bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrohydraulie Hardline MuItiplex Contral System for BOPT'S
Authors: Henry M.
Published: October 2008

Fifteen million sq miles of sedimentary basins lie between 1,000 ft and 10,000 ft. Drilling and production in increasing water depth will demand an equally increasing reliability of the subsea equipment; components must be as autonomous and separate as possible so that the failure of one of them does not endanger the whole assembly; link between the surface and the subsea equipment must be reduced as much as it can be due to their vulnerability.

Previous subsea blowout presenter systems, whether fully hydraulic or electro hydraulic, are using multisided and require large-diameter expensive and troublesome umbilical?s. Now the industry has available a remote control system for BOP's stack in deep-sea drilling operations that only requires a pair of wires coupled with two hard line multiplex electronic units.

A backup acoustic control system is also attached to the main system, in order to undertake the main function in case of accident on the multiplexed cable. As for the hydraulic energy, it can be pumped from the surface as usual, or directly produced on the stab assembly by means of a subsea hydraulic power unit in closed circuit.

The MATRA Bops? remote control system is designed according to 10,000-ft water-depth specifications. Two hard line multiplex electronic systems (TESUMA) give full redundancy to the control, and an acoustic system (TELTAC) is used as a backup, in case of emergency. Two independent electro hydraulic units, directly connected to each hard line multiplex, deliver the necessary power to the presenters.

INTRODUCTION

A typical BOP stack consists of a certain number of organs hydraulically operated such as: connectors, rams, wedge locks, annular presenter, choke and line valve operators, and so on. The operation of most of these organs should be made in limited time (4s to 20s) at a pressure of 1,500 psi above the ambient pressure. Other organs, such as bag-type BOP and ball joint, should have a pressure regulated from 1,500 to 3,000 psi.

The operation of the stack is insured by two hydraulic units, coded yellow and blue, located on the stab assembly. Each unit consists of a bank of accumulators and an electro hydraulic block. The two sets of accumulators normally isolated can be remotely coupled. The total useful capacity of hydraulic fluid allows one full cycle of all stack function operations, plus an additional availability of 25 percent of the operating volume with a pressure decrease from 3,000 to 1,200 psi over ambient.

The subsea accumulators are of the bladder type in cylindrical shape.

There is no possible absorption of the nitrogen precharged by the fluid. Recharge is currently 1,000 psi above ambient hydrostatic exhaust pressure, the minimum pressure being then 1.2 times the recharged pressure and the maximum pressure: 3, 000 psi over.

The capacity of each accumulator ranges from 12.5 to 50 gal and provides approximately between 0.25 for 10,000 ft and half volume for 1,000 ft of useful fluid.
The Use of Sand Probes In Offshore Operations
Authors: Swan Richard D. , Reimer Charles M.
Published: October 2008

Sand probes have proven to be a reliable means of detecting sand production from oil and gas wells and activating surface shut-in equipment. The probes, which are thin walled, hollow steel cylinders with a closed end, are installed perpendicular to flow in the flow line and connected to a pilot valve. When the wall of the probe has been penetrated by sand erosion, flow stream pressure is transferred to a pilot valve which effects closure of the safety valve on the Xmas tree.

Based on the successful results of both laboratory and field tests, Exxon had installed sand probes on alto its Offshore Louisiana wells by January 1,-1973. Field experience to date has shown that the probes will successfully shut in wells before flow line equipment damage can occur. In addition to providing an increase in safety and a decrease in pollution risk, the use of probes has significantly reduced the costs associated with equipment failures due to sand erosion. The data obtained from sand probes is also used analytically to evaluate precautionary sand control walkovers.

I. INTRODUCTION

Equipment or flow line erosion caused by produced sand has long been a major operating problem in many areas, both in terms of cost of equipment replacement and in terms of the risk of pollution and/or fire caused by flow line or equipment cutouts. While it is obvious that a dependable, long-lasting sand control work over procedure would be the best solution to this problem, such a procedure has yet to be attained, and a method of detecting produced sand prior to well standup or equipment cutout is necessary.

Until the development of sand probes, the foremost obstacle in the path of controlling sand erosion was the fact that there was no continuous, 'on-stream' way to detect the erosion of flow lines or equipment until a cutout actually occurred. The occasional detection of sand production by shakeout was not particularly helpful, as this gave no indication of how much, if any, damage had already been done. Ultrasonic and radiographic inspection are expensive and only indicate damage already done. What was really needed was a device which would detect the presence of sand as it was being produced and then provide some type of an output signal so that appropriate measures could be taken to prevent equipment failure. The sand probe satisfies these requirements.

