bluuebunny/crossref_metadata_2025_split huggingface dataset:
FPSO Integrity; Structural Monitoring of Glas Dowr
Authors: van den Boom Henk , Krekel Max , Aalberts Pieter 
Published: October 2008

Abstract
The objective of the Joint Industry project 'FPSO Integrity' is to provide insight in the fatigue loading of FPSO's and the accuracy and validity of computational models. The results should contribute to reliable life time prediction and site assessment studies for this relative new concept of production.
Within the frame work of this JIP, 'Glas Dowr', a new build double hull FPSO operated by Bluewater for Amerada Hess at the Durward and Dauntless fields in the North Sea, has been instrumented extensively.
The objective of the instrumentation was to measure sufficient signals to derive the fatigue loading on the vessel. The dedicated monitoring system comprised the instrumentation of two cross sections of the vessel with strain gauges, pressure transducers and wave height radar's. Also the deck and the turret were equipped with strain gauges. Both the wave induced motions and the low frequency positions and orientation of the vessel was recorded. For the analysis of the measured signals the wind, wave and current conditions have been recorded as well as the vessel parameters such as draft, trim and tank loads. Data from the Glas Dowr has been collected from October 1, 1997 to 1 August 1999. The data has been subjected to long term statistical analysis and for selected periods to more detailed spectral and statistical analysis as well as rain flow counts.
The results have been used for validation of existing fatigue load calculation methods used by five classification societies and for the development of new fatigue load prediction software.

INTRODUCTION
For design, engineering and site assessment of Floating Production Storage and Offloading (FPSO) units, a reliable fatigue life prediction is essential. A computational model of the fatigue life of an FPSO comprises a description of the environment, a model of the fatigue loads and a model of the fatigue response.
As the operation of an FPSO is completely different from a trading tanker, in 1996 a Joint Industry project named FPSO Integrity was initiated to provide insight in the fatigue loading of FPSO's and the accuracy and validity of computational models. The background, objectives and structure of the project are described in further detail in ref [1].
The FPSO Integrity JIP comprised four major tasks:Structural monitoring of FPSO 'Glas Dowr' operated by Bluewater for Amerada Hess on the Dauntless and Durward field in the North Sea.Analysis of the measured data to derive the fatigue loads on the vessel.Development of a fatigue load assessment method, which can be used for a fatigue lifetime prediction.Comparative Study on the existing fatigue analysis methods currently used by the five Classification Societies involved in the project.
As the ultimate goal of the project was not only development of new calculations procedures but also comparison against existing methods and real life data, the project demanded a strong input from all stakeholders in the FPSO industry.
Measurement and Analysis of Ice Forces on Cook Inlet structures
Authors: Blenkarn K.A. 
Published: October 2008

ABSTRACT
The paper presents results of ice force measurements made in Cook Inlet, Alaska, over a number of years. Data include measurements made on a specially instrumented test pile as well as strain gauge records from a number of different platforms.
Ice force values are interpreted within the framework of a conceptual model corresponding to visual observations of the behavior of ice impinging on structures. Forces are related to ice conditions and related meteorological influences. Correlations are made between ice thicknesses measured in Cook Inlet and published ice growth formulas. Such correlation provides a basis for prediction of expected extreme thicknesses on the basis of historical weather records. Consideration is also given to the effect of ice temperature upon ice forces on structures.
Force records show details of the dynamic response of structures to ice loading. Conclusions drawn from study of the recorded dynamics are summarized.
From extensive observations of ice conditions in the Cook Inlet area, a variety of ice phenomena are described and analyzed in relation to their potential effect upon structures. With all such phenomena considered, the paper develops predictions of maximum ice loading to be anticipated.

