bluuebunny/crossref_metadata_2025_split huggingface dataset:
Operational Problems of Offshore Oil Loading and Possible Solutions To Overcome the Weather Limitations
Authors: Sterzenbach M. 
Published: October 2008

ABSTRACT
Offshore loading systems have often shown unsufficient reliability and therefore often influenced the regularity of oil transportation from offshore production facilities to shore.
Most of the unregu1arities were caused by environmental conditions and handling difficulties.
This paper reflects on the problems with loading systems in the past, shows future development tendencies and describes a loading system which helps to avoid the problems which occured so far.
The author was in charge for the mechanical and operational development of the subsea oil loading system - SOLS.

INTRODUCTION
The production and transportation of oil and gas is done in a century old technology and does not cause problems so long the field is onshore. When the oil production started offshore the development of the necessary technology to achieve this production became a real challenge for the engineers. The environment and the waterdepth generated the tallest buildings on the world - the production platforms and the most expensive oil and gas transportation systems: either pipelines or loading systems for tanker transportation.
For offshore installations, the greatest design influence is not defined by the production quantity of oil and gas, but by the environment.
Therefore the greatest attention has to be paid to the optimization of the system ability to withstand the environmental forces.
This is normally done by strengthening the design or optimization of e.g. motion behavior or decksload. In the following the problems of oil loading systems are discussed and a system is presented which is not affected by the harsh environment conditions.
The presented new oil loading system was developed to overcome the environmental and operational problems. In order to achieve this requirement a total change in design compared to present loading systems was necessary.

PRESENT LOADING SYSTEMS
The loading systems used today are:
(Available in full paper)
some other designs appeared on the scene like flexible steel risers as e.g .. Monopi1e (Fig. 5) anchored floating towers as recently proposed for Shell's Norwegian Draugen field, bow or center turret mooring systems which are mainly used for fixed mooring of ship based production systems. In the latter case the transportation tanker connects to the stern of the production ship.
Each system offers particular advantages and also disadvantages as explained lateron.
All concepts and realized systems have a surface mooring line connection to the tanker and a free hanging or floating hose connected to a tanker manifold. While the floating hoses of the SBMs are connected to the midship manifold, the ALPs, the realised UKOLS and the SALM use a hose connection to an additional bow manifold at the tanker.
The moored tanker weathervanes around the loading system.
The only concepts which do not use a surface connection method are SUBLOAD (Fig. 6) and SOLS (Fig. 7). These systems use a subsea connection method comparable to drilling riser connections.
Scour From Cyclic Lateral Loading of Piles
Authors: Reese L.C. , Wang S.T. , Long J.H. 
Published: October 2008

ABSTRACT
Two types of scour can be identified at piles supporting offshore structures:erosion of the sea bottom (sea-bottom scour) at obstructions due to oscillatory waves and unidirectional currents, andthe loss of soil around a pile due to the cyclic deflection of the pile under wave forces. The second type (pile scour) is associated with cohesive soils and is the subject of this study.
Observations during onshore testing have revealed that the loss of lateral capacity of a pile in cohesive soils is due principally to the creation of a gap at the pile-soil interface and to the subsequent ejection of water from the gap at the space opens and closes during the cyclic loading.
The paper describes the phenomenon of pile scour, presents the details of a laboratory test to investigate the scour potential of various soils, discusses the significant findings of a research study, and indicates the influence of pile scour on the design of laterally loaded piles for offshore structures.

INTRODUCTION
A 24-in (610 mm) 0.D. pipe pile was driven into overconsolidated clay at a site near Manor, Texas and tested under static- and cyclic-lateral loading (1). The test was conducted in a shallow pit and water a few inches deep was kept in the pit at all times. The following statement is abstracted from the report on the, testing program.
"During cyclic loading, considerable scouring action was observed around the pile. The cyclic loading caused a pumping action in the water in the gap between the pile and the soil. This pumping action eroded the soil and widened the gap between the pile and soil; a hole to the side and slightly behind the pile developed during cyclic loading; the hole at the side was approximately 4 in. (100 mm) in diameter and 2 ft (600 mm) deep."
A test of a 3 by 3 group of piles, each 10.75 in. (273 mm) in diameter and on a center-to-center spacing of 3 diameters, was conducted at a site on the campus of the University of Houston (2). The surface soils were overconsolidated clays that were jointed and slickensided. The investigators reported that grayish silty clay, existing below a depth of 4 ft (1.2 m), was pumped up to the ground during cyclic loading.
The objectives of the study described herein were to present a qualitative description of the mechanism of scour or soil erosion at the interface of pile and clay (pile scour) and to provide a means of identifying clays that are susceptible to such scour. The mechanism of scour at the pile-soil interface is described in general terms, and details are presented of a laboratory test for investigating the scour potential of various soils. In the laboratory tests, soil samples with different characteristics were selected and tested. Studies (4) were made of natural soils from the Sabine, Texas site (5), the Manor, Texas site (1), and from a North Sea site.
Suction Anchors as an Anchoring System for Floating ,Offshore Constructions
Authors: Larsen P. 
Published: October 2008

