bluuebunny/crossref_metadata_2025 huggingface dataset:
Effective and Holistic Approach to produced Water Management for Offshore Operation
Authors: Georgie W.J.
Published: October 2008

The disposal of produced water from offshore operations in the North Sea, the Gulf of Mexico and other seas worldwide becomes an important and critical issue to the operators concerned, governmental and regional organizations as well as to the environment. In order to establish a better understanding of the produced water management and handling issues and to determine the optimum solution in dealing with increased volume of produced water discharged into the sea, a better approach and tool for evaluating the different options are necessary.

Handling and treating produced water should be dealt with from the source of the problem. Therefore a holistic approach is needed in order to address the problem more effectively.

From operation experience, it has been established, an effective approach in dealing with the produced water problem should include all relevant upstream facilities, including design of the process system and separators, method of operating the plant and the configuration and routing of the different fluid streams. Different parts of the process equipment can play a major part in either improving or reducing the overall efficiency of produced water.

In addition, understanding the characteristic of both the produced fluid chemistry and all other production chemistry aspects of the system will be a critical part in achieving an effective produced water management.

Therefore it is fundamental to the whole process of produced water management to have an integrated approach to deal with the undesirable water. This approach should include from the early stage of development as well as later production, design aspects, selection of equipment and instrumentation as well as a clear understanding of all produced fluid issues.

Although produced water handling issues are crucial to any operation onshore or offshore, this paper will address primarily the offshore aspects of handling produced water. However, the principle of treatment and the design basis of produced water handling facilities should not be any different regardless if it is related to onshore or offshore operation. In many respects the onshore operation will have the benefit of endless space for locating equipment and required facilities, whereas the offshore operation does not have this advantage. However, overall the disposal of produced water onshore can be just as challenging if not more complicated in certain geographical locations.

Using past and current experiences as well as a full understanding of operation limitations of different technologies, the means to troubleshoot and optimize produced water systems and to establish an effective management approach for the long term can be established on the understanding of the holistic approach to produced water management offshore.

Introduction

Produced water is a secondary product that oil and gas producers worldwide have to deal with both onshore and offshore. There are equal challenges if not more complicated in dealing with this secondary product onshore as well as offshore.
Truss Spar Time Domain Inplace Structural Strength Analysis
Authors: Wang J. , Zhang B. , Berg S.
Published: October 2008

There are many unique challenging aspects in the structural analysis and design of a Truss Spar. This paper provides indepth discussions on inplace strength analyses of the truss structure based on the author's firsthand design experiences. Inplace structural strength design criteria are outlined, and an integrated procedure based on random wind and wave time domain analyses is presented. Technical issues related to structural and hydrodynamic modeling, computer software requirement, time domain environmental load simulation and extreme global load prediction for structural design, structural load mapping, and time domain design load case selection are discussed. Analysis results are presented for a generic Truss Spar design to illustrate the various loading conditions for the Gulf of Mexico environment and inplace structural behavior of the truss structure.

Introduction

The first two Truss Spars have been installed in 2001 in the Gulf of Mexico. More Truss Spars are currently in various design and fabrication stages, and will be installed in the future. Compared to the Classic Spar, the Truss Spar design replaces the cylindrical midsection of the hull with the truss section as shown in Figure 1, hence the name Truss Spar. The truss section is a space frame consisting of tubular members similar to a jacket type structure. The truss structure is inherently more efficient, with well over 50% less steel weight than the plated cylindrical midsection of the Classic Spar, as a structural link between the upper hard tank and the soft tank at the keel of the platform. The heave plates are integral parts of the truss design, normally consisting of a stiffened plate structure with girders supported by the truss horizontal braces, knee braces and vertical braces. The main function of the heave plate is to provide added mass and damping for heave motion of the Spar platform. The truss and heave plates also provide lateral support for the risers.

For inplace conditions, the truss structure is subjected to continuous dynamic loading due to wave excitations and Spar motions. Since the truss section has the least structural redundancy compared to the hard tank and the soft tank, considerable structural analysis and design efforts are required to ensure the adequacy of the truss and its connections for structural strength and fatigue. Unlike the tension leg platform and other floating platform concepts, the Spar platform is a truly compliant system, whose natural periods for all the six degrees of freedom of motions are significantly greater than the predominant wave period. Hence, the low frequency loads, such as slow varying wind load, wave drift force, and second order nonlinear wave excitations, will have significant impact on the dynamic response of the Spar. In particular, the time varying dynamic wind load contributes significantly to the pitch/roll motion, which in turn contributes the most to the global bending moment and shear force in the truss structure.
High Resolution Surveys With Auvs
Authors: Willcox Scott , van Mierlo Frank
Published: October 2008

In the past two years, Bluefin has fielded several AUV systems. The survey systems that Bluefin build for the US Navy have seen almost continuous use. In addition to the Bluefin operations these vehicles participated in three Navy Exercises and one international science cruise. This paper presents the results of some of these high-resolution surveys. Figure 1:(Available in full paper) Figure 2:(Available in full paper)

