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

SPE Journal ◽  
2011 ◽  
Vol 16 (04) ◽  
pp. 981-992 ◽  
Author(s):  
Ahmed I. Rabie ◽  
Ahmed M. Gomaa ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Mass Transfer ◽  
Rotational Speed ◽  
Reaction Rate ◽  
Rotating Disk ◽  
Effect Of Temperature ◽  
Kinetics Parameters ◽  
Calcite Dissolution ◽  
Rock Samples ◽  
Rate Of Dissolution

Summary In-situ-gelled acids have been used extensively in matrix acidizing and acid fracturing for acid diversion and reducing the leakoff rate, respectively. A few studies investigated the rate of dissolution of calcite in polymer-based acids, yet none has addressed in detail the in-situ-gelled acids. Therefore, the aim of this work is to examine the mass transfer and the kinetics of the reaction of 5 wt% HCl in-situ-gelled acids with calcite and determine the effect of Fe crosslinker on the rate of calcite dissolution. The rate of reaction of 5 wt% HCl in-situ-gelled acid was measured using the rotating-disk apparatus. Rock samples of 1.5in. diameter and 1-in. length were used. The effect of temperature (100-250°F) and disk-rotational speed (100-1,800 rev/min) was investigated using Pink Desert limestone rock samples. Calcium concentration was measured in the collected samples and was used to determine the acid-reaction rate. Experimental results showed that the rate of calcite dissolution at 150°F was controlled mainly by the rate of mass transfer of the acid to the surface up to a disk rotational speed of 1,000 rev/min and by the rate of the surface reaction above this value. On the basis of the results obtained, the diffusion coefficient of 5 wt% HCl in in-situ-gelled acid at 150°F; the activation energy; and the reaction rate constant at 150, 200, and 250°F were determined for the first time. A power-law kinetic model was used to determine the kinetics parameters. The presence of Fe3+ crosslinker had a significant effect on the rate of dissolution in comparison with reactions with gelled acid (no crosslinker) at the same condition. The reaction rate decreased by a factor of 2.2 and by a factor of 1.4 when the reaction was conducted at 100 and 1,500 rev/min, respectively. A gel layer, formed on the surface, acted as a barrier between the acid and the rock, which reduced the rate of calcite dissolution.

A New Method for Predicting Acid Penetration Distance

1975 ◽  
Vol 15 (04) ◽  
pp. 277-286 ◽  
Author(s):  
L.D. Roberts ◽  
J.A. GUIN
Keyword(s):  
Mass Transfer ◽  
Reaction Rate ◽  
Rotating Disk ◽  
Core Sample ◽  
New Method ◽  
Laboratory Model ◽  
Penetration Distance ◽  
Small Core ◽  
Core Samples ◽  
Mixing Patterns