ABSTRACT
The paper describes the result of model tests carried out with circular-cylindrical suction anchors. The purpose 6f the tests is to examine the mechanical behavior of soil and structure during installation and to determine the horizontal pulling capacity of the anchor at oscillating load compared to the pulling capacity at static load. The test results confirm the efficiency of the down suction method for installation and demonstrate that the horizontal ultimate pulling capacity of the anchor for fine-grained soils depends on the variation of the load with time.

INTRODUCTION
During the last decade the concept of using differential water pressure as driving force when structures are to penetrate the seabottom has been increasingly applied due to the increase in offshore activities. The method has been applied in the Danish part of the North Sea for anchor structures at the "Gormn" field (Senpere 1982) and recently in the Norwegian part for concrete skirt penetration tests on a large scale at Gullfaks (Tjelta 1986).
A suction anchor will often be constructed as a circular-cylindrical pile with a small length-to-diameter ratio. The ultimate resistance of a rigid pile against transversal static forces may be calculated by means of a method proposed by J. Brinch Hansen (1961). The calculations are based on the principle that the pile rotates as a rigid body around a point approximately 0.2× pile length above the pile tip as. indicated in figure 1.(Equation available in full paper)
In order to evaluate the test results, the theoretical pulling capacities calculated on the basis of the above calculation methods developed by J. Brinch Hansen and B. Broms are shown in figure 7.
In most cases only static load tests are performed with the anchor after installation, even though the load may be cyclic.
With the aim of comparing the horizontal capacity of the suction anchor at static load to the capacity at cyclic load a series of model tests with circular- cylindrical anchors in sand and clay has been conducted at the Danish Geotechnical Institute.

MODEL TESTS
A total of 15 model tests were performed, 11 of which were in sand. Of the 4 remaining tests 2 were carried out in clay and 2 in kaolin. A detailed description of the tests is given by P. Larsen (1987).
Behaviour of Embedded Mooring Chains in Clay During Chain Tensioning
Authors: Dutta A. , Degenkamp G. 
Published: October 2008

ABSTRACT
With the help of experimental results, this paper first describes the behavior of embedded mooring chains connected to a buried anchor point. The tests were carried out on three different sizes of chain in two clays with different undrained shear strengths. Subsequently, the effect of changing the effective chain widths (for calculating soil resistances) on the chain forces at the anchor point has been discussed with certain analytical results. The studies are believed to be useful to the practicing engineers.

INTRODUCTION
Over a few decades, the anchor pile-chain system is being widely used with the single point mooring (SPM) systems of CALM-buoy type. In addition, as the offshore activities are moving towards deeper sites having soft soil, it is inevitable that the anchor pile-chain system will find wider application in connection with the mooring system of floating platforms and articulated structures like Guyed Towers. Hence, it is understood that the present topic is of relevance to the design practices of the mooring system with buried anchoring arrangement.
The connection point between the mooring chain and the anchor pile, which is commonly known as "pile lug", is generally positioned a certain distance below the seabed level. The basic season behind such a design is to economise the anchor pile design, utilizing the following two important factors:Embedded chain experiences a considerable amount of soil resistances which in turn, reduces the forces at the pile lug.Embedded pile lug minimizes the bending stress level in the pile section.
The optimum design of the pile lug location is however a critical issue; and this is so due to the pull-out and pile driving considerations. These two considerations can well be satisfied if the pile lug is positioned near the seabed level. On the contrary, the economy in pile design is achieved if the pile lug is located around the mid-height of the pile. Therefore certain trial and error approach is adopted in practice to obtain the most suitable lug depth, which may not essentially be an absolute optimum solution.
The analysis and design of an anchor pilemooring chain system involves the analysis of a part of the mooring chain (referred here as embedded chain) considering all probable soil-chain interactions. Basically, during the initial chain tensioning operation, the embedded chain length (which indeed varies with the line tension) starts cutting the soil medium deeper and moves away from the anchor pile. During this chain movement inside soil two types of soil resistance are developed. These are :resistance against cutting or bearing resistance, andresistance against sliding or sliding resistance.
These resistive forces from the soil medium can be idealized as normal and tangential distributed forces along the embedded chain length, and can be expressed in terms of undrained shear strength of soil (Su) as discussed by several authors (1 – 8).
Computation of Nodule Abundance From Seabed Photos
Authors: Sharma R. 
Published: October 2008

