Calcium Control Agents - Week 2 Flashcards
Gypsum - Composition
Ground calcium sulphate dihydrate (CaSO4 +(2)H2O)
Gypsum - Primary Function
To formulate gypsum based muds to inhibit shale swelling
Gypsum - Secondary Function
To reduce carbonate levels of water based muds without increasing pH
Gypsum - Limitations
Calcium solubility is limited by pH and chloride levels. To increase calcium levels it may be necessary to decrease pH on increase chlorides
Gypsum - Treatments
For conversion to gypsum based muds 2.0-5.0 ppb are typical. For carbonate removal, the concentration used will depend on the amount of carbonates to be removed
Mil-Lime - Composition
Calcium Hydroxide - Ca(OH)2
Mil-Lime - Primary Function
Varies as follows for WATER BASED MUDS :
- To flocculation clays in spud muds for increased hole cleaning
- To treat out soluble carbonates
- For corrosion control for hydrogen sulfide applications
- For pH increases although not recommended except #3 and above
- Use in clear water drilling to help flocculate corrosion solids
- To prepare lime muds
Mil-Lime - Limitations
- Over treatment can cause flocculation
- High lime concentrations may cause muds to be rhologically unstable at temperatures >250 F
Mil-Lime - Treatment
As needed to achieve desired results
Mil-Lime (Oil base and synthetic muds) - Primary Function
To activate certain emulsifiers ( CARBO-TEC OR OMNI-TEC)
Mil-Lime (Oil base and synthetic muds) - Secondary Function
To provide excess lime for reaction with hydrogen sulfide and carbonates
Mil-Lime (Oil base and synthetic muds) - Limitations
None
Mil-Lime (Oil base and synthetic muds) - Treatment
4 pounds per gallon of emulsifier. As needed for excess lime, usually 1-4 ppb