bluuebunny/crossref_metadata_2025_split huggingface dataset:
Open-Sea Terminal In Hostile Environment
Authors: Koman B. 
Published: October 2008

ABSTRACT
A ship loading terminal near Punta Arenas, the southernmost city of the world (53 ° -10'S, 70 ° -54'W) is described. Strong winds, choppy seas, frequent gales, rain and snow make it difficult to load ships at an offshore berth in this area. Detailed site investigations, including a wind recording program, supplied sufficient information for the analysis of operating conditions. The weather pattern of the entire region, including the predictability of gales, was utilized in the analysis. The results showed that a bulk loading terminal at this location is feasible, provided that the design takes into consideration the specific problems of the site. The final layout shows a terminal that can be approached from several different directions, depending on the direction of the wind. The mooring system-is arranged to allow alternative ways of attaching and casting off mooring lines and executing docking and departing maneuvers.
The berth is supported on piles and contains the minimum of structures, relying on a slewing ship loader to reach the ship in any position, with only limited fore and aft shifting of the vessel for loading the extreme hatches.
Results of wind recording, statistical analysis of wind and wave data, operating criteria and the results of berth availability analysis are included in the paper.

INTRODUCTION
Construction of a terminal capable of loading 3 million tons of coal per year into 60,000 DWT bulk carriers was a basic condition for opening the Pecket mine near the southernmost city of the world, Punta Arenas, Chile (Lat. 53 ° -10' South, Long. 71° -54' West). The only location close enough to the mine to allow economical transportation is on the eastern shore of Otway Sound, a large body of water accessible from both the Pacific and Atlantic Oceans via the Strait of Magellan and the Geronimo Channel (Fig. 1). This area is exposed to prevailing onshore winds that often reach gale force, generating choppy seas and heavy surf. Summer rainstorms and winter snowshowers occur with considerable frequency.

OCEANOGRAPHIC AND ATMOSPHERIC CONDITIONS
Otway Sound (Fig. 2) covers 2,750 square kilometers (800 square nautical miles). The fetch of open water over which waves can be generated by the prevailing westerly winds is approximately 37 kilometers (20 nautical miles).
The weather pattern of the region is dominated by the large Pacific Ocean air masses whose eastward flow is obstructed by the Andes mountain range. Being forced south, these masses burst through the Strait of Magellan area with explosive force. As a rule, gale or near-gale force winds blow for several days, followed by a calmer period before the next gale. During the Southern Hemisphere summer the gales occur with greater frequency than during the winter. The arrival of these strong winds can usually be predicted several days in advance, from simultaneous readings of the atmospheric pressure at two or more meteorological stations located hundreds of miles apart.
Reliability of TLP Tethers Under Maximum and Minimum Lifetime Loads
Authors: Harding S.J. , Banon H. 
Published: October 2008

ABSTRACT
This paper describes reliability analyses which were performed to determine the adequacy of TLP tether maximum and minimum tension design criteria. Reliability analyses for other potential tether failure modes such as fatigue were not performed. The calculated reliabilities were compared to typical calculated reliability levels of steel piled jackets. The effect on tether loading of vertical wave impact on the underside of a TLP deck was also considered for the maximum tension case. Tether load analyses were performed using frequency domain analytical tools and reliability was calculated using the advanced, first order, second-moment analysis technique. A probabilistic methodology for combining time-variant and time-invariant tether load components was developed. The results of the study are limited by assumptions discussed in the paper.

INTRODUCTION
The present economic climate in the oil and gas industry encourages the search for low cost deepwater production systems. One of the challenges in the evaluation and development of such systems is establishing criteria which lead to safe, but not overly conservative designs. Since little or no actual service experience exists for new concepts, a probabilistic reliability analysis is a means of calibrating the design criteria. This is accomplished by comparing the calculated reliability of the new structure with that of conventional offshore structures which have demonstrated their safety over time.
The subject of this study is the Tension Leg Platform (TLP). The TLP, Figure 1, is a deepwater production system that has a semisubmersib1e type hull and integral deck permanently moored to the ocean floor by tethers which are kept in tension due to excess buoyancy of the hull. The tethers are the most novel and also the most critical feature of the structure.
There are several potential modes of tether failure. The two studied here are maximum tension in which the tensile capacity of the tethers is exceeded, and minimum tension, in which loss of tension leads to unacceptable stresses caused by retensioning or excessive tether bending. While the TLP can still function properly with a tether damaged or removed, it is not known how much damage a ruptured tether falling to the ocean floor could cause to risers, adjacent tethers or foundation and well templates. In this paper, failure of the TLP system is defined as failure of one tether. Reliability analyses for other failure modes such as fatigue, which was not critical for the Gulf of Mexico application being studied, were not performed.

