Case History Discussion:
The objective was to displace the wellbore in a two stage displacement. Displacing the riser first then displacing the wellbore. Removing the 12 lb/gal synthetic base mud from wellbore and riser separately and replacing with filtered 9.2 lb/gal CaCl2 completion fluid.
Rig-Chem designed a displacement package utilizing specialized surfactants and viscosifiers to clean and water wet all surfaces. The products used for wellbore displacement meet all EPA regulations for passing the oil and grease test. This eliminated the expensive task of capturing and disposing of products. The surfactant package designed, works under high turbulence eliminating needed contact time, while reducing expensive rig time.
By utilizing Rig-Chem displacement model software operations were prepared for actual rates and pressures that would be experienced during displacement operations.
Wellbore Information
Rig Semi-Submersible
| Water Depth | 4,421 ft |
| PBTD | 28,959 ft |
| Riser | 19 ¾ in |
| Casing 1 | 10 ¾ in |
| Casing 2 | 9 7/8 in |
| Casing 3 | 7 ¾ in |
| Workstring 1 | 5 7/8 in |
| Workstring 2 | 4 ½ in |
| SBM Mud | 12 lb/gal |
| CaCl2 | 9.2 lb/gal |
| Volume | 3,026 bbls |
| Two Stage Displacement |
Results
- Job was pumped as designed
- Minimum interface of < 75 bbls
- Rotation & reciprocation of workstring
- Immediately after spacers completion fluid was
- was maintained through displacement less than 100 NTU’s and proper density
- Spacers returned on time and easily recognizable
- Preformed short trip and jetted stack, returned to BPTD, circulated to less than 30 NTU’s in < 1 hour
- Workstring and clean out tool were clean and water wet(Picture on right)