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Abstract The basic requirements of marine vessels as stable working platforms in the North Sea has existed since commencement of exploratory drilling. This requirement has now expanded to include year round construction and maintenance for associated oil and gas producing platforms, and lately for emergency disaster and blowout control. During the development of the Occidental Petroleum Consortium's Piper and Claymoe fields, Petroleum Consortium's Piper and Claymoe fields, based on 56 vessel-months of construction support anchored adjacent to platforms, an on-going need was realized for a comprehensive marine vessel, outfitted to support these developments. The additional requirement of fire-fighting and disaster control resulted in the emergence of a uniquely designed semi-submersible multifunction support vessel (MSV). Occidental has now placed a keel-up order in a Japanese shipyard for 1979 delivery of this special unit. The specifications for the unit have been developed in conjunction with Redco Inc., and Earl and Wright, a subsidiary of Sedco Inc. The requirements for such a multifunction support vessel are unique to the individual operations to be carried out, and specifications include those necessary for dynamic positioning, fire-fighting cranage and a comprehensive saturation diving system. Development of these specifications resulted in a dynamically positioned column stabilized semi-submersible vessel equipped with the following unique features:Extensive on board maintenance facilities for support of platform production and maintenance operations:A dynamic positioning system suitable to D.P.on all sides of a burning platform in Beaufortstate 10 while effectively fire-fighting.Fire-fighting equipment to provide for fire control platform abandonment, and remote manipulation and removal of debris associated with such disasters.A sixteen man saturation diving system, featuring a tethered and manned Mobil Diving Unit.

Abstract Several years ago, Exxon instituted a survey of contracted mobile offshore drilling units to evaluate structural integrity and readiness to properly respond to marine emergencies that might arise offshore. Results showed structural integrity and marine readiness varied from rig to rig and prompted Exxon to implement an ongoing and more rigorous Marine Safety program throughout its offshore operations. This paper will briefly describe results of Exxon rig inspections and Exxon's on-going Marine Safety program. Work in progress by the American Petroleum program. Work in progress by the American Petroleum Institute (API) and the International Association of Drilling Contractors (IADC) to promote industrywide upgrading of the mobile drilling fleet will also be highlighted. Introduction During the past six years, the offshore drilling industry has experienced three major marine losses -the ALEXANDER KIELLAND, OCEAN RANGER, and GLOMAR JAVA SEA. ALEXANDER KIELLAND. The semisubmersible ALEX-ANDER KIELLAND was lost because of a structural failure. Results of the Official Norwegian Ministry of Local Government and Labour Inquiry indicated the initial structural failure occurred because of improper welding detail at a hydrophone - high stresses at this location propagated fatigue cracks which caused the member propagated fatigue cracks which caused the member to eventually fail during a storm. This first failure then led to the failure of other members and loss of the rig. One hundred and twenty-three men of the 212 on board were lost. OCEAN RANGER. The semisubmersible OCEAN RANGER was lost during a severe winter storm because of a stability problem. Results of Official Inquiries by the United States Coast Guard and the Canadian Royal Commission indicate the loss was due to a ballast control system failure. All 84 men on board were lost when personnel were unable to safely abandon the rig in heavy seas and cold weather following the ballast system breakdown. GLOMAR JAVA SEA. A recent United States National Transportation Safety Board report suggests the drillship GLOMAR JAVA SEA sank because of fractures in the hull caused by Typhoon LEX. The fractures allowed flooding of two tanks on the starboard side; the rig then lost stability and capsized. One lifeboat was launched, but it was never located. All 81 men on board were lost. Although the specific cause of each loss was different, these disasters had several factors in common: Rigs sank at night in severe weather All experienced high loss of life Emergency procedures and on board lifesaving systems were not effective. Exxon considers the first line of defense against a major marine disaster to be the structural integrity of the rig. However, in the event personnel must abandon the rig and helicopter support is not available, equipment and personnel training must be adequate to successfully abandon the rig. Surveys of rigs contracted to Exxon worldwide in areas such as Australia, Southeast Asia, Gulf of Mexico, Eastern Canada, and the North Sea indicated structural integrity and marine readiness varied from rig to rig. After careful evaluation of survey results, Exxon found it necessary to implement an ongoing marine safety program to assure both structural integrity and adequate emergency equipment and personnel training to successfully respond to emergencies. P. 379

This report presents the results from manual and robotic dry hyperbaric FCAW down to 450 msw. The influences of welding parameters, technique and consumables on overall weldment quality have been investigated. Based on the obtained results, which comply with BS 4515-84 and API 1104-83, a preliminary definition of welding procedures using the studied consumables, can be made.