ABSTRACT
Correlation between water depth, nodule coverage, abundance from seabed photos-and grabs and the relative abundance has been studied in different seabed settings .based upon thickness of sediment water interface boundary' (SWIB)I layer and extent of nodule burial at different locations. Whereas, nodule coverage and Abundance have an inverse relation with thickness of SWIB layer (due to nodule burial)l, there is a good correlation (? .75) between nodule abundance in photo -and grab. Relationships between actual nodule population and -variable burial under the associated sediments have been established and mathematical formulae worked out to compute nodule abundance from seabed photos in different environmental settings.

INTRODUCTION
Nodules are known to be buried to varying extents under the uppermost uncompacted sediment on the seabed or the Sediment-Water Interface - Boundary (SWIB)1 layer (Cronan and Tooms, 19671; Sorem and others, -1979), leading to an underestimation of nodule abundance from seabed photos. (Frazer and others, 1978, Bastein-Thiry, 19791 Anonymous, 1982). Studies on comparison of nodule abundance from grabs and photos have emphasized the need for a correction factor to be applied to photo estimates to account for buried nodules (Fewkes and others, 1979; Felix, 198?). However, no single correction factor can be applied to all estimates (Felix, 198?), as the nodule burial also depends upon the varying thickness of SWIB layer at each location (Sharma, In press).
Several methods have been proposed for estimating nodule abundance from photos (Bastein Thiry, 1979; Fewkes and -others, 1979; Handa and, TsuIusaki 1981) and have attained an accuracy of 5?-8f? -% with respecit to actual nodule abundance. This study aims at quantifying the burial of nodules and thickness of SWIB layer in-different seabed settings -which can be used to estimate nodule abundance accurately, so as to make seabed photography an independent and reliable tool for nodule exploration.

METHODS
Seabed photographs at 285 location, were taken, using cameras attached to freefall grabs, 1-1.5 m above the seabed, Nodule (C) was estimated in percent by superimposing a graph sheet and counting the number of squares falling on nodules with respect to area of the photograph.
(Equation available in full paper)
Metallic Sealing Technology in Downhole Completion Equipment
Authors: Blizzard W.A. 
Published: October 2008

ABSTRACT
Metallic seal systems are relatively new to downhole completion equipment. Their incorporation into downhole products represents a trend toward higher technology in extreme service applications. The foundations for metal seal design have long been established in other industries such as aerospace, high pressure and temperature autoclaves, cryogenic and chemical industries. This paper will examine why metal Seal technology exists and to what extent downhole well completion equipment is affected.

INTRODUCTION
As new frontiers emerge in the oil and gas industry, new problems arise. Higher temperature and pressure, greater well depth and severe corrosion significantly affect downhole products. These factors combine to create severe performance and longevity problems which manufacturers of downhole equipment must work to solve. Polymeric seals in downhole equipment are the leading cause of equipment failure.1 Since reliability of the well completion is of utmost concern to today's operator, the push toward better seal systems has generated the current influx of metal seals.
Metal seals provide excellent service in many currently marketed products2. However, metal seals are not the panacea of downhole sealing requirements. As much as the industry would like to convert to metal seals, certain downhole products have yet to prove easily adaptable to metal configurations. Incorporating metal seals downhole requires basic seal design consideration. Extensive time and financial support is also required. In general, metal seal technology costlier to develop than non-metal.
Inroads have been made toward developing all-metal equipment. The subsurface safety valve is the first significant dynamic product to utilize all-metal seal technology. It is currently field proven and a readily available item. The safety valve utilizes all aspects of metal seal design and has laid the groundwork for products that follow.

SEALING THEORY

GENERAL
TO understand what makes a "good" seal, one must realize that there is no current accepted definition of the term "zero leakage". An acceptable seal in the oilfield may be totally unacceptable by aerospace standards. In general, however, zero leakage dictates the use of polymeric seals. When metallic seals are desirable, zero leakage must be quantified. For example, Advanced Technology Labs (G.E.) defines zero leakage to be less than 10−8 cm3 per second of helium at atmospheric pressure.
Exploration of Nearshore Placers Off Konkan Coast, West Coast of India
Authors: Gujar A.R. , Ramana M.V. , Rajamanickam G.V. 
Published: October 2008

