bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Disposal Systems for Offshore Platforms
Authors: Gunn B.G. , Gueringer S.L. 
Published: October 2008

Abstract
The different methods used in handling gas effluent from offshore platforms are discussed in this article. The presentation is directed toward the type of system to select for gas disposal based on production, location, and safety factors for an offshore site.
Some of the means of gas effluent disposal to be discussed are vents, flares, and mechanical devices. The selection of the particular method for use would be dictated by the type of equipment used, water depth, ambient conditions, and the type of crude produced. Alternate applications of the methods such as undersea venting, local venting, or remote venting are reviewed to determine the best application for a particular platform.
Safety factors which affect gas effluent are examined. A few of these items are the amount and type of gas to be released, type of equipment, and location.

Introduction
Offshore production platforms are built to provide a working area to separate water, liquid hydrocarbon and gas. Separation is required offshore because of the extremely large pressure drops experienced due to two (2) phase flow of liquid hydrocarbon and gas being shipped together by pipeline. The dissolved gas would also require a large storage system for barge or tanker transportation of crude oil. Separation of crude oil and gas then is made offshore to allow single phase transmission of crude and gas through their separate transportation systems.
Means of handling the gas offshore have developed slowly as producers have tried many ways to safely and economically process the crude. Some of the various ways that have been used in the past are presented in this article. Factors used in the selection of a particular means of gas disposal are presented to assist operators in offshore operations. Safety and economics are the two yardsticks used to evaluate gas disposal applications. These two yardsticks are presented briefly in the following discussion.. But to arrive at the optimum system for gas disposal, the complete platform should be developed and studied.
Dubai Khazzan - Pioneer of Large Undersea Storage System
Authors: Curtis L.B. , Shepler James C. 
Published: October 2008

ABSTRACT
Like most applied concepts similar in nature to the huge submerged storage unit placed on the bottom of the Arabian Gulf off Dubai in 1969, it was born of need. With an oil discovery some 60 miles from the Dubai shore and located in moderately deep water, the projected costs of a pipeline, pumping system and shore terminal facilities were of such magnitude as to warrant study and application of less costly methods of storing and offloading crude oil. Since the ensuing application of the large submerged storage unit was unique, it was necessary to thoroughly analyze all areas of design, operation and environmental conditions under which the system would be functioning. Even with this very thorough investigation, there remained a residual risk, normally inherent in a new idea, which had to be equated with potential economic gain.
Wide margins of safety were established and the design parameters, both structural and operational, were maintained well within the limiting environmental probability boundaries. Perhaps the most critical of all design factors was the piling system employed to fix the tank to the sea floor and ensure long trouble free operation. Extensive testing and data collection were required to quantify critical relationships pertaining to soil mechanics and bonding.
Now operational the tank has performed fully as anticipated. This unique system offers some distinct advantages both from an operations view point and also in the construction and placement of large structures. It is indeed an international achievement as a multinational partnership was involved in the entire project.

INTRODUCTION
Dubai Petroleum Company, a Wholly owned Subsidiary of Continental Oil Company, as operator for a group of international companies composed of Dubai Marine Area Ltd. (Compagnie Francaise des Petroles and British Petroleum), Deutsche Erdol-Aktiengesellschaft, Dubai Sun Oil Company and Continental Oil Company discovered commercial oil in June, 1966, 'offshore in the Shiekdom of Dubai. Hispanoil has now replaced British Petroleum as a partner of the OOMA group. The shiekdom of Dubai is one of seven Trucial States on the southern end of the Arabian Gulf (Figure 1). It is an established center of commerce for coastal shipping operating out of a shallow water port. However, its shoreline has no natural deepwater area near shore which is essential for crude oil export in deep draft tankers.
The discovery well, Fateh A-l, flowed 30° API crude from the Lower Cretaceous Ilam and Thamama at 7,500 to 8,500 feet. Two confirmation wells were drilled two miles to the southwest and two miles to the northeast on either side of the original well and along the major axis of the structure. These first three wells confirmed the presence of the Fateh field some 60 miles offshore in water depths ranging from 110 to 180 feet(Figure 2) and triggered a number of feasibility studies to determine the optimum development method.
Titanium for Marine Applications
Authors: Feige N.N. 
Published: October 2008

ABSTRACT
Titanium alloys have had increasing application in marine structures over the last three-year period. The four principal areas of application have been its strength per weight advantage, its complete immunity to corrosion by sea water, heat transfer capabilities, and its high corrosion fatigue design limits in both low and high cycle fatigue. Present experience with high performance structures fave further defined its area of applicability and has pointed out the distinct design advantages of incorporating titanium in composite or mixed material structures. The author reviews a series of designs and relates service experiences encountered back to the initial design of the units.

