Capacity Upgrading of Offshore Oil and Gas Production Facility

Abstract

The design of existing offshore processing facilities for oil and gas often need to be reconsidered after some years of production due to changes in operating conditions. One example is the Ekofisk 2/4 J facilities. Here, the water production is increasing and increased amount of lift gas is required to maintain and increase the current oil and gas production. The recycle of lift gas requires capacity in the gas treatment and compression train, limiting total available capacity for export gas. The objective of this work has been to develop a HYSYS model of the processing facility at Ekofisk 2/4J and analyze and review capacity upgrade options. Several cases were established in order to identify the relevant bottlenecks in the processing facility by increasing the production of low-pressure and high-pressure gas. The findings in this thesis indicates that there are three major bottlenecks in the gas processing system at Ekofisk 2/4 J. Those are: The capacity of the LP separator. The capacity of the Lift Gas compressor. The capacity of the dehydration tower.Several debottlenecking options are discussed and analyzed, in order to estimate the potential increase in lift gas production and to determine whether the bottlenecks are easy or difficult to overcome. On the basis of the results and discussion in this report, the recommended changes to the processing facility at Ekofisk 2/4J are as follows: Increase the volumetric utilization of the LP separator, if possible. Replace the current lift gas compressor and driver with new high-capacity equipment. Make internal changes to the dehydration tower in order to increase the flow capacity.