INTRODUCTION
Subsequent to drilling of the first discovery wells in 1962, the upper segment of Cook Inlet, Alaska has been the site of an intensive offshore oil development activity. The most notable feature of the offshore development in this area has been the design and construction of 14 large offshore structures capable of resisting the extreme environment. Although the region is subarctic, Cook Inlet can develop a substantial ice cover. The potential destructiveness of the ice is magnified by a tide range of more than 20 feet and the accompanying 6-knot current.
In the absence of design information applicable to the conditions of Cook Inlet, an extensive effort was devoted to a study of the region and to determination of ice forces. This effort was primarily executed by two groups of oil companies, Pan American Petroleum Corporation being operator for one of these groups. The in-field work involved extensive reconnaissance testing of ice as well as the direct measurement of forces on several types of structures installed in the Inlet. A part of this activity has been described (Refs. 1, 2 and 3), but results are presented only in a general way. The purpose of the present paper is to summarize specifically the results of ice force measurements and to relate these force measurements to ice conditions. In addition, attention is devoted to study of the dynamic response of structures to the action of sea ice floes.

NATURE OF COOK INLET ICE
Most of the ice cover which forms on Cook Inlet has properties similar to ice Observed in other parts of the world. In standard ice observation terms, the seasonal ice cover on Cook Inlet is thin, first-year ice. The floes of the ice cover vary from medium to large floes, individual floes more than one-quarter mile across being common.
Rock Salinity Variations as Earth Stress Indicators
Authors: Overton Harold L. 
Published: October 2008

INTRODUCTION
Shales have recently been shown to be sensitive to both fluid and solid transmitted pressures, in the earth. l The salinity principle has shown that shale porosity, fluid pressure, rock stress and water salinity exist in mechanical and thermal equilibrium. The following two equations have been shown to be applicable whenever marine sands and shales are subject to variations in salinity gradients.
(available in full paper)
The porosity ?sh is directly related to the effective pore pressure, ?-P, which is the difference between solid and fluid transmitted stresses. The constant c depends upon geologic time and may be found in Ref. 1. It also may be noted on a graph of shale porosity or sand salinity whenever a profile of these parameters is available down to 8, OOO-ft depth. In general, c is 6 × 10−5/ft, for middle Pliocene, but may be solved directly from the SP curve.
(available in full paper)
Hence, the SP and density logs may be used to corroborate each other when viewed kiloscopically [on a kilometer scale]. In general, these three equations can be used to locate faults, unconformities and zones of high pressure. Pressures may be accurately calculated from Eq. 2 whenever the density log is run over the entire length of the wellbore. In the following equation a simple method uses the two depths at which similar shale densities are found.
(available in full paper)
In Eq,. 4, G fluid is the weight in Ib/gal of the average salt water gradient at any depth D. .6D is the difference between depths at which the shale densities are equivalent; G is the pore pressure gradient encountered by the drill.
Since all parameters in Eqs. 2 and 3 are now measurable, with the exception of ?; the rock stress is now calculable. However, since there generally is no way by which to check the calculations, the author will restrict the analysis to more practical evaluations. Quick checks on rock stress calculations are possible with casing collapse, sand fracturing and thrust, faulting. Sand fracturing will be reserved for I a subsequent paper.

FAULT STRESSES
Fig. 1 shows a salinity analysis where a review of the introductory statements is possible. The following features are plainly visible in Fig. 1.The critical compaction depth for Gulf Coast shales is 3)100-ft or less. Shales bind salt readily below that depth.Sand salinity varies quite uniformly, according to Eg. 3, on a depth profile with the exception of some faulting near 7, 000 ft. At this depth) salinity decreases in the downthrown block [in tension], while compression causes salinity increases in the up-thrown block.The boundary between Pleistocene and Pliocene is readily apparent at 5) 500 ft. This unconformity yields a salinity contrast due to a possible difference in compaction between the two intervals.Overpressure may be located and calculated at the depths of lowest water salinity. Both acoustic travel time and shale porosity yield similar pressure gradients.The shale-compaction coefficient of 4.96 × 10-5/ft indicates that the zone below 4, 000 ft is upper P1iocene. l
Subsea Tree Changeout with a Light Subsea-Well-Intervention Vessel
Authors: McGennis Eamonn 
Published: October 2008

