolymer is synthesized through free radical aqueous solution polymerization. The best optimum synthesis conditions are optimized by the single factor experiment and orthogonal test:the mole ratio of AMPS/AM/DMDAAC/SSS is5/7/2/1, the monomer concentration is30wt.%, the initiator concentration is0.8wt.%, the reaction temperature is75℃, the pH is10and the reaction time is6hrs. The structure of the quadripolymer is characterized by Fourier transform infrared spectroscopy and Nuclear magnetic resonance hydrogen spectroscopy. The results show that the quadripolymer contains all the designed functional groups. The thermal stability of the quadripolymer is tested by TGA and DSC. The results show that the polymer has excellent thermal stability.The performance evaluation of the AMPS/AM/DMDAAC/SSS quadripolymer was measured by rheological and filtration loss experiments. The results show that the water solution of the copolymer has the typical characteristic of polymer solution and its rheological curve suit the power-law mode and its viscosity curve also conform to shear thinning. Besides the quadripolymer also exhibit excellent reduction the filtration loss in fresh water,4.0wt.%salt-water, saturated brine-water drilling fluids. The high temperature high pressure fluid loss experiment results also show that the quadripolymer fluid loss additive has excellent temperature-resistant performance. The temperature has less influence on the filtration loss of the AMPS/AM/DMDAAC/SSS quadripolymer drilling fluid compared with the AMPS/AM/NVP/SSS quadripolymer, SMP-Ⅱ and PAC-142.The compatibleness experiments are carried out to acquire a prescription of water based drilling fluid resistant to high temperature:4%clay+0.2%FA-367+0.2%XY-27+2.0%SMP+3.0%SPNH+3.0%AM/AMPS/DMDAAC/SSS+barite powder, which can efficient improve the capacity of filtration loss under the180℃and control the FL(API)-2mL and FL(HTHP)=9mL.Finally, the mechanism of action of the AMPS/AM/DMDAAC/SSS quadripolymer is simple discussed through Particle and Zeta potential. The results show that the quadripolymer can significantly improve the drilling fluid of clay particles size and size distribution, and promote the hydration dispersion ability of clay particles effectively. The high density filter cake can be formulated through the close accumulation of clay particles so as to reducing the filtration loss.