Improving Jack-Up Rig Spudcan Penetration Predictions in Malaysian Waters

Day 3 Thu, March 24, 2016

Sha'ari

Rahman

et al. 2016

Self Cite

This paper was selected for presentation by an OTC program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not been reviewed by the Offshore Technology Conference and are subject to correction by the author(s). The material does not necessarily reflect any position of the Offshore Technology Conference, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Offshore Technology Conference is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of OTC copyright.the weakest admissible path, is an output from the simulation. In contrast, a conventional spudcan penetration analysis is performed based on a Љwished-in-placeЉ approach without taking into account of the occurrence and effect of the composite footing formed by the spudcan and the sand plug. In the conventional approach, the sand layer is assumed to diminish as the spudcan penetrates beyond the clay-sand interface.

Section: Introductionmentioning

confidence: 99%

Large Deformation Finite Element Analysis of Spudcan Penetration in Sand Overlying Clay Profile

Day 3 Thu, March 24, 2016

Sha'ari

Rahman

et al. 2016

Self Cite

Improving Jack-Up Rig Spudcan Penetration Predictions in Malaysian Waters

Day 3 Thu, March 24, 2016

Sha'ari

Rahman

et al. 2016

Self Cite

A review of the performance of jack-up rig spudcan penetration predictions in Malaysian Waters over the past ten years is performed with the aim of improving the predictions for future deployments. This work is part of an ongoing initiative to further improve the safety and efficiency of jack-up rig deployments in Malaysian Waters.During the first phase of the study, field measured spudcan penetrations at maximum preload from 100 jack-up rig emplacements in different subsoil conditions are compared against the corresponding spudcan penetration predictions. These spudcan penetration predictions, which originated from third parties and are presented anonymously, consist entirely of Class-A predictions made prior to the jack-up emplacement. A significant scatter is noted between predicted and actual spudcan penetrations. Possible causes of discrepancy between predicted and actual spudcan penetration depths in Malaysian Waters are postulated.In a significant proportion of the cases reviewed, the final spudcan penetration is found to be governed by bearing capacity in clay. Consequently, bearing capacity solutions for clays detailed in SNAME (2008) and ISO (2012) were reviewed. The bearing capacity equations in SNAME (2008) and ISO (2012) are based on the work of Hansen (1970) and Skempton (1951) respectively. Both SNAME (2008) and ISO (2012) noted that the value of undrained cohesive shear strength can be taken as the average value over a distance of B/2 from beneath the level where the maximum spudcan diameter is in contact with soil. The undrained shear strength profiles in Malaysian Waters are found to be more irregular as compared to those encountered in Gulf of Mexico. It is therefore the objective of the current study to assess the influence of undrained shear strength averaging distance for soil condition encountered in oil and gas producing regions offshore Malaysian Waters and to recommend the most applicable value for use in Malaysian Waters.The next phase of the study also aims to evaluate the need for revised calibration factors to SNAME (2008) / ISO (2012) based equations and to define the tolerance for acceptance of the leg penetration analysis (LPA) predictions in Malaysia Waters.

Regional Suitability Mapping PRSM Project - An Update

Day 3 Thu, March 22, 2018

Marzuki

Chan³

et al. 2018

The PETRONAS Regional Suitability Mapping (PRSM) project was initiated in 2013 with the aim of optimising operational cost efficiency and minimising potential incidents during jack-up emplacement. This project, which is executed as a Consortium Industry Project with PETRONAS Carigali Sdn Bhd (PCSB) as the anchor, and local as well as international consultants as the consortium members, is currently in Phase 2 with Phase 1 being successfully completed in June 2016 ahead of schedule. This paper is intended to discuss the framework of this project, disseminate the key findings and provide an update on the ongoing activities of PRSM Phase 2. The PRSM project involves integration and analysis of data from various data sources including geotechnical and geophysical site investigation data. These data, which originate from multiple sources, must first be consolidated into a common database before these data can be meaningfully analysed. This is achieved by leveraging on the capability of Geographical Information System (GIS) technology. Data integration and management are key enablers to fully maximise the value of the site investigation data, which were gathered at significant expense. With the data residing in a structured database, an objective hazard analysis framework can be systematically applied to produce a series of individual hazard maps, which are then consolidated into a composite hazard map. The hazard analysis framework, which is established through engagement and consultation with key stakeholders, is efficiently executed using the geo-processing capability of the GIS software. At the completion of PRSM Phase 1, more than a thousand regional and site-specific hazard maps have been produced. The pertinent conclusion from various stakeholders is that the PRSM project elevates the visibility of a multitude of hazards potentially affecting jack-up emplacement such that these hazards can be pre-empted and managed at an early phase. This paper will also discuss the steps taken to overcome the challenges of incorporating legacy data, which are of a different standard and format to those commonly adopted today. In order to maximise the completeness of the database, data from as far back as the 1970s were successfully processed and integrated into the common database.