Study On Preparation And System Of Potassium Tert - Solid Drilling Fluid

Clay-free drilling fluid is composed of soluble salts and thickening polymer and other agents, it can avoid the damage of reservoir and cementing in screenless completions caused by clay minerals. Tackifier plays an important role in the system to maintain good rheological properties. In this paper, to develop a good thickening property, non-toxic and environmen-tally friendly thickener, and develop clay-free drilling fluid system with potassium.Designing the molecular structure of the target product, selecting monomers and analysis synthetic feasibility, determined to choose acrylamide(AM) as the main synthetic monomers, and anionic monomer2-acrylamido-2-methylpropane sulfonic acid(AMPS)and a cationic monomer methacryloyloxyethyltrimethyl ammonium chloride(DMC) in ammonium persufate ((NH4)2S2O8) with sodium bisulfite (NaHSO3) oxidation-reduction initiator systems aqueous solution polymerization, the copolymer named PADA. By single factor method for apparent viscosity and intrinsic viscosity measurement, determine the optimal reaction conditions for the synthesis:ammonium persulfate and sodium bisulfate mass ratio of2:1, AM:AMPS:DMC mass ratio of8:2:1, total monomer concentration of30%, causing the system to increase the amount of0.5%of the total mass of the monomer, the pH of7,the reaction temperature is45℃reaction lasts4h.ForPADA infrared spectroscopy, nuclear magnetic resonance spectra characterization of the rheological properties of PADA solutions was evaluated.Selection and optimization of PADA tackifier, tackifier agents, temporary blocking agents, fluid loss control agents, shale inhibitor and lubricant to determine the potassium clay-free drilling fluid formulation system:10%to50%potassium(density range:1.05g/cm3-1.32g/cm3)+0.45%PADA+0.3%xanthan gum(tackifier)+3.5%superfine calcium car-bonate+2%JX-JL (fluid loss additive)+1.5%HLB(lubricants)+2%JX-YZ (inhibitors). The development of potassium formate drilling fluids were evaluated, laboratory tests showed that: the apparent viscosity of potassium formate drilling fluids of moderate, high system dynamic shear and plastic viscosity, high dynamic plastic ratio, a small amount of fluid loss(FLAPI=4.8mL, FLHTHP=11.8mL),temperature resistance up to120℃,anti-calcium and salt contami-nation ability, shale inhibition ability, good lubricant performance, extreme pressure lubrica-tion coefficient ofO.075, shale rolling recycling more than90%, to achieve the protection of oil and gas reservoirs.Study of potassium formate drilling fluids without solid gel breaking system to deter-mine the formula:KCl mixedsaline+4%JX-GB+2%HCS.