Laboratory Acidization of an Eolian Sandstone at 380°F

Wehunt, C.D.; Arsdale, Howard Van; Warner, J. L.; Ali, Syed A.

doi:10.2118/25211-ms

Cited by 25 publications

(4 citation statements)

References 7 publications

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“…Calcium sulfate is a scale type that was found to have low solubility with high pH dissolvers . Also, dissolvers that have low pH will increase the tubular corrosion and therefore damage the facilities’ integrity. , Recent research studies − are directed to provide chemical dissolvers with high pH to sustain the well downhole and surface equipment, processing units, and facilities; also, this will save the corrosion inhibitor and intensifier cost that is commonly added to the treatment operations for low pH dissolvers. , Ahmed et al added tetrakis hydroxymethyl phosphonium salts (THPS) to ethylenediaminetetraacetic acid (EDTA) to formulate a slightly alkaline chemical solution with about pH value of 8. Another recent research was executed and provided a chemical dissolver with a 12.5 pH value for composite sulfate/sulfide scale removal at low temperatures, and the results showed scale solubility efficiencies of 91.8% at 45 °C and 79% at 35 °C …”

Section: Scale Removalmentioning

confidence: 99%

“…24 Also, dissolvers that have low pH will increase the tubular corrosion and therefore damage the facilities' integrity. 25,26 Recent research studies 27−30 are directed to provide chemical dissolvers with high pH to sustain the well downhole and surface equipment, processing units, and facilities; also, this will save the corrosion inhibitor and intensifier cost that is commonly added to the treatment operations for low pH dissolvers. 31,32 Ahmed et al 28 added tetrakis hydroxymethyl phosphonium salts (THPS) to ethylenediaminetetraacetic acid (EDTA) to formulate a slightly alkaline chemical solution with about pH value of 8.…”

Section: ■ Introductionmentioning

confidence: 99%

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Development of a Unique Organic Acid Solution for Removing Composite Field Scales

et al. 2021

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Removal of oil field scales commonly requires low pH acid, which may cause many issues under downhole conditions. Because of the deposition of different scale types and the economic effect, there is a need to develop a remedial descaling fluid that can be effectively used to remove different types of scales at a different position in the well. This paper provides a new scale dissolver that is noncorrosive and has high scale dissolution performance for composite scales. This study shows a series of comprehensive experimental lab tests as scale characterization, equilibrium brine compositional analysis, fluid compatibility and stability, solubility test, precipitation tendency for the dissolved solids, corrosion test, and core flooding. The scale samples contain magnetite, kaolinite, calcium carbonate, and sulfate scales. The results showed that the dissolution rate was higher than 74% for composite field scale samples after 6 h at 70 °C, while the new dissolver completely dissolved the two samples at 100 °C after 5 h. The new dissolver outperformed the common commercial dissolver used in the oil and gas industry. The new dissolver has a pH of 9 and showed safe use regarding the precipitation of dissolved solids that can be produced during the scale treatment and a low corrosion rate of 0.063 kg/m 2 at 6.9 MPa and 100 °C for 6 h. Also, the new dissolver was tested through core flooding for Indiana limestone and showed core permeability enhancement; the treatment with the new dissolver enhanced the core permeability from an initial value of 0.67 milliDarcy (mD) to record 1.29 mD.

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Section: Scale Removalmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Development of a Unique Organic Acid Solution for Removing Composite Field Scales

et al. 2021

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“…It is also common for investigators to use continuous interpretation and report their results as the ratio of current to initial permeability k/k o , for example as shown in Fig. 2 in Wehunt, et al (1993). When pseudo-continuous results are presented as k/k o , the usual assumption is that viscosity is constant and it can be neglected; however, this is not always-and perhaps not even usually-true.…”

Section: Pressure Data Interpretationmentioning

confidence: 99%

Permeametry Pitfalls and Opportunities

Wehunt

Nasr‐El‐Din

2013

SPE European Formation Damage Conference &Amp; Exhibition

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Permeameters have been used for more than 80 years in the oil and gas industry, either to measure porous media permeability ("K" studies) or to interpret permeability alterations by various unintended or deliberate processes ("ΔK" studies). It is the latter experiment class-the ΔK studies-which are this paper's focus.Darcy's law is an empirical observation that permeability is proportional to the fluid velocity and the applied pressure gradient, and inversely proportional to the fluid viscosity. In experimental utopia, the simplest variable to measure is the only one that must be recorded during an experiment; however, in practice, interpretation errors frequently arise from ignoring factors that are more difficult to measure or predict, such as viscosity changes within cores during a test. Using data from previously published studies, this paper examines some interpretation pitfalls from past experiments and shows how some of these can be avoided. In addition to ignoring changes in factors that are not actually constant, another pitfall is not fully utilizing the available information. This paper identifies permeametry interpretation improvement opportunities for past or future studies using commonly available data, especially for those tests involving, parallel-flow, dual-or multi-cell tests, or carbonate matrix acidizing optimization studies.

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“…Organic acids have been extensively used in the acid stimulation of hydrocarbon reservoirs (Harris 1961;Scheuerman 1988;Wehunt et al 1993;Fredd and Fogler 1998;Shuchart and Gdanski 1996;Coulter and Jennings 1997;Nasr-El-Din et al 1997;da Motta et al 1998;Huang et al 2000a, 200b;Wang et al 2000;Nasr-El-Din et al 2001;Frenier 1989;Hashem et al 1999;van Domelen and Jennings 1995;Smith et al 1970;Chatelain et al 1976). The use of a combination of organic and inorganic acids dates back to 1978 (Dill and Keeney 1978).…”

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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Laboratory Acidization of an Eolian Sandstone at 380°F

Cited by 25 publications

References 7 publications

Development of a Unique Organic Acid Solution for Removing Composite Field Scales

Development of a Unique Organic Acid Solution for Removing Composite Field Scales

Permeametry Pitfalls and Opportunities

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

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