Hydrate risk management at end of field life: opportunities to maximise recovery

Abstract

Hydrate management is a pervasive challenge for the offshore oil and gas industry. The consequences of a hydrate blockage in a flowline can be significant due to deferred production and additional expenditure to remediate a blockage. A common hydrate management strategy for gas-condensate systems is to avoid hydrate formation using a thermodynamic inhibition strategy. Towards end of field life, costs associated with inhibiting produced water can increase OPEX and CAPEX. The reduced production and increased costs associated with hydrate avoidance can create economic pressure to discontinue production. An alternative to this is to consider a commercial risk-based hydrate management strategy, which can result in considerable OPEX and CAPEX savings, making marginal developments economic. A case study on the adoption of a successful risk-based hydrate management strategy is presented. The goal was to maximise production from a declining asset to deliver incremental business value. Historically a hydrate avoidance strategy had been used; to continue with hydrate avoidance would have needed further capital outlay to manage the produced water from the declining reservoir. It was determined that during normal operation, hydrate risk could be managed without the need for continuous injection of a hydrate inhibitor. Further, in the event of an unplanned shutdown, where the hydrate risk is greater, it was also demonstrated that the production system could be restarted with minimal intervention.