Research On Kinetics And Morphology Of Carbonate Scaling In ASP Flooding

The ASP flooding technology,which is of great benefit to improving oil recovery,has been tested in many oilfields in China and achieved ideal effects for increasing oil production and reducing water content.However,there are some issues obstructing the wide application of this technology,such as scaling problem.The scaling occurs in the whole process of oil production and seriously hinders the production.The calcium carbonate scale,which is the precursor of all the oilfield scales,not only can affect an injection,but also damage the reservoir to a certain extent.Therefore,it is necessary to research the calcium carbonate scaling for the oilfield production.In this paper,five systems were studied.They are(1)distilled water,(2)distilled water with polyacrylamide,(3)distilled water with surfactant,(4)simulated high mineralized water,(5)oilfield produced water.The rate constants of calcium carbonate scaling had been derived by measuring the effect of time on solution conductivity in the process of nucleation formation and growing up,respectively.The activation energy had been calculated by transforming temperature in system(1)and(4).The effects of ASP flooding reagents on rate constants had been explored by adding different concentrations of polyacrylamide or surfactant in distilled water.The morphology had been analyzed by electronic microscope.The date of calcium carbonate scaling can be represented by the first order reaction rate equation in the process of nucleation formation and growing up,respectively.In system(1),the rate constant is 0.055012 and 0.0057,and the activation energy is 21.107 KJ/mol and 5.699 KJ/mol,respectively.In system(2)and(3),the rate constant decreased and amplitude of nucleation formation is greater.The inhibition effects increased as concentrations of ASP flooding regents increased.In system(4)and(5),the rate constant decreased and amplitude of nucleation formation is bigger.The effect of temperature on rate constant for system(4)is much larger than system(1)and amplitude of nucleation growing up is greater.In system(1),the produced calcite is smooth and regular.The crystal size increased as supersaturation increased and vaterite transformed into calcite when temperature increased from 10? to 40?.In system(2),the calcite decreased and amorphous and spherical calcium carbonate increased as polyacrylamide concentration increased.The morphology in simulated high mineralized water is mainly rough similar to calcite and spherical calcium carbonate.In system(3),the'roughness degree of spherical and cubic calcium carbonate increased as surfactant concentration increased.There is various morphology of calcium carbonate in simulated high mineralized water.In system(4),the amorphous calcium carbonate transformed into calcite when supersaturation increased.In system(5),the produced calcitet is little.The clavate calcium carbonate increased as supersaturation increased.