Abstract
There are currently over six hundred active subsea wells in the United Kingdom Continental Shelf (UKCS) and with this extensive inventory of operational wells a need has developed for intervention and maintenance services for the actual subsea trees used on these wells. In certain cases the maintenance work required on subsea trees can be undertaken in situ on the seabed by either Remove Operated Vehicles (ROV) or by saturation divers. There are many cases however where more complex tasks are required. In theses cases it can often prove more effective to recover the trees to surface. This will reduce the risks and costs if an effective tree recovery procedure can be implemented.
As a result procedures have been developed for use from a Dynamically Positioned (DP) Well Services Vessel (WSV) (Ref. 1) and have been used successfully on twelve occasions in the UKCS. This activity includes seven tree changeout operations, three tree recoveries and two projects for tree deployment. This experience has shown that it is both cost effective and safe to temporally plug a producing well to recover the tree back to surface for maintenance. This paper will review the development of this subsea tree changeout procedure and how a WSV can effectively complete this complex operation.
The paper will outline the current procedure used for this operation and how it has been refined with recent experience. This experience was put to good use in June 2000 when a tree was recovered to deck for a maintenance operation. Once the tree was on deck it was recognised that it would have to be returned to shore for major work leaving a good producer shut in. To overcome this problem the WSV reconfigured a Water Injector (WI) tree on deck. The reconfigured WI tree was then run back in place of the production tree. This allowed the well to come back into production and so avoided an expensive loss of production from the well.
The flexibility and speed of the WSV solution offers significant advantages over the conventional rig based options. The WSV solution has proven to reduce risks and costs allowing work to be carried out that would otherwise be uneconomic. This is a technique that should allow many older fields remain profitable and in production.

Introduction
During routine inspection of producing subsea facilities in the Central North Sea (CNS) of the UKCS a major operating company became concerned with a particular technical aspect on one of the subsea production trees. To rectify the problem it was decided that there would be real advantages if the tree could be brought to surface for a detailed inspection and repair by the Original Equipment Manufacturer (OEM). As the work on the tree appeared straightforward it was estimated that the operations could be carried out on site.
Installation Method Evaluation of Export SCRs
Authors: Wang X. , Zhou X. , Ginnard A.J. , Sprot J.T. 
Published: October 2008

Abstract
The Banjo oil and Seahawk gas export risers are the first dynamic SCRs to be installed on truss spars and hosted by Jtubes. Each of the two truss spars, located at the Boomvang and Nansen fields in 3,440 ft and 3,670 ft of water depth, respectively, in the Gulf of Mexico, has one oil and one gas export SCR. This paper presents the detailed, post-lay, SCR installation method evaluations for these field developments, from vessel requirement, SCR pick-up, keelhaul under the spar mooring, positioning to J-tube bell-mouth, and pull-in to its hang-off position.

Introduction
The export systems of Boomvang and Nansen fields in East Breaks Block EB643 at 3,440 ft of water depth and Block EB602 at 3,670 ft of water depth, respectively, consist of one oil export line and one gas export line for each field. A truss spars at each field serves as the surface floating production system. SCRs (Steel Catenary Risers) connect the subsea pipelines to the topsides. Cantilevered J-tubes for the SCRs serve the function commonly accomplished by a flexjoint or stress joint, mitigating the bending moment at the support of the SCRs. All four SCRs employ such cantilevered J-tubes that extend from the bottom of the hard tank at elevation (-) 160 ft to the keel-tank with a bell-mouth exit at elevation (-) 507 ft. The SCRs, extended from the bottom of the hard tank where the J-tube ended and up through the moon-pool, hangoff at elevation (+) 51 ft with anchor flanges supported by split collars. All SCRs have a nominal departure angle of 14 degrees as their host J-tubes. For the Boomvang spar, the oil and gas export SCRs use 16-inch nominal diameter pipe with 0.812-inch wall thickness and 18-inch nominal diameter pipe with 1-inch wall thickness, respectively. For the Nansen spar, both the oil and gas export SCRs employ 12-inch nominal diameter pipe with 0.562-inch wall thickness. The wall thicknesses for the SCRs are controlled by the reel-lay method not mechanical integrity. The reel-lay method is selected for the pipe-laying of all four export pipelines and their SCRs. All SCR pipes are grade X65 seamless. The J-tube insider diameters are 19-inch, 23-inch, and 25-inch for the 12-inch, 16-inch, and 18-inch SCRs, respectively.
Due to the field development schedule, all four export SCRs will be laid prior to the arrival of the Boomvang and Nansen spars. After the spars are placed in position, mooring lines attached, the SCRs are then picked up and installed utilizing construction vessels. Two technical challenges exist in the installation of these SCRs. First, each SCR will need to be picked up by the support vessel, keelhauled through three spar mooring lines to reach the SCR hang-off side of the spar. Second, the SCRs on the truss spars are hosted by J-tubes, which extends from the bottom of the hard tank to the keel tank.
Reliability and Safety of Pipeline Laying by Reeling Technology in Deepwater
Authors: Kershenbaum Naum 
Published: October 2008