This paper first describes the sand probe and its operation, laboratory and field testing of sand probes, full-scale field installations, and the reporting system used to keep both operations and engineering personnel informed of sand probe status on each well. Evidence is then presented to demonstrate the success achieved through use of the sand probe as a safety device, and finally, the use of -the sand probe as an analytical tool is discussed.
Sea Trials of a High-Seas Oil Recovery System
Authors: Blockwick Thomas N.
Published: October 2008

INTRODUCTION

This report presents the results of the at-sea tests conducted on the Ocean Systems, Inc., oil Recovery System (ORS). The tests were conducted without oil, the purpose being to qualify the ORS with respect to strength) stability, operational function, ease of handling, compatibility with the Coast Guard buoy tenders.

Previous testing of the ORS had been limited to tank tests conducted at Battelle Northwest, in Richland, Washington. - These tests were conducted in calm water in two-foot waves, using two different grades of oil. In these tests the capability of the ORS to recover oil at high efficiencies (percent oil in the recovered stream) was demonstrated.

GENERAL DESCRIPTION OF THE OIL RECOVERY SYSTEM

The 2000 gallon per minute oil recovery system (ORS) consists of a weir/ basin recovery unit, a pumping and power system, a control system, and handling and packaging components.

The weir/basin recovery unit contains primary and secondary weirs for effecting the collection and separation of floating oil from the water surface. Both weirs are supported by discrete foam flotation elements which allow the unit to be highly surface-conforming.

The primary weir plate is angled and is maintained in this position by bridles attached to an external tension line. The external tension line takes the loads imposed on the system by waves and currents. The external tension line and the primary and secondary weirs are all fabricated in a parabolic configuration to minimize stresses. The general arrangement and configuration are shown in Figure 1.

A hose manifold is attached to the secondary weir sections for attachment to the four oil pumps, which is mounted on the system near the secondary weirs. The oil pumps are gear pumps and are driven by low-speed, high torque hydraulic motors. The hydraulic power for the pump motors is supplied by a diesel-hydraulic power supply.

Control of the oil pump f low is performed with a sensor array and an electronic pump control system which detects the oil level in the recovery basin and controls the pump flow depending upon the desired level. Control may also be performed manually at the hydraulic power unit.

Launching and retrieval of the weir/ basin is accomplished with a lifting frame consisting of a strong back and cross-arms which contain quick-release attachment points.

The system is packaged in special containers and pallets which are suitable for truck transport or air transport in a Lockheed C-130B aircraft. The total weight including packaging is approximately 28,000 lbs.

FOREWORD

This report presents the results of at- sea testing of the Ocean Systems, Inc. 2000-gpm Oil Recovery System, the ORS- 2000.
Testing the Lockheed Disc-Drum Rough Water Oil Recovery System
Authors: Scharfenstein C.F. , Leary John F.
Published: October 2008

The United states Coast Guard through the efforts of Lockheed Missiles & Space. ComplarJ1L Inc., Sunnyvale, California, has developed and tested a device for recovering spilled oil from the high seas.

This paper discusses the qualification, testing of the Lockheed prototype High Seas Oil Recovery System. These tests were:an inland pool test using oila high seas test in an operational environment (Sea State 4)a high seas test in a survival environment (Sea State 6)

The tests proved the system capable of being transported in an HC-130B Coast Guard aircraft, buoy tender and by truck over the road. The system (one unit) also proved to be capable of recovering oil up to the rate of 1000 gpm under certain conditions of current, oil thickness and viscosity.

The system proved that it will be capable of surviving a severe sea state condition after certain minor redesign.

INTRODUCTION

The United States Coast Guard developed through the efforts of Lockheed Missals & Space Company, Inc., Sunnyvale, California, a prototype High Seas Oil Recovery System unit based on Lockheed-patented rotating disc-drum principle. The unit is capable of recovering up to 1000 gpm oil under certain conditions of thickness of oil, relative current and oil viscosity.

A considerable amount of information has been presented on the Lockheed-developed High Seas Oil Recovery System. Much of the prototype design and actual structure of the system is well known within the industry through prior publications in scientific and trade journals. In 1972 and 1973, Coast Guard authors Commanders Lehr and Leigh, and Lockheed author Bruch, presented technical papers which amply described the disc-drum principle. However, a brief description of the rough water oil recovery machine is in order at this point. The 14,750-1b machine is 27-ft wide and 23-ft long. It is 8-ft high, draws 20-in water, and with the main deck safety rails, presents an excellent radar and visual target. The 4-ft digester disc-drum oil recovery device is 13-ft long. It is suspended between twin machinery hulls, port and starboard (PiS), that are connected by the rigid cross structure over the disc-drum. The diesel prime mover and starting air bottle are in the cross structure.