ABSTRACT A new underwater welding process has been under continuous development since 1968. It permits the welder/diver to work in-the-wet while the actual welding is performed in a dry gaseous environment using a specially-developed portable miniature habitat. The actual welding, done by a metal-inert-gas (MIG) process, consistently produces API 1104 Code welds in all welding positions in a large range of steel types and grades. Successful welds have been made to depths of 95 feet possible applications include new construction and repair of virtually any steel subsea structure with surface-quality welding. It is believed that the process will be adaptable to aluminum and any other weldable material. INTRODUCTION Early Welding Developments Welding underwater has been done with varying degrees of success from the beginning of the arc welding process. The achievement of quality underwater welds has always been hampered by the quenching effect of the water on the heat-affected zone and the deposited weld metal. Prior commercial attempts, as well as those used by the various navies of the world,1 have attempted to remove this unfavorable quenching effect by using a stick electrode with a special coating that generates a gas bubble around the arc as illustrated in Figure 1. Additional efforts to achieve quality welds have been made with the MIG process generating a large free bubble around the arc for the same purpose. All such attempts with both processes have, until recently, produced a marginal weld which rarely approached acceptable standards. This is attributed to such factors as the size of the bubble which, being too small, allowed a rapid quench. With increasing water depths, the size of the bubble is compressed further, with still more unfavorable results. In unfavorable welding positions, the free bubble becomes even more difficult to control. These and similar factors lead to welds with an uneven deposit of weld metal containing entrapped gas and/or slag material. The quenched metal in the heat-affected zone becomes too brittle resulting in an inferior weld. Recent Welding Developments Stick Electrode A recent process which was the subject of a previous paper2 has been commercially introduced in this country and used in some locations overseas. This process is thought to use a stick electrode with a special coating to give a larger, more controllable, free bubble. A similar process currently under development in England has been used on at least one commercial job. Although little has been published about the technical aspects of this process, it is believed to represent the best efforts with an optimum coating on the rod combined with rigorous and continuous training of the welder/diver to an acceptable weld under many conditions. It is known that special must be used with each different type of metal. Further, inferior results have been reported when welding high carbon, high strength steels.

Abstract The Pure Oil Co.'s initial installation in the Vermilion Block 39 Field operates a remote platform approximately 1–3/4 miles distant from a central platform. The remote platform contains three gas-condensate wells and their allied production equipment in conjunction with the require safety and aid to navigation equipment. The production equipment consists of low temperature extraction units with the gas and condensate being measured by orifice meters. Twenty-one temperature and pressure functions are continuously telemetered and recorded. Twelve additional temperature and pressure functions are telemetered on a selective basis and only indicated at the control platform. Twenty-three supervisory control points are provided for operational and safety requirements. A 6700-MC microwave system utilizing three channels for the telemetered and control functions and one voice communication channel provide the connecting link between the remote and control platform. Required power is supplied by diesel driven generators at each platform. This arrangement brought about a problem in frequency control and automatic synchronization of generators. Selection of equipment and its application was based upon a fundamental requirement of "fail safe" operation with the viewpoint of its application being expanded to encompass a much larger area of operation. It is believed that this installation will point the way toward means of reducing costs, increasing safety, and increasing efficiency in offshore gas-condensate production. Introduction The trend toward semi-attended or unattended production facilities in the oil industry has been gaining momentum during the past two or three years. Even prior to the present "recession," this trend was well established. The ever rising costs of lease production including supplies replacement parts, salaries, etc., caused the oil industry to seek some means of reducing these operating costs, and further aggravating the situation of increasing costs were decreasing profits.

