Construction of die BP Endicott facility offshore Prudhoe Bay Alaska was completed and oil production began in October 1987. The facility consists of two gravel islands, the Main Production Island (MPI) and the Satellite Drilling Island (SDI), linked to one another and the mainland by two gravel roads. The islands are located in water between 2.1 m (7 ft.) and 3.7 m (12 ft.) in depth and have a working surface elevation of 3.7m (12 ft.) with respect to mean sea level. The Endicott facility is unique in the world in that it is the first offshore production system founded on a gravel island at any arctic location. All production modules were placed on concrete spread footings whose upper surface is level with the island surface. The main modules weighed between 2,200t and 5,200t. The seabed underlying Endicott consists of about 10m of frozen silts, clays and organics, underlain by silty sands and gravels. There was concern during the facility design that the settlement of the footings due to strain of the gravel and the seabed, and due to thawing of the frozen seabed near the production wells, might lead to excessive footing settlements and overstressing of the module framing and of connecting piping. As a result, after placement, the footings' elevations were measured biannually for a period of 10 years for the process modules and 4.5 years for the lighter pipe rack modules. The settlement data indicated that the settlement rate steadily decayed with time. After a few years the modules experience either a settlement “shut off” or heaving, probably due to thermal cooling of the gravel in the islands. The largest recorded footing settlement was 50 mm (2 inches). The maximum differential settlement was 12mm giving a settlement to span ratio (△/L) of I/575. As well, small seasonal fluctuations of about 5mm (0.2 inches) were clearly visible in the data indicating heaving of the modules during the winter and settling during the summer. The information obtained from Endicott on footing settlement is being used for the design of gravel island production structures in deeper water.
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机译：Die BP endicott设施的建设近岸Prudhoe Bay Alaska完成了1987年10月的石油产量。该设施由两个砾石群岛，主要生产岛（MPI）和卫星钻井岛（SDI）组成，彼此联系在一起大陆两条碎石路。岛屿位于2.1米（7英尺）和3.7米（12英尺）之间的水中，深度为3.7米（12英尺），相对于平均海平面具有3.7米（12英尺）的工作面升高。 endicott设施在世界上是独一无二的，这是第一个在任何北极地点的砾石岛上创立的海上生产系统。所有生产模块都放在混凝土蔓延的基础上，上表面与岛表面水平。主要模块在2,200t和5,200t之间。海底底层诺基特鹦鹉由大约10米的冷冻淤泥，粘土和有机物，由粉质和砾石底层。在设施设计期间存在担心，由于砾石和海底的菌株，以及由于生产井附近的冷冻海底的解冻而导致的基础，可能导致模块框架的过度沉降和过度关容。连接管道。因此，在放置之后，将距离较轻的管道架模块为4.5岁的平台上升到10年的升高。结算数据表明结算率稳定地随时间腐烂。几年后，模块经历了沉降“关闭”或起伏，可能是由于岛上的砾石的热冷却。最大录制的基础沉降为50毫米（2英寸）。最大差分沉降为12mm，为I / 575的跨度比率（△/l）提供沉降。同样，在冬季期间模块的起伏时，清晰可见的小季节性波动约为5mm（0.2英寸），并在夏季沉降。从Endicott获得基于终结结算的信息，用于更深的水中的砾石岛生产结构的设计。
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