The oil recovery rate is dependent upon the rotating discs which are preferentially wet by the oil which is then collected from the discs by wipers. Wipers direct the oil onto an axially aligned trough through which it flows into the PIS hull sumps. From the sumps the oil is pumped through 300-ft of la-in diameter, lightweight transfer hose to a manifold on the tender. It goes to available storage from the manifold. Alternately, the manifold can be attached to the unit and two 6-in hoses used to transfer the oil directly to available storage. The unit is designed for remote control through a 300-ft long umbilical that also serves as a refueling hose for the on-board diesel prime mover.
Nuclear Power for Offshore Arctic Oil Exploration
Authors: Schaff E.C. , Cannell C.W. , Hollett E.S.
Published: October 2008

This paper addresses the problems of pursuing the search for oil in perhaps the most costly and hostile region yet considered for offshore exploration, the offshore Arctic. The total task force for these operations and the feasibility of using nuclear power in the support ships are discussed. Nuclear power is shown to have an early economic advantage over fossil-powered ships even though the nuclear plant develops only 40,000 HP, one-third that normally considered cost effective for marine use.

INTRODUCTION

This paper is presented to discuss two questions:Why is the oil industry looking to the Arctic?Why is nuclear propulsion being considered to power ships intended for Arctic use?

It includes results of a recent feasibility study of a nuclear-powered ship whose mission is to support offshore hydrocarbon exploration in the Arctic regions of the world. The feasibility study was conducted under the auspices of the Maritime Administration and was performed by Global Marine Inc., Babcock & Wilcox, and General Electric Company.

For several years now, Global Marine has been studying concepts and designs to enable exploration for hydrocarbon reserves in the offshore Arctic. The design of an exploratory unit is almost' complete and the concept of an Icebreaking Drilling Ship (IBDS) was presented last year at the Offshore Technology Conference.

B&W has been designing and developing the Consolidated Nuclear Steam Generator (CNSG) for commercial marine applications since 1959. An early version of the CNSG is now plying the seas in the German Ship, OTTO HANN.

In 1972, Global Marine began intensive investigations into the support that the IBDS would need because of the environment in which the drill ship is intended to operate. It was soon obvious that this environment would require a type of supply boat not previously envisioned by the offshore industry. The companies (GMI, B&W, and G.T.) joined forces in 7g73 to take the first engineering steps leading to a support ship configuration that could routinely venture into regions where year round waterborne operation is rare.

WHY THE ARCTIC REGIONS?

The interest shown in Arctic regions of this planet is a natural extension of the exploration and exploitation spirit of man. Whatever curiosity might be attached to the scientific exploration of these areas has recently been overshadowed by the latest problem -- a growing worldwide energy shortage. The Arctic is no longer an area to be studied merely forint$ unique weather and climatology; its importance as a potential reserve of energy resources is taking precedence.

We are rapidly consuming the most available and cheapest oil reserves, yet our rate of consumption continues to increase. The highest priority is being assigned to the search for new fossil fuel reserves because of long term dependence and extensive development of uses for this form of energy.

When the easily exploited land sources first showed signs of depletion, the quest led to submerged areas adjacent to land sources.
Offshore Dredging Systems For Beach Nourishment Projects
Authors: Nonner R. , Dooremalen J.J.C.M. , Ziegler R.B.
Published: October 2008

Beach erosion is a serious international problem. In the United States alone, it has been reported by the Corps of Engineers that measures to control erosion appear justified along 2700 miles of coastline. The cost of this work is estimated at $1.8 billion.

The natural forces causing beach erosion are complex, involving effects of wind, and upland erosion. A discussion of these factors is beyond the scope of this paper. Suffice it to say, beach erosion is with us to stay.

It is possible in many cases to overcome the problem by modifying current patterns through use of artificial structures, and by replacing the lost sand with sand dredged from the sea floor.

This paper deals with an analysis of several dredging systems that can be effectively employed for rebuilding eroded beaches, a process referred to as beach nourishment. Beach nourishment can be accomplished with both permanent, and portable, dredging systems.

1.1 An example of the former is a system installed in Italy along the Liguria Sea between Massa and Carrere. The need for a permanent installation is the exception however, and in most instances replenishment can take place on a periodic basis, using portable dredging plant.

1.2 If sand is available onshore immediately near the beach to be replenished, it can be pumped directly to the beach site through a delivery pipeline, using established dredging techniques. In many cases, however, the sand is only available immediately seaward of the beach. This paper will review the various dredging systems which can be employed in this latter case.

To provide a means for selecting the dredging system most appropriate for a given replenishment project, this paper will present calculations of (1) the cost per cubic meter of sand deposited on the beach, and (2) the return on investment in dredging plant.

2. INFLUENCING FACTORS

Generally speaking t the following factors must be considered in selecting the appropriate dredging and transportation system.2.1 The location of the offshore sand deposit and the characteristics of the deposit2.2 The number of cubic meter of sand required for replenishment2.3 The sand delivery site2.4 Type of dredge

2.1 Sand deposit

As mentioned in the introduction t this study pertains only to cases in which the source of sand for beach replenishment lies offshore in the open sea. In all cases the supply site should be a sand deposit of sufficient volume and suitable grain size characteristics. A "suitable sand composition" is defined as follows:(Equation Available In Full Paper)

Selection of dredging system t and the cost per cubic meter of sand deposited on the beach t are determined to a large extent by the distance between the offshore sand deposit and the sand delivery site. If the distance is not too great t and the dredge is equipped with machinery of sufficient power t it may be possible to pump sand directly through a pipeline from the offshore deposit to the beach.
An Analytical and Experimental Study of Stiffened Tubular Joints with Multiple Branches
Authors: Miller Clarence D. , Trammell J. Hugh
Published: October 2008

This paper describes a method developed by Chicago Bridge & Iron Company for analyzing a.ring-stiffened tubular joint with multiple non-intersecting branch members, each branch member being arbitrarily loaded. A computer program has been developed for analyzing a maximum of six branches, only three of which may intersect any one stiffening ring. For example, a triple K-joint may be analyzed.

