Reaction of Calcite With Surfactant-Based Acids

Nasr‐El‐Din, Hisham A.; Al-Mohammed, Abdullah Mohammed

doi:10.2118/102838-ms

Cited by 13 publications

(6 citation statements)

References 39 publications

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“…These include calcite marble (CaCO 3 ) (Lund et al 1975;de Rozieres 1994;Frenier and Hill 2002), dolomite marble [CaMg(CO 3 ) 2 ] (Lund et al 1973;Herman and White 1985), Indiana limestone (Mumallah 1991), St. Maximin and Lavoux limestones (Alkattan et al 1998), Haute Vallée de l'Aude dolomite (Gautelier et al 1999), Bellefonte dolomite (Herman and White 1985), San Andres dolomite (Anderson 1991), Kasota dolomite (Anderson 1991), and Khuff dolomite reservoir cores (Nasr-El-Din et al 2002b). The effects of common acid additives on calcite and dolomite dissolution rates were reported in detail (Frenier and Hill 2002;Taylor et al 2004b;Al-Mohammed et al 2006). The effects of impurities such as clays on rock dissolution have not been reported.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Acid Reaction Rates in Carbonate Reservoir Rocks

2006

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It is generally assumed that the reaction of acid with limestone reservoir rock is much more rapid than acid reaction with dolomite reservoir rock. This work is the first to show this assumption to be false in some cases, because of mineral impurities commonly found in these rocks. Trace amounts of clay impurities in limestone reservoir rocks were found to reduce the acid dissolution rate by up to a factor of 25, to make the acid reactivity of these rocks similar to that of fully dolomitized rock. A rotating disk instrument was used to measure dissolution rates of reservoir rock from a deep, dolomitic gas reservoir in Saudi Arabia (275°F, 7,500 psi).More than 60 experiments were made at temperatures of 23 and 85°C and HCl concentration of 1.0 M (3.6 wt%). Eight distinctly different rock types that varied in composition from 0 to 100% dolomite were used in this study. In addition, the mineralogy of each rock disk was examined before and after each rotating disk experiment with an environmental scanning electron microscope (ESEM) using secondary and backscattered electron imaging and energy dispersive X-ray (EDS) spectroscopy. Acid reactivity was correlated with the detailed mineralogy of the reservoir rock. It was also shown that bulk anhydrite in the rock samples was converted to anhydrite fines by the acid at 85°C, a potential source of formation damage.

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Section: Introductionmentioning

confidence: 99%

Anomalous Acid Reaction Rates in Carbonate Reservoir Rocks

2006

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“…In-situ buildup of the apparent viscosity reduces the dissolution rate of calcite with HCl acids (Hansford and Litt 1968;Al-Mohammad et al 2006;Nasr-El-Din et al 2008b). …”

Section: Mechanism Of Viscosity Buildupmentioning

confidence: 99%

“…It was observed when conducting the rotating-disk experiments that the flow pattern in the reactor was a function of the disk rotational speed (Hansford and Litt 1968;Al-Mohammad et al 2006). Because of the normal forces created in a non-Newtonian fluid, the flow pattern changes from a reverse flow at low rotational speeds to a toroidal flow at intermediate rotational speeds to a centrifugal flow at high rotational speeds.…”

Section: Mathematical Modelingmentioning

confidence: 99%

“…This instrument has been used extensively to investigate the reaction of HCl, organic acids, and chelating agents with carbonate rocks (Hansford and Litt 1968;Lund et al 1975;de Rozieres et al 1994;Fredd and Fogler 1998a, 1998b, 1998cFredd 1998;Conway et al 1999;Gautelier et al 1999;Gdanski and Van Domelen 1999;Frenier and Hill 2002;Taylor et al 2004aTaylor et al , 2004bTaylor et al , 2006Alkattan et al 1998Alkattan et al , 2002Al-Mohammad et al 2006;Al-Khaldi et al 2007;Nasr-El-Din et al 2008b). It has also been used to study mass and heat transfer in non-Newtonian fluids (Hansford and Litt 1968;de Rozieres et al 1994;Al-Mohammad et al 2006;Nasr-El-Din et al 2008b).…”