Introduction

After developing several key AUV technologies at MIT and building 12 prototype vehicles in the process, the Bluefin team became a commercial enterprise in the fall of 1999. Bluefin's engineers have now built seven new AUVs for a range of commercial, military, and academic customers. Measured in terms of numbers of vehicles sold, Bluefin Robotics is the world's largest commercial manufacturer of autonomous underwater. Figures 1 through 5 show several of Bluefin's AUVs in action. This paper presents some of the field data that was taken with these AUVs. Specific data of the Bluefin 5000 is presented in detail. Both the sonar and the navigation data shows the success of Bluefin's "small is beautiful" design philosophy. Bluefin's current class of vehicles are the smallest survey systems in the commercial survey market. Current development efforts at Bluefin are pushing the envelope even further by fielding a new class of AUVs with a diameter of 12.75 inches. Modularity is crucial to this new design and it will allow the integration of a whole new class of survey sonars. Current developments in synthetic aperture sonars are particularly exiting and promise to revolutionize the way that data will be gathered in the not so distance future. Simultaneously, Bluefin is pushing the state of the art in the areas of mission autonomy, energy sources, and navigation systems.

Bluefin 5000

The BLUEFIN 5000 is part of the new Odyssey III class of vehicles that that have been designed by Bluefin. The BLUEFIN 5000 is specifically designed for wide-area high resolution surveys missions. As such, the vehicle's main payload is a high-resolution, multi-beam side-scan sonar, the Klein 5000. The BLUEFIN 5000's oceanographic payload sensors include CTD, fluorometer, and light-scattering sensors. The design of the BLUEFIN 5000 is modular, with all essential vehicle components (main electronics pressure vessel, computation, propulsion, navigation and attitude sensors) contained in the aft modular section of the vehicle. The forward modular section contains the Klein 5000 sidescan sonar, the CTD, the fluorometer, and the light-scattering sensor. The forward modular section also contains two redundant battery packs in separate battery housings. Spent battery packs are easily replaced by removing the BLUEFIN 5000's hemispherical nose-cone, sliding each cylindrical battery housing out of the vehicle, and then re-inserting charged batteries. The forward battery arrangement allows the vehicle to be serviced rapidly between missions, with on-deck turn-around times as short as 30 minutes, excluding data download.
Embankment Construction on Yielding Sea Bottom
Authors: Stamatopoulos Aris C. , Kotzias Panaghiotis  C.
Published: October 2008

THE APPROACH

Conventional embankment design practice calls for a factor of safety against base failure higher than 1, usually of the order of 1.5. Such factor of safety would exclude the construction of embankments in projects where no practical alternative exists. Moreover, as marine embankments are often less costly than structures on piles, there is considerable economic advantage in constructing them to the maximum possible extent.

The approach used in the design and follow-up of construction of the embankments described in this paper differs from the conventional approach. In the four cases presented the design was not based on some fixed value of the factor of safety. The location of expected failure along the embankment axis was estimated, and as embankment construction came near this location, measurements were taken to obtain early warning of failure. As embankment construction proceeded beyond the location of the first appearance of failure, the extent and consequences of the failure were followed quantitatively. Construction was discontinued when the consequences of base failure exceeded a certain tolerable limit.

This approach, allowing construction under a condition of a factor of safety less than 1, has been found satisfactory in the marine embankments discussed in this paper. In these projects,the soft clay supporting the embankment was of low sensitivity,a base failure could not cause damage to any adjoining structures,there was no construction alternative of a comparable cost andthe owner had been advised of the expected base failure.

APPROXIMATE STABILITY EQUATION

A stability equation based on simplifying assumptions is as follows (derivation is presented in Appendix, A):(Mathematical Equation available in fullpaper)

where c is the average cohesion (equal to the shear strength) of the soft clay supporting the embankment; h1 and h2 are the heights of the embankment above and below water level, respectively, when failure is just starting; r1 and r2 are the unit weights of the embankment material above and below water level, respectively; s is the cotangent of the angle of the embankment slope with the horizontal; and d is the depth of the soft clay layer supporting the embankment.

Simplifying assumptions are as follows:base failure develops along a single cylindical surface,axis of cylindrical Simplifying assumptions are as follows:base failure develops along a single cylindical surface,axis of cylindrical surface of failure passes through the toe of the slope of the embankment,radius of cylindrical surface is equal to the depth d of the soft layer,strength of soft clay is equal to cohesion (angle of internal friction is zero),embankment material offers no shear resistance andd ? (hl + h2) s.

Assumption 1 is commonly accepted in stability problems involving sliding.
Parametric Study of Steel Weight of Large Oil Tankers
Authors: Johnsen Inge , Hagen Erik , Boberg Bjørn
Published: October 2008

The steel weight constitutes a major factor of the production cost of a ship as well as being indirectly an important factor with respect to the operational cost efficiency of large tankers.

