Development Of Slow - Viscosity Admixture Type Acid Liquid Slow Admixture

Acidizing is one of the important measures to increase production reservoir yield. With the development of the acidizing technology, acid corrosion crack length becomes the key to reservoir acidification transformation effectively. How to effectively obtain larger acid acidification technology needs to solve the problem of distance. At present, Routine use of gelled acid fluid viscosity is higher, pumping difficulties, easy to cause secondary damage to the reservoir, therefore, develop a highly efficient retarding admixtures realize the deep acidification, the reservoir is of great significance to increase production.A low viscosity adsorption quadripolymer of acrylamide (AM), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), allyl alcohol polyoxyethylene ether (APEG). and Cationic hydrophobic monomer (DMP) is synthesized by solution free radical polymerization. The influential factors of Polymerization reaction have been studied through single factor method such as mole ratio of monomers, concentration of monomers, temperature, reaction time and initiator dosage. The best synthetic conditions are determined: mole ratio of monomers is n (APEG):n (DMP):n (AMPS):n (AM)=0.5:0.3:0.5:30, concentration of monomers is 15%, reaction temperature is 50℃, reaction time is 6h, initiator dosage is 0.3%(monomers mass fraction). The molecular structure of quadripolymer is characterized by Fourier transform infrared (FTIR) and’H Nuclear Magnetic Resonance (’HNMR) spectroscopy, and molecular weight distribution is determinate by gel permeation chromatography (GPC). The results show that the copolymer molecular chain with the initial design of molecular groups, product structure and design. The molecular weight is Mn-232077, Mw=460593, MP=534288, Mz=661719, Mz+1=790871, Mw/Mn= 1.984657.Through CO2 gas collection device to evaluate the retarding effect of admixture and the admixture MCJS best added amount to 0.5%, acid temperature 75℃, the initial viscosity of 6.0 mPa s. Static retarded time of up to 170 min, dynamic retarded time of up to 160 min, salt resistance, calcium resistance effect is better. Under different acid rock reaction countenance and rotor speed, the dissolution rate than with the face and the rotor speed increases, face than 1 cm2:4 mL, static in slow time of up to 130 min in slow performance, the rotor speed of 800 r/min. admixture dynamic slow time of up to 120 ml. Compared to the conventional gelled acid FL-46. admixture MCJS has added quantity is little, low viscosity, acid retarding effect good advantage, and after acidification, rock surface formed a uniform grooves and pore, gap better connectivity, rock skeleton structure relatively stable.Finally, using the infrared spectrum, element analysis and electron microscope scanning of admixture MCJS retarding mechanism was studied. The results show that the acid rock reaction when 30 min of the surface of the rock containing N, S elements, and admixtures of functional groups, and form a layer of protective film, the film can prevent H+contact with rock, slow reaction speed of acid salt, as acid-rock reaction is completed, protective film from the surface of rock, rock surface without residual admixture, the secondary damage to the reservoir.