Section: Introductionmentioning

confidence: 99%

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Quantitative Analysis of Reaction-Rate Retardation in Surfactant-Based Acids

Nasr‐El‐Din

Al-Mohammed

Al-Aamri

et al. 2009

SPE Production &Amp; Operations

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Fracture acidizing has been a dominant practice in the industry to enhance well productivity in low-permeability carbonate reservoirs. Many acid systems have been developed to improve this stimulation process. The most desirable characteristics for an acid system to be suitable for fracture acidizing are leakoff control and retarded reaction rate. These characteristics are required for deep acid penetration, so that when the fracture closes, long flow channels are etched on the fracture surfaces. Leakoff control can be achieved by pumping a pad containing a viscosifying agent or solid bridging agents to plug wormholes generated by acid dissolution. Reaction retardation is attempted usually by lowering the effective diffusivity of the hydrogen ion.It is well known that during an acid-fracturing operation, the overall reaction rate of hydrochloric acid (HCl) with limestone is mass-transfer-limited. Designing the treatment requires knowing the effective diffusivity of the hydrogen ion in the acid system, which, to the best of the authors' knowledge, has not been determined before. Because of their combined leakoff-control and retardation capabilities, surfactant-based acids have been used in acid-fracturing treatments. Because more carbonate reservoirs are treated by use of this acid system, it is important to obtain the effective diffusivity of H + .The rotating-disk device has been used to investigate the reaction kinetics between a reactive solution and carbonate rocks because the thickness of the boundary layer is uniform throughout the disk surface. This paper discusses the reaction-rate data generated recently for surfactant-based acid by use of a rotating-disk apparatus and presents the methodology used to determine the effective diffusivity from the measurements.The results obtained indicated that the viscoelastic surfactant examined (carboxybetaine-type) reduced the dissolution rate of calcite with HCl acid. The surfactant reduced the diffusion coefficient for H + . The effect of temperature on the diffusion coefficient did not follow the Arrhenius law.

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“…With the exception of the citric acid system, these acids have been extensively studied and successfully employed in acid fracturing treatments (6)(7)(8)(9)(10)(11)(12)(13) .…”

Section: Introductionmentioning

confidence: 99%

Diffusivity of Citric Acid During its Reaction With Calcite

AlKhaldi

Sarma

Nasr‐El‐Din

2010

Journal of Canadian Petroleum Technology

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Summary The mass transfer process during the reaction of citric acid with calcite was investigated using a rotating disk apparatus. The effects of disk rotational speed, initial citric acid concentration and temperature on the effective diffusion coefficient of citric acid were examined. Using various citric acid concentrations (1 wt%, 2 wt%, 5 wt% and 7.5 wt%), the diffusion coefficient of citric acid was calculated at 25°C, 40°C and 50°C. The effective diffusion coefficient of citric acid was found to be a function of the interplay between the calcium citrate precipitation and the presence of the counter-calcium ions. At high-initial acid concentration (5 wt% and 7.5 wt%), the effects of calcium citrate precipitation and counter-calcium ions were significant and the calculated citric acid diffusion coefficients were not comparable with those obtained using the rotating disk. However, the effects of both the calcium citrate precipitation and the counter-calcium ions on the citric acid diffusivity were minimal at low-initial citric acid concentrations. The effect of temperature on the diffusion coefficient of citric acid at a constant citric acid concentration was found to follow Arrhenius law, and the activation energy was 37.9 kJ/mol.

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Reaction of Calcite With Surfactant-Based Acids

Cited by 13 publications

References 39 publications

Anomalous Acid Reaction Rates in Carbonate Reservoir Rocks

Anomalous Acid Reaction Rates in Carbonate Reservoir Rocks

Quantitative Analysis of Reaction-Rate Retardation in Surfactant-Based Acids

Diffusivity of Citric Acid During its Reaction With Calcite

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