Effect of Shear Rate on the Propagation of Polymer-Based In-Situ-Gelled Acids Inside Carbonate Cores

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

doi:10.2118/142927-pa

Cited by 8 publications

(6 citation statements)

References 22 publications

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“…As the acid entered the core, the pressure drop increased due to the higher acid viscosity. However, the pressure drop changed in a cycling manner where the crest and trough of each cycle increased with time as it described by Gomaa et al 2011. As the acid entered the Core# A5, the pH of the acid increased due to acid reaction with carbonate.…”

Section: In-situ Gelled Acid Injectionmentioning

confidence: 94%

Effect of Residual Oil Saturation on the Propagation of Regular, Gelled, and In-Situ Gelled Acids inside Carbonate Formations

Gomaa

Nasr‐El‐Din

2011

SPE European Formation Damage Conference

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In oil fields, serious difficulties with acid-induced sludge, a major source of well damage, can vary from a viscous, stable emulsion. A chemical analysis of sludge shows that hydrochloric acid (HCl) is present in the sludge structure. Also, Fe(III) ions in HCl formulations can cause a large amount of sludge. Even though ferric ion could not be detected in the oil phase or in the sludge, it induces sludge mainly because it works as a phase-transport catalyst for HCl. Therefore, the objective of this study is to determine the effect of residual oil saturation on the performance of regular, gelled, and in-situ gelled acids, that based on Fe(III) as crosslinker agent, inside the carbonate cores.

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Section: In-situ Gelled Acid Injectionmentioning

confidence: 94%

Effect of Residual Oil Saturation on the Propagation of Regular, Gelled, and In-Situ Gelled Acids inside Carbonate Formations

Gomaa

Nasr‐El‐Din

2011

SPE European Formation Damage Conference

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“…Recently, a coreflood study at high temperature and pressure was conducted with limestone cores [57]. The propagation of the acid, polymer, and crosslinking agent inside the long cores was examined in detail.…”

Section: Polymeric Acidsmentioning

confidence: 99%

Gelling agents

2015

Petroleum Engineer's Guide to Oil Field Chemicals and Fluids

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Organic and inorganic gels are used to seal formations with high permeability. Sealing can be permanent or temporary. In this way, undesirable flows in the formation can be suppressed. Gelling agents are mainly used for water shutoff and limiting sand production. Some agents can also be used for primary plugging of surface and flow strings, as well as for eliminating lost circulation [1]. However, the high prices often limit wide applications.Flow-deflecting technologies based on gel-forming agents are effective in highly water-invaded multizone reservoirs. Redistribution of the flow is achieved by equalizing the injectivity profile of the injection wells and reducing the content of produced water in the producing wells. Redistribution also reduces the consumption of electricity, demulsifiers, and fuels used for oil treating in the field.To broaden the use of gel technologies, it is necessary to solve certain problems of developing and manufacturing mobile units for preparing and injecting large volumes of gel compositions in wells and for producing non-freezing agents for year-round stimulation treatments [2].Petroleum Engineer's Guide to Oil Field Chemicals and Fluids. http://dx.Aluminum trichloride, a cheap, abundant waste product of the chemical industry, forms a gel under certain conditions with carbonates and on mixing with alkalies. Laboratory and field tests showed that aluminum trichloride can be used as a gelforming agent for reducing the permeability of water-conducting channels [16].

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“…As the acid entered the core, the pressure drop increased because of the higher viscosity of the acid. The pressure drop then changed in a cycling manner as described by Gomaa et al (2011). The cycling behavior of the pressure drop indicates that the gel structure was formed and the acid was able to change its direction inside the core.…”

Section: Coreflood Studymentioning

confidence: 99%

HCl/Formic In-Situ-Gelled Acids as Diverting Agents for Carbonate Acidizing

Rabie

Gomaa

Nasr‐El‐Din

2012

SPE Production &Amp; Operations

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In highly heterogeneous carbonate reservoirs, several acid systems have been used to enhance acid diversion during matrix acidizing such as surfactant-based acids and in-situ-gelled acids. In-situgelled acids are also used to reduce leakoff rate in acid fracturing. The main acid used in this system is hydrochloric acid (HCl). However, high reaction rates and severity of corrosion problems, especially for wells completed with Cr-based tubulars, limit the use of HCl at high temperatures. On the other hand, mixing organic acids with HCl either increases the acid penetration or reduces the necessary strength of HCl and the necessary load of the corrosion inhibitors. A few studies addressed the systems that use both advantages.The objective of this work is to investigate the behavior and the performance of different in-situ-gelled HCl/formic acid blends as diverting agents by conducting viscosity measurements, reactionrate measurements using the rotating-disk apparatus, and through coreflood study.Formic acid was blended with HCl, and four in-situ-gelled acids were examined. Formic acid concentration varied from 0 to 6.31 wt%, and HCl concentration ranged from 0 to 5 wt%. Pink Desert limestone was used for reaction-rate and coreflood experiments. The rotating-disk apparatus was used to measure the reaction rate at 250°F at disk rotational speeds of 100 and 1,000 rev/min. The effect of formic acid concentration and zirconium crosslinking on the reaction rate was examined. Coreflood experiments were conducted at 250°F using two different rates of injection (2 and 10 cm 3 /min), and the core samples were imaged using a computed-tomography (CT) scan technique after each coreflood experiment.Increasing formic acid concentration decreased the reaction rate of in-situ-gelled HCl/formic acid with calcite at both low and high disk rotational speeds. This was confirmed by viscosity measurements, which showed that increasing formic acid concentration increased the viscosity of the live acids and decreased the viscosity of the spent acids. Coreflood results showed that increasing formic acid concentration in HCl/formic acid blends reduced acid ability for diversion. In the selected range of acid concentration and for the type of polymer and crosslinking agent used, the insitu HCl/formic acid behaved more like gelled acid and reached a breakthrough in all coreflood experiments. The higher the formic acid concentration, the higher the pore volume of the acid required to break through.

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Effect of Shear Rate on the Propagation of Polymer-Based In-Situ-Gelled Acids Inside Carbonate Cores

Cited by 8 publications

References 22 publications

Effect of Residual Oil Saturation on the Propagation of Regular, Gelled, and In-Situ Gelled Acids inside Carbonate Formations

Effect of Residual Oil Saturation on the Propagation of Regular, Gelled, and In-Situ Gelled Acids inside Carbonate Formations

Gelling agents

HCl/Formic In-Situ-Gelled Acids as Diverting Agents for Carbonate Acidizing

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