Boris KurochkinScientific Research Institute of Drilling TechniquesMoscow
A mixture of latex and drilling mud clay controls lost circulation in large carbonate fractures by coagulating when it mixes with the formation fluids.
The mixture forms large aggregates capable of plugging large formation fractures and is not prone to being washed out by formation water.
In the Ural-Povolzhie oil regions in Russia, drilling mud lost circulation occurs in several horizons located at different depths. The lost circulation zones at depths to 300-400 m are usually cased. The next interval is typically drilled with a 215.9-mm bit, and 146-mm production casing is then run.
Below the surface casin...