Model test results are presented for a three-way Y-joint and for a single K-joint. Each branch of the three-way Y-joint was loaded simultaneously with several combinations of axial, radial and tangential loads. The K-joint was loaded with axial loads only. Photoelastic coating was applied to the branch-to-chord intersections to obtain the full field distribution. Electrical resistance strain gages were placed on the models to obtain the load distribution in the branch member near its intersection to the chord member and to obtain the surface stresses on the outside of the shell and the inner fiber of the stiffening rings. Also several transducers were used for measuring radial deflections of the stiffener rings. The models representa 1:12 and 1:13 scale of a structure with a 52 foot diameter chord member. A comparison is shown of the experimental and analytical results.

INTRODUCTION

For platforms in deep, rough water there is a tendency to use fewer but larger members, each member supporting a larger share of the total load. As member sizes get larger, strengthening the joints by increasing chord wall thickness becomes impractical.

In the above situation there is definite reduction of wave forces if the wells are drilled through one or more large legs of a platform. Also since there are no wave forces on theconductors, guides can be lighter in weight. To drill down the legs, however, requires the legs to be kept relatively open and not restricted at every joint by diaphragms and bulkheads.

These two points led to a consideration of tubular joints using ring stiffeners to strengthen the chord walls. Very little analytical or experimental work on such joints was found in the literature so a research program was started to develop a method of analysis which could be used to select the number and size of stiffeners required. The primary purpose was to develop a design tool which would predict thrusts, shears, moments and deflections in the rings with sufficient accuracy for design use.

The finite element method. is too cumbersome, time consuming and expensive for use as a routine design tool. A single structure requires the design of many joints, each for several loading conditions. Some finite element analysis will be done to provide an additional check on the proposed design method and hopefully to fill in any gaps between the analytical and test results. The finite element study will not be covered in this paper.
Sharply Peaked Wave Energy Spectra In the North Sea
Authors: Rye Henrik , Byrd Robert C. , Torum Alf
Published: October 2008

Recent research results on the growth mechanisms of a wind-wave field, combined with actual wave measurements of extreme sea states in the North Sea, show that the Pierson-Moskowitz type of spectrally may not always be adequate for the description of extreme and operational sea states. Evidence is presented which shows this statement to be true, and a more sharply peaked wave spectrum is proposed for supplementary use. The importance of the spectral shape of a wave field for structural behavior is considered.

INTRODUCTION

For offshore operations, an adequate description of the environmental conditions is important. A better understanding of the wind, wave and current conditions experienced in the hostile areas of the North Sea will provide improved criteria for offshore activity. This paper deals with the results from recent studies of the North Sea wave conditions and of their implications for the North Sea exploration.

Empirical data and the conceptual idea of a lively developed ll sea state, led Pierson and Markowitz (1964) to propose a formula for a spectral description of the wind generated sea state. This spectrum has been adapted for a great variety of engineering applications?; i. e. testing of offshore structural behavior in irregular waves, and for the statistical description of severe sea states.

Wave recordings from the North Sea however, show that the Pierson - Markowitz spectrum may not always give a realistic description of the sea states; in particular duping the wave growth stage. In addition, scientific results, both theoretical and field experiments, show that the wind wave spectrum during wave growth is much more sharply peaked and contains more energy than the correspond ing Pierson - Moskowitz spectrum., Further, the existence of a-"fully developed" sea state questioned

THE "JONSWAP" EXPERIMENT

In order to improve-the understanding of the processes that develop a wind-way field, a multi-national experiment was conducted in the North Sea. Thirteen wave stations spaced along a 160 km profile extending westward from the Island of Sylt (North Germany) were in operation, recording over 2000 wave spectra. They found traitor-wave growth conditions, the source function S in the spectral energy balance equation

(available in full paper)
A Test Particle Dispersion study In Massachusetts Bay
Authors: Hess Wilmot N. , Nelson Terry A.
Published: October 2008

The development of predictive models to estimate in advance of a dredging operations where the fines in a dredge plume will travel is an important goal.

On June 11, 1973, 2700 kilograms (3 tons) of small (0.5<d<50?) particles were released into the water column in Massachusetts Bay and their movement tracked for 10 days. Also, oceanographic data were collected and analyzed and a dispersion model was formulated.

