Floating Storage And Offloading Research Articles

PROGRESSIVE COLLAPSE ANALYSIS OF A „LAY-DOWN” STRUCTURE UNDER FIRE CONDITIONS

The scope of this paper is to present the strength capability under fire action of a typical naval top side structure (lay down area structure) of a FSO(Floating, Storage and Offloading Unit).Where mechanical resistance in the case of fire is required, steel structures shall be designed and constructed in such a way that they maintain their load bearing function the relevant fire exposure.The present study covers the yielding and buckling checks of the top side structure fire exposure.The analysis tools used for the structural analysis of the FSO areDNV Nauticus Hull and FEMAP with NASTRAN NX ver. 11.4.

Risk Assessment of Ship Collision on FSO Abherka and Oil Spill Modelling Due to Structural Damage

Floating storage and offloading (FSO) is an important vessel in offshore as shuttle storage of crude oil before it will transfer to the onshore facility located near the drilling platform. One of the locations that use FSO is Poleng Field in West Madura Offshore by operating FSO Abherka. Poleng field is supplying for two regions in Java and Kalimantan, it can affect the energy supply of the regions if there is an accident. The possible accident is a ship collision with FSO Abherka in addition the location is near Surabaya West Access Channel (SWAC). It is necessary to conduct a risk assessment of ship collisions on FSO Abherka and a consequences analysis of oil spills due to structural damage. Calculating ship collision frequency using CRASH method using two traffic scenarios found the result of ship collision frequency for external and internal powered collision: 4,20E-03 and 1,28E-03, and external and internal drifting collision: 4,51E-03 and 4,01E-03. Consequences of Collision simulation is conducted in three variations of collision scenario and impacting to the hull damage. Total asset & equipment loss due to collision in various degree of 30°, 60°, and 60° as follows: $23.462.196,03, $23.666.532,98, and $23.921.683,88. Those total asset & equipment loss and environmental impact from the oil spill is on the category of unacceptable. Applying a traffic monitoring system is effective to reduce the frequencies by about 71-93%.

Mooring Lines Reliability Analysis Case Study: Fso Abherka,

Floating Storage and Offloading (FSO) demands good designs. One of the design is FSO’s mooring lines. The mooring lines of the FSO would face various environmental conditions, so that they are required to have good reliability. FSO Abherka, installed in the Madura stratit, has dimensions of LOA 242.90 m, LPP 232 m, Breadth 41.6 m, Height 19.7 m, Draft 12,894 m, and a deadweight of 85829 tons. The strait has a water depth of 100 m with contour variations of ± 2 m. Each four cluster of mooring lines of FSO Abherka has three mooring ropes. This study analyzed the strength of mooring lines in intact and damaged conditions using DNV software Genie and DNV HydroD. This study models a hydrodynamic FSO. This study also measured the reliability of the mooring lines from 2 cases: 1 intact and one damage from the most dangerous conditions. This study used the mean Value First Order Second Moment method to find the reliability of these mooring lines. Based on the reliability calculation set by DNV according to DNV-OS E301, the mooring lines design meet the established reliability criteria

Identifikasi Keberadaan Air pada Proses Penyaluran Fluida Produksi di Lapangan Minyak Lepas Pantai

Oil production that flows from the Platform to the FSO (Floating Storage and Offloading) "A" is derived from PT. "B" and the "C" Oil Company in the Madura Strait. The total oil production flowing from the Platform to the "A" FSO is currently around 6000 BOPD. As a result of the delivery system using the same channel, a problem arises, namely oil losses between the Platform as a delivery point and FSO "A" as a receiving point. Besides that, the water that is involved in the oil distribution process will be a deduction factor that will be used as a correction for oil shipments, the more water the less amount of oil will be received at FSO "A". The oil samples that have been taken are then observed for their characteristics, namely density, composition (%-mole), BS&W, emulsion, flash, shrinkage at PPPTMGB "Lemigas" Laboratory Jakarta. The specific gravity of samples is around 1,018. While the characteristics of the two are different from the characteristics of sea water; this difference is shown by the results of SG (1,018 vs 1,025) and the salt content of sea water is much higher than the water formation of PT "B" and PT "C". The oil samples of PT "B" and PT "C" have almost the same SG, which is 0.79. BS&W oil in both ships is quite low; this shows that the separation of oil and water on the Platform went quite well. However, BS&W samples in incoming FSO "A" are very high, at 5%; this indicates an off-set at the water-oil interface level settling time on the Platform separator so that water can be joined with the oil flow from the Platform to the FSO "A"

