High-Viscosity-Yield Acid Systems for High-Temperature Stimulation

Welton, Thomas; Domelen, Mary Susan Van

doi:10.2118/98237-pa

Cited by 9 publications

(6 citation statements)

References 38 publications

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“…The effect of formic and acetic acids on the viscosity of live in-situ-gelled acids was investigated by van Domelen and Jennings (1995). The authors showed that increasing formic acid concentration increased the viscosity of the live acids, and they related that increase to the stability that organic acids add to the polymer at higher temperatures (van Domelen and Jennings 1995; Welton and van Domelen 2008). This claim is confirmed by the results shown in Fig.…”

Section: Resultsmentioning

confidence: 89%

“…Several laboratory and field studies have been reported also in the literature (Buijse et al 2004;Chang et al 2008). Welton and van Domelen (2008) evaluated gelled and in-situcrosslinked HCl/formic-acid blends equivalent to 28 wt% HCl and claimed that HCl and formic acid can be successfully crosslinked in situ. They observed that some synthetic polymer/acid gelling agents provide high initial viscosity in HCl/formic acid blends and stated that the gelled HCl-formic acid blends are more robust (than HCl blends) and maintain higher viscosities for longer periods at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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

Rabie

Gomaa

Nasr‐El‐Din

2012

SPE Production &Amp; Operations

View full text Add to dashboard Cite

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“…Experiments were performed for 5 minutes while maintaining a nitrogen pressure of 1,100-1,150 psig in the reaction vessel to keep CO2 in solution and maintain a singlephase fluid (Welton and Domelen 2008;Nasr-El-Din et al 2008;Taylor and Nasr-El-Din 2009). Samples of acid (3 cm 3 ) were withdrawn from the reaction vessel every minute, and the sampling line was purged with air after each sample was withdrawn to prevent sample contamination.…”

Section: Experimental Studiesmentioning

confidence: 99%

A Calibrated Computational Fluid Dynamics Model for Simulating the Rotating Disk Apparatus

et al. 2021

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Summary Reaction kinetics between calcite and acid systems have been studied using the rotating disk apparatus (RDA). However, simplifying assumptions have been made to develop the current equations used to interpret RDA experiments to enable solving them analytically in contrast to using numerical methods. Previous work has revealed inadequacies of some of these assumptions, which necessitates the use of a computational fluid dynamics (CFD) model to investigate their impact on the RDA results. The objectives of the current work are to develop a calibrated CFD and proxy model to simulate the reaction in the RDA and use this model to estimate the diffusion coefficient and the reaction rate coefficient of the reaction in the RDA. The present work developed the first calibrated CFD model to determine the diffusion coefficient and the reaction rate coefficient in the RDA with minimum assumptions in the hydrochloric acid (HCl) carbonate reaction. More specifically, the model relaxes the constant fluid properties, infinite acting reactor boundaries, and constant reaction surface area assumptions. The proxy model obtained results in reduced computational time with minimal compromise on accuracy. Finally, the proposed model showed an improvement of 63% in predicting the reaction kinetics between calcite and HCl compared to traditional methods.

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“…The reason for the low permeability of the reservoir could be due to two reasons: one is that the reservoir is a naturally low permeability reservoir (II reservoir); the second is that the permeability of oil reservoirs are reduced owing to the pollution close to the well in the process of oil and gas development. [1][2][3][4] These unprocessed segments mean that production will be reduced and a certain amount of the reserves will be lost. Therefore, retarded acid technology is applied to give deep acidication in order to improve the effect of acid treatment, see Fig.…”

Section: Introductionmentioning

confidence: 99%