bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real-Time Digital Signal Processing for High-Resolution Seismic Survey
Authors: Girault R. , Mathevon G. 
Published: October 2008

ABSTRACT
Specially designed for very hi9h resolution seismic survey, DELPH1 allows digital recording and real time processing and display of the data. The system is based on an IBM-PC computer and on specific acquisition and processing board with a digital signal processor.
The same equipment can be use for replay or post-processing.

Il INTRODUCTION
The new DELPH1 system presented here, is a digital recording and real time processing system, specially designed for very high resolution single channel seismic.
Digital recording in conventional multi-channel seismic has demonstrated highly improved resolution while allowing more sophisticated processing, therefore providing far better quality of the seismic profiles.
Real time processing and plotting of the seismic data allow controlling the quality of the acquisition parameters as well as on-site interpretation, thus avoiding the formerly necessary delays and increased cost due to remote processing
DELPH1 is implemented on an IBM/PC like computer which provides display and storage of the data and uses a digital processor for the real time data processing.

II) DIGITAL RECORDING
Digital recording provides several advantages over analog recording although the latter is still currently used in high resolution single channel seismic.
Primarily, digital recording improves the dynamic range of the recorded data and gives a truer reproduction of the frequency contents of the seismic signal.
The greatest advantage of digital recording lies in the ability to apply powerful digital processing.
The original data can undergo multiple processing using different parameters leading to far better quality final data and thus, interpretation.
SOllie processing such as disconsolation and multiple removal which can not be implemented with analog techniques, are possible with digitally recorded data.
Available analog processing is limited to very few possibilities (e.g. band-pass filter, swell filter, Time Variable Gain).
Lastly, immediate and convenient replay of the data is then possible, thanks to modern mass-storage devices (tape, optical disk, hard disk), As a result, the use of digital recording offers the opportunity to use modern up-to-date workstations.

I) REAL TIME PROCESSING
Real time digital processing is an opportunity to reduce the delay and cost of processing. Furthermore, it provides the availability of fully processed data on the acquisitions site. This feature can be used to optimize the organization of the survey and/or to start the interpretation work on the site.
The concept of real time processing refers here to the processing done during the time available between the acquisition of two consecutives samples, and during any non-recording time between two consecutive shots.
This is done onboard the vessel, simultaneously while recording the seismic profile.
The processed seismic section, presented in variable area, is available at the end of the profile. The raw data is saved onto hard disk.
The Design of Jacket Appurtenances To Withstand Pile-Driving Vibrations
Authors: Prins M.D. , Wardell J.B. 
Published: October 2008

ABSTRACT
A procedure for analyzing and designing jacket appurtenances which are subjected to pile driving vibrations is presented. This procedure is based on having a known (either measured or simulated) acceleration in the jacket structure and exciting the appurtenance at its attachment point to the structure in a manner similar to a seismic analysis. Resulting dynamic stresses are used to estimate fatigue life of the appurtenance expressed in number of hammer blows. Mobil's Beryl B pile driving data, as described in OTC paper 4879, is used as an example input acceleration. Analytical fatigue life predictions are consistent with field reports that pile driving can cause appurtenance damage. Results also show that, in many cases, fatigue life can be significantly improved by changes in appurtenance detailing. General recommendations for improving piping and anode details are also presented.

