Acrylamide-Polymer/Chromium(III)-Carboxylate Gels for Near Wellbore Matrix Treatments

Sydansk, R.D.

doi:10.2118/20214-pa

Cited by 110 publications

(51 citation statements)

References 17 publications

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“…For those experiments involving partially formed gels, the gel aging time (i.e., from crosslinker addition to the polymer solution to initiating gel solution injection) was selected using the bottletesting procedure that is described in Ref. 26. Utilizing the gel-strength-code assignment as a function of gel aging time at 41°C (105°F), the aging time was determined when the first visually detectable gel formation occurred.…”

Section: Methodsmentioning

confidence: 99%

Conformance Improvement Using Gels

Seright¹

2003

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This report describes work performed during the second year of the project, "Conformance Improvement Using Gels." The project has two objectives. The first objective is to identify gel compositions and conditions that substantially reduce flow through fractures that allow direct channeling between wells, while leaving secondary fractures open so that high fluid injection and production rates can be maintained. The second objective is to optimize treatments in fractured production wells, where the gel must reduce permeability to water much more than that to oil.Pore-level images from X-ray computed microtomography were re-examined for Berea sandstone and porous polyethylene. This analysis suggests that oil penetration through gel-filled pores occurs by a gel-dehydration mechanism, rather than a gel-ripping mechanism. This finding helps to explain why aqueous gels can reduce permeability to water more than to oil.We analyzed a Cr(III)-acetate-HPAM gel treatment in a production well in the Arbuckle formation. The availability of accurate pressure data before, during, and after the treatment was critical for the analysis. After the gel treatment, water productivity was fairly constant at about 20% of the pre-treatment value. However, oil productivity was stimulated by a factor of 18 immediately after the treatment. During the six months after the treatment, oil productivity gradually decreased to approach the pre-treatment value. To explain this behavior, we proposed that the fracture area open to oil flow was increased substantially by the gel treatment, followed by a gradual closing of the fractures during subsequent production.For a conventional Cr(III)-acetate-HPAM gel, the delay between gelant preparation and injection into a fracture impacts the placement, leakoff, and permeability reduction behavior. Formulations placed as partially formed gels showed relatively low pressure gradients during placement, and yet substantially reduced the flow capacity of fractures (with widths from 1 to 4 mm) during brine and oil flow after placement. Regardless of gel age before placement, very little gel washed out from the fractures during brine or oil flow. However, increased brine or oil flow rate and cyclic injection of oil and water significantly decreased the level of permeability reduction.A particular need exists for gels that can plug large apertures (e.g., wide fractures and vugs). Improved mechanical strength and stability were demonstrated (in 1-to 4-mm-wide fractures) for a gel that contained a combination of high-and low-molecular weight polymers. This gel reduced the flow capacity of 2-and 4-mm-wide fractures by 260,000. In a 1-mm-wide fracture, it withstood 26 psi/ft without allowing any brine flow through the fracture.Cr(III)-acetate-HPAM gels exhibited disproportionate permeability reduction in fractures. The effect was most pronounced when the gel was placed as gelant or partially formed gels. The effect occurred to a modest extent with concentrated gels and with gels that were "fully formed" when p...

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Section: Methodsmentioning

confidence: 99%

Conformance Improvement Using Gels

Seright¹

2003

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“…• Other polymer microgels are often used in conjunction with crosslinkers that develop large viscosities after a characteristic reaction time (Sydansk, 1993), and resins are also formulated to solidify after a set time (Morris et al, 2012). Table 1.2 is a comparison of some of these alternative technologies based on factors regarding cement fracture application.…”

Section: Sealant Technologymentioning

confidence: 99%

The Use of a pH-Triggered Polymer Gelant to Seal Cement Fractures in Wells

Tavassoli

Patterson

et al. 2016

SPE Drilling &Amp; Completion

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Summary The potential leakage of hydrocarbon fluids or carbon dioxide (CO2) out of subsurface formations through wells with fractured cement or debonded microannuli is a primary concern in oil-and-gas production and CO2 storage. The presence of fractures in a cement annulus with apertures on the order of 10–300 µm can pose a significant leakage danger with effective permeability in the range of 0.1–1.0 md. Leakage pathways with small apertures are often difficult for conventional oilfield cement to repair; thus, a low-viscosity sealant that can be placed into these fractures easily while providing a long-term robust seal is desired. The development of a novel application with pH-triggered polymeric sealants could potentially be the solution to plugging these fractures. The application is based on the transport and reaction of a low-pH poly(acrylic acid) polymer through fractures in strongly alkaline cement. The pH-sensitive microgels viscosify after neutralization with cement to become highly swollen gels with substantial yield stress that can block fluid flow. Experiments in a cement fracture determined the effects of the viscosification and gel deposition with real-time visual observation and measurements of pressure gradient and effluent pH. Although the pH-triggered gelling mechanism and rheology measurements of the polymer gel show promising results, the polymer solution undergoes a reaction caused by the release of calcium cations from cement that collapses the polymer network (syneresis). It produces an undesirable calcium-precipitation byproduct that is detrimental to the strength and stability of the gel in place. As a result, gel-sealed leakage pathways that were subjected to various degrees of syneresis often failed to hold backpressures. Multiple chemicals were tested for pretreatment of cement cores to remove calcium from the cement surface zone to inhibit syneresis during polymer placement. A chelating agent, sodium triphosphate (Na5P3O10), was found to successfully eliminate syneresis without compromising the injectivity of polymer solution during placement. Polymer-gel strength is determined by recording the maximum-holdback pressure gradients during liquid-breakthrough tests after various periods of pretreatment and polymer shut-in time. Cores pretreated with Na5P3O10 successfully held up to an average of 70 psi/ft, which is significantly greater than the range of pressure gradients expected in CO2-storage applications. The use of such inexpensive, pH-triggered polyacrylic acid polymer allows the sealing of leakage pathways effectively under high-pH conditions.

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“…Typically, applied solution for matrixfluid shutoff system is polyacrylamide gels crosslinked with chromium (III)-acetate, chromium (III)-malonate, or chromium (III)-propionate (Sydansk, 1990a). This is highly water-soluble and readily mixes with polymer solutions.…”

Section: Downloaded By [Umeå University Library] At 21:53 19 Novembermentioning

confidence: 99%

A Review of Polymer Conformance Treatment: A Successful Guideline for Water Control in Mature Fields

Chung

Bae

Nguyen

et al. 2011

Energy Sources, Part A: Recovery, Utilization, and Environmenta

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Waterflooding has been practiced for several decades as a means of secondary recovery. This process is successful if there is uniform resistance to the injected water. However, due to its nature of heterogeneity, the injected water flows to the less resistant path, resulting in poor sweep efficiency. As one of many candidates to overcome this problem, polymer systems mixing with several types of chemical agents have been researched and applied for several years. In this article, the authors reviewed and summarized the Relative Permeability Modification/Disproportionate Permeability Reduction and water shutoff treatments.

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Acrylamide-Polymer/Chromium(III)-Carboxylate Gels for Near Wellbore Matrix Treatments

Cited by 110 publications

References 17 publications

Conformance Improvement Using Gels

Conformance Improvement Using Gels

The Use of a pH-Triggered Polymer Gelant to Seal Cement Fractures in Wells

A Review of Polymer Conformance Treatment: A Successful Guideline for Water Control in Mature Fields

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