A stepwise approach for identification of water production mechanisms in gas reservoirs

Abstract

Gas resources play a key role in nowadays energy supply, and it provides 24% of the diverse energy portfolio. Water encroachment is one of the main trapping mechanisms in gas reservoirs, and it causes subsequent recovery reduction. There are various reactive techniques that have been applied to cope with excess water production as long as many industry failures for treating water production consistently. The key to effective water control is the source and mechanism of water invasion identification. Reviewing the literature, there are 10 mechanisms for unwanted water production. Although there are a few general approaches to deal with undesirable water production, a stepwise approach to diagnose the source and mechanism of unwanted water production is missing.This paper presents a comprehensive approach employing all available data to identify the mechanism of water production. The proposed approach investigates all the possible water production mechanisms regardless of the severity of the problem. By applying some filters and screen out the irrelevant mechanisms, finding the main mechanism and consequently the necessary counter-reaction is more comfortable. As a case study, this approach was applied in a carbonate gas reservoir encountered a sever water production problem. The water rises 24 meter per year. By applying this approach, the main source and mechanism of water production in this field was recognized without any further diagnostic tests. As a consequence, the appropriate reservoir-based solutions were replaced with previous well-based treatment methods in the field with more than 20% recovery improvement.