Abstract The different methods used in handling gas effluent from offshore platforms are discussed in this article. The presentation is directed toward the type of system to select for gas disposal based on production, location, and safety factors for an offshore site. Some of the means of gas effluent disposal to be discussed are vents, flares, and mechanical devices. The selection of the particular method for use would be dictated by the type of equipment used, water depth, ambient conditions, and the type of crude produced. Alternate applications of the methods such as undersea venting, local venting, or remote venting are reviewed to determine the best application for a particular platform. Safety factors which affect gas effluent are examined. A few of these items are the amount and type of gas to be released, type of equipment, and location. Introduction Offshore production platforms are built to provide a working area to separate water, liquid hydrocarbon and gas. Separation is required offshore because of the extremely large pressure drops experienced due to two (2) phase flow of liquid hydrocarbon and gas being shipped together by pipeline. The dissolved gas would also require a large storage system for barge or tanker transportation of crude oil. Separation of crude oil and gas then is made offshore to allow single phase transmission of crude and gas through their separate transportation systems. Means of handling the gas offshore have developed slowly as producers have tried many ways to safely and economically process the crude. Some of the various ways that have been used in the past are presented in this article. Factors used in the selection of a particular means of gas disposal are presented to assist operators in offshore operations. Safety and economics are the two yardsticks used to evaluate gas disposal applications. These two yardsticks are presented briefly in the following discussion.. But to arrive at the optimum system for gas disposal, the complete platform should be developed and studied.

A new generation of construction equipment an evolving for offshore work in heavy seas. The progenitor of the line is Choctaw, the world's first column-stabilized construction barge. She is capable of sustaining operations in seas up to 16 feet and of maintaining her station in unrestricted oceans. Foreword Increased worldwide demand for oil and oil products, together with political uncertainties in some of the major oil producing areas, is accelerating the search for oil offshore and extending its boundaries to deeper and rougher waters. Offshore oil production necessitates the construction of platforms and production facilities, as well as underwater storage and pipelines. A great many construction barges have been built to fill this need. Until June, 1969, all construction barges had conventional box-shaped hulls, a feature that limited their operations to seas not exceeding 5 ft. Because of the excessive motion in high seas, these barges had to be towed away to sheltered waters whenever a storm was forecast. In June, 1969, the construction barge Choctaw was christened. Choctaw represented an important turning point in the industry in that she is the first column-stabilized construction barge and is capable of sustaining operations in seas up to 16 ft and maintaining her station in unrestricted oceans. The design principles used in the vessel are discussed in detail in Ref. 2. To restate the basic design philosophy, the designers recognized that a construction barge is seldom called upon to use her maximum crane capacity. For this reason, Choctaw was designed to operate in two different drafts. In the low draft, the crane can handle up to 800 tons at 90-ft outreach, and in the high draft, the crane can handle 150 tons at 110 ft with full deck load and no ballast compensation. On several occasions the vessel was called upon to perform lifts heavier than 150 tons while in the high-draft condition. These exercises were carried out by maintaining the list angle to a minimum through transfer of ballast. Lifts of this type necessitate that careful planning and exacting calculations be carried out by the barge engineers. The crane was designed to sustain a dynamic load produced by roll motion of 5 degrees in 9 seconds double produced by roll motion of 5 degrees in 9 seconds double amplitude (for all but the 800-ton load condition). The force produced by a 50-knot wind was superimposed on the dynamic loading. The crane was designed to sustain a 3 degrees barge list when lifting 800 tons. The vessel was designed to operate in adverse climates: in temperatures ranging from -35 degrees to + 120 degrees F. Both design and construction were closely monitored and approved by Lloyd's Register and the U.S. Coast Guard.

