Enhancing the Technology for Deepwater Installation of Subsea Hardware

Abstract

This paper describes key findings from Phase 1 of the Deepwater Installation of Subsea Hardware (DISH) JIP. The objective of DISH Phase 1 was to identify key gaps in the offshore industry's technology for installing subsea hardware in water depths beyond 2,000m, by comparing present-day capabilities of the installation industry with likely deepwater installation requirements of oil and gas operators over the next 10 years. Technology gaps were identified by interviewing engineering and installation contractors, oil and gas operators and specialist suppliers; by carrying out a literature review study; and by holding a Phase 1 Mid-Flight Workshop to identify and prioritise the key gaps. The results were further refined before finalising the Phase 2 work programme. A review of the capabilities of wire rope lifting systems showed that self-weight will make conventional wire rope systems inefficient for water depths in the range 2,000m to 3,500m, and impractical on most installation vessels. The industry will therefore have to turn increasingly to deepwater fibre rope deployment systems. Key challenges are to establish the industry's confidence in fibre rope deployment systems, and to provide key information about the engineering properties of man-made fibre ropes and of the loading on such systems. Lack of knowledge of fibre rope behaviour was considered to be a fundamental, show stopper', which will inhibit the adoption of fibre rope deployment systems for ultra-deep water installation. DISH Phase 1 is now completed, and Phase 2 was launched in January 2002, based on the priority technology gaps and challenges identified during Phase 1. Background The DISH JIP was instigated following a pan-industry Workshop held in November 2000. At that time hydrocarbon developments were being planned in water depths close to 2,000m, and deeper fields were already being considered. Speakers from major installation contractors and BP believed, however, that established techniques for lowering and installing heavy items on the sea floor may either prove impractical or uneconomic in water depths beyond 2,000m, such as in emerging areas of the Gulf of Mexico. Furthermore, the deepest fields so far developed have been in relatively benign ocean environments, and the installation methods used to date are not necessarily transferable to harsher environments. A number of technical advances will therefore be needed to make some deepwater developments economic and practical. These issues were discussed further in a paper presented at a SNAME Workshop in February 2001 [1], which summarised possible technology gaps in the areas of lifting and lowering technology, load control and positioning, metocean effects and weather window requirements. General Approach DISH Phase 1 aimed to identify key technology gaps by comparing present-day capabilities of the installation industry with likely deepwater installation requirements of oil and gas operators over the next 10 years. The goal of achieving a common understanding spanning operators, contractors and suppliers worldwide, across the whole industry, was considered to be particularly important.

Vibration Suppression for Coupled Wave PDEs in Deep-Sea Construction

“…DCVs are often used for installation of underwater parts for an offshore drilling platform, such as a subsea manifold, a subsea pump station, a subsea distribution unit along with associated foundations, flowlines and umbilicals [25]- [26]. A DCV is depicted in Fig.…”

“…a) Deep-sea construction vessels: In deep-sea oil exploration, a deep-sea construction vessel (DCV) is an important device used to install equipment such as a subsea manifold, a subsea pump station, flowlines and so on, at the designated locations around the drill center on the seafloor [25], [26]. A dominant component in the DCV is a long cable with timevarying length, of which the top is attached to a ship-mounted crane and the bottom is attached to the equipment (referred to as payloads hereafter).…”

Delay-Compensated Control of Sandwiched ODE-PDE-ODE Hyperbolic Systems for Oil Drilling and Disaster Relief

“…The first motivation of this work arises from off-shore oil drilling, where some equipment, such as a subsea manifold, a subsea pump station, a subsea distribution unit along with associated foundations, flowlines and umbilicals should be installed at designated locations [28,29] around the drill center on the seafloor. The installation of this equipment is completed by deepwater construction vessels (DCVs) [28], because the installation sites are located outside a radius 45 m of the floating drilling platform (Fig.…”

“…Inserting (124)-(125) into (127) and (126), applying(30),(29) we haveα(0,t) − pβ (0,t) − (x)α(x,t)dx − K3 Ŷ (t) − (x)β (x,t)dx −C 0 X(t) = (0, x) − K 3 (0, x) + x 0 K1 (y)K 3 (y, x)dy + x (y)K 2 (y, x)dy − K1 (x) z(x,t)dx − (0, x) − J 3 (0, x) − x (y)J 3 (y, x)dy − x (y)J 2 (y, x)dy + K2 (x) w(x,t)dx + pλ (0) − γ(0) − K3 Y (t) = 0,(255)Ẋ(t) − A 0 X(t) − E 0 β (0,t) − (x)α(x,t)dx − (x)β (x,t)dx − K6 Ŷ (t) − B 0 U(t) − h 1 ( ṽ(2,t)) )K 3 (y, x)dy + x (y)K 2 (y, x)dy − E 0 K 2 (0, x) − K4 (x) z(x,t)dx− (y)J 3 (y, x)dy +x (y)J 2 (y, x)dy+ E 0 J 2 (0, x) − K5 (x) w(x,t)dx − )γ(x)dx + E 0 λ (0) − K6 Y (t) = 0. (256)For (255)-(256) to hold, conditions (134)-(139) are obtained.…”