Hiltek Resource Recoverywith BioActive Services

Wellbore BioChemistry Root cause 5 of 7

Scale in Oil Wells: Causes, Costs and the Remedy

Mineral scale crystallizes out of produced water as pressure and temperature fall, or when incompatible waters mix. It narrows tubing and perforations and shortens pump life.

What it is and what it costs

Mineral crusts the water keeps bringing

Cross-section of scaled production tubing with a narrowed boreBlockage
From the water
What it is
Mineral crusts: calcium carbonate and barium, strontium and calcium sulfate, often mixed with iron sulfide.
What causes it
Produced water drops its minerals as pressure and temperature fall on the way up, or when incompatible waters mix: injection water or frac fluid with formation brine.
Lifting costs: the usual fixes and why they repeat
Inhibitor squeezes that last about 3 to 12 months, acid for carbonate scale, and milling for sulfate scale, which barely dissolves in acid. The water keeps bringing minerals, so the jobs repeat.
Profitability
Scale narrows the tubing and perforations, can build up in 24 hours or less, and shortens pump and motor life; a stuck pump means a pulling job.
  • 30,000 barrels a day to zero in 24 hours: one North Sea well choked by scale. Cleaning out that single well cost about as much as the chemicals to treat the whole field.
  • Under a year to over 1,100 days: pump run times in an Argentine field before and after a scale inhibitor program.

What this does to a well’s life: Lifting Costs and Well Life

SPE PetroWiki; Habibi, JPT (2019); Hart Energy.

The remedy

What ChainBreaker does about scale

Removing biofilm takes away places for scale to attach. BioActive reports that bond cleaving keeps calcium carbonate, barium sulfate and strontium sulfate from forming problem scale, while existing scale dissolves slowly, layer by layer.

In fracked wells, frac fluid meeting formation brine adds to the scale: see Fracked Wells.

Keep the safeguards. Keep scale inhibitors in place until water analyses and pull records show a sustained improvement.

Start with a Production Pilot How ChainBreaker works

Sources for this section