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract This paper presents the safety practices as applied by Gulf Oil Corporation to simultaneous drilling and producing operations in the Gulf of Mexico. Safety rules and regulations, both company and Coast Guard, are set forth and some detailed instructions are given as to the procedures to follow in particular situations. Personnel safety equipment and training, safety devices, safety practices and Hurricane Action Plans are explained. The use of special systems for control of small fires and the procedures for cheeking and maintaining this equipment has increased the confidence of the personnel engaged in offshore operations. Routine testing of equipment and daily practice drills have reduced the time to close a drilling well in from the 5 to 10 minutes required 10 years ago to an average of less than 1-1/2 minutes today. Another result of the safety practices employed has been the maintenance of near normal production rates while a drilling rig is in the process of drilling and completing a particular platform. The over-all result of the application of these safety practices has been the establishment and maintenance of high morale among all personnel involved in the exploitation of petroleum resources in the Gulf of Mexico. Introduction The application of good safety practices has been recognized for many years by operators and drilling contractors. The benefits derived from an effective safety program are large in terms of tangibles and intangible. The greatest intangible reward is better morale which is the most important single incentive that will keep a man returning to his job and performing to the best of his ability. Since the advent of large scale offshore operations in the late 1950's, one of the basic problems confronting a major company operating in the Gulf of Mexico has been the development of proper habits and training of men to safely drill wells while producing from the same platform.

ABSTRACT The time and cost required for offshore operations are often dominated by the influence of weather. Whenever comparisons are. made between alternate project proposals, or between alternate construction bids, weather effects must be considered. There is no simple, deterministic method which Will provide accurate answers to such problems. However, by use of historical weather data it is possible to obtain a probabilistic solution Based upon this, a rational evaluation of the alternatives can be made. A Monte Carlo procedure which incorporates computer simulation of weather has proved to be a valuable tool in such decision making. The program cannot make the decision. It can, however, provide the user with an analysis of the risk. involved in choosing any single proposal. The program has been used to evaluate bids on pipeline projects in the Gulf of Mexico, and the results have compared favorably With actual costs. INTRODUCTION The offshore operator is faced With risks which exceed those of most other industries storms, fire, structural or mechanical failure, pollution. Each of these possibilities must be taken into account by the cost estimator, since each must be reflected in the real price of construction or operation. Perhaps the most illusive of these, yet the most important from the standpoint of actual cost, is weather. Were it not for weather, construction costs could be radically reduced, and construction estimates made considerably more simple. One traditional method of accounting for weather has been to estimate the number of "working days" for each season of the year based upon actual experience. Under this method records of past jobs are analyzed to determine the time lost because of weather.1 If there are sufficient data, this approach is a valid one. Unfortunately, the percentage of working days depends not only upon the season, but upon the locality, the type of equipment used, and the nature of the job. Since there is seldom adequate "down time" nformation which applies to a specific set of these variables, the tendency has been to lump all data into a single package to arrive t a weather factor. This factor has often been used, Without discrimination, for all types of work. A second method has been to rely upon various types of weather forecasting. For short periods of lead time, such as a day or two, this is valuable information. Long range weather forecasting, however, is an inexact science at, best, and should be used only as a modifying influence on other methods of estimating. Another approach to. the problem. consists of using weather data directly to estimate'; the expected lost time. Records showing magnitude and probability distribution of waves, Wind, temperature, and rainfall are available for many parts of the world. 2 These distributions are translated into the percentage of time that work can be accomplished. This type of interpretation, however, does not tell the whole story. Periods of bad weather are often magnified in their effect on operations since some types of work require an uninterrupted period of good weather.