Analysis of coastal state regulation impact on the capacity optimization of floating storage and offloading using multi criteria decision making

Floating Storage and Offloading (FSO) that is opted by most of offshore company to directly resettle crude oil and/or gas from the well during exploitation period has been commonly known as the results of the tanker conversion due to technical similarity as well as time and cost consideration. Some of the users are not aware that the compliance with the Coastal State and/or State’s institutional body where FSO will be permanently operated can be triggered to a great impact within the building and operation stages. Hence, the optimization process to satisfy all aspects such as technical, economical, and regulatory need to be conducted properly. This paper is aimed to analyse the impact of the regulations issued by a Coastal State of where FSO will be permanently operated toward the vessel capacity in the optimization process. The method used to analyse impact of regulation in optimization process is multi criteria decision making (MCDM). The mandatory provisions to convert the ship domestically is put into the influence factor of the ship optimization. Analysis result shows that cost is the most determining criteria, while coastal state’s regulation among top three aspects that influence on FSO capacity optimization.

Integrated Design Assessment Optimizes Layout and Engineering of Timor Gas Field

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 19391, “An Integration of Geology, Geohazards, Geophysics, and Geotechnics for Pre-FEED Site Layout and Engineering Design of an Offshore Gas Field in the Timor Sea,” by Pattarapong Chullabrahm, Korn Saranyasoontorn, and Maythus Svasti-Xuto, PTTEP, et al., prepared for the 2019 International Petroleum Technology Conference, Beijing, 26–28 March. The paper has not been peer reviewed. Copyright 2019 International Petroleum Technology Conference. Reproduced by permission. The complete paper presents an integration of geology, geohazards, geophysics, and geotechnical assessments for a design of an offshore gas production facility and an associated export pipeline. The gas field described in the paper is off the northwest coast of Australia in the Timor Sea at a water depth of approximately 130 m. Introduction The gas field is envisioned to include a subsea production system, a fixed central processing platform (CPP) for separation and treatment, and a floating storage and offloading (FSO) vessel for condensate. Processed gas will be transported by a new gas export pipeline (GEP) that connects the CPP with a tie-in point on an existing export pipeline. A schematic of the infield facilities is shown in Fig. 1. Regional Geology and Geohazards To understand the seabed geology, the associated geohazards, and their effect on the proposed development, an initial desktop study into the seabed and shallow subsurface geology was undertaken. The main output from the desktop study was a preliminary geological ground model that helped determine the most suitable geophysical and geotechnical survey techniques to obtain accurate information needed to model the ground conditions further in preparation for engineering design. Regional Geology. The field development lies within the Vulcan sub-basin of the Bonaparte Basin, which contains sediments to a depth of 15 km. The sub-basin is a southwest/northeast-trending extensional depocenter comprised of a series of fault bound horsts, grabens, and terraces and is active tectonically. The resulting deformation is dominated by extensional fault structures (e.g., normal faults). During the late Pliocene epoch and early Quaternary period, sedimentation of the Bonaparte Basin was dominated by shallow water carbonates in a tropical ramp setting, including the development of isolated, intrashelf carbonate buildups that are often referred to as pinnacles or shoals. Avoiding these steep-sided shoals is an objective in selecting a preferred pipeline route; however, acknowledgement of other, unmapped seabed features such as terraces, banks, and valleys must also be considered. The base-case GEP route, called the Southern Bypass route, has a length of approximately 347 km and is proposed to link the field to the tie-in point. A more-direct route between the field and the tie-in point could shorten this route significantly (up to 70 km). This provides an opportunity for a significant expense savings for GEP construction but only if a technically feasible route through a major subsea canyon—the Lambert Shelf Valley (LSV)—can be found. This canyon is up to 100 m deeper than the surrounding seabed and has steep-sided slopes ranging between 30 and 50°. Geohazards. The LSV has the potential to influence the proposed seabed infrastructure. The geohazards associated with this canyon have a direct effect on the GEP. The following geohazards required investigation: Slope instability Turbidity currents Hard ground Mobile bed forms Pockmarks and shallow gas Soft soils Liquefaction

