Underwater Engineering

1. Equipment Capacity

1.1 Offshore Oil 286

1.1.1 Overview of ship

Offshore Oil 286 deepwater engineering ship is China's first ocean engineering vessel representing world-class technology difficulties and 3,000 m operating water depth. It is specially used for deep-water oil-gas exploitation. It features high technology, excellent maneuverability and seakeeping, and is provided with a 400 t large-scale offshore engineering crane with heave compensation function and a remote operated vehicle with the maximum operating water depth reaching 3,000 m. With the functions of lifting large subsea structure, laying umbilical cord cable and cable, providing support for saturated diving operation and inspection & maintenance of deep-water facilities, the ship occupies a leading position in integrated operation capability among similar ships in the world.

1.1.2. Technical features

Offshore Oil 286 deepwater engineering ship has a total length of about 140.75 m, a width of about 29 m and a depth of 12.80 m. The ship has short forecastle, bulbous bow, Class B ice area strengthening, one layer of continuous freeboard deck and helicopter take-off and landing platform at the bow, bow thrusting and telescopic full rotary propeller, and full rotary fixed pitch rudder and propeller devices driven by diesel electric propulsion system. Service speed is 11 knots and maximum cruising ability is 10,000 miles. It can operate at 3,000 m depth and complex sea conditions, and has excellent maneuverability, seakeeping and positioning ability (DP-3 level). The ship meets the requirement of C3V3 of DNV in comfort level. It is an all-steel, double-bottom and double-hull multi-purpose vessel (MPV). Compared with our other auxiliary ships, Offshore Oil 286 has smaller cabin, more operation functions, higher automation level of integration, higher installation and commissioning technology requirements of equipment and systems, and its equipment and systems are more advanced, the layout of equipment, pipelines and cables is more complex, and design and construction are more difficult.

1.1.3 Operation functions

The main functions of the Offshore Oil 286 deepwater engineering ship are: lifting and subsea mounting of deep-water large structures (such as Christmas trees, underwater pipelines, etc.) (equipped with a 400 t large-scale offshore engineering crane with heave compensation function), flexible pipe laying in seabed (hose reel under the main deck can carry 2,500 t cables), ROV operation support (maximum operating water depth of 3,000 m), saturated diving operation support, comprehensive inspection, maintenance and repair of offshore engineering, route investigation, underwater pipeline and cable maintenance, deep-water anchor handling, mooring and FPS (tension leg, semisubmersible, Spar, FPSO), including anchor pile installation and pre-laying, connection, recovery and repair of mooring leg.

1.2 Offshore Oil 289

1.2.1 Overview of ship

As a kind of DP2 dynamic positioning offshore subsea construction vessel (OSCV), Offshore Oil 289 is the world’s most advanced offshore engineering support ship and a remarkable achievement of the South China Sea deepwater strategy. The main generator set, propulsion system and dynamic positioning system are in the world’s leading position. It has internally installed two world’s most advanced heavy duty ROVs with the operating water depth of 3,000 m, and one crane with 250 t heave compensation function. The ship is equipped with two operation moonpools, helicopter deck, S6 saturated diving system and room for 100 people in high standard and with low noise level. The main functions of the ship include: underwater installation support, subsea structure installation, saturated diving operation support, ROV support, hose laying, cable laying, deepwater facilities inspection, maintenance and other functions. Its comprehensive operation ability is at the world level.

1.2.2 Technical features

Offshore Oil 289 has a total length of 120.8 m, a width of 22.0 m, a depth of 9.0 m, a total tonnage of 8,922, a net tonnage of 2,677, a maximum draft of 6.6 m, and a main deck area of about 1,350 m2. It can bear 10 t per square meter. According to DNV environmental protection concept, the ship is designed with STX new low-resistant bow, 690V low-fuel-consumed diesel electric propulsion system to optimize fuel consumption, helicopter take-off and landing platform at the bow to minimize the deck occupancy and increase its cargo capacity, two variable pitch tube thrusting and articulating boom full rotary propellers, and two fixed pitch full rotary propellers. Economical speed is 11 knots and maximum cruising ability is 12,000 miles. It can operate at 3,000 m depth and complex sea conditions, and has strong wind and wave resistance, excellent maneuverability, seakeeping and positioning ability (DP-2). It is an all-steel, double-bottom and double-hull multi-purpose vessel. Compared with our other ships, Offshore Oil 289 has more operation functions, higher installation and commissioning technology requirements, higher automation level of integration, higher operation stability, lower fuel consumption, higher economic performance and its equipment and systems are more advanced. The ship is ahead of other ships in terms of the design and manufacturing technology in the world.