ABSTRACT Humble Oil & Refining Company has made operational a high volume oil and gas production system in the Grand Isle area, Offshore Louisiana. The system processes approximately 50,000 barrels per day and has a capacity of 90,000 barrels per day. Gas facilities provide fuel gas for two offshore sulfur mines and compress gas for sales and injection into underground reservoirs. Notable features of this system include:desanding and associated sand cleaning equipment,a pneumatic control system for gas distribution and failsafe operation,capacitance probes and turbine meters for computerized net oil measurement,check valve system for compounding pumps during production surges,measurement and pumping of gas-saturated crude at 55 psi, anduse of engine waste heat for gas dehydration. This paper reviews the design concept, process flow, control system, packaging, installation, and operating experience of the facility. INTRODUCTION Grand Isle Block 16 is Humble's largest offshore field and in cumulative production is the sixth largest oil field in Offshore Louisiana. This field produces approximately 50,000 barrels of oil and 60 million cubic feet of casinghead gas per day. Secondary recovery projects utilize both water and gas injection. In addition to the oil and casinghead gas, 760 long tons of sulfur per day are extracted by the Freeport Sulphur Company Caminada Mine. Fig. 1 shows the location of the field, about 10 miles south of the Grand Isle base Until recently, well-head pressures were utilized to flow field production via pipeline to onshore treating facilities. However, increasing producing rates brought on by additional development, reservoir unitization, and higher allowables imposed excessive back pressure on flowing wells through pipeline pressure losses. It became apparent that oil rates would exceed capacity of the two-phase line to shore. FIELD OPERATIONS Grand Isle Block 16 Field was discovered in 1948 and has twenty producing platforms, one quarters platform, and one compressor platform in water depths ranging from 40 to 65 feet. The field, which is associated with a piercement type salt dome, produces from approximately 200 active completions, ranging in depth from 6,000 to 13,000 feet. Flowing tubing pressures range from 25 to about 2,500 psi with most being between 500 and 1,500 psi. Prior to 1968, oil and gas flowed two phase to the centrally located "L" Platform for separation. You will note in Fig. 2 the gathering system to the central facility. Separator oil with its gas in solution then flowed directly to a 12-inch pipeline to Grand Isle. Approximately 8-10 million cubic feet of separator gas provided primary fuel supply to Freeport Sulphur Company's Grand Isle Mine in the adjacent Block 18 Field. The remainder of the separator gas was either injected into reservoirs or compressed and transported via gas pipeline to a Gas Plant at Grand Isle for processing and subsequent sales. By mid-1966, with a field oil rate of 32,000 barrels per day, producing well back pressures were "550 psi at the central gathering platform and 800 psi at remote outlying platforms.

Construction of system for Southern California Edison Co's Huntington Beach Steam Station located on coastline 30 mi south of Los Angeles; initial capacity of station is 400,000 kw with provision for future expansion; use of ocean water for cooling presents special problem; effects of corrosion, control of fish, and control of marine growth; model studies conducted; consideration given to earthquake problem.

This paper was prepared for the Second Annual European Meeting of the Society of Petroleum Engineers of AIME, to be held in London, England, April 2–3, 1973. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract Site fabrication of production and processing facilities for offshore processing facilities for offshore or for very remote locations are often several times the cost of facilities constructed inland near industrial areas. The high costs result from inherently low manpower efficiency, the high cost of mobilizing manpower, skills, machinery and materials and the very frequent need for high priced stand-by equipment and services. Time requirements and costs are substantially reduced by pre-assembly and delivery of modules to the site where water transportation to the site is possible or where large skids or modules may be easily moved by sea and land. Complete production and processing plants are now being manufactured and tested mechanically and electrically in efficient factory environments where necessary components, skills and manpower are readily available. Engineering expertise has been developed and refined for positive module fit-up and for minimizing costly offshore construction and commissioning activities. Introduction Most offshore oil and gas production and processing platforms and some remote land and swamp locations represent the most expensive construction sites in existence. Costs are high for support structures for operating facilities in deep water where poor soil conditions prevail. Costs are directly related to horizontal space requirements and total weight loading of the support structures and bearing surfaces or for decks to hold the production equipment. After costs for the support structures and space requirements have been optimized, production and processing facilities themselves are still very costly. These high construction costs are directly related to the many facets of inherently inefficient mobilization and utilization of manpower in hostile environments and at remote locations.

For shoreline harbors where littoral drift occurs along shoreline, certain design, construction, and maintenance problems are present; summary of basic considerations in generalized terms; case histories of typical shoreline harbors for which operational information extending over long period of years is available. (64 refs.)

In the literature, different authors attribute between 15% to 30% of a wind farm’s costs to logistics during the installation, e.g., for vessels or personnel. Currently, there exist only a few approaches for crew scheduling in the offshore area. However, current approaches only satisfy subsets of the offshore construction area’s specific terms and conditions. This article first presents a literature review to identify different constraints imposed on crew scheduling for offshore installations. Afterward, it presents a new Mixed-Integer Linear Model that satisfies these crew scheduling constraints and couples it with a scheduling approach using a Model Predictive Control scheme to include weather dynamics. The evaluation of this model shows reliable scheduling of persons/teams given weather-dependent operations. Compared to a conventionally assumed full staffing of vessels and the port, the model decreases the required crews by approximately 50%. Moreover, the proposed model shows good runtime behavior, obtaining optimal solutions for realistic scenarios in under an hour.

