Analysis of Gas Influxes in Oil-Based Muds in the Gullfaks Field

Abstract

Several gas-influx events have occurred during drilling with oil-based mud on the Gullfaks field. These have usually started when hard chalk stringers were penetrated, and abnormal pressurized gas bearing zones were drilled into. These zones are often of low productivity ·and val ume.Based on all available data from the influxes in wells I and II, the events have been analyzed. The analysis has helped to explain the development of the influx events, and also the control phases have been evaluated.