Gas Shut-Off Foam Treatments

Abstract

Abstract In reservoirs with a thin oil rim below a gas cap, oil production can be severely hampered by gas coning or cusping problems. Oil production can be improved by means of in-situ generation of a gas-blocking foam barrier in the near wellbore area. Candidate wells in the Eastern Division of Shell Petroleum Development Company of Nigeria were selected for field testing Gas Shut-Off foam treatments on the basis of high Gas/Oil Ratios (GOR), low BSW, reserves availability etc. Laboratory tests were conducted to identify suitable foamer systems and construction of reservoir simulation models took place to estimate the potential of the treatments with respect to oil production and GOR reduction. Eight wells have been treated using two foamer systems and two different foam generation techniques. The results vary between a significant reduction in GOR for more than twelve months, i.e. from 7000 scf/bbl to 2000 scf/bbl at an increased oil rate from 340 to 450 bopd and treatments resulting in a minor GOR reduction for only a few weeks. It can be concluded that, on average the treatments have a 50+% success rate. P. 459