Nitrogen Cushion : A cushion of nitrogen gas placed on top of a liquid column to reduce the downhole pressure. Also use in the annulus for an expansion cushion in the event of annular fluid expansion
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}