The current study describes the mapping and analysis processes of a company in the Brazilian shipbuilding and offshore construction sectors, according to Business Process Management assumptions. As for methodology, applied research using a case study, where semi-structured interviews were conducted as data collection tools. As for the interview scripts, six process parameters were established and used for data collection, which was of qualitative nature. Creation of the flowchart, resorted to the standard flowgram tool ANSI, this allowed for detailed viewing of the activities that compose the process as well as a general view of the process. Resumo O presente trabalho descreve a proposta de mapeamento e análise de processos em uma empresa do setor de construção naval e offshore brasileira seguindo os pressupostos da Business Process Management. No que tange aos aspectos metodológicos, a pesquisa caracteriza-se como aplicada e foi conduzida por meio de um estudo de caso, tendo entrevistas semi-estruturadas como instrumento de coleta de dados. Para a realização do roteiro de entrevistas foram estabelecidos seis parâmetros processuais, utilizados para a análise dos dados, a qual ocorreu de forma qualitativa. A elaboração do fluxograma foi realizada por meio de ferramenta fluxograma padrão ANSI, o que permitiu a visualização minuciosa das atividades que compõem o processo, assim como uma visão geral do mesmo.

The research examines the impact of corporate and industrial relations strategies on company performance as measured by changes in labour utilisation, based on a study of Scott Lithgow, a shipbuilding and offshore construction yard.

Ocean structures for oil development have been constructed, or planned for construction, on continental shelves off 60 countries and in water as deep as 840 ft. Descriptions of four significant structures, in the Gulf of Mexico, Cook Inlet, North Sea, and Persian Gulf illustrate design and construction features of pile foundation systems currently used offshore in areas of severe environmental conditions. Pile size selection is dominated by substructure design considerations. Pile lengths to develop required axial capacities are estimated from static analyses using boring and test data. Designing pile wall thickness requires difference equation analyses to predict bending stresses resulting from wave and other lateral forces. Estimates of vertical and horizontal pile movements, as required to assist substructure design, are also obtained using difference equation solutions. Pile installation is primarily achieved by driving, using hammers with rated energies up to 600,000 ft-kips. Research needs to support the rapidly advancing development of ocean structures are examined.

Simultaneous drilling and producing on offshore platforms is a standard worldwide practice and can be conducted safely with significant attendant benefits. These include timely procurement of critical reservoir data to ensure proper reservoir development and improvement in reservoir development economics related both to and near term production acceleration and potential improvement in ultimate recovery.Qualitative and quantitative assessments show that incremental risks associated with simultaneous drilling and production are small compared to the basic risks involved in offshore development drilling. The assessments have led to the identification of various specific safety practices which are recommended for simultaneous drilling and producing operations.The possibility of intersection between a drilling and a producing well is considered to be one of the major areas of concern in concurrent drilling and production. A statistical approach, based on probable directional survey errors, has been developed for determining the minimum safe measured separation between drilling and producing wells as a function of depth. All producing wells falling within this minimum safe distance from a drilling well must be shut-in below the deepest point of potential interference.Where possible the use of surface controlled subsurface safety valves (SSVs) for shutting-in completed and perforated wells to meet the minimum safe distance criterion is preferable to the more traditional practice of using wireline set tubing plugs. In addition to being much cheaper, the SSV method should render simultaneous drilling and production considerably safer by minimising the number of wireline operations; accordingly, directional well planning and the setting depth of SSVs should be such that the SSV is located below the deepest point of potential interference in as many cases as possible. In instances where the SSV is located above the deepest point of potential interference, tubing plugs will have to be set.

