Circulation, Loss of (or Loss Circulation) : The result of drilling fluid escaping into the formation by way of crevices or porous media. (Bul 10C, Bul D11)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}