INTRODUCTION
On a few recently installed offshore platforms, grout piping systems, anodes, and other underwater appurtenances have sustained considerable damage during the pile driving operation, requiring costly remedial actions and repairs.
This damage was due to pile driving induced vibrations in the jacket structure. During pile driving, the pile hammer transmits energy to the pile in order to force the pile downward into the soil As the pile moves downward, it contacts the jacket leg or skirt pile guide (Figure 1) and transfers some of the driving energy to the jacket structure, causing the structure and the attached appurtenances to vibrate. The mechanism by which vibration energy is transferred from the pile to the jacket is not completely understood and is not addressed here since the outlined procedure is based on a known jacket acceleration. (Others, however, have addressed the transfer mechanism issue - see Reference 1.)
The authors are aware of several offshoreinstallations on which pile driving vibrations damaged jacket appurtenances. Two substantiated cases are:Conoco's V-Field accommodation jacket andEsso Production Japan's Iwaki jacket.
On Conoco' s V-Field accommodation jacket, damage occurred at the connections of the catholic protection anodes to the structure while driving with the Merck MHU2100 hammer (see References 2 and 3). Remedial action was to cut the piles at the base of the structure, lift the jacket back onto the transport barge, and take it onshore for repair. On Esso' s Iwaki jacket, the grout piping which was to be used to grout the skirt piles to the skirt pile sleeves was severely damaged during driving with the Menck MHU1700 hammer. Cracks occurred in numerous piping joints, and in some cases the piping was completely severed. Remedial action was to grout the piles using diver deployed hoses and contingency grout ports. Typical piping and anode damage locations, based on both the V-field and Iwaki jacket damage, are shown schematically on Figure 1.
Concrete Tension Leg Platforms for the Gulf of Mexico
Authors: Lokken R.T. , Gunderson R.H. , Davenport G.F. , Fjeld S. , Wold M.O. 
Published: October 2008

ABSTRACT
Concrete-hulled tension leg platforms for the Gulf of Mexico are technically feasible and cost competitive. This paper discusses design criteria for concrete TLPs and presents results for four Gulf of Mexico design cases. Site selection criteria are described and construction methods proposed. Cost and schedule estimates support the economic viability of the concrete TLP in the Gulf of Mexico, indicating that additional work should be undertaken by industry to develop the concrete hull as a competitive option to the steel hull.

INTRODUCTION
Recent successful exploration of deep water fields in the Gulf of Mexico (GOM) has accentuated the need for feasible and cost effective structures for hydrocarbon production in water depths of 300 to 1500 m (1000 - 5000 ft). The tension leg platform (TLP) concept has gained considerable attention as a candidate for these applications.
TLP technology has matured in a relatively shorttime. After six years' successful operation on the North Sea Hutton field in 148 m water depth (485 ft) [1] and the recent installation of the Jolliet TLWP in 536 m (1760 ft) [2] in the Gulf of Mexico, the technical feasibility and economic viability of the TLP concept is generally recognized.
Fabrication has started on a TLP for the North Sea Snore field in 310 m (1020 ft) [3] of water and a TLP for the GOM Auger field in 872 m (2,860 ft) [4] of water is being designed.
All of these TLPs have steel hulls. However, a concrete TLP hull has been proposed for the North Sea Heidrun field in 350 m (1150 ft) [5] of water. The basic layout of a concrete TLP is the same as a steel TLP except that, generally, the concrete hull has a greater displacement and a Dee-per draft.
The construction of a concrete-hulled TLP in the North Sea utilizes the technology developed in Norway for the large offshore gravity-based platforms [6]. The present paper discusses the application of this technology in the Gulf of Mexico, and is based mainly on TLP studies carried out by Norwegian Contractors a. s and Exxon Production Research Company on behalf of Esso Norge a.s. The investigation included both GOM and North Sea designs to achieve the best possible basis for comparison of costs, construction methods and schedules.
The study focused on a full production and drilling platform with 19,743 mt (metric ton) deck payload in 750 m (2460 ft) of water as the base case. Three sensitivity cases were also considered, including the base- case TLP in 1,500 m of water, a wellhead TLP with a payload of 9,830 mt in 750 m of water, and the wellhead TLP in 1,500 m of water.
The key conclusions of the study are: concrete hulls are technically feasible for deep water GOM applications; the concrete-hulled rtP can either be built on the U.S. Gulf Coast or in Norway and towed to the Gulf of Mexico; and the concrete TLP appears to offer an economic incentive when compared to a steel-hulled TLP.
API Level III Inspection of Mississippi Canyon 194 "N' (Cognac) Using an ROV
Authors: Miller S.H. , Hennegan N.M. 
Published: October 2008