OIL SPILL TRAJECTORY AND FATE FORECASTING, RESPONSE AND CLEANUP OPTIONS FOR A COASTAL ENVIRONMENT: A GREEN FIELD MODEL OFFSHORE INDONESIA

The environmental impacts of an oil spill and the attendant response applied for ecological restoration would mostly depend on the conditions of the spill, nature of the area, quantity and type of oil released, meteorological and climatological factors, as well as the effectiveness of response techniques. The Indonesian government and operators have been considering best ways of shielding the environment and their reputation from spill hazards, in cognizance of the region's high sensitivity and vulnerability. This paper thus undertakes a risk assessment for the potential environmental effects of possible spillage of medium light crude pumped to the Floating Storage and Offloading (FSO) terminal installed to handle production and bulk distribution of oil produced from a green oilfield offshore Indonesia. GNOME and ADIOS were deployed to forecast the trajectory and fate of oil spilled from the FSO during loading operations to ocean-going tankers, respectively. Key environmental data obtained from ESI maps were built into the models to yield desired results. The likely trajectory of oil released from the FSO as depicted by GNOME results for nine days after the spill and the contact probabilities show that 5,200 barrels of the oil would beach on the ninth day. Response efforts must thus be effected before this occurs. The results from ADIOS were captured for both winter and summer conditions; indicating that more spilled oil would remain after a 5-day period, if it occurs during winter, than would be obtained for a spill during summer. This implies less complicated cleanup operations in summer than in winter. However, since the oil is medium light, the lighter fractions would readily evaporate out, leaving behind heavier oily residues that may form tar balls with the submarine sediments and sink to the sea bottom or arrive at the beach, as shown by GNOME. Subsequent Net Environmental Benefits Analysis suggests that dispersants would not be a good response option due to their toxicity to the ecologically sensitive ecosystem. It is thus recommended to contain imminent spills using dykes and booms within a few hours of occurrence, before further dispersion and beaching. Subsequent in-situ burning would then enable all the hydrocarbons and most other contaminants present to burn off, thus protecting the shoreline and submarine resources. The study will guide spill responders and serve as a basis for future oil spill contingency plans (OSCPs) in the field and others within the Southeast Asian hydrocarbon provinces.

Fatigue Life Re-Assessment of FSO Spread Mooring System

Re-assessment fatigue life on spread moored system of Floating Storage and Offloading (FSO) vessel moored in irregular wave has been carried out based on hybrid time-frequency domain approach. Previous assessment work result obtained the fatigue life very conservative about thousands of year, whilst existing mooring system was designed for the operational life of 10 years. Different method from previous work was used in fatigue damage calculation approach for undertaking a fatigue mooring analysis in present work. Present works aim to show that the simple summation method used for previous assessment that cause the large variation in fatigue life obtained by comparing different methods of combining fatigue damage. Comparison between the result of fatigue life both previous assessment and present work (re-assessment) of fatigue life are made and discussed.