Abstract
The paper presents the results of reeling pipeline stresses and strains amplification investigation and describes the practical proved method to suppress the phenomenon, prevent a failure, and provide pipelay reliability and safety.
Advantages of pipeline laying by reeling are the cause of worldwide use of this method for pipe diameters up to 16-inch and even more in a future.
Some time ago there were several occurrences of pipe rupture during reeling in area of pipe properties changes (wall thickness or pipe grade) from previous joint to the next one. The rupture surface inspections have shown significant and unusual overstress in the area as a result of stress / strain reallocation. Stress / strain amplification occurs at any joint with different properties along the pipeline on a reel drum and especially when the connection is leaving a drum surface. The pipeline reeling failures have caused companies significant losses. It is suggested an amplification suppression method by utilizing a special form transition joint between different properties adjacent joints. The presented procedure allows control of the transition joint stress / strain values depending upon joint geometrical and steel property variations. The analysis is based on curvilinear beam non-linear stress - strain consideration and presented in spreadsheet form.
The above method has been successfully used during BPX Pompano Phase II Project and Pennzoil Flowline and Riser Project.

Introduction
Modern subsea pipeline construction uses the most cost-effective methods of installation. The pipelay by reeling technology is one of them providing the construction, acceptable cost and terms. This technology has been used with success for a relatively long time. The method and equipment are adapted now to lay pipeline up-to 16 inches in diameter and probably will be used for pipe-in-pipe assembly installation.
Reeling technology is associated with a high level of bending strain, which is often just slightly below pipe shell buckling strain values.
The approach is generally acceptable because there is a good reeled pipe axis curvature. Indeed, the curvature is maintained by the reel drum radius magnitude. That is correct until the reeled pipe has unchangeable properties: beam bending stiffness and pipe's moment-to-curvature non-linear characteristic values. If there is any changes in the reeled pipe properties then, the bent around reel drum stiffer pipe section generates the certain moment value, which could not be acceptable for the weaker pipe section being the extension of the stiffer pipe.
Diana / Hoover Installation: Overview
Authors: Arthur Timothy T. , Meier Jayme K. 
Published: October 2008

Abstract
This paper provides an overview of the ExxonMobil Diana/Hoover offshore installation, including both surface and subsea components in a record water depth of 4,850 feet.
The use of equipment advancements and industry firsts are presented together with a description of the organization and management of the project. The paper concludes with an overview of performance results and lessons learned.

