Description

Pressure balance between the wellbore and formation is often quite sensitive due to narrow pore pressure and fracture pressure window. It gets more attention while drilling through fractured or vuggy rocks, which could easily attribute to downhole mud losses. Sealing the loss zone is of great concern, since it may take significant amount of resources before re-commence to drilling in a safe environment. GEOS has successfully cured a challenging thief zone with specially tailored LCM blends while drilling for a major operator.

Situation:

While drilling through a vuggy, cavernous, and fractured tuffs in 12 ¼ in hole with WBM, faced and cured downhole losses rates of which varied from seepage to total loss.

Challenges and Problems:

* Highly fractured and vuggy volcanic rocks and marls, loss zones confirmed with geomechanical study

* Offset well was abandoned due to downhole losses

* Erratic downhole losses with rates between 20 bbl/hr to total losses.