Caracterización fisicoquímica de polímeros base poliacrilamida y evaluación de la estabilidad del triacetato de cromo empleado para generar sus geles usadas en procesos de recobro de petróleo

Abstract

Among the many industrial applications is the partially hydrolyzed polyacrylamide to viscosity water for injection into oil fields, in order to improve oil recovery efficiency, reducing the mobility ratio water/crude (ideally it is 1.0). The physicochemical characterization of these aqueous solutions used for evaluation of parameters such as: determining the moisture content, which indicates the state of purity of polyacrylamide; the percentage of hydrolysis to know how reactive is the molecule of polyacrylamide with injection water or brine and QA / QC is tracking field of polymer injection processes to quantify their concentration. This paper describes the methodology used for the validation of three methods of characterization of these polymer solutions, which were: Percentage of moisture, percentage of hydrolysis and determination of concentration of polyacrylamide. For the validation of the techniques involved statistical procedures as residual standard deviation (Sy / x), process deviation (s), coefficient of variation (CV) using the regression method they were used. Additional validation process stability formed from aqueous solutions of polyacrylamide and chromium acetate, gels which are of great importance to block high permeability zones in a reservoir, in order to improve injection profiles were evaluated water for oil recovery. The evaluation of the stability of these gels was performed in porous media through displacement with brines 12000 ppm of KCl prepared at different pH's and determining the concentration of Cr (VI) in the effluents obtained, which allowed establishing the degree oxidation of Cr (III) to Cr (VI) that can occur at set pH conditions. The polymers used for this project were samples of the type partially hydrolyzed polyacrylamide (HPAAM), labeled as QP-90, QP-204 and QP-370, which were supplied by commercial houses. The results obtained in this study allowed to establish that the gels based HPAAM chromium triacetate may be unstable under acidic pH conditions (4.0), as well as basic pH conditions (10.0), resulting in the production of chromium VI, in concentrations that could affect the integrity of the wildlife ecosystem of influence.