Final data show the plume movement to be west toward Boston Harbor, eastward toward Stellwagen Bank and southward along the coast into Cape Cod Bay where a counterclockwise gyre is suggested.

Introduction

The New England Offshore Mining Environmental Study (NOMES) was a joint effort of NOAA and the Commonwealth of Massachusetts to determine the effects on the environment of offshore sand and gravel dredging. This study was begun in June 1972 and terminated short of 'its goal in August 1973 The importance of a NOMES type study can be appreciated when one considers the significant problems which can be caused by the rain of silt from overboard dumping of dredge spoil. These are:The effects on metabolism and survival of organisms confronted with high concentrations of fine particulate matter;The effects on the benthic habitat caused by sediment removal and redeposition;The chemical and physical response of resuspended bottom deposits; andThe types, amounts and methods of chemical constituent transfer to the water column or sediments, and their amplification by organisms through the marine food web.

An actual dredging operation in which 764,000 cubic meters (1 million cu. yds.) of sand and gravel were to be removed from a dredge site 12.87 kilometers (8 mi.) out of Boston was to be the focus of the study. It was estimated that approximately 3% of the 764,000 cubic meters of dredged material would be dumped overside from the dredge. This means 22,938 cubic meters (30,000 cu. yds.) of silt (d < 64?) would be introduced into the water column.

Development of a predictive model to estimate in advance of the actual dredging where the fines in the dredge plume would travel was considered of extreme importance. The actual dredging operation could be used to test and refine the predictive model.

Previous investigations of diffusion in coastal and oceanic waters have utilized fluorescent dyes such as rhodamine Band tracked the plume continuously through use of fluorometers. These dyes were deemed inadequate for the study of a dredge plume mock-up since dye does not exhibit the fallout characteristics of natural sedimentary particles. It was therefore necessary to use a tracer composed of particles which exhibited settling characteristics similar to natural silt and clay-size sediments, but were easily identifiable from particles indigenous to the local water column and substrate.
Preventing Vibration Problems. Caused by Reciprocating Compressor Pressure Pulsation
Authors: Floyd James K.
Published: October 2008

Pressure pulsation from reciprocating compressors can cause excessive piping and structure vibration on offshore platforms, which may result in shutdowns or piping fatigue failures. This paper describes how to avoid such problems through proper use of pulsation dampeners, analog computer analyses, piping layout and supports. Field test results on actual installations are used to illustrate the effectiveness of these measures.

INTRODUCTION

Reciprocating compressors are sources of pressure pulsation. This pulsation propagates through the compressor piping, frequently causing appreciable vibration of both the piping and its supporting structure. The vibration can be strong enough to result in piping fatigue cracks and unscheduled shutdowns.

Particular attention must be given to pulsation induced compressor piping vibration on offshore platforms because of the greater potential for exciting other systems coupled through the structure. The common compressor pulsation frequency range of 5 to 100 Hz. often coincides with the natural vibratory frequencies of both the piping and structural members supporting the piping. When excitation and natural vibration response frequencies coincide, high vibration amplitudes and cyclic stresses can develop.

This paper discusses prevention of pressure pulsation induced vibration problems through the proper selection and use of:Pulsation dampeners.Analog computer analysis.Piping layout and supports.

PRESSURE PULSATION CHARACTERISTICS

By its inherent design, a reciprocating compressor does not provide a smooth steady flow but, instead, produces a series of periodic displacements produced by the intake, compression, and 0ischarge cycle basic to this type of compressor. This periodic displacement action superimposes a pressure pulsation wave on the intake and discharge system mean pressures. In addition, higher harmonic pulsation components are usually present because of the abrupt opening of the compressor valves which excites the acoustic response properties of the gas columns within the compressor passages and piping.

The origin of a pressure pulsation wave can be illustrated by the single reciprocating compressor cylinder shown in Fig. 1. The gas is compressed until the cylinder pressure exceeds that of the discharge system sufficiently to open the discharge valves. The discharge piping and passages are acted upon by a pressure pulsation having a fundamental frequency coinciding with the compressor displacement frequency and higher harmonic components. Similar effects are seen in the suction passages and piping.

Pressure pulsation waves propagate at sonic velocity (approximately 1400 fps for natural gas) through gas contained in both the suction and discharge piping. The pulsation travels upstream and downstream through the gas media which is flowing at a slower velocity of approximately 3D to 60 ft/sec. This can be visualized as being similar to the ripple action produced from a rock thrown into a flowing stream.
Problems Encountered in Maintaining Deep Draft Channel at Mouth of Mississippi River During and After Flood of 1973
Authors: Curtis William W. , Schorr Henry R.
Published: October 2008

THE MISSISSIPPI RIVER

The Mississippi River and its tributaries drain forty-one percent of the 48 contiguous states. The basin covers 1,245,000 square miles and includes all or parts of 31 states and parts of two provinces of Canada. The waters of the Mississippi River are distributed to the Gulf of Mexico through several outlets. The principal outlets at the mouth of the river are Pass A Loutre, South Pass and Southwest Pass. The intersection of these three outlets is known as the Head of Passes. Points located above or below this intersection are measured as miles Above Head of Passes (ARP) or miles Below Head of Passes (BHP). Figure 1. Another main outlet of the river is through Old River Control Structure, Mile 314 ARP, into the Atchafalaya River.

