| Author | Kathawut Weerayutwattana |
| Call Number | AIT Thesis no.OTM-11-06 |
| Subject(s) | Pipelines--Risk management
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Offshore Technology and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. OTM-11-06 |
| Abstract | Submarine Pipelines play important role in the transmission of oil and gas which are the main
energy resources in the entire world. Risks such as fire, explosion and unintended accidents
to pipelines should be kept under an acceptable level. Risk assessment of dropped objects to
subsea pipelines is a necessary procedure to evaluate pipeline operational risks but the
primary factor affecting damage is kinetic energy distribution therefore kinetic energy
distribution must be considered carefully since a small change in a dropped object's velocity
significantly changes the kinetic energy distribution (damage) to a pipeline.
This study presents the kinetic energy distribution of slender dropped objects onto the seabed
for risk assessment purposes. Small-scale physical experiments were performed to capture the
motion of dropped objects. Three types of casings and one type of drilling collar were
examined. Each object type was dropped from four different levels. The angles between
dropped object and water surface were fitted to the most appropriate statistical distribution by
CESTTEST software. Monte Carlo simulation was performed using the angle probability
distribution and motion path equations of dropped objects under sea water. The motion path
simulation gives kinetic energy of object at the seabed. The simulation was generated for ten
water depth to obtain the kinetic energy distribution of dropped objects as a function of water
depth. The kinetic energy distributions were generated for ten water depths and compared to
DNV RP F-107. Moreover, the kinetic energy distributions obtained from this study are taken
into risk assessment to consider the differences in term of annual release frequency of
hydrocarbon from subsea pipeline due to dropped objects compared with the annual release
using DNV kinetic energy distribution.
The kinetic energy distributions obtained in this study are different from DNV distributions
in terms of magnitude and variation of kinetic energy. The results show that the DNV
distributions are not conservative for lifting operations in Gulf of Thailand. The comparison
of risk in term of annual release frequency of hydrocarbon from subsea pipeline shows
different risks at different water depths and pipeline properties. It is recommended to use
kinetic energy distributions from this study in Gulf of Thailand because they give a more
rational estimate of dropped object risk for various water depth and pipeline in Gulf of
Thailand. The results of this study contribute to the fundamental knowledge base for the
kinetic energy of dropped objects at the sea bed, and can be used by operators and service
companies to quantify risk of damage due to dropped object so as to make informed decisions
regarding pipeline protection and operational safety. |
| Year | 2011 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. OTM-11-06 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Offshore Technology and Management (OTM) |
| Chairperson(s) | Chiu, Gregory L. F. |
| Examination Committee(s) | Pornpong Asavadomdeja;
Winai Ouypornprasert |
| Scholarship Donor(s) | Chevron Thailand Exploration and Production, Ltd. |
| Degree | Thesis (M. Eng) - Asian Institute of Technology, 2011 |