bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Murchison Cathodic Protection System
Authors: Levings E.A. , Finnegan J.E. , McKie W.M. , Strønmen R.D. 
Published: October 2008

ABSTRACT
The Cathodic Protection System installed on the Murchison Platform sets new standards for the operation of cathodic protection in the arduous conditions of the North Sea.
It has demonstrated its effectiveness and flexibility since being commissioned in November 1980. Extensive data has been accumulated from the system monitors, comprising zinc reference potentials, current outputs from impressed and monitored sacrificial anodes, and from underwater surveys of potential and current density.
An improved understanding of the dynamics of cathodic protection systems can only be achieved through analysis of data from actual structures. The nature of the Murchison cathodic protection data has enabled computer modelling1 of characteristic current density and potential optimum protection level is projected from this model and the hybrid system adjusted to satisfy the demands of the structure.
This paper briefly describes the system, the stages to successful operation and indicates the developments with which this unique system has enhanced our understanding of cathodic protection parameters.

INTRODUCTION
The Murchison jacket was to be the largest ever launched by barge when in September 1979 the limited launch barge capacity required a weight saving alternative to the proposed 1200 Tonnes of sacrificial aluminium anodes. Various options were considered 2 and the system adopted for Murchison is an unique hybrid.
The main impressed current system is designed to automatically maintain potentials within set limits using numerous impressed current anodes which are mounted directly on the structure and controlled in small groups by nearby reference cells. A sacrificial system designed to provide protection to sensitive areas during period when the impressed system is switched off is also installed. Sacrificial anodes modified to monitor current output are located strategically on the submerged structure.
The system was designed to comply with the cathodic protection design criteria available in 1976/1977, i.e. that a current density of 130mA/m2 is necessary to ensure adequate initial polarisation of the structure.
Basic parameters of the design comprise:-A sacrificial system to provide limited levels of protection at sensitive areas for the period between float out (Sept. 179) and commissioning (Nov. 180) and when de-energisation of the impressed current system is necessary.An adequate monitoring system to enable effective control and monitoring of the system.An automatically controlled impressed current system using suitable anodes located directly on the structure.Robust design of the underwater parts of the system to ensure maximum integrity for the life of the platform, together with facilities for retrofitting of additional anodes if required.
The main parts of the system equipment are summarised in Table 1, and are more fully described elsewhere.2,3.
Satellite Tree Subsea Completions Permit Marginal Reserves Production Offshore East Kalimantan, Indonesia
Authors: Bunnell R.L. , Hawkins J.G. 
Published: October 2008

ABSTRACT
The hydrocarbon-bearing sands in the fields offshore East Kalimantan were deposited in a de 1taic environment and are complicated by faulting. This faulting results in small accumulations which cannot be economically exploited by conventional means.
Three of these accumulations had been discovered in the Attaka Field in water depths of 160-190 feet. Even though the weather conditions are mild, conventiona1 platforms were ru1ed out on economic grounds. An alternate method employing subsea completions was found to be economically Viable. This subsea system is characterized by its "off-the shelf" configuration and simplicity. To reduce the possibility of required well workovers, the wells are single string, gravel packed completions.
This project, then, is an example of a subsea completion system being chosen for marginal reserve deve1opment based on economic grounds. Additionally, these are the first subsea completions in Indonesia and yielded much information for use in designing, scheduling, and costing similar installations. The wells were all previously drilled and suspended exploratory wells, and the completion operations were performed from a floating vessel.

INTRODUCTION
The Attaka Field is located in the Makassar Straits, 12 miles offshore from Tanjung Santan, East Kalimantan, Indonesia in ±200 feet of water (see Figure 1). Union Oil Company of Indonesia is the Operator of the Attaka Field in a unit with Indonesian Petroleum Ltd. (Inpex). Each company has a separate production sharing contract with Pertamina, the Indonesian State Oil Company.
The Attaka Field structure is a symmetrical anticline trending north 10° west with gentle 10° to 200 flank dips. The main Attaka sand reservoirs were deposited in a de1ta ic environment and range in age from Middle Miocene to Pleistocene. The structure is intersected by several sub parallel normal faults trending northwest-southeast with displacement varying from 100 to 900 feet. Field reserves are attributed to twenty-two separate sands found between 2800 and 7600 feet. Porosities of the sands range from 20 to 35 percent with permeabilities as high as five darcies. Most reservoirs have a gas cap, are saturated, and display varying degrees of natural water drive. The oil has a low sulfur content, and its gravity varies with depth between 35° and 43° API.
Discovery of the Attaka Field occurred in August 1970, and primary development was completed in September 1973 after the drilling and completion of 52 wells from six wellhead platforms. The wells were completed, for the most part, with dual strings and from three to five packer intervals. Between 1973 and the present, 18 additional platform wells have been drilled and completed and two more platforms installed (see Figure 2). Production from the Attaka Field peaked at 117,000 barrels of oil per day in November 1977 and now averages 62,000 barrels of oil per day.
The IPOD Geological/Geophysical Data Bank
Authors: Rabinowitz P.O. , Brenner Carl 
Published: October 2008