ABSTRACT
In 1988 Shell Offshore Inc. (SOl) performed an API Level III inspection of the Mississippi Canyon 194 "A" (Cognac) platform in 1025 fsw (Fig. 1) and Mississippi Canyon 311 "A" (Bourbon) platform in 425 fsw using an ROV. This paper presents experience gained by SOl during the inspection and shows that an ROV can be used to perform cost-effective inspections of deepwater structures. Average member end inspection rates and inspection efficiencies are presented.

INTRODUCTION
Remotely operated vehicles (ROVs) are rapidly becoming the method of choice for many tasks that have traditionally been handled by divers. The current trend toward developments in depths greater than 1000 fsw have created the need for improved deepwater inspection capabilities. SOl performs Level III underwater inspections (UWI) of deepwater structures on a five-year interval in compliance with internal policy and those mandated by the United States Minerals Management Service.
This paper presents experience gained during the 1988 ROV API Level III UWI of SOl's Cognac and Bourbon platforms. Highlights from the 1988 inspection are presented with a brief summary of SOl's inspection nexperience. A discussion follows covering the selection of the ROV, scope of the inspection work, acceptance testing, and contractual agreements. Finally, inspection rates, major sources of downtime, and a comparison of costs with saturation diving are presented.

PREVIOUS EXPERIENCE
During the early 1980's, SOl explored alternate approaches for the cleaning and inspection of deepwater platforms. The motivation for this was to reduce costs, provide safer operations, and prepare for water depths beyond the capabilities of divers. The most successful of the alternate approaches used an advanced ROV with a high pressure water blaster to remove the marine growth and black oxide (ref. 1). This ROV proved to be uneconomical due to poor reliability, slow cleaning rates, and poor cleaning quality. Although the program failed to economically replace divers, developments were made that aided in the advancement of inspection ROVs. The most significant of these were:A high pressure water blaster attached to the ROV for cleaning.The use of suction pads to attach the ROV to the structure. Most problems experienced by the prototype ROV could be traced to a small number of design deficiencies. A major flaw was locating the high pressure pumps in the ROV tether management system. This required a high pressure hose to be incorporated in the tether to deliver water from a pump on the tether management system to the ROV.
The stiffness and weight of the tether significantly reduced maneuverability and increased the complexity of the system. In addition, the high pressure water and hydraulic power systems were new designs which experienced repeated failures.
A New Concept in Steerable Tow-Fish Design
Authors: Smitt L.W. 
Published: October 2008

INTRODUCTION
The study of how fish behave in relation to fishing gear has become increasingly important.
The Danish Fisheries Technology Institute (DFTI) is engaged in a major research project on this theme, with particular emphasis on video observation of fish in relation to cod ends, including the survival of small fish that escape through the meshes, to help in the design of more selective fishing gear. Also the effect of fishing gear on the sea bed IS being studied.
For this project DFTI needed a steer able tow-fish carrying a video camera with ±180° horizontal and ±90°vertical line of sight capability and able .to be steered into any position near the gear or even In the mouth of the trawl.
The vehicle was required to be stable and highly maneuverable in the speed range 1 to 6 knots.. With 500 m towing cable it should be capable of flying up to 80 m on either side of the track of the tow Ship, from the surface to the sea bed in a water depth of up to 200 m. At the same time it had to be compact, light and robust for ease of handling from a small fishing boat, and to be "snag free" after coming into contact with trawls or nets.
Market research showed that no existing vehicle would satisfy the specifications set up by .DFTI. However, the Danish Maritime Institute (DMI), In an badvisory capacity, felt confident that a vehicle that would meet the specification could be developed. DMI was then commissioned to develop and subsequently to build a prototype vehicle.
The experience with the prototype shows that it is easy to handle, highly maneuverable and very stable in flight.
These qualities make the new type. of tow fish very relevant for various offshore applications, especially pipeline inspection.

