Reaction Rate Of Steering Acid With Carbonate Considering Common-Ion Effect

With the technology progress of acid fracturing stimulation treatment, the acid fluid systems constantly enrich and develop. In order to delay the acid-rock reaction rate, reduce the acid filter loss and realize the acid deep etching penetration, a lot of researches on Steering acid and acid-rock reaction rate of it were conducted all around the world, especially on effect of different factors on acid viscosity and acid-rock reaction rate, but influence of common-ion effect on reaction rate is deficient. Based on a large number of domestic and foreign literatures, experimental researches on reaction rate of Steering acid with limestone in Sichuan, the influence of the common-ion effect on Steering acid viscosity and acid-rock reaction rate have been analyzed in this paper. Combined the flow pattern of acid in the fracture, calculate the effective penetration distance of the acid, and come up with common ion effect of in-situ gelled acid to modify the field application. Obtained results were as follows:(1) Based on the analyzed of molecular contact live on the basis of the theory of surfactant micelle formation mechanism and combined with the Chem3d software and the Gaussian quantum chemical calculation software, the ionic surfactant molecules of charged by change, inorganic ions Cl-、Ca2+、Mg2+charge shielding, such as hydrogen bonding, ionic hydration, electric glue phenomenon etc. multiple effect on the formation of the micelle and the influence of the micelle size, which changes to the sour acid viscosity have been studied.(2) Through the common-ion effect of different concentration to the influence of acid viscosity experiments, the following result shows that:Considering the effect of ions with Steering acid as a whole is without considering the effect of ions with Steering acid bright acid viscosity (about2～9times); With common-ion effect makes the Steering acid peak viscosity is fresh off to low acid concentration (from16%to14%). Steering acid viscosity difference Δμ and Ca2+concentration into a quadratic equation of the origin relations:the Δμ first increased and then decreased with the increasing concentration of the Ca2+concentration.(3) Acid system by applying different viscosity acid rock reaction kinetics parameter measurement device, compared to acid with common-ion effect and did not consider the common ion effect of fresh acid rock reaction rate experiment with higher common-ion effect makes the reaction series, reaction constant is reduced, the overall makes to a sour rock reaction rate lower. With the ion effect on Steering acid reaction rate ΔJ and turns to acid fluid viscosity difference Δμ. into linear relationship, the Δμ. increase, and the Δ J increase, there is a linear relationship between Ca2+concentration and ΔJ, the Ca2+concentration increase, the ΔJ increase, and shows that the concentration increase the effect of acid rock reaction rate;(4) At the initial moment of a sour rock reaction, the viscosity into acid has more effect on the common ion effect; As the reaction progress, whenCCa2+=1.35mol/L, the common-ion effect through the viscosity and directly with the influence of ion effect is the same; the influence on viscosity of Steering acid less is than the common-ion effect.(5) With the C/C0changes that affect the common-ion effect of acid etching an effective role in steering away gradually emerged:When C/C0>0.65, the common ion effect no major impact on the effective distance eclipse Steering acid, just because the common ion effect slows down the rate of acid-rock reaction, will grow construction time; when C/C0<0.65, the common ion effect makes an effective role in Steering acid erosion increased distance. If defined C/C0=0.1as the residual acid, with the increase of displacement, the effective action distance to acid increased, and the common-ion effect on Steering acid effectively the influence of rate of β, along with the change of displacement is Le同=β×Le鲜,β average is2.533.(6) be verified by X-well, Steering acid effective distance of acid-rock reaction common-ion effect influence coefficient-β, has a distance and actually have some errors, these errors are due to the impact caused by other factors. But the overall design of acid feacturing with Steering acid, there are certain guiding significance.