Many gas wells in Adriatic Sea are suffering from both water and sand production. An original sand control polymer technology has been successfully implemented and has proven to be an efficient way to stop sand production and thus maintain gas well under steady production. In many wells, a reduction of water production was observed as side effect. Nevertheless, the main objective remained sand control and not water control.
The present paper describes a polymer treatment performed in an offshore well equipped with sand control gravel-pack downhole completion. This well was suffering of high level of water production inducing a severe decline in gas production. The preparation of the treatment consisted of lab coreflood tests aiming at checking the behavior of the selected polymer (P-321) in actual reservoir conditions. The product was shown to have good injectivity and to strongly adsorb on the reservoir rock. Moreover, it has good RPM properties, inducing a strong reduction in water relative permeability while preserving gas relative permeability.
The treatment proceeded in the bullhead mode, i.e. through the gravel pack. The polymer was followed by a Nitrogen postflush to squeeze the product deep in the formation and help restarting the well. Immediately after treatment, gas rate increased while water rate levelled off. Both gas rate and GWR (Gas Water Ratio) stopped declining and remained at same level for two years. After two years, the estimated additional gas production was 13,330 KSCM and the well keeps flowing steadily instead to be probably shut in if it had followed its initial decline trend.