The study presents an outline of the influence of parametric variation in main design characteristics of oil tankers with respect of steel weight.

The characteristics which have been discussed are main dimensions, steel qualities and primary and secondary structural arrangements. The vessel sizes will vary from 50.000 t.dw. to 500 .000 t. dw.

The parametric study also includes variations with reference to hull steel weight of internal arrangement and optimization of part structures. The influenceof non-dimensional parameters (LID, LIB, etc.) have been dealt with in this connection. The study is based on the Rule design programs (CBC-programs) of Det norske Veritas. The results of the study are so presented as to facilitate fast and easy application on actual design projects.

Introduction

The built-in steel of a ship constitutes a substantial part of the total cost of the ship. It is therefore important both for the shipbuilder and the ship owner that the weight may be estimated at the project stage with an acceptable degree of accuracy.

As the ships, particularly oil tankers, combined carriers and bulk carriers, have increased so rapidly in size during recent years, it may be difficult for shipyards to apply their weight statistic and their usual methods for weight estimates at the project stage. These estimates are usually based on weight relationships which apply to basis ships or sister ships together with corrections which have relevance to the deviations of the particular design from the design and dimensions of the basis ship. Many useful weight calculation methods have also been published, such as cubic number, weight per foot, method of differences, group eights as well as detailed calculation. [5], [6], [7]. These conventional method: may be applicable when they are adjusted to current yard practice, owner's requirements etc.

Another way of supplying weight data is to apply the requirements of classification societies directly to the ships in question and have the corresponding scantlings and the steelweights calculated. This method will generally require the use of computers to carry out dimensioning of structural parts and scantling selection. This is, needless to say, an extremely powerful method. One can carry out weight studies of a series of ship projects and work out optimum designs in a short time at low cost, and more efficiently than by other "short-cut" methods.

As only a very limited set of ship data are available at the initial project stage, such a method should not require much information about the ship in question. Such a method has been applied in the rule programs (CBC) developed by Det norske Veritas.
Telecommunications Offshore
Authors: Summers James H.
Published: October 2008

A survey of telecommunications systems and equipment now in use by offshore operators is presented. The costs, effectiveness, and availabilities of the various services and systems is evaluated and comparitive analyses are offered. A discussion of new services and hardware is undertaken with studies of their costs, capabilities, and limitations according to geographic location. The paper concludes with informal remarks by the author concerning telecommunications as a service offshore and attitudes toward it within the offshore industry.

Introduction

The physics, electronics, logistics, and politics of offshore oil exploration and production are such that telecommunications for that phase of the industry is somewhat different than for similar applications ashore. Radio waves propagate differently, the environment is generally more severe, maintenance activities are more costly, and since offshore work is simply more expensive than for similar activities ashore, the communications user on the geophysical vessel, supply boat, or drilling rig has come to demand a measure more from his system or service. He may be getting it and not know it; he may not be getting it but thinks he is. Good communications, like good food, is an elusive creature.

Just as in every other specialized field related to petroleum, communication has a vocabulary all its own, and a fair comprehension of this terminology is essential to a basic understanding of the subject. If the reader is not thoroughly familiar with the jargon used in the industry, he might benefit from looking over the short glossary at the end of this paper before proceeding. Some of the definitions are my own and may not have the same meaning to others. Even among communications specialists one can find disagreement over basic terminology. I would ask the expert reader to overlook any misnomers he may find and that the uninitiated accept the definitions as accurate within the scope of this paper.

Telecommunications is not an end in itself. It has but one purpose in offshore activities: to provide a service to the user, and to do only to the level of sophistication needed, and at the lowest possible cost. Perhaps in no other service activity is it easier to misjudge what is best. Hence, the purpose of this paper: to try to sort out the myriad systems and services available offshore, define and evaluate each to a reasonable degree, and to make recommendations as to how to proceed for the several "predictable" types of offshore activities. We will try to take into account as many of the variables in the problem as possible such as the unfortunate variations in legal restrictions from place to place, and the differences in public communications service availabilities and costs.

Finally, we will not delve too deeply into the technical aspects of communications.
Reliability of Circular Piles Subjected to Ocean Waves
Authors: Schueller Gerhart I.
Published: October 2008

1. Introduction

Wave forces exerted on structures are of vital interest to offshore drilling stations and various other marine structures. Because the piles constitute the major or entire support for the whole structure the engineer must ensure that those piles successfully withstand the forces to which they are subjected. In this regard, the most important piece of information is the occurrence of wave forces at the site of the proposed structures.

The design problem is complicated by a number of factors. First, wave characteristics change as a wave approaches the shore. Secondly, local wind-generated waves become superimposed on large ocean waves, creating a complicated surface. Thirdly, the forces exerted by waves of similar properties vary greatly. This variation is caused by fluctuations in fluid particle velocities as well as eddies and turbulance around piles caused by the rapidly reversing flow. Consequently, a deterministic approach to wave force prediction appears to be impossible.