TLP TETHER LOADS AND DESIGN CRITERIA

TLP Description
The TLP analyzed in this study was designed for 762-meters (2500-feet) of water in the Gulf of Mexico. It has a square, four-column, symmetric conf1guration with circular columns and square pontoons. The pontoons have rounded edges. The displacement is 52200 mt (57540 st) and the platform weight is 34330 mt (37840 st). The column center-to-center span is 62.8 meters (206 feet),
New Global Earth Model and Seafloor Gravity Analysis for Offshore Exploration
Authors: Kim V.E. 
Published: October 2008

ABSTRACT
An improved seafloor gravity analysis for offshore exploration is developed using a new global Earth model (NEWGEM) based on exact solutions of the ellipsoidal layer model of the rotating Earth with local and global corrections. The new analysis is expected to be capable of extracting more reliable in situ mass-density profiles under the seafloor since it uses many available geophysical data such as sea surface gravity and seismic surveys as well as seafloor gravity and bathymetric surveys.

INTRODUCTION
Presently, it is customary to select offshore exploration drilling sites based mostly on seismic data analysis. Gravity surveys are not used as extensively as seismic surveys, primarily because gravity analysis is not developed to its full capabilities and sensitivities. In this report, a new gravity analysis method is described to remedy the above situation.
The new analysis method is a hybrid interactive method involving both partial inversions of gravity survey data and forward modeling of density profiles and uses interactive graphics and expert systems. The new method is complementary to the existing seismic analysis methods, since it uses the results of the seismic and geological surveys. The new analysis is expected to give an improved in situ mass density profile under the seafloor from seafloor gravity surveys and other surveys. In particular, it will be extremely useful when a choice for the final site is to be made from several potential sites determined from seismic and other surveys.

NEW GLOBAL EARTH MODEL (NEWGEM)
Some knowledge of the mass distribution in the interior of the Earth is emerging from seismic studies4,5 and rather detailed knowledge of the Earth's crust and surface is becoming increasingly available in many places. Therefore it is desirable to introduce a new physical representation of the mass distribution for the entire Earth which can be refined to accommodate new and more accurate data as it becomes available and which can describe many different component properties and processes of the entire Earth system on both global and regional bases. A new global Earth model (NEWGEM)1.3 has been recently proposed to provide a unified description of the Earth's gravity field inside, on, and outside the Earth's surface using the Earth's mass density profile as deduced from (1) seismic studies,. (2) elevation and bathymetic information, and (3) local and global gravity data. Using NEWGEM, it is possible to determine the constraints on the mass distribution of the Earth imposed by gravity, topography, and seismic data. Seismic studies indicate that the Earth has a concentric shell structure with deeper shells having larger mass densities. This structure of the Earth is summarized in the Preliminary Reference Earth Model (PREM).4 PREM defines the Earth as consisting of eight principal layers. It specifies the thickness of each of these layers and give polynomial expressions for calculating, as a function of radius, the density in each layer.
An Analysis of Piles in Marine Clay Under Cyclic Axial Loading
Authors: Wathugala G.W. , Desai C.S. 
Published: October 2008

ABSTRACT
A finite element procedure based on the Biot's theory for dynamics of porous media is developed to analyze nonlinear soil-structure interaction problems including pile foundations. The method is verified by back predicting field behavior of cyclic axially loaded instrumented pile segments, tested in a saturated marine clay, near Sabine Pass, Texas, in collaboration with Earth Technology Corporation (ERTEC), Long Beach and Houston. .'A new and advanced anisotropic hardening constitutive model is' developed based on laboratory tests on undisturbed samples from the site. For the preliminary analysis presented here, a simplified, associative version of the model is used.