1.2.3 Operation functions

Offshore Oil 289 is a deepwater engineering ship with a very strong operation capability. Its main operation functions include: lifting and subsea mounting of deep-water large structures (such as underwater expansion, riser, protective cover, etc.) (equipped with a 250 t large-scale offshore engineering crane with heave compensation function); flexible pipe laying in seabed, sea cable repair, emergency repair of subsea pipeline, seabed trenching, installation of FPSO pile legs, ROV operation support, offshore scientific research operation support, offshore accommodation vessel, etc. The maximum operating water depth of the ship is up to 3,000m; with S6 saturated diving system, the ship has the capabilities of offshore oil platform inspection, maintenance and repair.

1.3 Offshore Oil 291

1.3.1 Overview of ship

Offshore Oil 291 is a multi-purpose vessel introduced by COOEC Offshore Division from abroad for implementing the deepwater development strategy of CNOOC, which is capable of deepwater mooring and installation with DP2 (dynamic positioning) ability, deepwater plough trenching and underwater engineering installation. It is also one of the comprehensive supporting projects for deepwater oil development projects in China. It was the most advanced multi-purpose underwater working ship for deepwater mooring and installation in China at the time of introduction and also one of the world's top offshore engineering ships. Offshore Oil 291 is Aker AH 04 designed by STX EUROPE. With great design flexibility, it is designed with one moonpool and reserved with a position for adding an A-frame, which has been enhanced structurally during construction. A helicopter platform is provided, equipped with a dedicated ROV hangar. It is the first ship of COOEC Offshore Division, which is equipped with 500 t deepwater mooring and installation winch, owns maximum lifting weight of 250 t and operating water depth up to 3,000 m with active heave compensation crane and helicopter platform. It is positioned as deepwater mooring and installation, plough trenching, underwater engineering support operation, platform supply and other operation functions.

1.3.2 Technical features

Offshore Oil 291 deepwater engineering ship has a total length of 109.4 m, a width of 24 m and a depth of 9.80 m. Equipped with two 7,680 KW main engines and four 2,600 KW generators, the ship has a power up to 34,500 Hp. According to different tasks, it can provide 9 working modes, including electric propulsion, main engine propulsion and diesel-electricity combination, which can save energy and meet various operating requirements. Configured with propeller equipment with different functions and performances, it provides strong power for ship navigation, berthing and unberthing, offshore construction, and DP system. Its service speed is 11 knots and maximum speed 19 knots. It can operate under 3,000 m deep water and complex sea conditions with its excellent maneuverability, seakeeping and positioning ability (DP-2 level). It is an all-steel, double-bottom and double-hull multi-purpose vessel (CAHV).

1.3.3 Operation functions

Offshore Oil 291 mainly functions as submarine trenching, FPS mooring and installation, ROV support, cable laying and saturated diving. Besides advanced deepwater oil and gas pipeline laying and trenching capacity in the world, Offshore Oil 291 is also capable of multiple trenching. When single trenching cannot reach the required depth due to hard soil or insufficient ship towing force, it can trench repeatedly and reach the maximum depth of 2.5 m through multiple trenching. The ditcher has multiple monitoring perspectives, which can transmit the image of the seabed to the control room in real time. When the sea condition is adverse, the sonar system equipped to the trenching plough will give full play to its greatest advantage. The main body of the ditcher is also equipped with a propulsion system, through which the ditcher can be safely and accurately lowered to the seabed. It has deepwater mooring and installation capacity, with ship bollard towing force reaching 361 t. It is equipped with a 500 t anchor handling main winch, two 500 t main working winches, a waterfall flow anchor handling winch formed by two 170 t storage winches, four 298 m3 anchor cabins, and a geared anchor chain of 3,800 m with a single cabin accommodating a diameter of 78 mm, and has strong deepwater anchor handling capacity.

It has strong professional equipment operation ability. The 250 t crane with heave compensation function, anchor handling winches, two track cranes capable of moving forward and backward and 360° omni-directional operation, and two working-level ROVs are at a higher level in the equipment configuration of similar engineering ships. The ship has good operation and positioning ability. Its dynamic positioning reaches DP2 level. Combining with good linetype, the ship can operate under relatively complicated sea conditions.

1.4 Offshore Oil 285/287

1.4.1 Overview of ship

Offshore Oil 287 is the most advanced deepwater engineering ship in the world, which is equipped with DP3 system, 250 t and 25 t crane with active heave compensation function and ROV retractors. It can complete various offshore construction operations with the maximum operating depth of 3,000 m. Offshore Oil 287 is a "multi-purpose deepwater repair ship” aiming at various maintenance operations of offshore engineering deepwater equipment and facilities. It is the world's top-level deepwater integrated operation ship with all-electric propulsion system. It can provide customers with full life cycle management services and various underwater operation support for oil and gas fields in various sea areas.

