21Lesson Twenty-one（ok）

Lesson Twenty-one Mobile Drilling Platforms The underwater search has been made possible only by vast improvements in offshore technology. Drillers first took to the sea with land rigs mounted on barges towed to location and anchored or with fixed platforms accompanied by a tender ship (Fig.1). A wide variety of rig platforms has since evolved, some designed to cope with specific hazards of the sea and others for more general work. All new types stress characteristics of mobility and the capability for work in even deeper water. The world’s mobile platform fleet can be divided into four main groupings: self-elevating platforms, submersibles, semisubmersibles, and floating drill ships. Fig. 1 Offshore fixed drilling platform The most widely used mobile platform is the self-elevating, or jack-up, unit (Fig.2) It is towed to Fig.2 Offshore self-elevating drilling platform. (a)----Underwater design (b)-----self-elevating drilling platform location, where the legs are lowered to the sea floor, and the platform is jacked up above wave height. These self-contained platforms are especially suited to wildcat and delineation drilling. They are best in firmer sea bottoms with a depth limit out to 300 ft (90m) of water. The submersible platforms have been developed from earlier submersible barges which were used in shallow inlet drilling along the United States Gulf Coast. The platforms are towed to location and then submerged to the sea bottom. They are very stable and can operate in areas with soft sea floors. Difficulty in the rapidity with which they can be raised or lowered, once on location. Semisubmersibles (Fig.3) are a version of submersibles. They can work as bottom-supported units or in deep water as floaters. Their key virtue is the wide range of water depths in which they can operate, plus the fact that, when working as floaters, their primary buoyancy lies below the action of the waves, thus providing great stability. The “semis” are the most recent of the rig-type platforms. Floating drill ships (Fig.4) are capable of drilling in 60-ft (18-m)to abyssal depths. They are built as self-propelled ships or with a ship configuration that requires towing. Several twin-hulled versions have been constructed to give a stable catamaran design. Floating drill ships use anchoring or ingenious dynamic positioning systems to stabilize their position, the latter being necessary in deeper waters. Floaters cannot be used in waters much shallower than 70 ft because Fig. 3 Offshore semisubmersible drilling platform Fig. 4 Floating drill ship. Such ships can drill in depths from 60 to 1000 tf (18 to 300m ) or more of the special equipment required for drilling from the vessel subject to vertical movement from waves and tidal changes, as well as minor horizontal shifts due to stretch and play in anchor lines. Exploration in deeper waters necessitates building more semisubmersible and floating drill ships. A conventional exploratory hole has been drilled 50 mi (80km) off the coast of Gabon in 2150 ft (655m) of water by Shell Deep Water Drilling Company using the Sedco 445 drill ship. The Glomar Challenger has drilled stratigraphic holes in the sea floor to a depth of 3334 ft (1016m) in water depths of 20000ft (6km). (From “McGraw-Hill Encyclopedia of Science and Technology”, Vol.9.1982) Technical Terms 1.​  2.​ mobile drilling platform 移动式钻井平台 3.​ offshore technology 离岸（近海）技术 4.​ driller 钻井船，钻机 5.​ land rig 陆用钻机 6.​ fixed platform 固定式平台 7.​ tender ship 供应船 8.​ rig platform 钻井平台 9.​ self-elevating platform 自升式平台 10.​ submersible （platform）座底式（平台） 11.​ semisubmersible (platform) 半潜式（平台） 12.​ floating drill ship 浮动式钻井船，钻井船 13.​ jack-up platform/unit 自升式平台 14.​ leg 桩腿 15.​ sea floor 海底 16.​ self-contained platform 自持式平台 17.​ wildcat drilling （打）预探井 18.​ delineation drilling （打）估产井 19.​ shallow inlet 浅水内湾 20.​ version 形式，变种， 21.​ bottom-supported unit 座底式平台 22.​ floater 浮动式平台（或船），漂浮物 23.​ virtue 优点 24.​ abyssal depth 极深的深度 25.​ twin-hulled version 双体船型 26.​ catamaran 双体船 27.​ dynamic positioning system 动力定位系统 28.​ tidal change 潮汐变化 29.​ stretch and play 绷紧和松弛 30.​ exploration 勘探 31.​ exploratory hole 勘探井 32.​ stratigraphic hole 地层孔 Additional Terms and Expressions 1.​  2.​ dynamic positioning drilling ship 动力定位钻进船 3.​ supply vessel 供应船 4.​ single point mooring 单点系泊 5.​ multi-point mooring 多点系泊 6.​ single anchor leg mooring 单锚腿系泊 7.​ Mobile Offshore Drilling Units(MODU) 移动式近海钻井平台 8.​ single buoy mooring 单浮筒系泊 9.​ surface units 水面浮式钻井平台 10.​ self-propelled units 自航式钻井船 11.​ column stabilized units 立柱稳定式钻井平台 12.​ drilling ship 钻井船 13.​ mobile maintenance platform 移动式维修平台 14.​  articulated buoyant tower 铰接式浮力塔 15.​  escort ship 护卫舰 16.​  submerged zone 全浸区，下潜区 17.​  tidal/splash zone 高潮水面与低潮水面之间的飞溅区 18.​  critical structural element 关键构件 19.​  primary structural element 主要构件 20.​  secondary structural element 次要构件 21.​  tubular joint node 管接头 22.​  tubular member 管状构件 23.​  conductor pipe 导管 24.​  brace tube 撑管 25.​  bracing 撑杆 26.​  cord 弦杆 27.​  modular shoring 模式支撑 28.​  jacking house 固桩区 29.​  vertical column 立柱 30.​  sole plate 底板 31.​  riser 隔水管 32.​  bypass manifold 旁道岐管 33.​  crossover sub 换向接头 34.​  directional sub 定向接头 35.​  orienting 定向环 36.​  survivalability 自存性 37.​  non-ductile 无延展性 38.​  postbuckling 后期屈曲 39.​  non-linear behaviour 非线性特性 40.​  inelastic deformation 非弹性变性 41.​  brittle rupture 脆性断裂 42.​  ultimate punch strength 极限冲击强度 43.​ plastic flexural hinge 挠性塑性铰 44.​  overstressing 超应力 Notes to the Text 1.​ to cope with 对付 2.​ All new types stress characteristics of mobility and the capability for work in even deeper water. 句中的stress作动词用，选择“强调”之意。 3.​ Difficulty in towing is a disadvantage, but this is partially offset by rapidity with which they can be raised or lowered, once on location With which they can be raised or lowered 定语从句，修饰rapidity.with which在从句中作状语。 “once on location(一旦就位后)”为省略句，参见第九课注3。 4.​ … plus the fact that, when working as floaters ,their primary buoyancy lies below the action of the waves thus providing great stability. that 引出同位语从句，修饰the fact.其中when working as floaters为省略了主语和谓语动词be的时间状语从句。 Providing great stability现在分词短语，置于句末表示结果。 5.​ “semis”为“semisubmersibles”的缩写，是半潜式平台之意。 6.​ …, the latter being necessary is deeper waters. 独立分词结构。The latter 指dynamic positioning systems参见第十二课注4。 7.​ Floaters cannot be used in waters much shallower than 70ft because of the special equipment required for drilling from the vessel subject to vertical movement from waves and tidal changes ,as well as minor horizontal