Title
Conductor Installation within Monopile Foundations using the Swift-10 Drilling Rig
Author
Smit, G.J.A.
Faculty
Mechanical, Maritime and Materials Engineering
Department
Offshore and Dredging Engineering
Programme
Offshore & Dredging Engineering
Date
2015-06-29
Abstract
In 2005 Shell introduced the first monopile satellite platform with the aim to reduce the capital expenditure required for offshore wells. Currently there are 6 of these platforms installed in the Southern North Sea managed by Shell. The main functions of these platforms are to house the wellheads and divert produced hydrocarbons into a subsea pipeline system. The wells of these platforms are located inside the 3.5 to 4.2 m wide monopile foundations. The first step of constructing such a well is the installation of a conductor pipe. This long steel pipe is usually installed to about 70 m below the mudline using a hydraulic hammer or a drilling & grouting technique. When in 2007 monopile platform L09-FA was built, NAM well engineers were tasked with installing 4 conductors within its monopile foundation. An impact hammer was used to drive the conductors to the designated depth. Soil resistance to driving however increased with the installation of each conductor, finally obstructing the fourth conductor of reaching its target installation depth at all. When in 2014 additional wells needed to be installed within the same platform, two additional conductors had to be constructed first. It was however not clear how these conductors should be installed, as impact driving had already shown to be limited and the application of the drilling & grouting technique was not permitted in this situation (by Shell standards). Hence well engineers had to come up with another way of doing this. A solution was found which consisted of a combination of vibratory driving and drilling & grouting. The two additional conductors were successfully installed using this method. It was however not clear whether the chosen solution truly was the best way of installing these conductors and whether this solution could be re-applied in similar situations in the future. The objectives of this research were to determine the best way forward for the installation of additional conductors within monopile foundations using the SWIFT-10 drilling rig and to determine how the prospects of the method identified as best way forward could further be improved. In order to complete the first objective, a wide variety of pile installation techniques were compared on their applicability and operational considerations. In order to complete the second objective a study into vibratory driving was conducted using a vibratory driveability prediction model provided by a geotechnical engineering company called Allnamics.
Subject
drilling
vibratory driving
swift
conductors
wells
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Embargo date
2025-06-19
Part of collection
Student theses
Document type
master thesis
Rights
(c) 2015 Smit, G.J.A.