As an alternative method in design, an engineer might determine his design by using a cumulative distribution function (CDF) of wave forces created from field data. If the distribution of wave forces is known, the engineer can then make reliability statements about his design.

The method used here utilizes a multiple linear regression analysis to develop a relationship between wave properties and the parameters 1 used in the Morison force equation. These parameters include velocity and acceleration of water particles and the drag and mass coefficients.

Using Monte Carlo simulation these regression relationships are then utilized to develop the probability density formation of wave forces.

2. Description of Force Equation

The forces exerted by ocean waves on a pile is one of the most complicated fluid flow problems because of the presence of both unsteady and oscillary motion. The generally accepted formula for a wave force on a pile is the so-called Morison formula,(Mathematical equation available in fullpaper)

The first part of this equation represents the for drag caused by surface shear. The second part is the acceleration force on the displaced volume of fluid including the virtual mass effect. The relative importance of inertia force increases with the ratio of the pile diameter to wave height.

Although the particle motion in waves is orbital, the method is based on flow. The fluid density and the pile diameter D are assumed to be constant. It is also assumed that the drag force and the inertia force can be treated separately, and the total force can be obtained by adding the solutions linearly. In previous investigations 1,2,3,4,5,6 water particle velocity and acceleration were calculated by stokes7 irrotational theory. The theory considers only waves of small but finite wave steepness.
Cost-Effective Design and Development of Hub Platforms
Authors: Huff Scott S. , Heijermans Bart
Published: October 2008

El Paso Energy Partners, L.P. ("EPN") has developed a portfolio of shelf and deepwater hub platforms with access to the flextrend and deepwater regions of the Gulf of Mexico. These hub platforms serve as production facilities for local and off-lease production and as gathering, pumping and compression stations for EPN's oil and gas pipelines.

This paper discusses the key technical considerations and strategies involved in the cost-effective design and development of these hub platforms. The paper addresses the design of new platforms and the re-development or expansion of existing platforms. Both fixed and floating facilities are considered.

Introduction

Hub platforms serve as central points for gathering, redistribution, and transportation of oil and gas. These platforms can also serve as primary processing facilities for local or off-lease production, pumping stations for oil pipelines, and/or compression facilities for gas pipelines.

This paper describes various strategies that can be employed to optimize the design of new hub platforms and the development of existing hub platforms. These strategies are intended to:ensure operability and reliability,preserve flexibility for future expansion, andoptimize current and future costs.

EPN's Hub Platforms

EPN owns various hub platforms in the Gulf of Mexico, as displayed on the map in Figure 1. These platforms are an integral part of EPN's infrastructure, since they host pumps and compressors and also act as portals for supply into the downstream pipelines.

Figure 1: EPN's Hub Platforms (Available in full paper)

EPN owns the following hub platforms in the Gulf of Mexico:

VK 817.

The VK817 platform is located in Viosca Knoll Block 817 in the Eastern Gulf of Mexico. The platform is situated in a water depth of 671 feet and was installed in 1995. The platform is designed to process gas and condensate production at maximum rates of 150 million cubic feet of gas per day ("MMCFD") and 5,000 barrels of condensate per day ("BCPD"). The platform serves as a junction platform for EPN's Viosca Knoll Gathering System and hosts a Taurus 60 driven gas compressor and a slug catcher for the Ram Powell gas pipeline. The platform processes production from EPN's VK817 field and from the Walter Oil & Gas deepwater field in Viosca Knoll Block 862. The platform was designed to:accommodate future tie-backs from the flextrend and deepwater, andhost additional compression for the incoming pipelines.

SS 332A.

The SS332A platform is located in Ship Shoal Block 332 in the Central Gulf of Mexico (Figure 2). The platform is situated in a water depth of 438 feet and was acquired by EPN from Arco Oil & Gas Company in the early 1990s. Arco's production from the SS332 field had ceased, and the platform was of value to EPN to support the Leviathan Offshore Gathering System, the predecessor of the Manta Ray Gathering System. SS332A became a cornerstone in the Poseidon oil pipeline system ("Poseidon") when EPN constructed Poseidon in 1995 and the Allegheny Oil Pipeline in 1999.
Modeling of Wind Over Water
Authors: Shemdin Omar
Published: October 2008

Modeling of wind over water can provide a useful tool in dealing with the nearshore and offshore environment where the wind stress plays a dominant role. The available field and laboratory information on shear stress coefficients is reviewed with emphasis on differences between field and laboratory conditions. Modeling relationships are proposed for the wind and the wind generated current. The procedure is applied to a laboratory model of a lagoon in the Atlantic trade wind region. Alternation of the physical boundaries produced a significant change in the wind induced circulation. The change in water circulation was used to predict the increase in the temperature of water used for cooling purposes.

