An operator in San Juan del Cesar in Colombia experienced differential sticking and significant non-productive time (NPT) while drilling a problematic formation consisting of reactive clays and fragile coal. These formations eventually led to mechanical and chemical instability. Conventional reactive solutions such as fishing, cement plug positioning, and whipstock were ineffective.
A proactive approach to eliminating wellbore instability was introduced. FLC 2000 was incorporated in the drilling fluid system before reaching the problematic formation. FLC 2000 was added to the drilling fluid at a concentration of 8 lb/bbl. Additionally, sand bed tests (SBT) were performed to verify the effectiveness of FLC 2000 in the fluid. After adding FLC 2000 to the fluid, SBTs results showed 6.5 cm of invasion.
The operator reduced NPT by over 80%. The operator drilled the problematic formation without differential sticking. There was also a measured reduction in torque values. The integrity of the formation and subsequent lubricity were maintained. The operator was able to achieve wellbore stability and reach the programmed total depth (TD). Furthermore, there were no issues while performing logging operations and an added benefit were higher rate of penetration (ROP) values while drilling. There was a greater percentage of core sample recovery.