Measurement of Acid Reaction Rates With the Rotating Disk Apparatus)

Abstract

The authors have published several papers on the rotating disk apparatus (RDA) in recent years. The RDA is used to measure acid reaction rates, reaction order and activation energy of acidizing fluids with carbonate reservoir rock. This paper summarizes the different ways that acid reaction rates are measured, the factors that affect the results and why this is important when modelling acid stimulation treatments in the field.In particular, experimental procedures used to obtain acid reaction rates vary widely and can produce very different results. These procedures are often not well-documented in the literature. The validity of different experimental procedures are carefully compared in this paper.In addition to experimental concerns, the reactivity of reservoir rock can also vary widely. It was recently reported that the reactivity of reservoir rock toward acid is strongly affected by mineralogy and by mineral impurities.In particular, clay impurities in calcite rock were found to reduce the dissolution rate by nearly an order of magnitude. Some calcite rocks containing small amounts of clay particles showed acid reactivity similar to that of 100 wt% dolomite.Acidizing additives such as polymers and corrosion inhibitors have been shown to significantly affect the way that acid reacts with the reservoir rock.

Diffusivity of Citric Acid During its Reaction With Calcite

“…Samples were collected every 2 minutes for the first 10 minutes, then every 5 minutes for 25 minutes, and the two final samples after 45 minutes and 50 minutes, respectively. Corrections were made to account for changes in the volume of the reactants that occurred because of sample withdrawal (24,25) . The rotating disk experiments were conducted to determine the effects of initial citric acid concentration (1 wt%, 2 wt%, 5.0 wt% and 7.5 wt%), temperature (25°C, 40°C and 50°C) and rotational speed (100 rpm -1,000 rpm) on the calcite dissolution rate.…”

Application of Citric Acid in Acid Stimulation Treatments

“…Samples were collected every 2 minutes for the first 10 minutes; and then every 5 minutes for 25 minutes; and the two final samples after 45 and 50 minutes, respectively. Corrections were made to account for changes in the volume of the reactants that occurred due to sample withdrawal (21,22) . The rotating disk experiments were conducted to determine the effects of initial citric acid concentration (1, 2, 5.0, 7.5 wt%), temperature (25, 40, 50°C), and rotational speed (100-1,000 rpm) on the calcite dissolution rate.…”

A qualitative simulation of a face dissolution pattern in acidizing process using rotating disk apparatus for a carbonate gas reservoir

“…Taylor et al measured the reaction rate between deep dolomitic gas reservoirs with hydrochloric acid at different temperatures. They also concluded that acid reactivity varies highly by rock composition [6,7].…”