Installation Overview
The installation of a Deep Draft Caisson Vessel (DDCV) drilling and production facility with related subsea pipelines and components in record water depths presented unique installation challenges, which required technology development, equipment advancements and a novel execution approach. Some of the "Industry Firsts" achieved were 1) the heaviest lifts onto a floating structure in open waters, 2) the deepest and largest Steel Catenary Risers (SCRs) installed 3) the largest mooring system installation, and 4) the heaviest lifts onto any type structure in the Gulf of Mexico.
The equipment advancements associated with the project included mooring system handling equipment, a two station J-Lay tower that installed the majority of the flowlines and SCRs, and a "long tether" pipeline touchdown monitoring ROV located on the pipelay vessel.
The 950+ man-year installation mostly occurred during the winter months of 1999/2000 in an area that routinely experiences high velocity eddy currents. These environmental conditions presented safety and operational issues that challenged the Diana/Hoover Construction vessels, which were among the largest in the world.
The execution approach was focused on selection of the most qualified Contractors working predominately under a risk sharing contract structure. A co-located integrated project team organization with common priorities was utilized to manage the offshore execution program. The team was expected to make decisions that were considered in the best interest of ExxonMobil (EM), the individual contractors and the overall project.
The components installed as part of this project are shown in Figure 1. The following sections provide additional detail regarding the platform and subsea installations.

Surface Components
The surface components installed included the DDCV hull, lower and upper deck modules, and various other packages that were lifted into place offshore. This work occurred over a 70 day period, with the Saipem S-7000, the world's largest semi-submersible crane vessel (SSCV), being utilized as the primary construction vessel.

DDCV Hull
The DDCV hull (Fig. 2) was 705 feet long, 122 feet in diameter and weighed 35,000 tons. It was fabricated in two sections in Pori, Finland, and each section was dry transported by heavy lift vessel to Corpus Christi, Texas. The two hull sections were joined in Corpus Christi and wet towed to site in the horizontal configuration. Once the hull arrived offshore it was prepared for upending and mooring.
A Probe for Characterization of Deepwater Commercial Sands
Authors: Cruickshank M.J. , Knapp R.H. 
Published: October 2008

ABSTRACT
This paper describes a new tool to measure, in situ, the engineering and environmental characteristics of unconsolidated seabed materials, particularly carbonate tropical sands, as much as 15 meters thick in water depths to a maximum of 20 meters from a small unanchored vessel. The initial prototype uses a pneumatic hammer to drive a video camera probe into the seabed. During penetration, the tool, which is shaped like a wood chisel, slices through the unconsolidated material leaving a virtually undisturbed face exposed to the camera. A selection of other physical, chemical and electrical sensors can be used to measure properties and composition of the sediments. In comparison with traditional sampling technology, it is anticipated that the cost of data acquisition may be reduced by an order of magnitude with this system. Although conceived for the characterization of offshore carbonate sand deposits, this unique tool will be adaptable to the characterization of other sites both on land and in the seabed.

INTRODUCTION
Sandy beaches in the tropical Pacific are, for the most part, derived from the erosion products of coral reefs surrounding islands. The sand budget is limited to the production of the reef corals and, in many places, the removal of beaches by storms or by commercial entities for the construction of infrastructure has resulted in serious degradation of the beaches with no hope of timely replenishment by natural means (Cruickshank, 1997). Shoreline loss in the State of Hawaii, and particularly O'ahu, is presently occurring at a significant rate. In 1997, "massive degradation" of Oahu's coast was reported with about 24% of the island's original 71 miles of sandy beach "either gone or so narrowed that at high tide it is unusable" (HA, 1997). It has now become paramount to find sources of sand for beach replenishment and maintenance that will be both environmentally and economically sustainable.
Recent discoveries by the United States Geological Survey (USGS) and others have indicated a potentially very large source of clean sand on ancient beaches between 70 and 130 meters deep. These beaches appear to be part of the Makua Shelf system formed some 40,000 years ago. Of particular interest is that they are outside the reef at depths below the impacts of storm waves, and the removal of sand should not affect the present shoreline in any way. Furthermore, it now appears that these deep water beaches just beyond the reef cliff might be found Pacific wide and there are no inhabited islands in the Pacific Basin that do not suffer from the same problems as O'ahu. This depth is considerably greater than normally anticipated and the characterization of the deposits using traditional vibracoring tools has been shown to be time consuming and expensive.