bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Analytical and Experimental Study of the Box-Type Joint for the Offshore Structure
Authors: Arita Yuko , Yamashita Masahiro 
Published: October 2008

ABSTRACT
This paper describes an experimental and analytical study on the states of stresses of a box-type joint and a further application of this type to a column stabilized drilling unit.
The box-type joint has been developed in lieu of the conventional tubular joint. The tubular members can be connected compactly by having them reshaped and formed into the box type section at the area close to the joint.. Regarding the transfer of load and the distribution of stress at joint, we have carried out the structural experiments using the three different types of models and analysis by the finite element method.
The result of the above shows that the distribution of stress at this joint is not so complicated as that at the tubular joint and that the coefficient of stress concentration in the former is less than that in the latter. The configuration of the box-type joint being comparatively simple, the analysis can be easily and accurately made and the flow of stresses can be clearly understood.
We have found that the local bending stress occurring around the area forming the box-type section from that of tubular shape was decreased by adding a suitable ring stiffener to this area and that the buckling strength in this area was sufficient.
It is expected that this type of joint having been already applied to the column stabilized drilling unit under construction at our Hiroshima Shipyard will prove to be perfectly effective and satisfactory.

INTRODUCTION
With the recent ocean development towards deeper and rougher areas of the sea, the column stabilized drilling unit and the drilling platform have come to be required to be larger in size and more reliable than ever before. To these offshore structures are usually applied tubular members to minimize the effects of waves, wind and tidal currents.
As is known, the thin cylindrical shell has such desirable characteristics, from the view point of structural strength, that it has superior properties in elasticity to the other ones. In order to make the best use of these characteristics, strength of the connecting joint between members has to be 'equal to or greater than of the members to be connected. This may well explain that the majority Taking into consideration the course of development of the joints in the offshore structures built for the past ten years, concerning the fixed type of the offshore structure, the gusset system was adopted, as a typical pipe structure for the tanker berth dolphin of the Cook Inlet; the flare joint system was also adopted for the, drilling platform operating in the same place.
Fatigue Tests On Anchor Chain-Cable
Authors: de Laval Gilbert 
Published: October 2008

Fatigue tests have been carried out on anchor chain-cable. Fatigue tests on steel normally are performed on specially machined specimens. Such a specimen is given an exceptionally smooth surface in order to eliminate as much as possible the probable influence of surface defects on the fatigue strength of the steel.
In order to obtain, in this case, a more realistic picture of the fatigue strength of anchor chain-cable than is possible with the ordinary fatigue test, these tests have been carried out on the chain links proper.
Three-link samples of 2-in. oilrig chain (Fig. 1) were tested at six different maximum loads. Chemical composition:C = 0.27 percentSi = 0.27 percentMn = 1.60 percentP = 0.024 percentS = 0.012 percentN = 0.008 percentMechanical properties:yield strength 47 kp/sq mm 67,000 psitensile strength 70 kp/sq mm 100,000 psielongation = 24 percentimpact resistance = 11 kpm at O°C, Charpy V-notchTesting requirements:proof load = 147 mp 322,000 lbbreaking load = 222 mp '" 488,000 lb
Before fatigue tests all samples were subject to proof load.
At each maximum load five samples were tested. The tests were made in an AMSLER 100 mp tensile testing machine with pulsator at the Government Testing Institute, Stockholm, Sweden The frequency used was 285 load changes/min and the amplitude varied between the maximum load and a minimum load of 5 mp.
The tests were carried out at room temperature in dry conditions. Records of test results can be studied in the table (Fig. 2) and diagram (Fig. 3) which show the number of load changes at rupture (small circles) at different loads. Mean values are indicated by big circles.
The samples were pulled to destruction or at least 2 million times.

