This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 133631, ’Henry Subsea Development - Challenges and Solutions,’ by Stephen Henzell, SPE, WorleyParsons Services Pty. Ltd., and Andrew Glucina, Santos Ltd., originally prepared for the 2010 SPE Asia Pacific Oil & Gas Conference and Exhibition, Brisbane, Australia, 18-20 October. The paper has not been peer reviewed.
The Henry and Netherby gas fields are in Victorian waters in southeast Australia. They have been developed by extending the Casino production system which comprises two subsea wells in the Casino field producing by pipeline to an onshore gas plant. The entire development is subsea. During the Casino design, provisions were made for future extension of the production system. The full-length paper discusses the provisions made and their effectiveness during the expansion project.
Introduction
The Henry gas development has developed the reserves of the Henry and Netherby reservoirs by extending the existing Casino subsea-production system. The Casino, Henry, and Netherby gas fields are approximately 250 km southwest of Melbourne. The Casino reservoirs began production through two wells in January 2006. Henry and Netherby reservoirs began production in February 2010.
Casino Production System
The Casino production system currently comprises four subsea wells, Casino 4, Casino 5, Henry 2, and Netherby 1. The subsea wells are arranged in a daisy-chain configuration. Each subsea well ties into the pipeline through a short 150-mm-diameter flowline approximately 40 m in length at a tee in the pipeline. The pipeline is routed to pass near each well.
The pipeline has provision for future wells along the pipeline route. The last 5 km of the pipeline extend beyond the Netherby-1 tee to the Pecten East field area. This section of the pipeline currently is suspended, waiting for successful drilling of an appraisal well. The 300-mm subsea pipeline is approximately 55 km in length, laid in two separate sections with a tie-in point between the two at the Casino-4 pipeline-end module (PLEM). The pipeline reaches landfall by a horizontally directionally drilled (HDD) section crossing the shoreline. The subsea pipeline is terminated onshore at the HDD exit in the mainline-valve (MLV) site. The 300-mm onshore pipeline continues approximately 12 km from the MLV site to the Iona gas plant (IGP), where raw gas is processed into export-quality gas and stabilized condensate.