DEVELOPMENT OF DESIGN CONCEPT

Hydrodynamic Principles
During initial concept discussions it had been agreed, that in addition to meeting the demands for stability and control over a large speed range all for high "stand-off" capability, it would be beneficial If the new tow-fish would also:Maintain nearly constant attitude in the water whether flying deep or high, following the ship track or off-set from it.Have independent control of horizontal and vertical position (for simplicity and easy manual control). Simple reasoning, as well as previous experience with Para vanes and several tow-fish, convinced the Author that the following rules should then be followed, for the main reasons indicated:The vehicle should be nearly neutrally buoyant. Reason: If not fulfilled the "stand-off" capability at low speed would be severely restricted.The centre of buoyancy, B, should be located considerably higher than the centre of gravity, G, to give good roll and pitch stability. Reason: With no active control of roll and pitch, a high "static" roll and pitch stability is essential.Considerable effort should be made to ensurethat the vehicle has "hydrodynamic symmetry" about a vertical and a horizontal plane of symmetry. The tow-point should be on the forward end of the vehicle on the intersection line between these planes of symmetry.
Installation of the Jolliet Field TLWP
Authors: Wybro P.C. , Bultema S.C. , Mueller J.L. 
Published: October 2008

ABSTRACT
This paper presents an overview of the installation of the Jolliet TLWP including the drilling template, foundationttmplate, tem30nsd TLWP itself. Novel installation techniques were Used and same of these are describes. Attention is focused on not only what went well, but also some of the problems encountered and the solutions achieved. The paper also describes some of the very intensive planning, installation engineering and testing that was performe3in preparation for the work. Specialized installation equipment procedures are described.

Introduction
The Jolliet project marks several -first in the industry, the most note worthy Of which is the world?s water depth record for a production platform and the novel Tension Leg Well Platform (?ITWP)approach to production platform design. Installation was, therefore a key consideration throughout the execution of the project beginning in the early conceptual phases. A driving consideration for nearly all the marine components of the TLWP was install ability -how to transport and install it off shore. This was particularly so for the templates and the tendons.
The TLWP is described in Reference 2 and will Not be repeated here, expect to focus on some Aspects of the various systems which have key implications to installation
The TLWP was installed in three distinct stages as follow :Stage1 - A field dedicated multi-use mooring system was installed followed by installation of the drilling template, allowing drilling operations to commence from a semi-submersible drilling vessel (SSDV). This was performed in June/July,1987.stage2 - The drilling operations were temporarily suspended, the drilling vessel moved off location, and the TLWP foundation template was installed with a large semi-submersible crane vessel (SKY). After template installation in August/September, 1988 the SSDV was Brought back in to resume drilling operations.Stage3 - After drilling operations were complete, the SSDV permanently moved off, and the TLWP was installed. This operation Was performed in June/July, 1989. The following text summarizes some key events And considerations in the three stages with particular focus also on the various planning and preparatory work that was involved in this job
Ice Gouging and the Safety of Marine Pipelines
Authors: Palmer A.C. , Konuk I. , Comfort G. , Been K. 
Published: October 2008

ABSTRACT
This paper describes results from a study of ice gouge interactions with marine pipelines, carried out for Canada Oil and Gas Lands Administration. It defines the conditions under which pipelines can withstand the forces applied by gouging processes.

