Completion and workover fluids are any fluids used in the completion of a well or in a workover operation. These fluids range from low-density.
Various types of fluids may be used for completion and workover operations:
1. Oil fluids
- Mineral oil
2. Clear water fluids
- Formation salt water
- Prepared salt water such as calcium chloride, potassium chloride or sodium chloride salt and zinc, calcium, or sodium-based bromides.
3. Conventional water-base mud
4. Oil-base or invert emulsion muds
Completion or workover fluids may be categorized as:
- Water-base fluids containing oil-soluble organic particles
- Acid-soluble and biodegradable
- Water base with water-soluble solids
- Oil-in-water emulsions
- Oil-base fluids
Three types of completion or workover fluids are
- Clear liquids (dense salt solutions)
- Weighted suspensions containing calcium carbonate weighting material, a bridging agent to increase the density above that of saturated solutions.
- Water-in-oil emulsions made with emulsifiers for oil muds
Clear liquids have no suspended solids and can be referred to as solidsfree fluids. Weighted suspensions are fluids with suspended solids for bridging or added density. These fluids can be referred to as solids-laden fluids.
For solids-free fluids, water may be used in conjunction with a defoamer, viscosifier, stabilized organic colloid, and usually a corrosion inhibitor. Solids-free completion and workover fluids have densities ranging from 7.0 to 19.2 pounds per gallon (ppg) (0.84 – 2.3 SG).
Solids-laden fluids may be composed of water, salt, a defoamer, suspension agent, stabilized organic colloid, pH stabilizer, and a weighting material/bridging agent.