Discussion Of Results
The ruptures occurred in the same place in the bent part of the link with location according to Fig. 4.
In Fig. 5, the mean values of Fig. 3 have been transformed to stress at maximum load. This stress value is simply the mean stress on the chain section obtained by dividing themaximum with the cross-section of the link [2 (?D2)/4] It is !mown that stresses in some parts of the link under load are considerably higher than this mean value.
It is perhaps allowable to define a fatigue limit for chain-cable. This limit could be defined as the maximum load at which the chain sample withstands at least 2 million load reversals without rupture.
Control Simulation Study of a Dynamically Positioned Pipelay Barge System for Deepwater Operation
Authors: Harris Bill J. , Morgan William A. , Stuart Francis X. 
Published: October 2008

Abstract
Extension of offshore pipe laying capabilities to water depths of 1500 feet or more is dependent upon the development of methods of controlling the pipelay barge at these depths.
Dynamic positioning through regulation of propulsion units is one method of control currently being considered. A simulation study was performed on a hybrid computer to investigate this technique, using direct digital control of the variables (pipe tension, pipe lateral load and barge position). In the study it was possible not only to evaluate the behavior of the system but ultimately to develop a successful scheme for controlling it.

Introduction
Recent years have seen offshore wells and pipelines extend into water depths over 300 feet. Now, with the latest techniques in drilling, platform construction, underwater completion and diving, technology exists that permits production in much deeper water. Accordingly, Brown &Root commenced an investigation of the means to extend their pipe laying capabilities up to 1500 feet or more in depth.
One of the major obstacles to pipelay barge operation in water depths much beyond the capability of present pipelay barges is the difficulty in maintaining barge position and progressing along the desired course using anchoring techniques. Anchor lines, even now, are up to 5000 feet long and they become longer for deeper water. In addition to the handling problems for these long wires, their permits excursions in position which might damage the pipe line. Both of these problems become progressively worse as water depth increases. For these reasons, the study of the deep water problem has centered around the dynamic positioning concept for control of the barge.
Dynamic positioning is not a new development It has been used on drilling vessels for a number of years. However, the pipelay barge application requires several unique features.
First, the lay barge does not have the capability of orienting itself to minimize environmental conditions, but must maintain heading in consideration of the direction of the intended pipeline. Thus power requirements and the forces tending to move the barge off station are both greater.
Second, the barge does not maintain a specific location, but must move either -continuously or in increments equal to each new joint of pipe as it is assembled. into the line on deck. Thus, permanently fixed sonar units or other such permanent facilities for maintaining a single location are unusable.
Third, some predetermined axial force in the pipe must be maintained in order to suspend the pipe from the curved stinger without overstressing. At the same time, the lateral load of the stinger on the pipe must be minimized to prevent lateral buckling.
Geotechnical Design of the Barracuda and Caratinga Suction Anchors
Authors: Hesar M. 
Published: October 2008

Abstract
The Paper presents the methodologies adopted for the design of mooring and riser anchors of the P43 and P48 FPSOs due to be installed in 2003 in deep water Campos Basin, offshore Brazil. It is shown how an efficient semi-analytical 3D finite element model can be used as a routine design tool for calculating the pull-out capacity of cylindrical suction anchors under combined horizontal and vertical loading. The speed of the FE model has allowed pull-out capacity contours to be developed which help in the selection of limiting installation tolerances. Fully coupled axisymmetric finite element consolidation analyses of the set-up phenomenon have been described in which the initial excess pore pressure field is established by simulating the final penetration stages of the skirts.

Introduction
The Barracuda and Caratinga fields are located in deepwater Campos Basin, some 150 km offshore Brazil. The average water depth is 825m at Barracuda and 1030m at Caratinga. A taut-leg spread mooring system has been adopted for both the Barracuda (P43) and Caratinga (P48) FPSOs. Each FPSO is moored by 18 lines, ten at the stern and eight at the bow. The mooring lines are made of polyester rope, combined with lengths of chain at the fairlead and seabed ends, Wibner1.
Various types of anchor were considered in the initial phases of the project. Suction anchors were selected as the preferred option for the following reasons, Sparrevik2:Relatively accurate positioning on the seabed, which isimportant in fields congested with flow lines and subsea facilities,Economical and simple installation method, avoiding the need for pile driving in deepwater or dragging and proof loading.Reasonably well-established design methods compared to other types of anchor, even though no Standard Code of Practice is yet available.
In addition to the 36 mooring suction anchors, 52 suction anchors in four different sizes were designed for restraint of the risers. The subject of this paper is the geotechnical in-place capacity of mooring anchors only and excludes installation aspects. The suction anchors were designed to comply with ABS Rules3 and current industry practice for 20 years service life.