1.4.2 Technical features

Offshore Oil 287 deepwater engineering ship is 125.75 m long, 25 m wide and 10.80 m deep, with maximum draft of 7.7 m, 120 crews, self-sustaining capacity of 60 days, endurance of about 15,000 sea miles, cargo area of about 1,600 ft. on deck, and maximum speed of about 14 kn. It features short forecastle, bulbous bow, Class-B ice strengthening, one continuous freeboard deck and a platform for take-off and landing of helicopters. It is equipped with: 2X bow thruster and 2X telescopic full rotary propeller. The main propellers are two full rotary fixed pitch rudder and propeller devices driven by diesel electric propulsion system. The world advanced DP3 system equipped can achieve precise dynamic positioning operation. The ship meets the C3V3 requirement of DNV in terms of comfort. It is an all-steel, double-bottom and double-hull multi-purpose vessel (MPV). Compared with other auxiliary ship of COOEC, “Offshore Oil 287”, which is equipped with the world's top operation control system and integrated control workstation, have achieved the highly integration of vessel DP system, propulsion control system, vessel integrated information display system, radar and electronic chart.

1.4.3 Operation functions

The deepwater engineering ship Offshore Oil 287 mainly functions as: route investigation, underwater pipeline and cable maintenance, maintenance of deepwater large structures (such as Christmas trees, etc.) hoisting, seabed installation (equipped with 250 t and 25 t offshore engineering cranes with heave compensation function), ROV operation support (maximum operating water depth of 3,000 m), saturated diving operation support, integrated inspection, maintenance and repair of offshore engineering.

1.5 Remote Operated Vehicle (ROV)

1.5.1 Overview of ROV

ROV is namely Remote Operated Vehicle. Its system consists of water-based and subsea units. Wherein, the water-based unit generally includes a power supply unit, a control computer, a display and other components, and the subsea unit generally includes a sonar, an altimeter, a depthometer, a compass, a thruster, an electronic communication device, a manipulator, a camera, a PTZ, an auxiliary lamp, buoyancy material and cable control unit. ROV has a variety of functions; different types of ROV are used to perform different tasks and are widely used in for armed forces, maritime, hydropower, offshore oil, maritime rescue and other industries.

1.5.2 Technical features

ROV is widely applied for deepwater drilling support, subsea structure installation support and subsea structure detection in offshore oil industry. It can be classified into observation-level and operation-level ROV depending on different operation capabilities. The core components of the observation-level ROV are subsea thrusters and subsea camera systems, and sometimes conventional sensors such as navigation and depth sensors. The observation-level ROV, attributing to small size, small weight and low power as well as flexible operation and low cost, is applicable for pure observation-type operations. The operation-level ROV features large size and high power and has an subsea manipulator, and therefore, it can carry subsea camera, sonar, hydraulic shear, hydraulic torque wrench and other types of subsea operation tools in actual operation, and complete the camera, observation, measurement, manipulator operation, operation in cooperation with external tools and other different tasks in water; it is characterized by safety, economy, high efficiency, high depth of operation, high intensity of operation and accurate data measured.

ROV has obvious advantages in safety, operation intensity and operation efficiency in the development of subsea oil and gas fields, especially deep-water oil and gas fields. For example, it can reduce the operation risk greatly since divers are no longer necessary to enter the water, and, due to its relatively low requirements for sea conditions, ROV can reduce the waiting time for ships depending on weather conditions; moreover, ROV can complete continuous tasks of high-intensity in water areas of different depths. All of the above are unavailable during operation by divers. With the gradual in-depth exploitation of offshore oil and gas fields, ROV will be irreplaceable in the exploration and development of subsea oil and gas resources.

1.5.3 Operation functions

Since its establishment in 2002, the number of ROV in ROV Operation Department of Subsea Operation Company of COOEC Offshore Division is increased from the original 1 from 17 at present, with the variety covering light-type, shallow water type, observation-level, heavy-type, deepwater type and operation-level ROV. Moreover, the department has 43 kinds of external tools in a total of 78 sets at present, such as torque wrench, injection skid, hydraulic shear, dredge pump, TSS440, imaging sonar and CP probe, with the operation capacity covering jacket installation, subsea pipeline laying, cable laying, anchor installation/ replacement, expansion bend installation, Christmas tree installation, subsea structure detection, deepwater structure installation, deepwater electric fly line / hydraulic fly line replacement and other various subsea engineering operations. The operation water depth of their offshore construction projects completed extends from 10 m to 1,500 m.