INTRODUCTION
Pile foundations are common in offshore structures. Wave forces on these structures create cyclic axial, lateral loadings and moments. Proper understanding of the soil-pile interaction under these loadings is important for the safe and economical design of foundations for these structures. In this paper, the case of only axial cyclic loading is considered.
Most of the available methods for analysis of pile-soil interaction problems under cyclic loading are based on highly simplified (often one-dimensional) idealizations, and similar simulations for soil behavior; popular semi-empirical methods such as the t-z curve approach are among these methods. These methods may not provide an insight into the soil behavior, and pore water pressure development around the pile.
A finite element procedure based on the theory of dynamics of porous media is developed and verified by backpredicting the field behavior of an instrumented pile segment under cyclic axial loading. The proposed procedure allows for axisymmetric idealization including coupled soil-fluid interaction and a new and generalized constitutive model for soils and interfaces. It allows for spatial and time dependent computation of displacements, stresses and pore water pressures around the pile. The proposed procedure can provide enhanced understanding of the response of the pile problem, and can lead to improved procedures for analysis and design of such soil-structure interaction problems involving dynamic loading.' This research is unique in the sense that it integrates modeling, laboratory tests for soil behavior and field verification.

DYNAMICS OF NONLINEAR POROUS MEDIA
Deformation of saturatl3d soil s under dynamic loading consists of deformation of soil grains, deformation of the soil skeleton, compression of water and movement of water through pores. The main contribution to the overall deformation is from the soil skeleton, and due to the movement of water through pores. Deformation of the soil skeleton is governed by effective stresses and is modeled using a new plasticity based constitutive model. Movement of water through pores is modeled using the well-known Darcy's law.
Detailed review of the theory or dynamics of porous media is beyond the scope of this paper; references present this theory, and reviews of relevant developments and applications.
Post Driving Prediction of Pile Capacity
Authors: Porter B.W. , Ingram W.B. 
Published: October 2008

ABSTRACT
Because soil is a heterogeneous media, pile installation response does not always proceed according to plan. When driving performance variability occur, the capacity of the piling must be determined and the cause of these discrepancies analyzed. Procedures for evaluating available soil borings, geophysical information and pile driving records to determine pile capacity are detailed.

BACKGROUND
During installation of a four pile jacket in the East Cameron area of the Gulf of Mexico, difficulties were encountered in reaching the design penetration of 323 feet. Piles 1 and 4 reached refusal after the final section was added when driving with a Menck 3000 hammer. A Menck 7000 hammer was tried on pile 4 and also met refusal. The typical definition for refusal used by installation contractors for a Menck hammer is 150 blows per foot for five feet or 250 blows per foot for restarting a pile. This definition differs form the API RP 2A(Ref. 1) recommendation of 300 blows per foot for five consecutive feet or 800 blows for one foot of penetration. This lower blow count for refusal is favored to prevent damage to the hammer which can be caused by excessive pounding with the hammer. In this paper the former definition for refusal was used.
Adding the final section and driving to refusal gained less than 10 feet of additional penetration and left a weld joint at a poor location for proper connection to the jacket. It was decided to drive piles 2 and 3 and to terminate pile driving after installation of the fourth section at a penetration of about 258 feet. This final penetration would leave the heavy wall pile section high in the profile, but in an acceptable location to provide the design lateral support because of proper underdrive design. The predicted pile capacity based on the nearby boring provided a capacity of about 5400 kips. This capacity of 5400 kips was sufficient for minimum design requirements but a determination of the as installed capacity consistent with normal design procedures was required to determine maximum allowable loading conditions. Final pile penetrations (measured from the seafloor) for piles 1,2,3 and 4 were 268.5, 259, 258.5 and 263.5 feet respectively.

QUESTIONS TO BE ANSWERED
The difficulties during installation on this project raised several questions on the design and installation of a jacket. The questions that were asked of Seafloor Engineers as geotechnical consultants and are addressed in this paper are as follows:What is the pile capacity of the piles in their as built condition?Based on a review of the boring log near the location, no driving problems were anticipated. Why did driving problems occur?
FulI-Scale Load Test of Pile Gripper for Bullwinkle
Authors: Digre K.A. , Kenney J.J. , Simic R.A. 
Published: October 2008

ABSTRACT
A full scale load test was required on a prototype pile gripper as part of its performance specifications. The test was conducted on a fully instrumented 84 inch diameter by 2.25 inch wall thickness, A572 - Grade 50 steel pile held in place by the gripper. Loading was increased in steps to a value of 7,50O kips. The test was successful and the prototype unit (one of four) was installed on the 1363 feet water depth Bullwinkle jacket. The four units were utilized during the platform installation, securing and stabilizing the jacket before grouting the "pin" piles and further pile driving.

