MEASURING CO2 MINIMUM MISCIBILITY PRESSURES - SLIM-TUBE OR RISING-BUBBLE METHOD

Determinations of carbon dioxide minimum miscibility pressures (MMP) u sing a slim-tube apparatus were compared with those using a rising-bub ble apparatus (RBA). MMPs were determined for 12 different oils, with gravities varying from 34 to 51 degrees API. The results were found to compare very well when using a specific criterion for the slim-tube M MP. Although the slim-tube method is often referred to as the industry standard, there is no standard design, no standard operating procedur e, and no standard criterion for determining MMPs with the slim tube. It is shown that the RBA is faster and more reliable than the slim tub e for determining MMP. Bubble behavior is described for both the vapor izing and condensing gas processes.