Tulsa-based Williams recently took delivery of DNV’s software package, Sesam, including the fully-coupled, timedomain, analysis module DeepC. The company’s Midstream business gathers, processes and transports natural gas, and gathers and transports crude oil from both onshore and offshore locations, primarily in the continental U.S. and offshore Gulf of Mexico.
From offshore locations, Midstream has three major oil pipeline gathering systems and six major gas pipeline gathering systems, each with associated production platforms, delivering their contents to onshore processing plants and distribution stations. In recent years, these gathering systems have been extended to floating production systems in deeper waters, some owned by Midstream and some serviced by Midstream export lines. As water depths increase, the capital investments and technical challenges of designing, installing and operating these export gathering systems of risers and pipelines increase dramatically.
In response to the technical challenges and business opportunities, Midstream formed a Deepwater Services Group in Houston. This staff provides specialised engineering assurance and project management for the riser systems and trunk pipelines that deliver gas and oil from the floating facilities to the onshore connection points. DNV Software’s Sesam, and particularly its module DeepC, are already being used to check the designs and design inputs for the newest gas and oil export risers that Williams will own and operate from systems in over 6,000 feet of water. Future applications of this software include integrity reviews of systems already in service, and checks of hull structures for future floating systems where Midstream might be an owner/ operator of the full floating facility.
DeepC provides unique modelling, analysis and post-processing capabilities for the coupled global response of deepwater floating systems. DeepC is unique in the sense that the damping coefficients are updated for each time step based on a non-linear analysis.
Author: Robin Converse, Williams