ABSTRACT
The IPOD Data Bank has served the JOIDES community since 1975 by finding and collating existing marine geological/geophysical data in the vicinity of prospective IPOD drill sites or transects of sites, archiving all data collected under the auspices of the IPOD Site Survey program, providing folios of data to the designed co-chief scientists on D/V GLOMAR CHALLENGER (and on request to the various JOIDES subject panels), and supporting the JOIDES and DSDP Safety Panels by providing data packets to its members.
At the Data Bank, U.S. institutional site survey data is stored digitally in NGSCD "mergedmerged" format and is available either in the form of a magnetic tape or a computer plot of annotated geophysical (bathymetry, magnetics, and gravity) values along track. In addition, seismic profiles collected during the surveys are also archived. Contour maps, heat flow charts, bottom photographs, and other forms of data presentation compiled in the course of the production of a cruise report are also often archived.

INTRODUCTION
By the early 1960s, scientists at the major oceanographic institutions recognized that substantial advances in marine geoscience were within grasp. Up to that point, the only sampling of the deep-sea floor was in the form of dredge hauls and cores. Though these contributed greatly to our understanding of the geological history of the ocean floor, these methods only provided data from the upper 20 m of the ocean floor. The need to penetrate deeper stratigraphic sections (and later into the ocean crust) was obvious. Four of the major institutions - Lamont-Doherty Geological Observatory of Columbia University (L-DGO), Scripps Institution of Oceanography of the University of California at San Diego (SIO), Woods Hole Oceanographic Institution (WHOI), and Rosenstiel School of Marine and Atmospheric Science of the University of Miami (RSMAS) - decided to work together in developing a unified program of deep sediment coring. In 1964, these institutions signed a memorandum of agreement and inaugurated the Joint Oceanographic Institutions for Deep Earth Sampling JOIDES.
The initial effort of JOIDES was managed by L-DGO under the sponsorship of the National Science Foundation (NSF) and drilled several deep holes on the continental margin off northern Florida in the region of Blake Plateau. The drilling vessel was M/V CALDRILL I, a converted 54 meter AKL-type navy vessel equipped for rotary drilling. l The success of this effort provided the impetus and framework for a more ambitious drilling program. Under the sponsorship of NSF, SIO was designated the operating institution for what became known as the Deep Sea Drilling Project (DSDP) and a world-wide drilling program commenced in 1968. The operating vessel was D/V GLOMAR CHALLENGER; this arrangement is still in existence today.
Overall Dynamic Characteristics of Tension Leg Platforms
Authors: Oran Cenap 
Published: October 2008

ABSTRACT
In TLP motion analysis, the problem is usually simplified by idealizing the tethers as weightless springs. While this approximation appears to be generally adequate for shallow waters, the relative tether/platform weight ratio increases very rapidly as the water depth increases, thus making it necessary to the at the TLP as a continuous system rater than as a rigid body with only six degrees of freedom. The purpose of this paper is to examine the variation of the overall dynamic response characteristics of a TLP as a function of the water depth, with particular emphasis on such important parameters as the tether/platform weight ratio, the periods of the "principal modes" (i.e., heave, pitch, roll, surge, sway and yaw) and the shapes and periods of the "secondary modes".

INTRODUCTION
Offshore platform technology for relatively shallow water (approximately less than 1000 feet) is well established. However, as the demand for oil continues to increase, the industry is gradually forced to move into more hostile environments, namely, deeper waters where conventional fixed platforms are no longer feasible and arctic regions where the engineers are faced with a variety of ice-related problems. Two principal concepts have thus far been advanced for oil product ion in deeper waters, namely, the "tension leg platform" which is usually referred to briefly as the TLP and the "guyed tower".
A central issue in the design of an offshore platform is the dynamic behavior of the platform under the action of wave, current and wind loads. The wave climate at a specific geographic location is usually represented by a "wave spectrum". A review of wave spectra representing the conditions at major offshore oi1 production areas of the world shows that the most critical wave period range is approximately 5 to 20 seconds. Accordingly, in order to avoid possible resonant behavior, platforms are designed in such a way as not to have a natural period within that particular critical range.
In the case of a fixed pl at form, the relevant vibration mode is the so-called "lowest mode", i.e. the mode that corresponds to the lowest frequency and, consequently, the largest period. It is clear that, if the largest natural period of the platform is kept below 5 seconds, the remaining natural periods will be even smaller so that one does not need to worry about them in the process of design. In the case of a tension leg platform, however, the situation is somewhat more complicated as wi11 be apparent in the following section.
Lena Guyed Tower Project Overview
Authors: Boening D.E. , Howell E.R. 
Published: October 2008

