I.M. KutasovMultiSpectrum Technologies Inc.Santa Monica, Calif.
Sodium chloride added to drilling mud left in the annulus helps lower the fluid's freeze point, eliminating the chance of casing collapse from thaw/refreeze cycles in the permafrost around the well.
Arctic drilling experience has shown that extensive washouts occur in the permafrost interval. Thus, the drilling mud cannot be properly displaced prior to setting of the surface casing.
When a well is shut in during or after drilling or after a short production period, thawed permafrost and water-based fluids outside the casing wilt refreeze and generate inward r...