INTRODUCTION
Titanium is a material developed in the early 1950's to meet the needs of the then emerging jet aircraft engine market. The suitability of its use in aircraft engines, airframes, and space structures is a high strength-to-weight ratio, good corrosion resistance to aircraft structure environments and temperatures and a moderate modulus of elasticity. Titanium has well met its expectations in this area and has shown increased usage both in total pounds and per cent weight on airframes.
Early interest and support in titanium was expressed by U. S. Navy investigators in 1950, (1) and its property advantages were well delineated by J. E. Cotton in 1956. (2) At that time metal availability and price prevented its serious consideration for many commercial applications. It was not until1963 when a need existed for a hull material for deep diving submersibles that further engineering work was done in this area by Navy investigators.
By 1966 the industry had sixteen years of maturity and had developed sufficient production volume and product diversity to sharply reduce raw material prices and increase odd lot availability of the mill product. Also, during the period there has been a significant increase in capable fabrication shops to handle titanium and its alloys. In this latter period, however, the greatest motivation to utilize titanium has been the rapid expansion of sophisticated structures in the sea more highly stressed which required the use of titanium to obtain the desired performance.
The present market is going through an evolution of 1963 experiments into production applications and is growing at a rate in excess of 15-per cent per year.
In the consideration of titanium versus the competitive structural materials in use in marine service, there are four general areas where it will be selected:Strength density advantage, such as a research submarine hull for a 20,000-foot diving depth.A corrosion critical machined surface which cannot be painted and which cannot corrode, such as the ball in a ball valve.A corrosion fatigue limited structure, either in the low stress or low cycle, high stress range. A ship's propeller blade or a mast structure on a boat are examples of this design.
AUV Applications Within E&P
Authors: Schostak Brian 
Published: October 2008

Abstract
In February 1999 Shell examined the current state of AUV development and evaluated the usefulness of the technology for enhancing our ability to explore for and produce offshore oil and gas. Our study addressed four questions:Can AUV's resolve our present problems?Will AUV's deliver a business benefit?Does AUV technology lend itself to easy implementation in the near future? AndWhat actions can we take to help catalyze the market?
Two separate types of AUV were identified for use within E&P: a survey class vehicle for data acquisition, and an engineering class vehicle for underwater intervention. For each type, this paper will describe the answers to the questions above; addressing the problems we hope to solve, our estimate of the feasibility of using AUV's to solve them, the business case for AUV's, and our analysis of the state of the market today.
A description of desirable attributes will be given for each type of AUV for a minimal case and a realistic ideal case.

Introduction
In late 1998 and early 1999 Shell conducted an internal study of Autonomous Underwater Vehicle (AUV) technology. The purpose of the study was to evaluate the usefulness of the technology for enhancing our ability to find and produce offshore oil and gas. As the name implies, an AUV is a robotic vehicle capable of independent actions underwater. Using sophisticated artificial intelligence software integrated with sensors that give it an awareness of its surroundings, the vehicle can carry out pre-programmed tasks and react to unexpected conditions.
We identified two separate types of AUVs for use within E&P. The first is the survey class vehicle for seabed data acquisition and the second is a work class vehicle for underwater inspection, repair, and maintenance (IRM). For each type of AUV, we examined four questions:Can AUV's resolve our present problems?Will AUV's deliver a business benefit?Does AUV technology lend itself to easy implementation in the near future (5 years)?What actions are necessary to catalyze the market?

Seabed Survey Problem
The use of appropriate seabed survey data affects the cost of offshore developments by providing information necessary for correct design and installation. Good survey data ensures that the local environment is fully understood so unnecessary safety factors are not incorporated into design. The data also helps to ensure minimal environmental impact and that there are no unforeseen hazards.
Survey data should allow for interpretation and identification of seabed morphology, natural and man-made seabed features, seabed soils, subsurface soils and features, and subsurface hazards. Data necessary to make these interpretations are obtained from a variety of sensors such as swathe bathymetric systems, sidescan sonar, and subbottom profiler. Additionally, magnetometer data and coring or sample data are used. Other information about the sensor platform and immediate environment is also needed to correctly use the data obtained from these sensors. The location, orientation, and attitude of the sensor must be measured.
Theoretical and Ohserved Performance of Mobile Rig Footings on Clay
Authors: Gemenhardt J. Peter , Focht John A. 
Published: October 2008

ABSTRACT
The observed foundation performance of eleven different jack-up mobile drilling rigs at 120 locations in the Gulf of Mexico was compared to their predicted theoretical performance. The foundation elements supporting all rigs included in the study are individual tank-type footings. The near-mudline soils at each rig location were clays; in addition, the soil shear strength and other properties were known (or could be estimated. Reasonable predictions of footing penetration were found to be obtained using the Skempton equation for the bearing capacity coefficient, N1c and strength data from unconfined compression tests on good quality undisturbed samples. Useable estimates of footing penetration were also shown to be possible for the Louisiana continental shelf by extrapolation of soil data on the basis of geologic and other evidence; the potential error tends to increase rapidly with increasing distance from the point where soil properties are known.

