Shell announced final investment decision for Stones in May 2013. This set in motion the construction and fabrication of the host floating production, storage, and offloading (FPSO) vessel and subsea infrastructure. In November 2015, construction was completed on the FPSO, which set sail from the shipyard in Singapore to its final destination in the Gulf of Mexico. Phase one of the project includes eight subsea production wells tied back to the FPSO. Multiphase seafloor pumping is planned for a later phase to pump oil and gas from the seabed to the vessel, increasing recoverable volumes and production rates.
The Stones field is estimated to contain over 2 billion boe. We plan to boost productivity and recovery in phases, using our innovative technology and project development expertise.
Stones is a phased development that will start with two subsea production wells tied back to a FPSO vessel and host facility. In later phases we will add six more wells with multiphase pumping. All eight wells will be connected to the FPSO through a single drill centre. The reservoir depth is around 8,077 metres (26,500 feet) below sea level and 5,181 metres (17,000 feet) below the mud line.
An FPSO design was selected to safely develop and produce the Stones ultra deep-water field. This concept design can handle a relative lack of infrastructure, a complex seabed, and unique reservoir properties. Tankers will transport oil from the Stones FPSO to US refineries, and gas will be transported by pipeline.
Stones will be Shell’s first FPSO in the Gulf of Mexico, but not globally. Shell is using FPSOs at other locations, including the Parque das Conchas (BC-10) project off Brazil with co-owners ONGC and Qatar Petroleum International.
The Stones FPSO will use a special type of flexible pipe that carries oil and gas to the FPSO for processing and transport, known as lazy wave risers. These were pioneered by Shell and are made of steel with extra buoyancy. An arch bend absorbs the motion of the FPSO and boosts riser performance at extreme depths.
The FPSO will also contain a turret with a detachable buoy that allows the vessel to turn in place during normal weather conditions. If a heavy storm or hurricane approaches, it can disconnect its mooring lines and risers from the well system and sail to safe areas.
Stones will be the first time a turret and disconnectable buoy is configured with lazy wave risers in order to unlock oil production in ultra-deep waters.
Environment and society
Shell prioritises social and environmental responsibility. Shell’s Gulf of Mexico operations are closely tied to Louisiana and the city of New Orleans. Following Hurricane Katrina, for example, we contributed to many recovery programmes. Shell is also involved in projects such as protecting the Louisiana coast and wetlands restoration.