Introduction

Modeling of wind over water can be useful in arriving at solutions to engineering problems where wind plays a dominant role in water circulation. Use of wind models is feasible provided the scale of the modeled area is small enough so that the effect of earth rotation may be neglected.

The available information on wind and wind driven circulation in the literature is primarily aimed at understanding and/or describing the properties of the shear flows in air and the induced motion in water. An abundance of field and laboratory results are reported but only a few studies provide insight relevant to modeling of wind over water. The question of what to model and to what scale is a central question. The scope of this study is limited to those problems where the wind plays a dominant role in the water circulation. In areas where both the tides and the wind are important the two effects may be included in a composite model.

Review Of Field And Laboratory Results

Of the many studies reported in the literature on air-sea interaction only a few are relevant to the scope of this study. In the field Van Dorn (1953) investigated the set-up and the surface drift in a pond under the action of the wind. By spreading a detergent on the water surface to suppress the wind generated waves he found the surface drift to remain constant. Keulegan (1951) found the surface drift to be 3% of the wind speed. The surface drift has been reported to vary from 2.4% to 5%. The 3% value appears to be a reasonable average.(Available In Full Paper) where K is the Von Karman constant and zoa is the roughness height. Such a profile is not uniformly endorsed by all investigators. Most recently De Leonibus (1971) reports that seldom did he encounter a logrithmic distribution in his field measurements of the wind profile using four cup anemometers. Ruggles (1969), however, indicates that 90% of his field measurements of the wind profile followed the logarithmic distribution. In the laboratory Lai and Shemdin (1971) reported that the wind profile can be approximated by a logarithmic distribution.
Membrane Technology for Offshore LNG
Authors: Deybach Frédéric
Published: October 2008

Environmental and financial issues will make LNG FPSOs and LNG FSRUs a reality.

The technical specificity of the membrane technology, with an outstanding record on LNG carriers, make it particularly adequate for offshore applications. Cost effective and reliable it also offers a great operational flexibility.

It has already found its first application in the LNG offshore industry : El Paso LNG Bridge? are being currently built in Korea.

Introduction

The membrane containment system is widely used on LNG carriers and it has been so for more than 30 years with an outstanding record for safety and reliability (two third of current new orders are placed with membranes). After reviewing some of the history of LNG, the nature of the membrane technology is described.

Environmental and financial issues that will make LNG FPSOs and LNG FSRUs a reality are addressed. Issues such as the growing concern about the location of gas terminals, and of course the benefit of having a mobile unit transferable to any part of the globe.

The technical specificity of the membrane make it particularly adequate for offshore applications:Large free open deck available for the installation of a liquefaction or a regasification plant.A containment system designed to withstand liquid motion and allows for all filling levels.Safety heightened by a strong and simple design of the hull structure, by a low windage area and by a continuous monitoring of membrane tightness.Light components allowing for on-site repairs & maintenance.Operation flexibility with no continuous cooling down required.

Background

The commercial use of Liquefied Natural Gas (LNG) was introduced in the 1960's to monetize natural gas reserves that were remote from the consumers. In order to transport this gas on long distances with no consumer on the way, the most cost effective way was to place it on ships. To maximize the amount transported, the cargo is liquefied to take advantage of the density increase (multiplied by nearly six hundred (x600)). The pressure at which natural gas remains in its liquid form at ambient temperature being unacceptable, LNG is stored and transported at ambient pressure and low temperature : -163°C. This low temperature is maintained by insulating the liquid from outside heat. Today this principle is applied both for land storages and for LNG vessels.

The containment system of the LNG must therefore face two challenges : resist such low temperature and provide sufficient insulation to keep natural gas in its liquefied state. A third challenge is of course to do that in a cost-effective way. Today, three metallic materials are used that retain ductility at this temperature : aluminum, stainless steel and nickel steel. Two different approaches have been developed : self supporting tanks (the structure of the tank in contact with the LNG is able to resist by itself the pressure of the cargo column) and membrane tanks (the membrane contains the cargo but relies on the ship / building structure to resist the pressure).
Operational safety analysis of FPSO - Shuttle Tanker collision risk reveals areas of improvement
Authors: Vinnem J.E. , Hokstad P. , Dammen T. , Saele H. , Chen H. , Haver S. , Kieran O. , Kleppestoe H. , Thomas J.J. , Toennessen L.L.
Published: October 2008

The risk of collision between shuttle tanker and FPSO during off-loading is strongly dependent on Human and Organisational Factors. The contributions to the collision frequency have been analysed in terms of Risk Influencing Factors, which are structured in an extensive risk influence diagram. Contributions from various Risk Influencing Factors is achieved by data from incidents and near misses, as well as from expert meetings. Recommendations for risk reduction are presented in relation to field configuration, minimum time to be available for recovery from drive-off scenarios, as well as crew competence, positioning systems, interface on shuttle tanker, FPSO and between the vessels.