ABSTRACT
The installation of the Lena guyed tower was one of the industry's most significant accomplishments of 1983. This paper serves as an introduction to a series of papers to be presented at the 1984 Offshore Technology Conference concerning the design, fabrication, and installation of the Lena guyed tower.
The purpose of the paper is to provide an overview of the entire project, including the evolution of the guyed tower concept and the extent to which this concept may be applicable to other prospects. The most important design features of the Lena guyed tower are briefly discussed in order to prepare the reader for the more detailed treatment provided by the other papers in this series.
Particular attention is focused on project management, primarily from the perspective of manpower usage, schedule control, and cost management. Successful techniques that may be of value in the management of future projects are identified.

INTRODUCTION

Guyed Tower Development
Since the offshore petroleum industry began in the 1940's, an economical means of developing reserves in progressively deeper water has been pursued. As water depths of interest increased, the size and cost of conventional, pile-founded, steel-jacket platforms increased at a much greater rate.
One approach to the problem of disproportionate increases in the size of the deepwater structures has been the use of guying systems. Exxon Production Research Company first considered the guyed tower in 1965. In 1975 Exxon and 12 other companies built a one-fifth scale model of a tower designed for use in 1500 feet of water. The unmanned, heavily instrumented test tower was installed in 300 feet of water in the Gulf of Mexico near Grand Isle, Louisiana. The foot-square tower had eight 3/4-inch guylines that modeled a full-scale system.
Test data from the tower confirmed that the basic guyed tower concept was sound. During 3 1/2 years of operation, the test tower experienced a number of waves that, in full scale, approximated or exceeded North Sea design conditions. Maximum measured guyline tensions and tower .motions matched well with predicted maximum tension and motions.

Lena Guyed Tower
In mid-1978, a decision was made to design a guyed tower specifically for the 1000-foot. Wterdepth at the Lena Prospect in the Gulf of Mexico. As shown in Figure 1, the Lena Prospect straddles the 1000-foot water depth contour line and consists of four tracts, all of which are in the Mississippi Canyon area.
The design of the Lena guyed over. Differed significantly from the test tower con. The use of a spud-can foundation was located to favor of eight centralized main piles to prevent settlement. Torsion piles were added at each of the four corners of the jacket to resist base torque and shear loads.
Time-Domain Model for TLP Surge Response in Extreme Sea States
Authors: Finnigan T.D. , Petrauskas C.D. , Botelho D.L.R. 
Published: October 2008

ABSTRACT
A time-domain model is presented and evaluated for the prediction of the surge response of a tension leg platform (TLP) will regular and random waves, in the presence of a current. The wave force equation in the model is a modification of the Morison equation. Wave diffraction effects are incorporated in an approximate manner.
The time-domain model is evaluated on the basis of experimental tests that were performed on a 1: 60 scale model of a TLP. The tests were specially designed to investigate the effect of combined waves and current on surge response. The tests were conducted in regular, random and grouped waves. Current was simulated by towing the model.
Two different forms of linear wave theory based on stretching and extrapolating wave particle kinematics from Airy wave theory up to the free surface are investigated. The maximum surge response is predicted well by the time-domain model, provided the extrapolation of Airy wave theory is used.

INTRODUCTION
The tension leg platform (TLP) is a compliant structure In order to design the TLP tendon and riser subsystems, the maximum offset the TLP will experience in extreme sea states must be accurately determined.
In such sea states, large offsets due to nonlinear wave-current interaction and free surface effects can occur. Methods for predicting the surge response must therefore account for these effects. Although frequency-domain methods are available for predicting the TLP surge response, 1,2 time-domain methods can more accurately account for the nonlinearities.
In this paper, a time-domain model to predict the surge response in extreme sea states is presented and evaluated. Its primary purpose is for final design verification. A secondary purpose is to develop response amplitude operators (RAO's) for frequency domain procedures. 1 The time-domain model is based on a modification of the Morison wave force equation in which forces are integrated up to the free surface. The modifications include a representation of a) the drag forces using relative velocities including current, and b) the inertia forces corrected to match MacCamy and Fuchs' closed form diffraction solution. 3 With these modifications, the time-domain model is able to depict the surge response at the wave periods (primary response), and at periods much longer than the wave periods (secondary response or slowly-varying drift). Although the TLP can respond at its natural period, no distinct response occurs there because of the high damping due to current.
Time-domain models have been developed by Hsu and Blenkarn, 4 Paulling, 5 Salvesen, 6 Morgan7 and others. The time-domain model in this paper differs due to the manner in which diffraction effects have been incorporated. Also the paper evaluates alternative wave theories. The results of this paper are expected to contribute further to the understanding of time-domain predictions of TLP surge motion.
In this paper, the theory used in the time-domain model is presented.
Produced Water Discharges into Marine Ecosystems
Authors: Pitre R.L. 
Published: October 2008

