Reaction of In-Situ-Gelled Acids With Calcite: Reaction-Rate Study

Rabie, Ahmed; Gomaa, Ahmed M.; Nasr‐El‐Din, Hisham A.

doi:10.2118/133501-pa

Cited by 38 publications

(20 citation statements)

References 25 publications

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“…Descriptions of the instrument, theory, and procedure were discussed in detail in previous publications (Rabie et al 2011;2012;2014). As a summary, core samples from blocks of Indiana limestone were cut into disks of 1.5 in.…”

Section: Materials and Apparatusmentioning

confidence: 99%

Effect of Acid Additives on the Reaction of Stimulating Fluids During Acidizing Treatments

Rabie

Nasr‐El‐Din

2015

Day 2 Tue, September 15, 2015

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The objective of matrix acidizing treatments is to remove the skin damage from the vicinity around the wellbore and enhance the permeability and the well productivity. While this is accomplished in sandstone by using reactive fluids to dissolve the clay and the surrounding cementing materials, carbonate stimulation is successful when the reactive fluids bypass the damage by creating conductive channels or "wormholes". It is rare in both treatments that the acids are used alone without several additives. The presence of any of these additives, which is required to achieve a certain function, may impact significantly the outcome of the acid treatment either positively or negatively. The objective of this study is to examine the effect of the type and concentration of several additives, which are currently in-use in the oilfield, on the calcite dissolution rate with HCl using the rotating disk reactor. Additives such as corrosion inhibitors, synthetic polymers, mono and divalent chloride salts, mutual solvent, dissolved iron, viscoelastic surfactants, and chelating agents were investigated.The results showed that more reliable data was obtained at lower acid concentrations. Higher acid concentrations were associated with significant surface changes and inevitable source of error. The effect of corrosions inhibitors was studied by investigating three corrosion inhibitors (CI-A, CI-B, and CI-C) obtained from three different service companies. The presence of two corrosions inhibitors was associated with a reduction in the dissolution rate (between 7 and 45%), while the presence of the third one (containing formic acid) increased the rate of dissolution up to 38%. The effect of all other additives was further examined in the presence of one of the corrosion inhibitors. The presence of a synthetic polyacrylamide polymer significantly reduced the reaction rate down to 96% compared to a blank acid solution that did not contain the polymer.Monovalent ions (sodium and potassium) showed little effect on the calcite dissolution rate, the presence of divalent ions such as magnesium chloride was associated with a reduction in the rate. Calcium chloride showed an increase in the reaction rate for both cases of the presence and the absence of a corrosion inhibitor.The results also showed that mutual solvent changed the dissolution rate and a minimum was observed at 5 vol%. These results were confirmed by changing the corrosion inhibitor and the same behavior was observed at the same mutual solvent concentration. Dissolved iron reduced the rate of reaction by 17% at iron concentration up to 5000 mg/l. At 17,000 mg/l, the rate was reduced by 39% and a reddish to brown precipitate of ferric hydroxide was observed on the rock samples after the reaction, indicating a ferric precipitate. The reaction of VES-based acid showed a minimum at 125°F, which matched the maximum viscosity at low shear rate. The presence of 5 wt% chelating agents increased the reaction rate of 0.1 N HCl by 12.7 and 25%, when the reactions were conducted with no ...

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Section: Materials and Apparatusmentioning

confidence: 99%

Effect of Acid Additives on the Reaction of Stimulating Fluids During Acidizing Treatments

Rabie

Nasr‐El‐Din

2015

Day 2 Tue, September 15, 2015

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“…8. The diffusion coefficient of lactic acid was estimated at 25 C following the method of Ribeiro et al (2005). Values for the diffusion coefficients of calcium and carbonate products at 25 C were taken from the assumptions of Fredd and Fogler (1998).…”

Section: Mass-transfer Studymentioning

confidence: 99%

Measuring the Reaction Rate of Lactic Acid With Calcite and Dolomite by Use of the Rotating-Disk Apparatus