Abstract A new method for calculating acid penetration distance in fractures bas been developed and tested experimentally. The method combines spending-time data from rotating-disk reaction pots with mass-transfer data obtained from laboratory fractures, thus allowing for both the effects of surface reaction kinetics and actual mixing patterns in the fracture. It is shown that the new method successfully predicts the acid spending obtained in laboratory fractures in both turbulent and laminar flow, using a reaction-rate constant obtained with a rotating-disk apparatus, This appears to be the first method that is easily applicable to small core samples and it allows properly for acid mixing in the fracture. Introduction Recently, there has been considerable interest in and research toward developing a more accurate method for calculating the acid penetration distance in a reservoir fracture. The acid penetration distance, defined as the distance the acid will travel before spending to some predetermined degree, is essential for estimating the production improvement obtainable by fracture acidizing. The first and probably most widely used method for calculating the penetration distance was based on the static-reaction test, in which a small core sample and a known quantity of acid were allowed to react for a given time in a small pot. By equating the spending time of acid in the pot to the residence time of acid flowing down the fracture (t = L/vi), a penetration distance was calculated. it has become penetration distance was calculated. it has become apparent that, because of the extremely fast surface reaction occurring in many acid-rock systems, the over-all acid spending rate to a large degree depends on the extent of fluid mixing at the rock surface. Since fluid-mixing patterns in small reaction pots may not be necessarily the same as those occuring in fractures, several experiments have been performed using actual laboratory model fractures. performed using actual laboratory model fractures. Recent investigations of this type have shown that, because of variable fluid properties, the mixing patterns in real fractures are very complex. To patterns in real fractures are very complex. To allow for this mixing and thereby to calculate more accurately the penetration distance in real fractures, design methods based on experiments in laboratory model fractures have been developed. Therefore, there appear to be two basic approaches to calculating the acid penetration distance, one using data obtained in small reaction pots, and the other using data gathered from model laboratory fractures. Both methods have some advantages. The former is quick, simple to operate, and applicable to the small core samples usually available for tests, while the latter method is more costly, more time consuming, requires special equipment, and is not applicable for use with small core samples. However, for reasons noted above, the latter method is probably more representative of mixing in actual reservoir fractures. In this paper we present a new method for calculating acid penetration distance that combines the advantages of both the above methods without incurring the disadvantages. The new method combines data from both reaction-pot experiments and laboratory-model fracture tests in a manner such that both the reaction rate of the actual rock (obtained conveniently from a small core sample) and the mixing occurring in an actual fracture are allowed for. Reaction-rate constants are obtained using a small batch reaction pot containing a rotating-disk core sample. These rate constants are then used with mass-transfer coefficients obtained from laboratory fractures to predict the acid penetration distance. penetration distance.The combined mass-transfer coefficient/ rate-constant method proposed here has several advantages over existing methods for predicting penetration distance. Since general correlations penetration distance. Since general correlations can be developed for mass-transfer coefficients (in fact, many applicable correlations already exist, most notably in the related field of heat transfer), A is not necessary, nor is it usually possible, to perform experiments in laboratory fractures for each perform experiments in laboratory fractures for each new field core sample obtained. SPEJ P. 277

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

SPE Journal ◽  
2014 ◽  
Vol 19 (06) ◽  
pp. 1192-1202 ◽  
Author(s):  
Ahmed I. Rabie ◽  
Daniel C. Shedd ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Mass Transfer ◽  
Lactic Acid ◽  
Concentration Gradient ◽  
Reaction Rate ◽  
Surface Reaction ◽  
Rotating Disk ◽  
Acid Fracturing ◽  
Rate Of Reaction ◽  
Indiana Limestone ◽  
Kinetics Of

Summary 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 Ca2+, Mg2+, and SO42− 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.

Chelating Agents as a Stimulation Fluid with a Negative Reaction Order: More Diluted Solutions React Faster with Carbonates

2021 ◽  
Author(s):  
Igor Ivanishin ◽  
Hamidreza Samouei
Keyword(s):  
Dissolution Rate ◽  
Reaction Rate ◽  
Chelating Agents ◽  
Reaction Order ◽  
Rotating Disk ◽  
Carbonate Reservoir ◽  
Reaction Behavior ◽  
Calcite Dissolution ◽  
Reservoir Rocks ◽  
Kinetics Of

Abstract Chelating agents are used to stimulate high-temperature carbonate reservoirs and remove mineral scales. For field applications, commercial chelates—EDTA, DTPA, GLDA, etc.—are commonly supplied as 3550 wt% (1.2-1.7 M) solutions and diluted two times in water. However, the dependence of the reaction rate on the concentration of chelate in solution has never been quantified. This paper focuses on determining the kinetics of calcite dissolution as a function of the dilution factor of commonly used chelates at acidic pH. Using a rotating disk apparatus, the kinetics of calcite marble dissolution in 0.10.25 M EDTA (pH=4.9-5.0), 0.1-0.25 M DTPA (pH=3.5-5.0), and 0.28-0.85 M GLDA (pH=3.7-5.0) solutions has been investigated. The dissolution of calcite in all chelates has a negative fractional-order that increases with temperature in the range -0.6 < n< -1.9. Thus, less concentrated chelate solutions react faster with calcite, and the effect of chelate dilution becomes less pronounced with a temperature increase. For example, three times dilution of pH=3.7 commercial GLDA solution—from commonly used 50 vol% (0.85 M) to 16.7 vol% (0.28 M)—increases calcite dissolution rate 8.4, 4.9, 2.7, and 2.0 times at 98.6, 116.6, 134.6, and 188.6°F, respectively. Dilution of pH=5.0 EDTA and pH=3.5 DTPA from 0.25 M to 0.1 M increases the dissolution rate of calcite 1.4-3.1 times at 98.6-188.6°F. Probable reasons for such an unusual reaction behavior are discussed in the paper. Presented results are integral for designing the stimulation operations in carbonate reservoir rocks and the removal of carbonate scales.