The Mississippi River and Tributaries is also the main artery of transportation for waterborne commerce for the Central United States. The river system interconnects the inland ports and also provides access to other United States ports and the ports of the world. The two major ports located in the lower reaches of the river are Baton Rouge, at Mile 229 AHP, and New Orleans, at Mile 95 ARP. The Port of New Orleans handled 130,000,000 tons of cargo and Baton Rouge handled 53,500,000 tons in 1973, being the second and seventh largest ports respectively in the Nation.

A channel 40 feet deep is maintained from Baton Rouge to the Gulf' through Southwest Pass. The width of the channel varies from 500 to 1,000 feet because of natural river characteristics or structures built to constrict the flow.

CONTROL STRUCTURES IN SOUTHWEST PASS

There are two rock and pile dike structures at the Head of Passes that maintain an optimum distribution of flows between the three principal outlets. One of the structures is located between Pass A Loutre and South Pass and the other between South Pass and Southwest Pass.

There are additional structures along the Southwest Pass channel and at the entrance to the Gulf to constrict the flow so that some natural assistance is achieved in maintaining the 40-foot deep channel. Permeable pile dikes perpendicular to the flow are located along the channel to contract the surface width of the flow to 1,420 feet. In this reach the navigable channel is 800 feet wide. There are controlled outlets through the banks on both sides of the pass that allow some loss of discharge; however, this is necessary because the material carried by the flow through these outlets strengthens the banks and nourishes the adjacent marches. There are jetties at the lower end of the 20.2-mile long Pass to guide the flow. The east jetty is 25,000 feet long and constructed of stone with a cover of heavy stone graded between 4 and 10 tons each.
The Reel Pipelay Ship - A New Concept
Authors: Goren Y. , Yenzer D.E. , Cushing C.R. , Friedland N.
Published: October 2008

To insure economic success, technological development must blaze the trail of any undertaking in the field of offshore oil production. In order to meet the requirements and challenges of pipelaying in deep and rough waters, the team who designed, constructed, and is successfully operating the world's first and only column-stabilized lay barges, have concentrated a massive effort to design the Reel Ship - a new concept, which is presented in this paper.

Following a discussion of the application, advantages and special features of the ship the paper describes the details of the Reel Ship system pipe lay operation. Following that, the paper presents the design criteria and features of the vessel, and, finally, a description of the various components of the pipe-handling equipment and the design procedures which led to their selection. The Reel Ship described herein is an engineering breakthrough which, without a doubt, will have a significant impact on future offshore development and production operations.

INTRODUCTION

1. General

Analysis of the requirements of the Offshore Oil Industry revealed the following general trends:

(Available In Full Paper)

Operational and economic analyses of the above trends led Santa Fe Engineering and Construction Co. to the development of the Reel Pipe-lay Ship discussed in this presentation. The engineering effort for the design of the ship and its systems was undertaken by Santa Fe Engineering Services Co. in late 1973. Utilizing the experience and know how acquired by the Company in pipe laying in rough sea conditions as well as operating the world's only reel pipe-lay barges. Santa Fe Engineering Services Co. designed the ship and is currently negotiating a contract for its construction. The design and preparation of the pipe- handling system and the final bid package preparation was the result of a massive effort by Santa Fe engineers, aided by number of subcontractor engineering firms.

2. Advantages of the Reel Ship

The primary advantage of the Reel Ship is attributed to the speed with which the pipe can be discharged at sea. This is due to the patented technique of straightening the pipe during unspooling and discharging operations. Another unique advantage of the Reel Ship is the welding of the pipe into continuous strings onshore, the x-ray examination and the corrosion protective coating applied irrespective of sea conditions and space constraints experienced by conventional barges.

The Reel Ship also has an advantage in being able to discharge pipe in very deep waters where it is extremely difficult or impossible for conventional welding barges to operate. This advantage stems from the peculiar geometry of the ship which allows the pipe to enter the water at very steep angles (up to 50°)while conventional barges are limited to about a 15 entry angle. This also allows the Reel Ship to work without a stinger, which is required by conventional barges.
Underwater Mateable Electromechanical Connectors for Power and Signal Cables
Authors: Wilson Jeffrey V.
Published: October 2008