INTRODUCTION
Jack-up mobile drilling rigs with individual tank-type footings and a general configuration as shown in Fig. 1 constitute about 40 percent of the nearly 200 mobile rigs now in service(l). The number of footings ranges from 3 to 14, the footing diameters vary from 16 to 45 ft, and the nominal operating water depths range from 80 to 300 ft. In its operation a jack-up mobile unit floats to location with its legs lifted. At the drilling site, the legs are lowered to the mudline and jacked down into the seafloor soils until the total footing resistance becomes equal to the rig weight. Then the rig begins to lift itself out of the water. The drilling deck continues to climb the legs in order to reach a desired operating height above water level. A rig operator would like to know in advance that the sum of the air gap below the hull (G), the water depth (W), and the footing penetration (D), as shown on Fig. 1, will be less than L1, which is that portion of the total leg length (L) that can safely extend below the hull bottom. Since G and Ware fixed for a specific location and L1 is a constant, the unknown factor needed for advance determination of rig suitability for the location is the probable footing penetration, D.
The study reported here was to determine if the penetration of jack-up rig footings into clay could be predicted reliably by conventional or modified soil mechanics procedures. The investigation consisted of a retrospective analysis of actual footing penetration where soil conditions were known or could be inferred.

SCOPE OF STUDY
Sources of Data. When this study was conceived in 1964, it was re-cognized that the approximate character of performance measurements, coupled with the lack of soil information for many locations, would require the assembly of a large body of data that could be analyzed on a statistical basis.
Amplitude-Preserved Subtraction of Multiple Events
Authors: Spitz S. 
Published: October 2008

Abstract
Any technique aimed at subtracting the multiple wavefield from the seismic data can be seen as a two step process. In the first step the multiple events are predicted. In the second step, the predicted wavefield is subtracted from the input data. This paper proposes a new approach to the subtraction of the predicted multiple events. This approach is based on the spatial predictability of the coherent events in the frequencyspace (or time-space) domain. Unlike the standard attenuation techniques, this new approach is able to subtract the coherent noise even in the presence of strong cross talk between the signal and the multiple components of the input data.

Introduction
A crucial issue when processing seismic data is the ability to remove coherent noise while preserving at the same time the amplitude of the signal component. It is indeed well known that multiple reflections, which interfere with the primary reflections, lead to incorrect pre stack attributes and to an erroneous interpretation of the final images at target level. Standard techniques for the attenuation of this coherent noise often fail, especially in case of strong interference, or when the noise field is spatially aliased.
Because the multiple wavefield is generated by a specific physical mechanism, it is sometimes possible to predict this wavefield without any a priori velocity model (Refs. 1 and 2). This is the case for instance for a marine 2-D acquisition. Thus, the removal of the multiple events can be seen as a twostep process: prediction and then subtraction of the predicted events from the input data.

The minimum energy assumption
Suppose that an input trace d is made of signal s and noise n. Suppose also that m, a realization of the noise component is known, and that this realization is a filtered version of the actual noise in the gather.
(Mathematical equations available in full paper)
It follows that at each frequency the quantity (n*s) is zero. In the time domain, the cross correlation between the noise and the signal vanishes. In other words, the minimum energy assumption estimates only that part of the signal that is uncorrelated with the noise.
The generalization to a gather d of N traces d1, ..., dN made of primaries and multiples is straightforward. If the gather m of N traces m1, ..., mN contains a prediction of the multiples such that mi = w* ni, i = 1, ..., N, the minimum energy assumption estimation of the scalar w produces primaries that are uncorrelated with the multiples.
The over simplistic approach based on the minimum energy assumption (adaptive subtraction) cannot account for the possible cross talk between primaries and multiples and gives distorted results when the primaries and multiples interfere. To solve the possible interference between primary and multiple events, predicting the multiples is simply not enough. Some information has to be given on the primary events themselves.
Operating Experiences With the Captain FPSO
Authors: Bradley Roger , Sanders Christopher J. 
Published: October 2008

Abstract
The Captain Field in the UK North Sea is a shallow heavy crude reservoir, which has been successfully developed using ESP's, long reach horizontal wells and an FPSO installation. The Field has been in production since the early 1997 and has maintained a high uptime during this period. However, there have been some notable occasions when production has been interrupted. Uptime data is presented and the reasons for production losses and the improvements made are discussed. The competence of FPSO crews has been the subject of concern to Operators and the Regulatory Authorities in the North Sea, and the system developed for the Captain FPSO is illustrated. Since the commencement of production, there have been some significant safety, health and environmental challenges associated with the Captain FPSO. These have been the result of design as well as operational constraints. A comparison of the Captain SH&E data with the rest of the industry is presented.

