Vertical pipe configuration happens in subsea well re-entry operations for wellbore drilling, subsea equipment installations, deepwater intake risers, among other scenarios, usually by hanging the marine riser at the top from a platform or ship. The simple operational configuration justifies its wide application; however, there are some drawbacks such as stress concentration, fatigue, among other issues. The purpose of this study is to contribute for the overcoming of those problems by improving the understanding of hanging risers through investigations of a vertical pipe forced to oscillate horizontally at the top. For this purpose, laboratory experiments with small diameter pipe model have been developed with oscillatory motions applied at the top termination through a mechanical device. Displacements over time and along the pipe length were measured by an optical measurement system. In the present study, a numerical scheme has been implemented for simulations to support evaluations of the experimental results. A vertical pipe response depends on several parameters, such as pipe overall length, frequency and amplitude of oscillation itself, among others. Due to existing relative velocity between the oscillating pipe and the water surrounding it, vortex shedding occurs along the pipe length which influences riser motion behaviour. The results from experiment and numerical simulations bring important insights for describing and understanding oscillatory vertical pipe behaviour, in the plane and the out of plane of the forced top oscillation. The obtained results provide a further step toward the modelling of Vortex-Induced Vibration (VIV) in marine risers, aiming to contribute to relevant technological advancements.

Vertical pipes are extensively applied on offshore petroleum operations, such as subsea wellbore drilling, wellbore re-entry, installations of equipment on the sea bottom, hydrocarbon production as the conductor for oil and gas from the wellhead at the sea bottom, among other applications. Recent oil and gas field discoveries in ultra deepwater brought an increase of the amount of produced and processed petroleum onboard of floating production system. Consequently, the process plant demands more cooling capacity. One of the alternatives is to elevate cold sea water. The present study aims to improve the understanding of the behavior of a vertical pipe forced to move at its upper end in a water tank. Displacements along the pipe length are measured, and main features of the behavior of the pipe model with its bottom end free are observed. Motions imposed at the vertical pipe intent to represent motions of the surface from the floating platform or ship, due to waves, currents and wind. Pipe model vibrations are analyzed, and results allowed improvements for the input in numerical model simulations to Orcaflex software. Developments of the analysis procedure and evaluations of the experiment allow more reliable design of riser operations with its bottom end free in actual sea operations. In the present work, a physical model with a pipe of small diameter has been developed for the laboratory experiment, and an optical measurement system is used to measure the pipe model displacement in the water tank. Motions are imposed at the top termination by a mechanical device. Experiment is described in details and comparative analyses between experiment and numerical simulations were carried out. Results from numerical simulations as well as from the experiment brought important contributions for description and understanding of the vertical pipe behavior.

For the selection of a field production system in order to decide among several alternatives, in general, an oil company bases itself mainly on economical analysis aspects, such as net present value and internal rate of return. However, the evaluation of a field development project, generally speaking, needs a methodology for the selection of the best alternative that complies proportionally with all the objectives of the company. Which means that several other aspects besides the financial one should be taken into account in the selection decision process. The main purposes of the present work is to present the methodology for decision-making that supports selection of the best floating production system, for a given offshore oilfield. As an example, a typical field development project is evaluated based on this method. The present paper shows the importance to include technological, safety and environmental risk besides the usual financial one, used for selecting the best alternative of a floating production system in offshore field development.

A study on dynamics of a vertical production riser under environmental loads is carried out. Current and wave loads along the riser, and surface vessel motions due to the environment at the riser top are taken into account. Based on descriptions of fundamentals of the Quasi 3D model previously proposed by Ferrari&Bearman (1999), numerical simulations for riser displacements have been performed. In line and transverse hydrodynamic current and wave loads on the riser are estimated and riser displacements thought Quasi 3D fashion are estimated in the time domain. Comparisons with literature results and experimental ones are carried out.

In the present paper, operational accidents, which occur during offshore drilling and production operations are carefully studied. Data were collected from literature for those operations and each accident was classified according to related operations and carefully analyzed. After that, each accident was classified according to the operation unit where it happened, i.e., drilling, completion, production and workover type unit. Classifying the accidents and analyzing the obtained results has shown that more than half of them are related to offshore petroleum production unit operations, followed by those related to drilling rig operations. The remaining observed cases are related to workover exploration and completion units. The evaluation of operational accidents in offshore petroleum drilling and production units could clarify the behavior of operational safety, particularly variations along the years. It was possible to identify the main factors that contribute to the increase of the number of those accidents in offshore units, as well as, the consequences of each accident. Finally, such procedures provided useful information that can assist engineers in making decisions improving operational safety programs for offshore drilling and production unit operations.

The present paper describes the behavior of a vertical riser in waves, currents and which is excited by displacements at the riser top. Fundamental equations for riser behavior are described and the Ferrari&Bearman model [4] is applied to estimate hydrodynamic load for “in-line” and transverse directions of the riser. Solution for riser behavior is obtained in time domain, calculations are performed for deepwater field production scenario and discussions are addressed. The influence of variation of riser diameter and drag coefficient along its length, the presence of floaters and effect of petroleum fluid flowing in the riser are investigated. Moreover, effects of the upper and bottom end conditions of the riser on its behavior are also taken into account in the analysis.