Determination of Reaction Rate of In-situ Gelled Acids with Calcite Using the Rotating Disk Apparatus

2010 ◽  
Author(s):  
Ahmed I. Rabie ◽  
Ahmed Mohamed Gomaa ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Reaction Rate ◽  
Rotating Disk

Monitoring Polymer-Assisted Mechanochemical Cocrystallisation Through in Situ X-Ray Powder Diffraction

2020 ◽  
Author(s):  
Luzia S. Germann ◽  
Sebastian T. Emmerling ◽  
Manuel Wilke ◽  
Robert E. Dinnebier ◽  
Mariarosa Moneghini ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Powder Diffraction ◽  
Reaction Rate ◽  
Polymer Additives ◽  
Time Resolved ◽  
X Ray

Time-resolved mechanochemical cocrystallisation studies have so-far focused solely on neat and liquid-assisted grinding. Here, we report the monitoring of polymer-assisted grinding reactions using <i>in situ</i> X-ray powder diffraction, revealing that reaction rate is almost double compared to neat grinding and independent of the molecular weight and amount of used polymer additives.<br>

The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface

1999 ◽  
Vol 39 (7) ◽  
pp. 91-98 ◽  
Author(s):  
Ryan N. Jordan ◽  
Eric P. Nichols ◽  
Alfred B. Cunningham
Keyword(s):  
Mass Transfer ◽  
Cell Membrane ◽  
Substrate Concentration ◽  
Water Interface ◽  
Industrial Systems ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Surfactant Sorption

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate concentration that the cell membrane “sees,” (i.e., the “directly bioavailable” pool) as well as (2) the rate of mass transfer from potentially bioavailable (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two processes are discussed. We propose the hypothesis that the sorption of (bio)surfactants at the solid-liquid interface is partially responsible for the increased bioavailability of surface-bound nutrients, and offer this as a basis for suggesting the development of engineered in-situ bioremediation technologies that take advantage of low (bio)surfactant concentrations. In addition, other industrial systems where bioavailability phenomena should be considered are addressed.

scholarly journals Color Response Modification of Encapsulated Liquid Crystals Used in Rotating Disk Heat Transfer Studies

1995 ◽  
Author(s):  
Cengiz Camci ◽  
Boris Glezer
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Rotational Speed ◽  
Rotating Disk ◽  
Point Of View ◽  
Centrifugal Acceleration ◽  
Relative Shift ◽  
Color Response ◽  
Stationary Conditions

The liquid crystal thermography can be successfully used in both transient and steady-state heat transfer experiments with excellent spatial resolution and good accuracy. Although most of the past liquid crystal based heat transfer studies are reported in the stationary frame, measurements from the rotating frame of turbomachinery systems exist The main objective of the present investigation is to determine the influence of rotation on the color calibration of encapsulated liquid crystals sprayed on the flat surface of a rotating aluminum disk. The investigation is performed for a rotational speed range from 0 rpm to 7500 rpm using three different liquid crystal coatings displaying red at 30, 35 and 45° C, under stationary conditions. An immediate observation from the present study is that the color response of liquid crystals is strongly modified by the centrifugal acceleration of the rotating environment. It is consistently and repeatedly observed that the hue versus temperature curve is continuously shifted toward lower temperatures by increasing rotational speed. The relative shift of the display temperature of the green can be as high as 7°C at 7500 rpm when compared to the temperature of the green observed under stationary conditions. The present study shows that relative shift of the liquid crystal color has a well-defined functional dependency to rotational speed. The shift is linearly proportional to the centrifugal acceleration. It is interesting to note that the individual shift curves of the green for all three liquid crystal coatings collapse into a single curve when they are normalized with respect to their own stationary green values. When the color attribute is selected as “intensity” instead of “hue”, very similar shifts of the temperature corresponding to the intensity maximum value appearing around green is observed. An interpretation of the observed color shift is made from a thermodynamics energy balance point of view.

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