INTRODUCTION
Pile grippers are constructed similar to grout packers. Each unit contains two inflatable inflatable actuation elements (nylon-reinforced rubber bladders) which force independent sets of flexural gripping members (steel fingers with machined teeth) against the surface of the pile. The entire unit is enclosed by an external steel containment cylinder. Grippers are usually mounted on %p of corner pile sleeves and serve as temporary structure to pile connections. Normally only used on an all skirt pilled jacket, their primary purposes are to provide some level of early resistance to storm loading and to prevent relative movement between the pile sleeves and piles during the time the permanent jacket to pile connection, consisting of grout, is setting and gaining its initial strength. A secondary purpose of the units comes in to action if a structure is set down or loaded such that it becomes out of tolerance with respect to levelness, Specific corners can be secured to a pile after adjustments are made and before installation of the other piles.
As platforms were located in progressively deeper water, it became desirable to develop a fast method of attaching "pin" piles to help the temporary foundations (mudmats) in resisting loadings during installation. Attachment of piles penetrating only under their own weight would even be of great assistance. In the extreme, with as little few as one pile driven to adequate penetration at each corner, design events could be tolerated, reducing risk,
In the design of the Bullwinkle platform, reduction of installation risk was a prime concern. A two-piece jacket was even considered (Ref. 1). The planned June installation could not be assured five years in advance, Early analyses indicated the jacket with no conductors installed, most legs still buoyant and no deck loading could safely survive major hurricane waves with only one pile driven to design penetration at each corner. The maximum pile load which could be resisted immediately after driving (50% of the design ultimate) was predicted as 7,600 kips compression or 5,000 hips tension.
Shell had experience using grippers on two projects, platform Eureka a 700 feet water depth structure installed offshore California and the Boxer platform (Ref. 2) installed in the Gulf of Mexico in 750 feet of water. Eureka had four 1,000 ton units for 60 inch diameter piles.
An Alternative FPS Concept for Offshore Oil Production
Authors: de Paiva Leite A.J. , de Freitas J.F. , Correa da Silva R.M. 
Published: October 2008

ABSTRACT
The discovery of giant deep water fields in Campos Basin pushed Petrobras towards seeking solutions which, in a simple and economically feasible way, would enable their exploitation.
Among several alternatives, a semi-submersiblebased system using rigid risers and dry production trees stands out, combining the simplicity of a semi-submersible with the advantages of a TLP.
The concept is developed bearing in mind the mild environmental conditions encountered off the Brazilian Coast and incorporates several original features. Amongst others, the modular deck arrangement, in addition to the unit's dimensional limitations, allow it to be fully built in a Brazilian dry-dock, reducing construction costs and schedule.

INTRODUCTION
In the wake of the first oil crisis in 1974, many countries were motivated to increase domestic production in order to diminish the amount of imported oil. Within a short time, some fields which before were not economically feasible, became attractive as the international price of crude peaked up.
In Brazil, the need for hard currency reinforced this tendency as it became of utmost importance to substitute domestic production for imported oil in the shortest time. The Early Production System (EPS) alternative fulfilled these demands quite well.
In august 1977, the EPS "Enchova I" started producing oil in 125 m water depth. Installed on a SEDCO 135 type semi-submersible, the system started with 10,000 bopd from one well, flaring the gas (see figure 1). At that time, some principles of the concept presented in this paper (from now on referred to as "Minimum Heave" concept) were applied, as the well was produced through a rigid riser (marine riser), although using a marine BOP and a flow head connected directly to the travelling block. This system allowed a 18 feet vertical displacement and was kept active for 3 years.
Other EPS's that came after "Enchova I" also had one well producing through a rigid riser. The longest record for this kind of system was the well RJS-218, Parati /Anequim field, in 107 m water depth, with 5 years of continuous operation. During this time, no marine riser disconnection caused by bad weather has been registered in any of these EPS's.
These historical records form a base upon which the minimum heave concept can rely, as they attest the mildness of the environmental conditions in Campos showing that a semi-submersible with dry production trees is perfectly feasible for the area, from a technical point of view. More than that, they suggest that the size of such a unit could lie in a range well under the size of similar ones for the North Sea or the Gulf of Mexico, where environmental conditions are quite harsher.
Provided that the size of the platform is kept within certain limits, the technical and economical advantages of the concept are evident and one of the company's goals at the moment is namely to design one tailor-made for the Brazilian conditions.