The Synthesis Of Polymer Gelatinizer And The Rheological Properties Of Ultra-high Temperature Fracturing Fluid System

In order to carry out the ultra-high temperature fracturing operation for deep well, a new type of synthetic anionic terpolymer gelatinizer was researched and produced in this paper, and the related influencing factors were studied. The temperature resistance, shear resistance and gel breaking performance of cross-linked gel fracturing fluid were also investigated. The ultra-high temperature resistant polymer fracturing fluid system which can resistant200℃was obtained. Furthermore, the pilot and production of polymer gelatinizer was carried out, and the proper pilot production process and polymer gelatinizer powder product were obtained. The oilfield tests for the polymer was performed, and better fracturing stimulation effect was achieved. Main conclusions were obtained as follows:1) Three acrylamide species monomers were taken as raw materials, solution polymerization was used and the anionic terpolymer gelatinizer which molecular weight was about4.5million was obtained. The factors such as monomer mass ratio, monomer mass concentration, reaction temperature, reaction time, initiator content and component, pH of polymerization system, content of the chain-transfer agent, and other factors on the copolymer product properties were illustrated. The laboratory synthesis process of high temperature polymer gelatinizer process was obtained.2) The ultra-high temperature resistant polymer fracturing fluid system which could endure200℃was obtained. The effects of base-solution concentration of polymer gelatinizer, the crosslinking ratio with crosslinker, the pH value of system and the related additives on the fracturing gel were illustrated. Through laboratory evaluation and research, the formulation of ultra-high temperature resistant polymer fracturing fluid system was achieved. At200℃, the crosslinked gel fracturing fluid was sheared at170s-1for120min, the viscosity was retained more than150mPa·s. The gel fracturing fluid possess good viscosity recovery ability under high shear, easily gel broken, less residue, low surface tension and the little filtration, which could be applied in ultra-high temperature deep wells.3) The results of Rheological research were shown that, the base-solution of pilot and laboratory synthesized gelatinizer and crosslinked gel fracturing fluid exhibited shear-thinning property, and excellent visco-elasticity. The sorts of products (laboratory synthesized sample and pilot product), the dry and smash process of pilot product, the amount of dispersant for prilling, the delayed-crosslinking agent on the visco-elastic and shear-thinning property of fracturing fluid were illustrated.4) The pilot and production process were obtained, and7.5t pilot polymer gelatinizer powder was successfully produced. It was proved that the fracturing gel formed with pilot polymer gelatinizer could endure200℃, and its viscosity was retained more than100mPa-s.The oilfield-test showed that, crosslinking ultra-high temperarture gel fracturing fluid system could be injected into the reservoir by multi-stage acidizing and fracturing, and good fracturing stimulation effect was achieved.