Challenging Development of Marginal Fields and Reservoirs
Authors: Valkenier Peter 
Published: November 2015

This paper will demonstrate some of the ways we use for refurbishment and re-use, smart engineering and the early adoption of new technologies. This allow us to develop the most marginal of developments. Cost reduction and cost saving have been a central part of our philosophy which has led us support the development of many innovative strategies in development and operations, some of which are expounded in this paper.

Wintershall has for many years been an operator in the south of the North Sea, in the relatively shallow waters of the Dutch sector and operates currently 24 platforms and about 1,300 Km of pipelines. One the most valuable assets we have are the people. We empower them to work smartly to resolve the difficulties that we encounter with developments in the sometimes challenging area of the world. The integration across departments start in the very early stage of the exploration, follows through seamlessly to the engineering and construction department. This has virtually a stand alone capability to design oversea and install the platforms and pipelines on almost an annual basis. By evolving and maintaining the knowledge in-house we are able to use the knowledge to deliver complex and economical solutions to some challenging offshore projects. Some of the examples of the difficulties that have been addressed are listed below and reflect the trust we have in our engineers to adopt innovative technologies as they become available.

Wintershall have recently designed and constructed a re-usable platform L6-B of which foundation and topside has been installed in one go. The platform is located in the Dutch continental shelf and the existing L8-P4 installation is used as the receiving facility and host for the L6-B platform. An umbilical from L8-P4 platform provides the L6-B platform with electrical power, fibre optic cable and chemicals. The platform is designed as a Wintershall Minimal Facility Platform (MFP). This means that the installation is operated as a Normally Unattended Installation (NUI) with no processing equipment and only limited utility equipment. The structural design life is 25 years. The structure has three suction piles with 10 m outer diameter with a 9 m penetration. This design allows for easy installation and for removal and re-installation of the platform. It has four deck levels i.e. boat landing deck, cellar deck mezzanine deck and a main deck. Since the MFP does not have a helideck, the only access to the platform is via boat transport. The Boat Landing Deck, located at ca. 6 m above sea level, has two access ladders to the sea level and one access ladder that leads to the cellar deck. The L6-B has two conductor slots. The maximum production is 1,2MNm3 day. The produced gas from the well is reduce in pressure with a choke valve. To protect downstream equipment, the pipeline and the L8-P4 host from overpressure, a High Integrity Pressure Protections System (HIPPS) is installed downstream the choke valve. A maximum shut-in pressure of 690 bar and a maximum temperature of 120 degrees are expected during early field life. The initial process conditions are 106 bar and 110 degrees. The gas is exported to the L8-P4 via an 8" CS pipeline. Methanol can be injected for start-up. Possibility to inject Corrosion Inhibitor (CI) and Kinetic Hydrate Inhibitor (KHI) is provided for and will be transported via umbilical from the L8-P4. The produced gas is treated and metered on the L8-P4 platform. The topside piping upstream the cooling loop is made from Duplex, to resist the increased corrosive condition a higher gas temperatures.