Effect of Rock Type and Acidizing Additives on Acid Reaction Rates Using the Rotating Disk Instrument

Abstract

This work uses a rotating disk instrument to measure dissolution rates of both calcite and dolomite rock samples. Results of more than 60 experiments are reported in this paper. The effect of common acidizing additives on the acid dissolution rate is measured for different acids containing quaternary amines, polymer, surfactant, mutual solvent, iron chelating additive, and dissolved iron. Measurements are made at 23 and 50 ºC for calcite marble and dolomite marble samples. Marble samples from Turkey, Greece and Italy were analyzed to find suitable reference materials. Marble composed of 100% calcite (calcite marble) as well as 91% dolomite (dolomite marble) was used and compared very well with previously published results. Results of acid dissolution rates with common acidizing additives showed significant differences.·1.5 vol% cationic acrylamide polymer decreased the calcite and dolomite dissolution rates significantly. At 1000 rpm the calcite dissolution rate with 1.5 vol% polymer and 0.1N HCl had a value that was 11.4% of the value measured with 0.1N HCl alone.·Polymer changed the acid-rock reaction from mass transfer limited to surface reaction limited with both calcite and dolomite. This is a surface effect possibly due to polymer adsorption.·10 vol% mutual solvent increased the acid dissolution rate by 9% for calcite and by up to 29% for dolomite.·5,000 mg/L iron (III) resulted in surface deposition of iron (III) hydroxide. At low rotational speeds, this surface layer had an inhibiting effect on dissolution rate for both calcite and dolomite.·2 vol% corrosion inhibitor decreased the calcite dissolution rate by approximately 9%.·Citric acid at 12 g/L decreased the dissolution rate of calcite by an average of 9%, possibly due to the formation of calcium citrate at the surface.·0.2 vol% nonionic surfactant had no significant effect on acid dissolution rate of calcite. Introduction The rotating disk instrument has been widely used in the petroleum industry for kinetic studies of the reaction of acidic fluids and chelating agents with reactive rock. This system allows the determination of rock dissolution rate, reaction rate constants, reaction order, and diffusion coefficients. Lund et al. studied the dissolution of both calcite and dolomite with the rotating disk instrument. Their work showed that at 25 ºC the dissolution of calcite is mass transfer limited even at high disk rotational speeds, while at –15.6 ºC both mass transfer and surface reaction rates limit the dissolution rate.In contrast, Lund et al. showed that the dissolution of dolomite was surface reaction rate limited at 25 ºC even at low disk rotational speeds. As the temperature was increased to 100 ºC, the dissolution process approached diffusion limitation even at relatively high rotational speeds.

Measurement of Acid Reaction Rates of a Deep Dolomitic Gas Reservoir

“…Disk preparation was identical for all experiments and the procedure of Fredd (8) and Taylor et al (15) was followed.…”

“…Full details of this equipment and its operation are given by Taylor et al (15) . Full details of this equipment and its operation are given by Taylor et al (15) .…”

“…The effects of common acid additives on calcite and dolomite dissolution rates were reported in detail by Taylor et al (15) . Different acids containing quaternary amines, polymer, surfactant, mutual solvent, iron chelating additive, and dissolved iron (III) were evaluated.…”

Acid Fracturing of a Gas Carbonate Reservoir: The Impact of Acid Type and Lithology on Fracture Half Length and Width

“…However, the former mineral was not detected in any significant amounts when reservoir cores were examined using XRD analysis. 10 The latter has a very low solubility in mineral acids. Magnesium and calcium released in the flow back samples from minerals other than calcite and dolomite are neglected.…”

Reaction of Emulsified Acids With Dolomite

“…Of the two dominant carbonates present in oilfield reservoirs, calcite and dolomite, calcite dissolution has received considerable work (Nierode and Williams 1971;Lund et al 1975;Busenberg and Plummer 1986;Chou et al 1989;Fogler 1997, 1998;Alkattan et al 1998;Taylor et al 2003Taylor et al , 2004aTaylor et al , 2006Nasr-El-Din et al 2008;Rabie et al 2011Rabie et al , 2012, while there have been fewer studies devoted to dolomite (Lund et al 1973;Busenberg and Plummer 1982;Herman and White 1985;Chou et al 1989;Wollast 1990;Anderson 1991;Orton and Unwin 1993). In the case of acid dissolving minerals [e.g., hydrochloric acid (HCl) with limestone and dolomite], the solid/liquid reaction process involves three steps: diffusion of liquid phase to the rock, reaction at rock surface, and diffusion of reaction products into the bulk solution (Lund et al 1973).…”