2014

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Lactic acid has been examined in various laboratories and applied in the oil field for acid fracturing and drilling-fluid-filter-cake removal, and as an iron-control agent during acid treatments. However, the reaction of lactic acid with calcite has not been addressed before. Determination of the reaction rate and the acid-diffusion properties is a critical step for successful treatments in matrix acidizing and acid fracturing. Therefore, the objective of this work is to conduct a detailed study on the reaction of lactic acid with calcite. Mass transfer and reaction kinetics are reported for the lactic acid/calcite system by use of the rotating-disk apparatus.Disk samples were cut from Indiana limestone or Silurian dolomite and were used in the reaction-rate experiments. The effect of lactic acid concentration (1, 5, and 10 wt%), temperature (80-250 F), disk rotational speed (100-1,800 rev/min), and different inorganic salts on the reaction rate was investigated. The diffusion coefficient of 5 wt% lactic acid was determined at low disk rotational speeds and reported at 80, 200, and 250 F. A model that accounts for the effect of the kinetics of the surface reactions and the transport of reactants and products was developed. The activation energy and the rate constant at 80, 150, and 250 F for the reaction of lactic acid with Indiana limestone were reported. Reaction experiments of lactic acid with dolomite at 150 F over disk rotational speeds of 100-1,800 rev/min, and at 1,500 rev/min over a temperature range of 80-250 F, were conducted and the results were compared with those obtained for the calcite reaction.At 80 F, the reaction of lactic acid with calcite was controlled by mass transfer at low disk rotational speeds (up to 500 rev/min) and was surface reaction limited at higher speeds. At higher temperatures (150, 200, and 250 F), both mass transfer and surface reaction influence the overall calcite dissolution. The kinetics of the surface reaction were influenced by both forward and backward reactions. At 80 F, the surface reaction contributes to 28% of the overall resistance. This dependence becomes much less (13 and 10%) at higher temperatures (150 and 250 F, respectively).The reaction of lactic acid with dolomite at 150 F was mainly controlled by mass transfer up to 1,000 rev/min and by the kinetics of the surface reaction after 1,000 rev/min. At 80 and 150 F, the rate of reaction of lactic acid with calcite was an order of magnitude higher than that with dolomite. At temperatures of 200 and 250 F, the rate of reaction of lactic acid with calcite is twice the rate of reaction with dolomite. The presence of Ca 2þ , Mg 2þ , and SO 2À 4 ions reduced the reaction rate, which is most likely because of the reduction in the concentration gradient of the products. The reduction in the concentration gradient will cause a reduction in the rate of diffusion of the generated calcium away from the surface, and hence a lower rate of dissolution.

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“…Gelled acids, which have been widely used to increase the viscosity of acid in the formation, can enhance diversion and achieve deep acid penetration and longer fractures. The reaction rate is used to determine the distance that acid can penetrate from the wellbore at a given pumping rate before it is completely spent [1] [2]. The reaction of gelled acids with calcite in the rotating disk apparatus is shown in Equation (1):…”

Section: Introductionmentioning

confidence: 99%

Measurement of Reaction Rate of Gelled Acids and Calcite with the Rotating Disk Apparatus

Liao¹,

Zhang²,

Peng³

et al. 2017

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An investigation has been made to study the reaction kinetics of gelled acids with calcite using a rotating disk apparatus. The rheological experiments revealed that all gelled acids behaved as non-Newtonian shear thinning fluids. With the rotating disk apparatus, the reaction kinetics parameters, activation energy, and effective diffusion coefficients were determined. It was found that the reaction of gelled acid with calcite was mass transfer limited at low polymer concentration and moving toward surface reaction limited at higher polymer concentration. And the diffusion rate marginally decreased, with increasing the polymer concentration.

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Reaction of In-Situ-Gelled Acids With Calcite: Reaction-Rate Study

Cited by 38 publications

References 25 publications

Effect of Acid Additives on the Reaction of Stimulating Fluids During Acidizing Treatments

Effect of Acid Additives on the Reaction of Stimulating Fluids During Acidizing Treatments

Measuring the Reaction Rate of Lactic Acid With Calcite and Dolomite by Use of the Rotating-Disk Apparatus

Measurement of Reaction Rate of Gelled Acids and Calcite with the Rotating Disk Apparatus

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