Introduction

Turret moored FPSOs of the mono-hull type have been used in the North European waters since 1986 [Petrojarl I], so far without serious accidents to personnel or the environment. The use of such vessels for field development has increased during the last 5-10 years, and in these waters more than 25 fields are currently either in operation or being developed with FPSO units, mainly new built vessels.

The vessels being installed in the North Sea, North Atlantic and Norwegian Sea fields have traditionally been designed for considerably higher environmental loads and often also higher throughput as compared to installations in more benign waters. Without exception, the ones so far installed or under construction for these areas have what is termed 'internal' turret, in the bow or well forward of mid ships, with transfer of pressurized production and injection streams through piping systems in the turret.

Although FPSOs are becoming common, operational safety performance may still be considered somewhat unproven, especially when compared to fixed installations. Floating installations are more dependent on manual control of some of the marine systems, during normal operations as well as during critical situations.

Accidents are often initiated by errors induced by human and organisational factors (HOF), technical (design) failures or a combination of these factors. Effective means to prevent or mitigate the effects of potential operational accidents are therefore important.

The overall objective of the programme was presented in Ref. 1. The programme has considered the following phases:Methodology development1996-1997: Pre project, definition phase1997-1998: Analysis of riser damage, inadequate turret operations1999-2000: Collision with shuttle tanker (ST)Collision Frequency Study2000-2002: Extended study of collision risk The work up to 1998 has been summarised in an OTO report (Ref.2), published by the UK Health and Safety Executive (HSE). The details of the analysis during 1999-2002 are presented in Refs. 3, 4, 5 and 6, of which the latter is published by the HSE. This paper is a summary of the work carried out during 2000-2002.
Quantifying Risks of Well Intervention, Oil Deferment and Loss of Reserves in Complex Smart Wells
Authors: Hother John , van Dongen Hans , Braithwaite Steve
Published: October 2008

This paper reports on the results of a Reversionary Mode Analysis Level-1 (RMA-1) to assess the 'do-ability' of three novel, complex, smart well designs. These are the Spider Well?, the Stacked Internal Gravel Packs (IGPs) and the Smart Wells options studied for a deepwater sub-sea field in the Gulf of Mexico.

Both the Spider Well?and the Stacked IGPs designs are more complex than Smart Wells, which in turn are more complex than conventional wells. These complex smart wells contain more equipment, which complicates the installation of the wells, and which must function for the lifetime of the well. In addition, several equipment items to be incorporated in the wells require new designs, or pressure rating extensions of existing technology.

Whole life-cycle plans were defined for each of those three well design options. Quantitative failure mode analysis incorporating economic consequences were performed on all well construction processes and production subsystems. The RMA software calculated "Risk-Dollars" by multiplying the probability of failure by the consequential costs of well intervention, oil deferment and/or loss of reserves.

The resulting risks were broken down into production system and construction process elements, and into the economic categories of intervention, deferred production and lost reserves. The assessed risks, together with various other factors, were input to the selection process of the preferred field development concept, which is outside the scope of this paper. Key risk drivers were identified from the analysis, allowing cost-effective targeting of reliability improvement actions. The three designs studied, the analysis method and the results are presented in the paper.

The use of quantitative risk results, expressed in economic terms, has wide application in making systematic comparisons between complex systems, both inside and outside the energy industry. The results clarify the reliability risks present in smart wells, even before considering more advanced alternatives.

The results show that failures are inevitable in all three options, but the Spider Well? carries the greatest overall risk, the highest total number of failure modes and more high-cost failures. The RMA method demonstrated its strength in being able to identify critical risks and 'drill-down' to root causes, allowing specific mitigating measures to be identified and evaluated. These included specific full-scale testing of prototype equipment, and specific quality management and reliability engineering measures. It was found that these mitigating measures, if implemented, would bring the risks to similar levels for all three well design options. Sand control failures present the largest remaining risk.

1. Introduction - Purpose And Objectives

This RMA-1 project was to assess the risks associated with a deepwater development opportunity comprising 8 stacked oil sands at 6,000 m in the Gulf of Mexico.
HPHT Well Control; An Integrated Approach
Authors: Rommetveit Rolv , Fjelde Kjell Kåre , Aas Bjarne , Day Norman F. , Low Eric , Schwartz David H.
Published: October 2008

This paper presents an integrated approach on HPHT well control in narrow pressure margin wells. The approach includes theoretical evaluations, computer simulations with advanced modeling tools, laboratory studies, well control training as well as implementation of learnings in procedures and operations. Examples from the North Sea on the application of advanced transient well control modeling for the planning of HPHT drilling as well as training are described in detail.

A special focus is directed towards gas diffusion during drilling operations; with its impact on a number of important parameters like rheology and barite sag. Both theoretical and experimental work is presented.

