Pipeline Replacement Project (PRP-7) – Dredging & Trenching
Project
Pipeline Replacement Project (PRP-7)
Client
Oil and Natural Gas Corporation Ltd.
Contractor
L&T Energy Hydrocarbon
Location
North Tapti Field West Coast - India
Project Period
Dec 2023 - May 2024
The Pipeline Replacement Project-VII (PRP VII) on the West Coast of India involved EPCIC (Engineering, Procurement, Construction, Installation, and Commissioning) activities. These included a pre-engineering survey, detailed engineering, procurement, load-out, transportation, installation of pipelines, followed by as-laid and as-built surveys.
OCS Scope:
The OCS scope on the PRP VII project in India included pre-trenching along the proposed pipeline route from NTP1 to NTP2 and dredging near Platform NTP1 using the Leighton Stealth vessel.
Project execution & outcome:
Pre-trenching was carried out to achieve the bottom of the pipe 3 meters below the existing seabed. Additionally, dredging near Platform NTP1 aimed to achieve a trench depth of 19 meters from the chart datum, where water depths varied between 8 to 10 meters.
The versatile configuration of the OCS equipment setup with a trailing arm, jetting head, and twin Toyo dredge pumps on Leighton Stealth enabled:
- Dredging near the NTP1 platform to a depth of 10-12 meters below the seabed.
- Pre-trenching in water depths of up to 45 meters.
OCS Equipment setup was a hybrid setup – jet lifting & slurry pump lifting + transporting.
Jet-lift dredging utilizes high-pressure water jets that impact the seabed at high velocity, creating a suction effect that lifts sediment from the seabed. OCS owned high pressure pumps on deck were used to supply high pressure water to the jetting/dredging head equipped with nozzles.
Robust heavy-duty submersible slurry pumps with inbuilt agitators (mounted on the dredging head) were used to lift & transport fluidized seabed material through the main cords of the trailing arm from the seabed to the surface for loading onto split hopper barges or side casting.
The ability to use the innovative hybrid setup for dredging and pre trenching as needed, all within a single package, was a direct result of OCS’s in-house expertise in engineering and construction management.