1.6 Trenching plough

1.6.1 Overview of the trenching plough

In 2018, the Subsea Operation Company of COOEC Offshore Division purchased a new set of large-scale deepwater trenching plough system. It includes the trenching plough body, the A frame (or A crane), an active heave compensation (hereinafter referred to as "AHC"), an umbilical cable winch, an air hose winch and an electrical and hydraulic control system. The construction attendant vessel is HYSY291. It is the largest model of subsea pipeline trenching equipment over the world. At present, there are only 3 similar types of equipment in the world. The trenching plough fills the gap in the field of trenching with large-scale equipment for rigid subsea pipeline in China and gains some advantages on resources in Asian and Southeast Asia markets. With the marine environmental protection and technical standards becoming more and more strict and improved, there will be more and more demand for pipeline landfill in offshore oil field.

1.6.2 Technical features

The trenching plough, with its body of 21.4 m long, 11.75 m wide, 9.65 m high and 180 tons heavy, is the largest model in the field of subsea pipeline ditching at present. Its applicable soil strength is 10-100 Kpa, applicable subsea pipeline is 75-1,420 mm, maximum bollard pull is 350 tons. Its two buoyancy tanks may provide 100 tons of buoyancy. It is equipped with advanced gyro, sonar, PTZ, camera and other sensor equipment, and is designed with two sets of hydraulic systems for backup for each other, thus it can remain efficient in the case of one set of failures.

1.6.3 Operation functions

The VMP500 type trenching plough has the operating water depth reaching 500 m, the capability for single ditching of 2.0 m, and the maximum ditching depth after multiple ditching of 2.5 m, and therefore, can realize the steering function of 7 degrees. The trenching plough has two adjustable rollers to meet the requirements for subsea pipeline ditching for different pipe diameters and weights. The maximum snatching capacity is 75 tons. The equipment has emergency operation function which is controlled by a deck control room and a third party ROV respectively, to realize emergency operation and recovery in case of failure and crash. Weak connection is provided when the pulling force is too large during ditching, and will break automatically when the pulling force is more than 350 tons to protect ships and trenching equipment. The cable winch is expected to have constant tension mode, and the receiving and releasing system has the heave compensation function, which greatly improve the operation capacity .

2. Core Business (Technology)

2.1 Construction of mooring system for offshore floating production facilities

COOEC Offshore Division has fully mastered the technology for construction scheme design and relevant installation analysis of the mooring system for 300 m-deep oil tankers, and has the capacity of newly building, maintaining and replacing mooring system of oil tankers. At present, it has completed the installation, replacement, maintenance and disposal of mooring system for more than 10 domestic and international offshore floating production facilities, covering single (multiple) point mooring system, FPSO mooring system, mooring system of semi-submersible floating platform, etc. Combined with the professional mooring installation engineering ship "Marine Oil 291" with 361 tons of bollard towing force, its comprehensive construction capability has reached the world advanced level.

2.2 Subsea structure installation

COOEC Offshore Division has mastered the technology for installation of expansion bends, jumper pipes, risers, protective tubes, base plate manifold and related calculation, analysis and simulation technology, and has successfully applied it in actual projects, with the maximum water depth of 200 m. It has completed the installation of hundreds of expansion bends and jumper pipes with the maximum pipe diameter of 30 inches, and has successfully installed dozens of risers and protective tubes; moreover, it has mastered the integral installation technology of "one card and two pipes", which greatly improves the construction efficiency. It has successfully installed more than 20 base plates, with the maximum installation weight of 177 tons. In addition, COOEC Offshore Division has mastered the technology for replacing 1,500 m-depth electric and hydraulic fly lines and implemented the "Replacement of Electric and Hydraulic Fly Line in Liwan 3-1 Deepwater Gas Field".

2.3 Construction of flexible pipe cable

COOEC Offshore Division has skillfully mastered the technology for the installation, maintenance and replacement of flexible pipe cables (sea cable, umbilical cable and hose), and related calculation and analysis technology with independent construction capability, and has successfully completed the installation-related work for more than 30 domestic and international flexible pipe cables, with the water depth from 30 m to 300 m and the maximum length of a single pipe cable of 50 km. Furthermore, COOEC Offshore Division has mastered the construction technology in connection to deepwater vertical laying, and, by using the deepwater vertical soft laying system on "Offshore Oil 286" ship, has successfully apply it in "Wenchang 9-2/9-3/10-3 Gas Field Development Project” for twice.