New coring fluid for vuggy carbonates

A salt-weighted coring fluid that contains a biodegradable cotton-fiber product, normally used to control lost circulation, was used to obtain 1,048 ft [319.4 m] of carbonate core from a well in the Arun field in northern Sumatra, Indonesia. The vuggy core was free of mud solids and required special cleaning only to remove salt deposits. This fluid should be beneficial in coring other vuggy carbonates, and modifications should make the fluid usable for both high-permeability and unconsolidated sandstones in which mud-solids invasion is a problem.