Gas Compression Tool Validation

Abstract

A decline in field developments on the Norwegian Continental Shelf over the last years has led to an increase in tie-ins of smaller- and more stranded fields to the existing production facilities. This results in more challenging oil and gas processing and handling, with increased emphasis on reliability and regularity. Altered conditions and production profiles on Njord have resulted in a total replacement of the export gas compressor system. Optimal performance of the process plant implies increased operational flexibility and plant energy efficiency. As a consequence, a reliable and predictable simulation tool with a high degree of accuracy which reflects the actual process is required. The main objective of this thesis is to document and evaluate Aspen HYSYS® v.7.2 with a primary focus on gas compression tool validation. This includes the validation of its fundamental calculations for gas lift compressor performance and a selection of control systems. The respective control systems include anti-surge, speed control and multiple molecular weight curve collections. The overall objective for the validation analysis is to develop a representative model for the new 4th and 5th stage compressors on Njord in order to identify any optimization potential for different production scenarios.