Glycolic Acid for Oil and Gas: Acidizing, Descaling, and Scale Removal

PureTech Scientific manufactures Glysolve™ O&G 70%, a 70% glycolic acid solution built for the oil and gas and energy services sectors. It’s chloride-free, NSF/ANSI Standard 60 certified, biodegradable (90% in 7 days), and produced domestically in Belle, WV.

How Is Glycolic Acid Used in Oil and Gas?

Glycolic acid serves three primary functions in oil and gas operations: acidizing to improve formation permeability, rehabilitating wells clogged with scale and rust, and finishing wellbore surfaces to prepare them for production.

Well Acidizing

During acidizing, operators pump glycolic acid into the wellbore to dissolve carbonate rock and mineral deposits that restrict the flow of oil and gas. As the acid reacts with calcium, magnesium, and iron, it forms glycolate salts. These salts are water-soluble, which means crews can flush them from the well without leaving behind insoluble residue that would re-block the formation.

Glycolic acid’s slower reaction rate compared to HCl is an advantage here. It penetrates deeper into the formation before fully reacting, which creates better permeability improvement across a wider area of the wellbore.

The table below shows the aqueous solubility of glycolate (hydroxyacetate) metal complexes, which determines how easily these reaction byproducts can be removed from the well.

Aqueous Solubility of Glycoalte (Hydroxyacetates) Metal Complexes

Ref: US6695968 'Removal of Water Soluble Organics', 2004, Baker Hughes Incorporated

Well Rehabilitation and Descaling

Over time, oil wells accumulate rust, carbonate scale, iron deposits, and other particulates that reduce production. Glycolic acid cleans these deposits by chelating the metal ions that hold them together. When glycolic acid complexes with a metal ion, it forms a soluble salt that operators can pump from the well. This makes it effective against calcium carbonate scale, magnesium deposits, and iron-based fouling.

Operators also use glycolic acid in pipeline maintenance to remove buildup that restricts flow. Its compatibility with other acids and oilfield additives makes it easy to blend into existing treatment programs.

Wellbore Finishing

After drilling and completion, glycolic acid prepares the wellbore surface for production. It cleans residual drilling fluids and mineral deposits from the well casing and formation face, which helps maximize flow from the start of production.

Why Use Glycolic Acid Instead of HCl or Mineral Acids?

Hydrochloric acid (HCl) has been the default workhorse for well acidizing and descaling, but it comes with trade-offs: aggressive corrosion to tubulars and equipment, high volatility, strong fumes, and chloride content that can cause secondary damage. Glycolic acid solves those problems while still delivering strong cleaning and dissolving performance.

Glysolve™ O&G 70% offers several operational advantages over mineral acids. It’s nonflammable with low odor and low vapor pressure, which simplifies handling and storage. It’s biodegradable and won’t add undesirable BOD or COD to formulated products. And it’s chloride-free, which eliminates the chloride-induced corrosion risk that comes with HCl.

The corrosion difference is dramatic. In 48-hour immersion testing at 70°C, glycolic acid caused 10.53% weight loss on C1018 carbon steel compared to 53.22% for HCl. That’s a five-fold reduction in metal loss. On galvanized carbon steel, glycolic acid showed 15.50% weight loss versus 100% for both sulfuric acid and HCl.

Percent Weight Loss at 70°C (10% Acid Concentration, 48-Hour Immersion, No Agitation)

Results are the average of triplicate analysis, 10% acid (100% basis). Immersed in 200 ml of solution for 48 hours with no agitation.

On stainless steel (SS304 and SS316), glycolic acid’s corrosion is nearly zero: 0.008% and 0.002% weight loss respectively. HCl caused 15.22% and 18.46% on the same alloys. For operators running stainless or copper-alloy equipment, glycolic acid is the clear choice.

How Does Glycolic Acid Remove Scale in Oil Wells and Pipelines?