Site Investigation
An integrated approach to SI was taken4,5. A comprehensive geophysical and geotechnical site investigation was performed in spring 2001 from the vessel Rockwater-1. Subsea7 (formerly Halliburton Subsea), performed the geophysical surveys consisting of swathe bathymetry, ROV high resolution sub-bottom profiling and side scan sonar imaging, while Fugro BV performed the following geotechnical SI from the same vessel:66 WHEELDRIVE Piezo-cone penetration testing (CPTU) to 30m penetration,12 WHEELDRIVE insitu vane tests up to 20m. One test every 0.4m and remoulded shear strength determination every second test,39 Push-in Piston cores up to 20m. The SI was followed by a programme of monotonic and cyclic laboratory testing both in Holland and the UK.
The First Year's Achievements of the Intelligent Well Reliability Group
Authors: Hother John 
Published: October 2008

Abstract
The Intelligent Well Reliability Group was formed as a spinout from the SPE's Smart Wells Forum in Europe in September 2001, and the contracts were signed in February 2003. The Group's objective is to increase the uptake of smart wells by promoting better understanding, and appropriate use of reliability methods and analysis. The 12 participants are a mix of operators and vendors, with an independent coordinator acting as 'honest broker'.
This paper reports on the work of the first 'year' of the Group, covering-A compendium of the parameters and metrics of reliability to establish a common language across the industry (completed);Guidelines on how best to address reliability in requirement specifications (review draft);Survey of system reliability analysis and prediction techniques (in progress);Survey of reliability testing and evaluation methods (in progress);Guidelines on the exchange of confidential information between the supplier and operator (in progress);Inventory of good operational practices and procedures for improving reliability (in progress). There will, no doubt, be significantly more completed work to report in the presentation at the OTC in May 2003.
The results can be applied by both operators and vendors, in the process of design, tendering, installation and operation of Intelligent Wells. Using the results will help to ensure that -the requirements are properly specified;the design meets the requirements;the design has been properly analysed and tested;the installation is properly controlled;the operational procedures extract the best performance. Oil operators have declared that improving reliability is at the top of their agenda - in international conferences and in direct dialogue with the rest of the industry. They have published performance reviews and set challenging objectives for reliability in service. Operators and service companies realise that they need to work together to achieve these goals. The results of this Joint Industry Project are expected to contribute significantly to the ability of the industry to meet the operators' objectives.

1. Overview of the Project
The Intelligent Well Reliability Group was formed as a spinout from the SPE's Smart Wells Forum in Europe. In the forum sessions, reliability and its perception had been identified as key issues. However, each SPE Forum is a oneoff event, and some of the key players wanted a new way of addressing these issues with continuity. At a break-out meeting of the key players, Proneta was tasked with formulating a draft Charter and organizing an inaugural meeting to turn that into an agreed Charter. That first meeting of the Group was in May 2002 in Galveston, Texas, the Charter was revised and agreed, and the contractual basis for the Group project was established. These are all described below, along with the results of the work to date (January 2003). It is expected that there will be further results to be reported by the time of the presentation of this paper at the SPE OTC in May 2003 in Houston, Texas.
Safety Performance of the Global E&P Industry 2001
Authors: Smith Don 
Published: October 2008