ABSTRACT
Formation waters which are produced in conjunction with oil or gas are discharged into offshore areas throughout the world. The produced water volume in petroleum production can vary from 20% to 150% of the oil production volume. Salinities of produced water can vary from 1,000 to 250,000 ppm. Before prod used waters are discharged to the ocean, they are passed through oil-water separators to reduce the oil content to acceptable levels. Temperatures of the produced water stream are normally about 45° C. The small amounts of oil released in prod used water discharges will either evaporate to the atmosphere or be degraded by marine organisms. Biodegradation can be enhanced with the addition of nutrients. Within the OCS of the United States, produced waters are regulated by NPDES permits issued by the U.S. Environmental Protection Agency. Produced waters from a Cities Service platform located in an area of coral reefs offshore of the Philippine Islands have been discharged to the surrounding seas for several years with no environmental harm. Environmental impacts from produced water discharges into marine waters are very minimal and have never caused a problem. Therefore, there is no precedent for stricter governmental regulation of produced water discharges into marine ecosystems.

INTRODUCTION
Produced water is formation water which is produced in association with oil and gas from the producing formation. Formation waters have existed for a very long time in the formation, usually under conditions of high temperature and pressure. Because this water contacts the minerals and crude oil in the rock formation, the water becomes saturated with the particular minerals present and with the soluble fractions of the untapped crude oil, especially the low molecular weight hydrocarbon gases and naphthenic acids. Why the water exists in the oil and gas reservoir and why its chemical characteristics vary as they do has not been shown through any accepted theories1 Most research assumes the water was deposited with sedimentary formations. The deeper, older formation waters are generally more saline; however, there are many exceptions to this rule depending on the composition of overlying formations. Other assumptions are that this formation water may have stayed where it was deposited, or it may have migrated into the oil and gas reservoirs.
Oil or gas and water, in the reservoir, exist separately in equilibrium. When formation water reaches the surface, where the surrounding pressure is much less than that in the formation, some amounts of the dissolved gases flash-off, and they are extracted. The characteristics of produced water from different offshore production areas are shown in Table 1. The produced water volume in petroleum production can vary from 20% to 150% of the oil production volume. Salinities of produced waters can vary from 1,000 ppm to 250,000 ppm1
Wave Runup and Overtopping: A Review and Recommendations
Authors: Gadd P.E. , Potter R.E. , Safaie B. , Resio D. 
Published: October 2008

ABSTRACT
It is not always feasible to design a coastal structure high enough to completely prevent wave overtopping by the maximum incident wave. Structures which are designed against lesser waves, such as the significant wave, will be overtopped under the design storm condition because the incident irregular wave train contains waves which exceed the significant wave height. When the purpose of a structure is to protect sensitive facilities whose failure could result in major environmental as well as economic losses, the rate of overtopping anticipated under the design condition must be predicted with reliable accuracy.
The study being reported in this paper evaluates the degree to which wave overtopping can be accurately predicted for a coastal structure in the Arctic environment. In support of this endeavor, an extensive search and review of literature was performed, including reports and papers originating in Japan where the study of wave overtopping has been pursued for a number of years. The study has led to recommended design procedures as the most practical solution available from the current state of knowledge. Discussions on research needs to improve the design procedures are also presented.

OVERVIEW
Goda (1970) proposed a scaling factor to describe various levels of overtopping intensity, as follows:(Mathematical equation available in full paper) which in this paper will be called the "overtopping index". "Q" is defined as the overtopping volume per wave per unit width of crest, and (HoLo) is the mass transport during the forward orbital motion of a sinusoidal wave in deep water. The overtopping index is non-dimensional.
According to Goda (1970), the overtopping index remains in the range of between zero and 10–4 when the overtopping consists only of wave spray. When the overtopping involves wave splash as well as spray, the index will rise to as much as 5 × 10–3. The next higher level of overtopping intensity, consisting of the leading edge of the wave run-up going over the crest of the slope, will raise the index to 10–2 The most severe overtopping situation, in which the wave itself plunges across the crest of the slope, will bring the index to a high of 10−1 Actual overtopping rates may be readily found from the overtopping index assuming a hypothetical storm wave of, say, Ho = 12 feet and T = 10 sec. The overtopping rates {in cubic feet/sec/foot of wave crest) corresponding to the upper limit for each class of overtopping intensity are: 0.01 cfs/ft for spray overtopping, 0.5 cfs/ft for overtopping by wave splash, 1.0 cfs/ft for overtopping by the leading edge of the run-up, and 10 cfs/ft for overtopping by the wave itself. It is obvious that even wave splash could pose a threat of localized flooding, depending upon incident wave characteristics.