INTRODUCTION
Surveys of the seabed of the shallow seas bordering the Arctic Ocean reveal large areas which have been heavily scarred by ice gouging. Ice masses are driven into shallow water by the force of other pieces of drifting ice, in turn driven by wind and current. The masses ground in shallow water, and cut deep gouges into the seabed. In the Beaufort Sea and in the Arctic Islands, gouging extends from shore out to water depths of 50 m. The greatest intensity of deep gouging is found in water depths between 20 and 35 m. A few gouges more than 5 m deep are found, but most of them are rather shallower. Still deeper gouges occur in much deeper water in areas where icebergs ground, such as Davis Strait and the Grand Banks.
Pipelines are generally agreed to be the most safe, reliable and economical method of bringing Arctic offshore hydrocarbon resources to land, but it has long been recognized that seabed ice gouging is a threat to marine pipelines. A further concern is that it might not be sufficient to set a pipeline just below the maximum expected gouge depth, because of the possibility that large seabed loadings from the ice might damage a pipeline, even though the ice did not itself reach the line.
It was at one time hoped in some quarters that the formation of deep gouges would turn out not to be at active contemporary process, so that the gouges we see today would be a relic of earlier climatic and oceanographic conditions, perhaps with a different sea level and larger ice masses than occur today. Repeated mapping has proved that hope to be unjustified, and has shown that new gouges are being formed now. It was also questioned whether the ice forces currently present are large enough to cut the gouges that are observed, or whether the ice itself is strong enough to do so. That again has proved to be incorrect: the forces are indeed large, but not large in comparison with forces measured on offshore structures, and the ice stresses present are within the limits set by ice fracture and deformation.
The depth of trenching required to set a pipeline below the largest gouges in the Beaufort Sea is much greater than the depth of trenching routinely used to protect pipelines against fishing gear in heavily fished areas such as the North Sea. It is beyond existing pipeline trenching technology, because there has been no demand for very deep pipeline trenches except over relatively short distances in shallow water for shore approaches.
Vessel Impact Design for Steel Jackets
Authors: Ronalds B.F. 
Published: October 2008

ABSTRACT
The sequential elastic, elastic-plastic and plastic modes of response of a tubular member under quasi-static lateral impact loading are described. The simple formulae correlate well with available experimental and numerical data to large deflections. The position of the load along the span is shown to be of importance in design. The overall collision resistance of a particular jacket, both during impact and in subsequent storm loading, is investigated by attaching the nonlinear model to an elastic structure. The results are compared with those of a globally nonlinear analysis, enabling suggestions to be forwarded regarding the philosophy for design against ship impact.

1. INTRODUCTION
This paper describes vessel impact studies performed during design of the Woodside Goldwyn A platform. Goldwyn will stand in 131 meters of water on the North West Shelf off Western Australia, with installation planned for 1992. The jacket and module support frame (MSF) is an eight leg configuration, similar to several expanded bay structures designed recently for the North Sea. The topsides is Substantial, being 94m long with an operating weight of 23,500 tones. The production capacity is 900 MMscfd of gas and 80,000 bpd of oil condensate.
The leg and bracing members addressed in the collision study are shown shaded in Fig. 1. The overall dimensions of the impacted members were dictated by environmental factors. The separation of the supporting plan bracing levels was chosen to control the effects of wave action. Drag induced by the steep cyclonic storm waves and very significant surface current was reduced by minimizing the member diameters. These decisions were less beneficial for vessel impact design, however. The stocky sections lowered the energy absorption in local denting and the higher column slenderness encouraged plastic hinging.
Design criteria for vessel impact were based on DnV guidance [1]. This Reference defines two scales of impact: 'operational' and 'accidental', and specifies the impact energy associated with each. The work boat is considered to be of 5000 tones displacement, with 40% added mass for broadside collision and 10% added mass for stern or bow impact. The collisionvelocities are 0.5 mls and 2.0 mls for operational and accidental impacts, respectively.
Goodwin was designed such that operational impacts could be tolerated without the need for repair, and accidental impact would not precipitate structural failure. Energy is dissipated in local denting and bending of the struck tubular and overall deflections of the structure. Ref. [1] gives typical load-deformation response curves for supply vessels so that the energy absorbed by the ship may also be incorporated into the calculations.