Abstract
Since 1985 the International Association of Oil and Gasb Producersa (OGP) has been collecting, analysing and reporting safety performance data on behalf of the global E&P industry. For 2001, OGP received almost 2,000 million workhours of E&P safety performance data, submitted by 41 companies, from their operations in 73 countries.
The paper presents the results from the analysis of the 2001 dataset. The 2001 statistics are compared to those of the proceeding 10 year period.
Analysis of the data shows that over the period 1991-2001 the industry has achieved a considerable improvement in its Lost Time Injury Frequency (LTIF), however little improvement is seen in Fatal Accident Rate (FAR) or Total Recordable Incident Rate (TRIR). For 2001, all these high level indicators were reported at their lowest values on record. In common with previous years, the most common types of incident leading to fatalities were vehicle related incidents, and persons being struck by moving or falling objects.

Introduction
The International Association of Oil and Gas Producers (OGP) has, since 1985, been collecting and reporting data relating to the safety performance of the global upstream oil and gas industry. This it has done through a series of annual publications, the latest of which is 'Safety Performance of the Global E&P Industry' [1]. These reports serve a range of purposes. Firstly, they present to the widest audience possible how the industry has performed, year on year, on a range of key safety measures. Secondly, it allows E&P organisations to benchmark their performance against that of their peers. Thirdly, it assists the industry to identify areas where it may need to concentrate effort. Most recently this has led to the formation of an OGP Land Transportation Task Force, the aim of which is to identify initiatives that may help to reduce the number of vehicle related incidents.
This paper presents the results of the analysis of the 2001 dataset. Industry recognised safety performance indicators are presented; Fatal Accident Rate (FAR), Fatal Incident Rate (FIR), Lost Time Injury Frequency (LTIF) and Total Recordable Incident Rate (TRIR). The 2001 data are compared with data from the proceeding 10 year period. The performance of both company and contractor personnel are compared, as are onshore and offshore performance indicators.
In addition to occupation injury data, the industry provides occupational illness data to OGP for analysis and reporting. However this paper is limited to a review of the occupational injury data. A review of the occupational illness data submitted to OGP for 2001 is available within a separate publication [2].
The paper provides a summary of the key features of 2001 safety performance statistics. The full analysis, including descriptions of each fatal incident and descriptions of significant incidents reported to OGP, is available within the annual report [1].
Mooring Design for Directional Spar Hull VIV
Authors: Magee Allan , Sablok Anil , Gebara Joe 
Published: October 2008

Abstract
Key issues for design of Spar mooring systems in the presence of VIV are discussed. The need to consider interactions between the directional effects of the Spar mooring and VIV response, together with the directional distribution of the loop current environment, is highlighted. For instance, the combination of current speed and varying sway natural periods for environment directions between and in-line with mooring groups give rise to variations in reduced velocity. Furthermore, the Spar response itself could be directional due in part to unsymmetric coverage of the VIV suppression strakes and other appurtenances located on the outside of the Spar. Directional stiffness and drag augmentation due to VIV may also affect maximum offsets and mooring line loads.
Two analysis methods are presented to determine governing mooring loads in the presence of Spar hull VIV. The first, called DRIVESIM, forces the motion of the hull in a pre - determined Figure-of-eight shape with given amplitude. Mooring loads consistent with measured drag loads are achieved by iteration on the effective hull drag coefficients. In the second method, called FORCE-IT, an applied force on the hull is used to achieve the required VIV amplitude, thereby allowing the mooring system non-linearities to achieve dynamic equilibrium. The second method shows a more realistic trajectory.