In support of a broad variety of submerged power and signal transmission applications, the Civil Engineering Laboratory is developing underwater mateable electromechanical connectors for the Naval Facilities Engineering Command and the Naval Sea Systems Command. These "wet" connectors are designed for the underwater interconnection of rigid structures (e.g., pressure housings), cable structures (e.g., instrumentation arrays) and for connection to submersible vehicle batteries. Power connector technology reported at the 1974 Offshore Technology Conference has been extended in several directions. The primary effort has been development of a coxial wet connector compatible with SD coaxial communication cable. This connector maintains an impedance match to within cable manufacturing tolerances (±O.7 percent), has a signal range from O. 1 to 1 mgH, has a corona noise extinction level of 6, OOO-v alternating current (rms), is designed for 20,OOO-ft immersion and carries the breaking strength of the cable (16,000 lb). These connectors maintain the true coaxial configuration of the cable and may be mated by submersible manipulators or by divers. Other CEL-developed connectors are described, including a 300-amp, 170-v-DC model used for connecting the battery charging umbilical cable of the Deep Submergence Rescue Vehicle and a 1,000 amp, 120-v-DC connector for the TRIESTE II battery harness. Work with the TRIESTE II connector has demonstrated that it is suitable for use in explosive environments because the sealed, oil-filled design effectively contains arcs drawn during unmating.

The availability of these wet-connector concepts offers new alternatives to a system designer. He can now plan undersea operations that are unencumbered by attached power and signal cables. With the availability of wet connectors, these cables can be connected after the equipment is properly located at its undersea site. In addition, by use of these wet connectors, reliable connections can be made now on the surface without protection from the environment. Typical offshore applications would include power distribution to seafloor production systems, power and signal umbilicals for running equipment, down-hole electrical connections, and emergency quick-release systems.

INTRODUCTION

The Navy program to develop wet (underwater-mateable) connectors was initially designed to fill two major gaps in able connector technology:power limitations (100 amp, 6OO-v maximum available) andwet mateability (existing commercial wet connectors could only carry low voltage and were not adapted to deep mating).

With the completion of the prototype development in 19731,2 CEL had established a successful concept that embodied new capabilities in both areas. The concept utilized an oil-filled female half that contained an 0-ring sealed piston. During mating the male pin and contact were wiped off by the O-ring as the piston was displaced any small leakage was dispersed through tile-liquid dielectric and was thus prevented from forming leakage paths.
Estimation of the Foundation Condition of a Fixed Platform by Measurement of Dynamic Response
Authors: Utt M.E. , Durning P.J. , Duthweiler F.C. , Engle D.D.
Published: October 2008

We analyzed the recorded dynamic response of the Monopod platform, in Cook Inlet, and simulated the response with computer models in an attempt to discover the reason for observed changes in the fundamental frequency. Using a 3-dimensional linear dynamic structural analysis program we-modeled the recorded response to ice impacts and simulated model response to an assumed earthquake. We matched the results of the dynamic program with a non-linear finite-difference soil pile analysis program to model the soil structure interaction.

By varying model parameters we found that for the Monopod, dynamic response was insensitive to-changes in deck load mass or virtual water mass, but was strongly influenced by soil stiffness. Other investigators have found mass and hydrodynamic effects more important for other structures. By comparing numerical model output with recorded structural behavior, we were able to estimate the condition of the soil and the pile foundation. This analysis revealed that the change in the fundamental vibration period was related to changes in the soil around the piles near the mudline.

We conclude that, for small deflections, the upper 20 feet of the oil does not contribute to the dynamic response Of the Soil-structure system. For the larger motions, associated with an assumed earthquake, this zone would contribute to dynamic response.

Monopod Platform Has Acceleration and Strain Recording System

When the Monopod platform (FIGURES 1 and 2) was installed in 1966, a strain gage system was installed to indirectly measure ice forces (FIGURE 3). With this system, structural vibrations were also observed. An accelerometer system and recorder were installed in 1972. as described by Durning and Engle, 1976. The system consists of three triaxial accelerometers, two on the production deck and one at the mudline in an unused well conductor. The locations of the accelerometers are shown in FIGURE 4. Data from tile accelerometers and from the previously installed strain gages are recorded on cassette tape decks located in the production office on the platform. The recording system remains inactive until it is activated by a seismic starter located on the production deck. Acceleration and strain data are recorded automatically, and the system shuts off ten seconds after the vibrations cease. The analog tape records were later digitized, with an 0.02 second sampling interval, for computer analysis, such as calculation of spectra.

Change in Vibration Period

The platform's fundamental period was determined to be 1.1 seconds from the strain gage measurements of 1967. After the accelerometer system was installed in 1972, the fundamental period was 1.3 seconds. This 18% increase in the fundamental period caused concern.

In 1974, we undertook research to investigate and verify the available dynamic and nonlinear analysis methods, and to determine the cause of the observed change in the Monopod's fundamental vibration period.
Cotton- The Natural Sorbent for Combating Oil Pollution
Authors: Meenaghan G.F. , Halligan J.E. , Ball A.A. , Leary John F.
Published: October 2008

On June 1, 1974, a nineteen month study was initiated between the United States Coast Guard and Texas Tech University. The overall purpose of this contract was to develop a sorbent dispersal, retrieval, and disposal system using cotton wasties to combat oil spill pollution.

