Key Chemical & Mineralogical Properties of Produced Solids: Part 1

The physical properties of produced sand, as covered in the previous seven articles, are the most important for designing a Facilities Sand Management system. The chemical and mineralogical properties of produced solids are of secondary importance, but can affect corrosion potential, sand cleaning, and oil coating of solids. These properties will be discussed in two articles so that the scope of sand properties is fully covered.

Produced Solids are Chemically Inert

Produced sand is inert (will not react or react only slightly) to most every condition experienced in oil and gas production

Silica/Quartz/Sand

• Not degraded by temperature, hydrocarbon, salinity, pH, CO₂/H₂S, or dissolved solids experienced in normal oil & gas production
• Negligibly affected by HCl and H₂SO₄ acids
• Can be dissolved by HF acid and pH >12 (concentrated NaOH)

Clay/Carbonate

• Not degraded by temperature, hydrocarbon, salinity, pH, CO₂/H₂S, or dissolved solids experienced in normal oil & gas production
• Carbonate attacked by all acids to varying degree
• Clay attacked by most acids to lesser degree and high pH

Corrosion Potential

One of the primary reasons for preventing solids build-up in production separators, is increased corrosion potential due to the presence of these solids.

• Sand itself does not cause corrosion – silica is not part of the galvanic cell
• However, settled solids form a stagnation zone beneath which pitting (crevice) corrosion is induced. Photo of pitting corrosion below (from here).