A system which can be set up in emergencies to moor an offloading vessel and transfer oil between it and a seabed pipeline, as to remove oil from a grounded tanker or to deliver fuel to the shore under hostile or emergency conditions. The system includes a barge containing a fluid swivel as well as a mooring buoy and buoy-holding chain. The barge can be towed to a desired location and pipes and hoses connected to the fluid swivel, and the barge then can be sunk to the seabed. Upon sinking, the barge is already connected to the seabed pipeline and to hoses that extend from the barge to the sea surface to connect to an offloading vessel, as well as being connected through a chain to a buoy floating at the sea surface which has a hawser for mooring the vessel. A vessel can be utilized to tow out the seabed pipeline, to facilitate installation of the pipeline as to enable connection of the pipeline to the fluid swivel on the barge prior to sinking the barge.

This paper describes the framework of the proposed intelligent structural design system, ISTRUDS, currently under development, and an implemented example, IPDOJS, intended for the preliminary design of fixed‐steel offshore jacket structures. The framework comprises of a knowledge‐based system development tool, a conventional structural analysis and design package, and an interfacing automatic data generator cum interactive graphic editor. Function of the latter is essentially to couple the first two tools into an integrated system so that the expertise knowledge in the implemented expert system can be used to guide the numerical procedures embedded in the analysis and design package. An interactive graphic editor has also been provided to facilitate visual modification of the pre‐ and postprocessed structural model. The objective of the example is to illustrate an approach to the development of an intelligent structural design system for the design of offshore and/or onshore structures.

Gas recycling, to increase early production and total recovery of hydrocarbon condensate, was implemented on the North Rankin 'A' platform to take advantage of excess production capacity prior to the commencement of the LNG export phase. By recycling excess 'dry' gas back into the reservoir, condensate production has been doubled, to around 3 000 kl per day (19 000 barrels) per day and ultimate recovery increased.The additional facilities installed included five injection wells, an additional production well, and a 23 MW gas turbine driven gas recompression facility that was retrofitted within existing facilities on the platform. Designed in-house, the facility involved relocation of some operating plant and piecemeal installation of a new 400 tonne module containing a 23 MW aero-derivative gas turbine driven high pressure (30 MPa) centrifugal compressor and ancillary equipment. The compressor set was extensively tested under full load conditions at the manufacturer's works in France before delivery.Offshore construction was complicated by the congested working area and the difficulties of working in and integrating with live production facilities but was completed without major incidents or causing undue interference to platform production. Commissioning proceeded quite smoothly. Full operation was achieved within ten days of initial start-up, and the facility has continued to yield impressive production results.

As onshore oil and gas deposits are becoming more difficult to locate, and as the world demands for energy continue to increase at an alarming rate, oil companies are channeling much of their exploration activities towards offshore operations, and in particular, towards operations centered off Canada's coast lines. Because of the environment, offshore drilling presents problems which are novel to the onshore-geared oil industry. J. M. Killey discusses in detail many of the considerations involved in drafting the offshore drilling contract, concentrating on problems such as the liability of the various parties; costs; scheduling; pollution; conflict of laws; etc. Similarly, he discusses service contracts (such as supply boat charters; towing services; helicopter services; etc.^ which are necessity to the operation of an offshore drilling rig. To complement his paper, the author has included number of appendices which list the various considerations lawyer must keep in mind when drafting contracts for offshore operations.

B.O.C. of Australia Limited has drilled five wells on the continental shelf of Northwest Australia using floating type oil exploration vessels. To date three different methods of anchoring have been used in the Group's operations depending on the type of sea bottom encountered and the progress of technology.On coral and shoal areas south of Timor good anchoring ground has been located. Both drilling exploration vessels S.S. "Glomar Tasman" and the "Investigator," a drilling barge, have been anchored in this area using all chain anchor systems.Three wells have been drilled in an area approximately 100 miles northeast of Barrow Island where surveys revealed smooth limestone sea beds of such hardness that conventional ships anchors could not penetrate the surface to obtain a firm hold. Anchor pilings to hold the "Glomar Tasman" have been successfully installed on the sea floor at two drill sites using a small vessel, M.V. "Nyhavns Rose," of 400 tons. These piles were drilled into the sea bed using a drill string and a power swivel at the surface, and utilizing a counter weight system to allow for vessel heave. At the first locality, in 180 feet of water, divers were used to manually connect the heavy pendant wires to the anchor piles. At the second location a diverless method of installing drilled in anchor piles with chain mooring pendants attached was designed and successfully used in a water depth of 265 feet.