ABSTRACT
A detailed geological and geophysical survey comprising sediment sampling, short cores, shallow seismic profiling and magnetics covering about 90 sq. km. was carried out in the nearshore area (up to 20 m water depth) of 2 bays, Pawas and Purangad, Kookan Coast, Maharashtra to explore the offshore extension of promising onshore placers. The onshore beach placer sands extend to offshore to a water depth of 10 – 11 meters beyond which it is covered by clays. The surficial sands in these bays contain upto 93.69% of heavy minerals with appreciable amount of ilmenite and magnetite. Seismic profiles and short cores confirm the presence of heavy mineral rich sands below clays after 11 meters of water depth. The thickness of heavy mineral rich sand is 2–3 meters. The basement in the area is undulatory and has a N-5 trending depression (about 200–300 m wide) in Pawas bay which probably acts as trap for accumulation of sediments. The magnetic picture in the area shows positive correlation with heavy mineral placers and basement configuration. The offshore reserves of ilmenite and magnetite are inferred to be about 1 and 3 million tonnes respectively. The extensive onshore and offshore deposits offer encouraging possibilities for future integrated development.

INTRODUCTION
The occurrence of heavy mineral beach placers are known from many localities along the Indian Coast. The major deposits are along Kerala and Maharashtra on the west coast and along Tamil Nadu, Orissa and Andhra Pradesh on the east coast. The placer sands with varying proportion of ilmenite and magnetite have been reported from the areas of Ratnagiri and Sindhudurg district of Konkan Coast Maharashtra. The continuity of these coastal beach deposits is interrupted by morphological features such as cliffs, promontories and drainage features like creeks Cll1d tidal inlets. These deposits in general, occur as beach deposit Which is immediately in contact with the sea, as a dune deposit further inland, as bars in river and creek mouths and also in the low laying interior area behind the bars in the marshy lands. Patel (1936) and Roy2 (1958) surveyed these coastal deposits at many places. Their survey indicated 54.4% of magnetite and titano magnetite, 29.4% ilmenite, 7. Z'1o rutile with other constituents like tourmaline pyroxene, quartz, and feldspar along Purangad, but during their survey the Pawas beach was not covered. The average thickness of Purangad beach sands is about 1 to 2 meters. The reserve of ilmenite is estimated to be about 0.025 million tonnes and along with this titano magnetite is also present Roy2 (1958). These beach placers and adjacent Pawas beach placers are expected to extend in the offshore regions.
Glamis: A Subsea Satellite Development
Authors: Craig I.G. , Oldfield G.A. 
Published: October 2008

ABSTRACT
Glamis is situated 8km south west of Sun?s Balmoral Field. Its development as a subsea satellite field represented a substantial extension of the Balmoral FPV and template facilities installed in 1986.
The three well development project was managed and engineered in house using proven Balmoral technology and experience wherever possible, although notable changes were necessary owing to differing design parameters and advances in technology.

INTRODUCTION
The Glamis Field is a 17.5 mm STR recoverable Jurassic accumulation. It was discovered in 1975 in 145 metres of water in Block 16/21a of the UK North Sea.
In 1985 three appraisal wells were drilled, tested and suspended as two future producers and one injector. The decision to develop the field was deferred until December 1987, more than a year after the Balmoral field came on streams.in order to optimise production profiles and fuel gas availability for the FPV.
The development comprises dedicated flowlines, control umbilicals, trees and protection structures, flexible riser system and a template manifold. Modifications to the Balmoral topsid.es facilities and subsea control system ?were also required.
During the development, economies of scale made it attractive to install extended well test (EWT) facilities to a nearby Blair prospect which lay in the pipeline right of way to Glamis. This project was run concurrently with Glamis but is outside the scope of this paper.

INITIAL STUDIES
Although allowances for expansion were made in the Balmoral Field development (Ref 1), Glamis presented a range of significantly different problems
The Jurassic reservoir is deep, at 10,150 feet TVDSS; hot at 120°C; corrosive, with a MOL C02 percent of 1.78; contains a relatively high GOR of 1037 scf/stb and has wellhead shut in pressures of 2900 psig compared to 1650 psig for Balmoral.
Initial studies projected a production rate of 10,200 bbl/d for 4 years, sustained b.v an immediate water drive of 20,000 bbl/d. Gas production at plateau would be 7 mm sc fd and no artificial lift facilities would he required owing to the high GOR.
It was concluded that the reservoir would be best depleted by retaining the existing wells in a three well development, (Figure 1). Both of the producers would require side tracking later in the well life owing to projected water cut build up and to access a new updip location in the reservoir.
Fiscal metering of Glamis production fluids would have required the installation of an additional separation train and metering skid on the FPV.