Glycolic Acid Improves Performance in the Oil and Gas Industry
Glycolic acid enhances cleaning and descaling processes in oil field and petroleum refining applications. This acid also provides metal complexing in a biodegradable form without adding undesirable biological or chemical oxygen demand to formulated products.
Glycolic acid's slower reactivity compared to mineral acids helps with acid finishing during well completion. Desalting crude oil, well acidizing, and synthetic drilling mud also rely on glycolic acid.
Glycolic acid is phosphate-free, biodegradable, and doesn't accumulate in the environment. This nonflammable, corrosion-resistant glycolic acid 70% tech grade has:
- Low odor
- Low toxicity
- Low vapor pressure
How Glycolic Acid Works
Glycolic acid can be used with hydrochloric or sulfamic acids to prevent iron precipitation in cleaning operations or water flooding. It also effectively eliminates harmful deposits while minimizing corrosion damage to steel or copper systems.
Scale Control and Remediation
Glycolic acid removes rust, scale, and particulate found in wells and production equipment. Glycolic acid complexes with the metal ions to form a soluble salt that can be pumped from the well easily. Low corrosion of the well's metal parts reduces the chance of equipment damage. Its strong acidification property removes carbonate based scale.
Horizontal Well Stimulation
Glycolic acid reacts more slowly and thus penetrates more deeply into formations before fully reacting. That characteristic leads to enhanced worm holing, because glycolic acid dissolves the equivalent amount of calcium carbonate (CaCO₃) as hydrochloric acid without the resulting corrosion.
Gypsum, or calcium sulfate (CaSo₄) scale, is a hard deposit that blocks pipes and is difficult to remove. In a case study that used a descaling solution of ammonium glycolate, ammonium malate, and water, the descaling solution was injected into a pipe and left to set for 22 hours. This one-step procedure resulted in 85 to 100% removal of the CaSo₄ scale, with a lower process downtime (24 hours rather than the usual 48 to 72 hours descaling often takes).
Metal Naphthenate Dissolution
Naphthenate is a carboxylic acid containing saturated cyclic hydrocarbons like cyclopentane and cyclohexane. Glycolic acid competes with naphthenate for metal cations to form water-soluble glycolate salt. Glycolic acid can also increase protonation by changing the solubility and phase partition of the naphthenates. Protonated naphthenic acids are much more oil soluble than ionized napthenates.
Removal of Water Soluble Organics
Oil consists mainly of dispersed organics—but some organics dissolve in water in measurable concentrations. Gravity-based separation methods do not remove water-soluble organics (WSO). These WSO are soluble in water at typical operating pH values and exist in produced water.
Oil pumped out of the ground is mixed with water, which the industry refers to as "produced water." In offshore platforms, produced water is cleaned to a low-enough water soluble organic (WSO) level and discharged overboard. WSO are the polar part of the evaporated hexane extract and include dissolved and polar organics in produced water.
Produced water overboard discharge—while permitted in much of the world—is subject to discharge limits. For example, in the Gulf of Mexico, hydrocarbons in produced water are limited to 29 mg/l (monthly average). US regulations define hydrocarbons as compounds that extract into n-hexane solvent from water at a pH >2 and that remain after the solvent has been boiled away.
Using glycolic acid in WSO removal is preferable to other methods because glycolic acid is:
- Far less corrosive
- Compatible with existing water clarifier treatments, unlike quaternary ammonium compounds (QACs)
- Effective in a wide treatment range, unlike QACs
- Usable in combination with anionic surfactants or mineral acids