Introduction

The drilling of HPHT wells pose special challenges compared to standard wells:High pressures and temperatures impact mud properties in a dynamic way, and can have effects on well controlSmall margins between pore and fracture pressures will prevail in sections of the wellThe conditions are above the critical point for the gas/oil/condensate influx; which means that the hydrocarbon influx is infinite soluble in the base oil of the mud.Hydrocarbon influx will totally mix with the base oil in oil based mud (OBM), and infinite amounts of gas can dissolve in the mudDrilling of inclined and horizontal wells will make the consequences of barite sag seriousSignificant quantities of gas can diffuse into a horizontal section of a well if OBM is used even if the well is overbalanced The frequency of well control incidents is higher than one per HPHT well, and an increasing number of these take place during completion.

The Physics of an HPHT Well

An HPHT well can be categorized as an integrated physical system. The well is defined as the flow conduit from the mud pump down the drill string, drill bit and up the annulus to the mud pits; with the drilling mud, etc. filling up this flow conduit. Maintaining the control of the well at all times is a question of understanding the physics of the well during changing conditions and using this knowledge to optimize the design of the well, to develop sound drilling procedures and to handle unexpected situations during drilling in an optimal way.

Traditional and well proven drilling practices and rules of thumb have been developed by "trial & error". In many cases, these represent optimal solutions. However, when the drilling situation differs significantly from the traditional, old rules may not apply, and one will need to analyze the problems scientifically to revise the practices. One can use transient computer models with the correct physics built into them to develop new procedures and practices for these wells.

Below the main physical parameters and interactions are discussed.
Next Generation Drill Pipe for Extended Reach, Deepwater and Ultra-deep Drilling
Authors: Jellison Michael J. , Payne Mike L. , Shepard Jeff S. , Chandler R. Brett
Published: October 2008

A new drill pipe size, 5-7/8 in. OD, represents enabling technology for Extended Reach Drilling (ERD), deepwater and other deep well applications. Most world-class ERD and deepwater wells have traditionally been drilled with 5-1/2 in. drill pipe or a combination of 6-5/8 in. and 5-1/2 in. drill pipe. The hydraulic performance of 5-1/2 in. drill pipe can be a major limitation in substantial ERD and deepwater wells resulting in poor cuttings removal, slower penetration rates, diminished control over well trajectory and more tendency for drill pipe sticking.

Hydraulic pressure losses are minimized with 6-5/8 in. drill pipe, but 6-5/8 in. drill pipe is an "over-design" solution in many cases. The 6-5/8 in. drill pipe is difficult to handle, requires excessive physical space on the rig, can limit setback capacity and generally requires significant rig handling equipment modifications. In addition, 6-5/8 in. drill pipe cannot be used to drill inside of 9-5/8 in. casing and 8-1/2 in. hole sections.

The 5-7/8 in. drill pipe provides a significant improvement in hydraulic efficiency compared to 5-1/2 in. drill pipe and does not suffer from the disadvantages associated with use of 6-5/8 in. drill pipe. It represents a drill pipe assembly that is optimized dimensionally and on a performance basis for casing and bit programs that are commonly used for ERD, deepwater and ultra-deep wells.

Realizing the full potential of 5-7/8 in. drill pipe requires a high performance tool joint connection. A second-generation double-shoulder tool joint connection, optimized for 5-7/8 in. drill pipe, provides exceptional torsional strength combined with a streamline configuration. Configured with a 7 in. OD tool joint the connection permits fishing inside of 9-5/8 in. casing or 8-1/2 in. open hole sections.

The first string of 5-7/8 in. drill pipe went to work on a Gulf of Mexico project in July 1999. Since that time more than 830,000 ft of 5-7/8 in. drill pipe comprising over 40 drill strings has been manufactured and put into the field. The drill pipe has been successfully used to drill ERD, deepwater and ultra deep HPHT wells in the South China Sea, Gulf of Mexico, Offshore Trinidad, Onshore Wyoming and Onshore Colombia.

The 5-7/8 in. drill pipe has improved penetration rates with large diameter bits and significantly shortened drilling curves to total depth in established fields. Drilling engineers are currently evaluating 5-7/8 in. drill pipe for use on major ERD, deep directional and deepwater projects in various parts of the world.

The paper discusses the engineering philosophy behind 5-7/8 in. Extreme Reach (XR) drill pipe, the design challenges associated with development of the product and reviews the features and capabilities of the second-generation double-shoulder connection. The paper provides drilling case history information on significant projects where the pipe has been used and details results achieved with the pipe.
Devils Tower Export Lines: 160 Miles of 18" OD Reeled Rigid Pipe
Authors: Menier Philippe
Published: October 2008

The Paper starts with a summary of the Devils Tower development in the GOM and gives the characteristics of the 18" Oil and 18" gas export lines from the shallow water platforms to the deep water terminations. It continues with the description of the sub-sea tie-ins branch in 14" diameter from the export lines to the SPAR in 5000' water depth including the Steel Catenary Risers at SPAR. Provisions for futures ties-ins of nearby fields will be covered.