A test program was conducted to develop the design data base required to evaluate the concept as well as the system components. Major variables studied included crude oil type, sorbent to oil weight ratios, sorbent contact time, removal efficiencies, squeezing techniques, disposal via incineration, and air pollution parameters.

The results of this effort has shown that the concept of using cotton as an oil spill cleanup agent is viable and that the system as operated was capable of retrieving approximately 95 percent of the oil confronted for water velocities of 2 feet per second or less and dispersion ratios of 0.05 pounds, or greater, of cotton per pound of oil.

INTRODUCTION

The first question which must be addressed when considering sorbent systems concerns the advisability of adding an additional component to an oil spill. At first, this may seem to complicate the cleanup process. However, practical experience in analogous situations has shown that such an addition is desirable. Examples include putting oiled sawdust down to clean up a floor, and the use of a mop to pick up spilled water. Therefore, the use of a sorbent to clean up oil spills may have practical advantages.

The purpose of the sorbent is to facilitate a change of phase. The desired effect is similar to that observed with the addition of a small amount of solid gelatin to water which forms a semisolid. Similarly, a properly dispersed sorbent can markedly change the properties of fifty to one-hundred times its weight of oil. Just as it is no particular task to pick up a gelled material with a fork, The opinions or assertions contained herein are the private ones of the writer(s) and are not to be construed as official or reflecting the views of the Commandant or the Coast Guard at large.

It is not difficult to pick up oil once it is within a sorbent structure. Since the sorbent oil, mixture has decidedly different physical properties than those of a fluid, this will aid in retrieval operations. This is particularly true when using vacuum hoses where a sorbent and a simple rake can markedly increase the efficiency with which small pockets of oil can be retrieved.

Another benefit of using a sorbent is its ability to capture and retain oil for retrieval at a later time. This may be a major advantage due to the rapid initial rate of spreading of oil slicks on water. In many cases, the oil sorbent mass is highly oleophillic and hydrophobic which leads to coalescence into clumps facilitating later retrieval.

Additional advantages of a properly chosen sorbent are selectivity, effectiveness, and general applicability.
Nile Submarine Fan: Sedimentation, Deformation And Oil Potential
Authors: Summerhayes Colin P. , Ross David A. , Stoffers Peter P.
Published: October 2008

The Nile Submarine Fan is one of the largest in the world. Fan sedimentation probably began in the late Pliocene, burying Miocene carbonates and evaporites (Messinian). Salt flow due to sediment loading caused uplift of the fan's eaStern flank to form the salt dome-studded Levant platform. The fan's western flank - the Nile Cone - is deformed by minor folding, faulting, and slumping. The modern fan ends at the Mediterranean Ridge, but formerly extended further, as Nile-derived turbidites are found beneath the ridge. Tectonic and salt-flow deformation of the ridge occurs as a response to subduction of the African plate beneath the European plate.

Piston cores about 10 m long show that carbonate sediment occurs west of the fan and on the Mediterranean Ridge. Channels on the Nile Cone contain thick, clean, well-sorted, coarse-medium sands. Thick sequences of thinly-bedded muddy turbidites occur between channels. On the Levant Platform are complex mixtures of thin turbidite sequences and carbonate muds, while young channel deposits are lacking. East of the platform in the Cyprus Basin are mainly grey hemipelagic muds. Thin sapropels (with up to 25% organic matter) are common in cores' from allover the area. The turbidites also contain substantial organic matter (up to 2%) mostly as plant fragments.

Sapropels and turbidites form potential petroleum source beds over the entire fan; channel sands form potential petroleum reservoirs that may be most common on the Nile Cone. Up-dip migration of oil to stratigraphic traps in abandoned channels makes the middle and upper parts (apex) of the Nile Cone of interest as a potential petroleum reserve. Similar traps, as well a8 structural traps, may occur beneath the Levant Platform.

INTRODUCTION

In the opinion of many marine geologists today (cf. Emery, 1973) the continental rise, a thick wedge largely of terrigenous sediment at the foot of the continental slope, may contain vast new petroleum reserves. Much of the rise is built by overlapping submarine fans that grow at the ends of submarine canyons at the foot of the slope, by deposition, from turbidity currents, of sand in channels and mud on levees and between channels (Whitaker 1976). Fan growth, both lateral &vertical, is a key factor in shaping the continental rise in almost every ocean basin. Because their muds contain substantial organic matter (so are potential source beds), and their channel sands are potential reservoirs, fans deserve careful examination in the search for new hydrocarbon deposits beneath the sea (Wilde & others, 1977).

In this paper we examine the geological development of one of the worlds largest deep-sea fans, the 70,000 km2 Nile Submarine Fan, that covers much of the floor of the eastern Mediterranean, off the coast of Egypt (fig. 1), and attempt to assess its potential as a locus for oil &gas deposits.