Introduction
The Captain Field is a heavy oil (19 degrees API) development in the Outer Moray Firth area of the North Sea. The Field facilities consist of a wellhead protection platform (WPP 'A') and an FPSO. A schematic of the field facilities is shown in figure 1. The installation of the existing facilities was completed early first quarter of 1997 and production commenced on the 1st April 1997. An extension to the existing facilities is planned to be installed in mid 2000 to recover the reserves from the eastern part of the field (Area B) and will consist of a subsea template tied back to a platform bridgelinked to the WPP 'A'. Production from these additional facilities is planned to commence in the December 2000.
The WPP 'A' is the drilling centre for the western part of the field (Area A) and well fluids are transferred to the FPSO for processing by a series of pipelines. All the wells have electrically powered submersible pumps and downhole chemical injection of demulsifier and corrosion inhibitor. A hydraulic submersible pump was installed on the WPP 'A' as part of the testing of equipment for Area B. The process system on the FPSO consists of a single two-stage separation train and an electrostatic coalescer. A schematic of the process is shown in figure 2. The process fluids are heated to approximately 90 degree's centigrade between the 1st and 2nd stage separators. Pressure support to the reservoir is provided by water injection facilities located on the FPSO, excess water may be discharged overboard. The FPSO generates all the electrical power for the Field through five tri-fuel generator sets.
The FPSO has an oil storage capacity of 550,000 bbls arranged in 3 sets of wing tanks and 2 centre tanks, and two slops tanks are available for the storage of liquids which are not of exportable quality. The vessel itself has all the normal equipment that is found on a tanker, eg. inert gas generator, ballasting systems etc.
Effects of Soil Information on Economics of Jackup Installation
Authors: Geer David A. , Devoy S. Douglas , Rapoport Vladimir 
Published: October 2008

Abstract
The authors address economic impact of quality and availability of site soil information on safe jackup installation. Preload operations based on sufficient and on limited (or insufficient) soil data are analyzed. Reliability and applicability of a variety of soil information sources are discussed.

Preloading
In order to prevent jackup settlement during drilling or during storm conditions, the jackup unit is preloaded during the initial stages of the installation procedure. The preloading of a three leg unit is normally performed by elevating up to a 3-5 feet air gap. Ballast water is then gradually added to preload tanks until the weight of the unit loads the soil under the spud cans to a level equal to or in excess of the anticipated spud can loads for the design storm conditions. During the preload process, increasing rig weight usually causes the legs to penetrate deeper until the bearing capcity of the soil becomes equal to or greater than the spud cans loads. One of the main potential problems during preloading is a sudden uncontrolled leg penetration caused by (a) a spud can punching through the stronger soil layer into the underlying weaker soil, or (b) by unit leaning instability in uniform soft clays.
The results of uncontrolled penetrations can be disastrous. There are some preloading strategies that can lessen or even eliminate the magnitude of uncontrolled penetrations and reduce the possibility of rig leg damage. One strategy is to preload at zero air gap (also termed "preloading in the water"). As preload is applied and the spud cans penetrate into the soil, the rig draft increases. However, to achieve full preload, the draft of the rig hull typically must be limited to about 2 feet. At drafts greater than this, the buoyancy of the hull will not allow full spud can loading. As shown on the Fig. 1, this procedure can significantly reduce the potential peak value of the soil loading during punch through, and resulting differential leg penetrations.
Another strategy to lessen the magnitude of uncontrolled penetrations is to sequentially preload each leg of the rig. Because the total weight of the rig is reduced, the load during the punch through is also reduced. Also, the other legs, due to lower load can be jacked during a punch through to lessen the out-of-level condition of the rig, and lessen the load increase on the punch through leg. When this procedure is used together with zero air gap, dramatic reductions in spud can loading during punch through can be achieved, as illustrated in Fig. 2.

SUBSURFACE INFORMATION AND MODU SITE ASSESSEMENT
To plan preloading operations, expected rig foundation performance should be evaluated. This information requires subsurface soil data including soil stratigraphy and engineering properties. The following information is typically gathered to assess MODU foundation stability:Geological information for the area, to understand physical environment.Site bathymetric data, to provide accurate water depth and seabed topography.