Temperature-Stable Acid-Gelling Polymers: Laboratory Evaluation and Field Results

Norman, Lewis R.; Conway, M.W.; Wilson, J. Michael

doi:10.2118/10260-pa

Cited by 11 publications

(4 citation statements)

References 4 publications

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“…The ratios of these monomers in the polymer will control the viscosity of the polymer on per-pound basis, the capability and nature of the crosslink, the viscosity profile as a function of temperature, and the upper temperature limit of the gelled acid fluid. 16,17 Polymer gelled acid may be pumped as linear gels or as insitu cross-linked systems. Linear gels typical have initial viscosities in the range of 15-30 mPa.s at surface conditions and thin with temperature.…”

Section: Rheological Testsmentioning

confidence: 99%

Long-Term Comparative Evaluation of HCl/Formic Acid System Used To Stimulate Carbonate Formations at Severe Conditions in Saudi Arabia

et al. 2006

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe high levels of carbon dioxide and low levels of hydrogen sulfide content of some deep and high temperature gas producers contributed in the requirement to complete these wells using super Cr-13 tubings. Due to the low permeability of the formation and the associated formation damage issues, acid fracturing treatments were required to optimize the productivity of these wells. This paper describes the selection, optimization and long term comparative evaluation of the gelled and in-situ crosslinked HCl/formic acid systems used this type of wells. The high temperatures encountered in deep wells and the susceptibility of super Cr-13 to severe corrosion in high concentration HCl systems used for stimulation purposes added one additional difficulty to the acid stimulation process. To overcome these problems, extensive experimental and field studies were performed to select an acid system to enhance the productivity of these wells.Core flood tests performed with HCl/formic acid systems showed their ability to create deep wormholes in tight carbonate cores; however the corrosiveness of these systems at downhole conditions could be severe if the correct type and concentration of corrosion inhibitor is not used. In general, for the HCl/formic acid systems at downhole conditions (275°F) it was found that high concentrations of corrosion inhibitors are required to protect the super Cr-13 completions.Based on lab tests study acid stimulations were performed, the flow back fluid was recovered and analyzed to observe the corrosion problems and to optimize the corrosion inhibitor.In all the cases the wells responded very well to the acid stimulation and the completion integrity was not compromised in a short or long term. The paper also shows for the first time a comparative long term well response to the acid stimulation of the two acid systems used in the area, showing the better performance of the in-situ crosslinked HCl/formic system over the gelled HCl/formic system.

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Section: Rheological Testsmentioning

confidence: 99%

Long-Term Comparative Evaluation of HCl/Formic Acid System Used To Stimulate Carbonate Formations at Severe Conditions in Saudi Arabia

et al. 2006

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“…Water-soluble polymers are important raw materials for oilfield development and are widely used in drilling fluid, completion fluid, polymer flooding, profile control and water plugging, acidification, fracturing, sand control and many other fields [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. The structure of conventional water-soluble polymers is unstable under high-temperature and high-salt reservoir conditions, particularly the commonly used partially hydrolyzed polyacrylamide (HPAM) in oil fields, which may lead to high-temperature cross-linking, chain breaking, functional group destruction, precipitation, and viscosity reduction [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

A Study on the Thermal Degradation of an Acrylamide and 2-Acrylamido-2-Methylpropanesulfonic Acid Copolymer at High Temperatures

et al. 2023

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As a temperature-resistant and salt-resistant polymer, acrylamide and 2-acrylamide-2-methylpropane sulfonic acid (abbreviated as AM-AMPS) copolymer is currently widely used in drilling, water control and oil production stabilization, enhanced oil recovery and other fields, but its stability under high temperature has been less studied. The degradation process of the AM-AMPS copolymer solution was studied by measuring viscosity, the degree of hydrolysis, and weight-average molecular weight at different temperatures and aging time. During the high-temperature aging process, the viscosity of the AM-AMPS copolymer saline solution first increases and then decreases. The combined action of the hydrolysis reaction and the oxidative thermal degradation leads to the change of the viscosity of the AM-AMPS copolymer saline solution. The hydrolysis reaction of the AM-AMPS copolymer mainly affects the structural viscosity of its saline solution through intramolecular and intermolecular electrostatic interactions, while the oxidative thermal degradation mainly reduces its molecular weight by breaking the main chain of the copolymer molecules, reducing the viscosity of the AM-AMPS copolymer saline solution. The content of AM and AMPS groups in the AM-AMPS copolymer solution at various temperatures and aging time was analyzed using liquid nuclear magnetic resonance carbon spectroscopy, demonstrating that the hydrolysis reaction rate constant of AM groups was significantly higher than that of AMPS groups. The contribution values of hydrolysis reaction and oxidative thermal degradation of the AM-AMPS copolymer at different aging time to viscosity were quantitatively calculated at temperatures ranging from 104.5 °C to 140 °C. It was determined that the higher the heat treatment temperature, the smaller the contribution of hydrolysis reaction to viscosity, while the bigger the contribution of oxidative thermal degradation to the viscosity of the AM-AMPS copolymer solution.

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“…Commonly used hightemperature, acid-gelling agents are copolymers consisting of various ratios of acrylamide, acrylamidomethylpropane sulfonic acid, quaternized dimethylaminoethylacrylate and quaternized dimethylaminoethylmethacrylate. The ratios of these monomers in the polymer will control the viscosity of the polymer on a per-pound basis, the capability and nature of the crosslink, the viscosity profile as a function of temperature and the upper-temperature limit of the gelled-acid fluid (Chatterji and Borchardt 1981;Norman et al 1981).…”

Section: Introductionmentioning

confidence: 99%

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

Welton

Domelen

2008

SPE Production &Amp; Operations

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This paper discusses the development of a unique in-situ crosslinkable acid system that uses a blend of hydrochloric acid (Hcl)/ formic acid as the base acid and a synthetic polymer gelling agent. The ability to in-situ crosslink an organic acid blend is novel. In addition, an unexpected result of the fluid development was the discovery of its unique rheological properties.Historically, both gelled and in-situ-crosslinked acids have been used for fluid-loss control during fracture acidizing and for diversion in matrix treatments in carbonate formations. Various synthetic polymers are used to gel the acid. Past research indicates that ∼20 cp base-gel viscosity is required as the first step in fluidloss control. In-situ crosslinking allows very high viscosities to be generated as the acid spends. The crosslinked gel creates a permeability barrier and subsequent fluid stages are diverted to other sections of the zone. When the acid fully spends, the gel breaks, giving a low-viscosity fluid.HCl is the most common base acid used for carbonate stimulation. Combinations of HCl and organic acids have been used because of their high dissolving power and relatively low rates of corrosion at elevated temperatures. In extreme cases, combinations of organic acids are used. While HCl/formic-acid blends have been used in the past, the unique rheological properties of these blends have not been fully explored.The chemistry and rheology of gelled and in-situ crosslinked HCl/formic-acid blends equivalent to 28% HCl will be described and compared with traditional gelled acid and in-situ crosslinked acid.

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Temperature-Stable Acid-Gelling Polymers: Laboratory Evaluation and Field Results

Cited by 11 publications

References 4 publications

Long-Term Comparative Evaluation of HCl/Formic Acid System Used To Stimulate Carbonate Formations at Severe Conditions in Saudi Arabia

Long-Term Comparative Evaluation of HCl/Formic Acid System Used To Stimulate Carbonate Formations at Severe Conditions in Saudi Arabia

A Study on the Thermal Degradation of an Acrylamide and 2-Acrylamido-2-Methylpropanesulfonic Acid Copolymer at High Temperatures

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

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