Drilling through Hydrothermal Dolomites
12 November 2015
Looking for any experience drilling in hydrothermal dolomites with significant losses. Will redrill an exploration well that encountered about 4000 ft of this dolomite with usual list of calamities due to the losses and looking for solutions to do it differently. Planned hole size is 17-1/2" intermediate hole with directional work planned.
We often encounter similar dolomites here in the Western Desert with significant losses in deeper sections although usually only a few hundred feet thick and in vertical hole. Normal course of action is to fight the losses to make it to next section and cover with a contingency liner. We have attempted cement across these zones with little success.
My understanding of hydrothermal dolomites are recrystallised
limstone formations with very large vugular porosity. Any input appreciated.