The application is any deep or ultra deep development up to 7,500' water depth of rigid or flexible flow-lines, steel catenary risers and umbilical.

The paper will give the elements to assess the performance of the Deep Blue / Theodore spool-base spread. Weather sensitivity and offshore performance is analyzed and the advantages to S- lay laying method in terms of safety and quality and further developed.

The high capability of the Deep Blue combined with the Theodore, Alabama onshore spool-base has offered an economic alternative to the conventional S-lay laying method for the Devils Tower development. It can be further applied to any mid-size rigid pipe flow-lines SCR installation in deep waters. It combines the advantages of the low cost steel pipe, of the large onshore line pre-fabrication and of the reduced offshore installation time.

Devils Tower Development Overview

Discovered in 2000, The Devils Tower field is located in Block MC-773 in the Mississippi Canyon, 140 miles southwest of New Orleans, in the Gulf of Mexico. The development by Williams Field Services Company consists of a SPAR platform in 5610 ft of water, and two export pipelines totaling approximately 165 miles of pipes. Technip Offshore has been contracted by Williams to design, supply and install the Mountaineer Oil Export Pipeline connecting the Devils Tower field to MP 313 platform and the Canyon Chief Gas export pipeline connecting the Devils Tower field to MP 261 platform. From the SPAR two 14" steel catenary risers run into two 14" sea-lines 6 miles long to tie-in point to the tow 18" export pipelines. From this point the two 18" main export pipelines run in parallel on the seabed, northerly towards block MC 114. At this point the Oil export continues north to the MP 313 platform, the Gas export line continues northeast to MP 261 platform. Both lines tin-in to shallow platforms via an 18" riser.

The SPAR will be able to handle 60,000 barrels of oil per day. The Mountaineer pipeline will have a capacity of 150,000 bpd; the Canyon Chief pipeline will have capacity of 350 million cubic feet of gas per day.

Figure 1. Devils Tower Deepwater Development Project(AVAILABLE IN FULL PAPER)

Technip-Coflexip Scope on Devils Tower

The Epic contract includes all necessary tasks to hand-over to Williams Field Services a complete pipeline system ready for production.
Feasibility Of a Lightweight Buoy Mooring Concept
Authors: Schwartz Arnold , Chen Philip M.
Published: October 2008

This paper describes the feasibility analysis and field test of a novel buoy mooring concept.* Successful field tests on the Severn River near Annapolis, Maryland, indicate that the concept is ready for engineering development. The technique allows for repeated latching to and release from a bottom emplaced anchoring station. Means are provided for relocating the bottom anchoring station, which may be very accurately positioned at initial emplacement. Thus, the need for resetting heavy anchors every time a lightweight buoy must be restationed can be eliminated.

Introduction

A major concern of those who use the waterways for travel and commerce is accurate knowledge of local bottom topography. This concern is seen in the duties of the sounding man made famous by Mark Twain and other writers. Indeed, Samuel Clemens adopted the call of the Mississippi river pilots "Mark Twain", indicating a depth sounding of two fathoms, as a pseudonym for his novels of river life. Aids to navigation can be considered as the traffic signs of waterways. They serve to channel traffic, warn of danger, and alert mariners to their location. The United States Coast Guard is responsible for the accurate deployment and maintenance of buoys in our nation's navigable rivers, lakes, and coastal waters. In certain areas, particularly the Great Lakes, this responsibility necessitates the annual deployment and retrieval of these buoys together with their mooring chains and concrete block anchors. The mass retrieval of these buoys is a preventive measure to protect the buoys from ice damage in the winter months. This repetitive operation involves excessive ship operational time as well as the gross expenditure of materials and labor.

Present technology has advanced to enable the development of lightweight buoys. These can be constructed of such advanced materials as sandwich cores, glass-reinforced plastics, or composites, and can reduce the arduous task of buoy deployment. In fact, the lightweight buoy would lend itself to deployment from a small tender or buoy boat. The problem still exists, however, of handling the 2000-lb, or greater, anchor that must be annually deployed and retrieved from rather sizable vessels.

A requirement exists for a device or system that can accomplish repetitive mooring of lightweight buoys in water of less than 100-ft depth. Such a system must be inexpensive, simple to operate, reliable, and deployable with high accuracy in repetitive moorings.

Introduction (Continued)

The Coast Guard does not necessarily have to identify every natural or manmade hazard. However, when they do mark such hazards in the interest of safety to navigation, they must do so accurately and competently. This fact has been seen in such litigation as SOMERSET SEAFOOD COMPANY versus the UNITED STATES (193F. 2d 631, 1952) where the responsibility of accurately stationing buoys was clearly established. In this case, a commercial vessel was sunk by a submerged wreck which was marked by an adjacent Coast Guard buoy.