Challenge: The 8½-in directional assembly, drilling in the Buzzard Field, encountered low rates of penetration.
Solution: SLB provided an addition of 2% by volume of SILDRIL system into the GLYDRIL system.
Results: Penetration increased from 15 ft/h to 40 ft/h.
| Well Information | |
|---|---|
| Well Information Location | Buzzard Field, 19/10 - 1z, North Sea |
| Well Information Mud System | GLYDRIL (KCl/ Glycol WBM) |
| Well Information Completion Date | January 2002 |
| Well Information Section Hole Size | 8½-in Sidetrack |
| Well Information Section Length | 6987 ft tangent |
| Well Information Hole Angle | 43º maximum |
The 8½-in directional assembly, drilling in the Buzzard Field, encountered low rates of penetration upon entry into the Rodby Claystone Formation. Rates dropped to below 10ft/hr, despite efforts to alter the drilling parameters. The assembly was pulled on two occasions where the bit found to be balled with compacted claystone.
Different Pills of KCL brine, Nutplug, GLYDRILL and caustic proved ineffective in improving penetration rates. Following a further trip to replace a failed mud motor and a continued rate of penetration of only 15ft/hr, it was decided to introduce silicate to the circulating GLYDRIL system.
Additional inhibition of the system may slow down the accretion process by slowing down the rate at which the shales hydrate hence remain in a plastic state longer. SLB provided an addition of 2% by volume of SILDRIL into the GLYDRIL System.
A pilot test with 5% by volume of sodium silicate liquor showed an unacceptable increase in the system rheology.
SILDRIL (SLB's Sodium Silicate Liquor) is the primary constituent of SLB's highly effective water based SILDRIL system, but has proved effective as a simple addition to SLB's GLYDRIL system to cure bit-balling.
Sodium Silicate Liquor can be used in a range of concentrations and has a HOCNS category E, so is therefore environmentally friendly, and facilitates full discharge to the sea.
If you’d like to know more about GLYDRIL or SILDRIL, please call the SLB office nearest you.