Description of Spar Hull and Mooring
Currently there are three Spar hull configurations that are installed or under design and construction: Classic Spar, Truss Spar and Cell Spar. The Classic and Truss Spar configurations are described in [1]. The Classic Spar has a circular cross section along its entire length. The Truss Spar hull consists of a hard tank, which has a circular cross section similar to Classic Spar, a truss structure with heave plates, and a soft tank which provides buoyancy during horizontal tow-out and holds fixed ballast in the in-place condition. The Cell Spar [2] has multiple circular cylinders joined together in contrast to a uniform circular section of the Classic and Truss Spar hull.
The Classic Spar hull and the hard tank of the Truss Spar hull are fitted with helical strakes to minimize hull VIV motion due to current. The Cell Spar similarly has strakes along its length. Due to construction and transportation considerations, the strakes on Truss Spars built to date do not provide full coverage, but are truncated or have reduced height along one side, as shown in Figure 1. This allows the hull to be built close to the ground and helps with transport and float-off from the transport vessel. It also eliminates the need to rotate the hull for adding strake sections after offloading from the Heavy Lift Vessel. Therefore, the strakes, on the Truss Spars to date do not provide full coverage. On the other hand, Classic Spars built to date were rotated after offloading and the strakes completed. Furthermore, there are holes in the strakes for the mooring chains to pass through that make the strakes un-symmetric for Truss Spars and even for Classic Spars.
Mitigating The Shallow Water Flow Risk At Mississippi Canyon 849: A Team Approach
Authors: Bruce Robert , McKeown James , Sargent Tim , Garrett Randal 
Published: October 2008

Abstract
Wells drilled near the Mars, Ursa and Europa Basins within the Mississippi Canyon Area, Gulf of Mexico, have experienced varying degrees of shallow water flow problems. Two wells drilled in Mississippi Canyon Block 849 (MC 849) penetrated overpressured sands within the shallow section causing catastrophic shallow water flow (SWF). Both wells were subsequently abandoned. A team of geohazards specialists, geologists, geophysicists and engineers worked together to identify and mitigate this SWF, and successfully drilled the exploration well (Slam Dunk) in MC 849.
Figure 1: Seafloor Rendering Showing Mississippi Canyon and MC Block 849.(AVAILABLE IN FULL PAPER)

Introduction
Mississippi Canyon Block 849 is located 145 miles southeast of New Orleans, LA, in about 3600 feet of water (Figure1). The Pliocene target of the two wells previously drilled on the block, the Norcen #1 (Norcen) and UPRC #2 (UPRC), is a well-defined series of vertically stacked amplitudes within a thickening wedge of seismic reflectors. These amplitudes are stratigraphically trapped on the flank of a large salt ridge, which separates the prospect from the Mars basin to the east. While attempting to drill this prospect both wells were lost due to SWF. A seafloor amplitude map generated from a subsequent TGS 3D geophysical survey over MC 849 showed areas of high seafloor amplitude around the Norcen and UPRC wells, which were interpreted to represent sand "mined" by the SWF. These areas are not visible in the original 3D seismic data acquired by Western Geophysical (Figures 2 and 3). The SWF encountered at the Norcen and UPRC wells was so severe that during the planning of the Figure 2: Seafloor Amplitudes Showing AmplitudeAnomalies at the Norcen and UPRC Wellsites Interpreted as â??Minedâ?? Sand from SWF. Figure 3: Seafloor Amplitude Map Prior to Drilling of Norcen and UPRC Wells.(AVAILABLE IN FULL IN PAPER) Slam Dunk prospect, it was debated if drilling a successful well was feasible.
SWF is defined as water or, sand and water flowing within and around the outside of structural well casing to the seafloor (Alberty and others, 1997). Isolating the specific stratigraphic interval where SWF was previously reported, and delineating the extent and distribution of the potential SWF sands were key factors in reducing the risk of encountering SWF at the Slam Dunk prospect.

Data Sets
The geohazards investigation was based on interpretation of reprocessed 3D seismic exploration data acquired by TGS. The 3D data cube contains 2-millisecond sample rate data to a record length of 3.5 seconds TWT below sea surface (BSS). The exploration data has been reprocessed with spectral whitening to enhance the higher frequencies in the tophole section. The dominant frequency of the 3D seismic data set is estimated to be about 50 Hz in the shallow section, which corresponds to a limit of separability of approximately 27.5 ft, assuming an average velocity of 5,500 ft/sec for the shallow sediments.