Glycolic acid’s chelation mechanism sets it apart from simple mineral acid dissolution. Both its hydroxyl and carboxylic functional groups participate in binding, forming stable five-member ring complexes with polyvalent metals like calcium, magnesium, and iron. These ring structures lock the metal ion into a soluble complex that flushes cleanly from the system.

This dual-functional chelation is more than a chemical curiosity. It means glycolic acid dissolves scale and holds the dissolved metals in solution, preventing re-precipitation downstream. Mineral acids can dissolve scale effectively but sometimes release metal ions that re-deposit elsewhere in the system. Glycolic acid’s chelation keeps those ions tied up.

The table below compares how much calcium carbonate (CaCO₃) each acid dissolves per kilogram of chelant over time.

CaCO₃ Scale Removal Efficacy (Grams of Calcium Carbonate Dissolved per Kilogram of Chelant)

Exposure time in minutes. Grams of calcium carbonate per kg of chelant.

At 300 minutes, glycolic acid dissolved 612 g/kg of calcium carbonate. That outperformed citric acid (323 g/kg), EDTA-sodium (237 g/kg), gluconic acid (222 g/kg), and lactic acid (447 g/kg). Only sulfuric acid came close at 510 g/kg, but sulfuric acid’s corrosion profile makes it impractical for many oilfield applications.

How Does Glycolic Acid Compare to Other Oilfield Acids?

Glysolve™ O&G 70% can replace or supplement a range of organic and inorganic acids used in oilfield operations. Here’s how it stacks up:

vs. Hydrochloric Acid (HCl): Glycolic acid offers dramatically lower corrosion (5x less metal loss on carbon steel), no chloride content, and a slower reaction rate that allows deeper formation penetration during acidizing. HCl remains faster-acting on carbonates at low temperatures, but the trade-off in equipment damage and handling hazards is steep.

vs. Citric Acid: Glycolic acid dissolves nearly twice the calcium carbonate that citric acid does at 300 minutes (612 g/kg vs. 323 g/kg). Citric acid plateaus early in the reaction, while glycolic acid continues dissolving scale over extended contact times.

vs. Phosphoric Acid: Both show moderate corrosion on carbon steel, but phosphoric acid is far more aggressive on aluminum (19.94% vs. 0.38% weight loss). Glycolic acid is also phosphate-free, which matters for environmental compliance in certain jurisdictions.

vs. Lactic Acid: Corrosion profiles are similar, but glycolic acid dissolves 37% more CaCO₃ at the 300-minute mark (612 g/kg vs. 447 g/kg).

vs. Acetic and Formic Acid: Glycolic acid provides stronger scale dissolution and better metal chelation, with the added benefit of NSF/ANSI 60 certification for use in potable water systems.

Industrial Boiler Cleaning for Oil and Gas Facilities

Beyond downhole applications, glycolic acid is available in formulations designed for industrial boiler cleaning. These formulations target boilers fouled with various scales, providing low-cost metal complexing in a biodegradable form that won’t add excess biological oxygen demand (BOD) or chemical oxygen demand (COD) to the treated water.

Why Formulators and Operators Choose Glysolve™ O&G 70%

Glysolve™ O&G 70% from PureTech Scientific combines strong chelation, low corrosion, and effective carbonate dissolution in a single product. It chelates rust, scale, and particulates into soluble salts that operators can pump directly from the well, and it does so with far less metal loss than mineral acids. It dissolves carbonate scale efficiently, works as a precise pH adjuster in treatment fluid formulations, and blends easily with other acids and oilfield additives. Operators pair it with hydrochloric and sulfamic acids to prevent iron precipitation during cleaning and water flooding. Corrosion testing should be performed on construction materials before use.

The product itself is built for practical field use. It’s highly water-soluble, chloride-free, nonflammable, and nonvolatile with very low vapor pressure and low odor. It’s biodegradable (90% in 7 days), low in toxicity (LD50 for rats = 1,938 mg/kg), VOC exempt in California, and NSF/ANSI Standard 60 certified for use in potable water systems. Those specs add up to simpler handling, easier storage, and fewer regulatory hurdles compared to the mineral acids it replaces.