What Does Workover Fluid Mean?
Workover fluid, in the context of drilling fluids, refers to the well-control fluid such as brine that is used during workover operations. Workover fluids are used during the reworking of a well after its initial completion. These fluids have to be clean and chemically compatible with the reservoir fluids and formation matrix, as there is constant contact between the wellbore and reservoir during workover operations. Workover fluids do not contain drill solids such as those present in drilling fluids.
Trenchlesspedia Explains Workover Fluid
Workover fluids can be gasses such as nitrogen or natural gas, brine waters or muds. They are used for remedial work such as removing tubing, replacing a pump, logging, reperforating, and cleaning out sand and other deposits. These fluids can also be used for operations such as well killing, drilling into a new production interval and plugging back to complete a shallower interval.
Workover and completion fluids can be categorized as:
- Water-based fluids containing oil-soluble organic particles
- Acid-soluble and biodegradable
- Water-based with water-soluble solids
- Oil-in-water emulsions
- Oil-based fluids
There are three types of workover fluids:
- Clear liquids (dense salt solutions)
- Suspensions containing calcium carbonate weighting material
- Water-in-oil emulsions made with emulsifiers for oil muds