Experimental fatigue and aging evaluation of the composite patch repair of a metallic ship hull

This article describes the fatigue analysis of a composite repair that was applied to the metallic hull of a Floating, Storage and Offloading (FSO) platform. The main objective is to address the durability and thus the expected operational life of the repair, with emphasis on the adhesive bonded interface between metal and composite. The adoption of this repair technology is increasing in Brazil and abroad and little is known about its long term performance when applied to harsh, dynamic applications like naval structures in operation. During repair installation, more than a year ago, an array of Bragg grating extensometers was applied for reliable structural behavior monitoring. Dynamic strain samples were acquired daily and remotely sent to shore for processing. In parallel, lap shear fatigue tests were performed at the lab in order to establish a suitable defect growth fatigue curve, concerning repair disbondment. The experimental strain data, together with a specific fatigue curved experimentally defined provided the input of a Finite Element Model of the repaired structure and resulted in the expected fatigue life of the repair metal-composite interface. Environmental aging was beneficial as it resulted in a12% increase in the critical shear stress of the interface.

Fuzzy inference system for fire and explosion risk assessment of floating storage and offloading vessels

A case study for the fire and explosion risk assessment of a floating storage and offloading (FSO) vessel is presented in this paper. The fire and explosion hazards affecting the storage tanker for different operating modes were first identified. Two approaches for risk assessment were then adopted. The first is a qualitative risk assessment approach using a qualitative risk matrix. The second is a fuzzy risk assessment approach using a fuzzy inference system (FIS). The use of a fuzzy representation for probabilities, consequences, and risk values takes into account the imprecision associated with the assignment of their values. A comparison is provided between the results obtained using the two approaches for an FSO vessel which is located about 120 km offshore from Libya. Results show that the use of an FIS approach provides a more robust framework for fire and explosion risk assessment and more output information than the qualitative matrix approach. The results also show that the computed risk values using a fuzzy risk index measure are consistent with those obtained using a qualitative risk matrix approach.

Repair of floating offshore units using bonded fibre composite materials

On ships, tankers and similar vessels structural defects such as cracks and corrosion damage are typically repaired by welding. However, welding is unwanted hotwork on floating offshore units (FOUs) such as floating, production, storage and offloading (FPSO) and floating, storage and offloading (FSO) vessels because it requires shutdown of parts of the vessel thus resulting in expensive production delays. Bonded fibre composite material patch repairs can be used as an alternative to overcome the hazards of hotwork associated with welding. The patches are bonded over the defect and the integrity of the original structure is hence restored. The patch repair technology can also be utilised to provide upgrades, such as life extensions and higher design requirements. A recommended practice (RP) has been developed that describes requirements for patch repairs used in FOUs. To provide flexibility and to fit different repair needs, the RP defines a range of Repair Classes that can be used depending on the urgency of the repair and the need for optimisation. The qualification effort increases with the degree of optimisation. The requirements are based on an extensive test program carried out in the laboratory (reported elsewhere) as well as experience from full-scale repair demonstrators. Two full-scale repair demonstrators were carried out on actual FOUs to demonstrate the feasibility of the RP for bonded composite patch repair. In addition the demonstrators also showed the viability of using bonded composite repairs under harsh conditions encountered in oil and gas exploration and production environments. The first repair was carried out to arrest a fatigue crack that had developed from the corner of a door, while the second repair was carried out to restore material loss on a heavily pitted deck floor. Both repair cases are used as examples to demonstrate the proposed qualification procedures whilst at the same time discussing the challenges and potential applications of this patch repair technology for FOUs in the oil and gas industry.

Structural analysis and modifications–2 tankers for offshore FPSO and FSO service

This paper addresses the unique structural requirements for successful conversion of tankers for floating production storage and offloading (FPSO) or floating storage and offloading (FSO) service. A description is given of the steps undertaken during two recent and very different conversions of a highly optimized 1980s VLCC to FPSO service, and a typical robust 1970s ULCC to FSO service. The paper describes the steps needed for ensuring the FPSO or FSO requirements are successfully met during conversion of the two tankers – each having its own history, e.g. date of build, original design, material choices, class society, voyage history and repairs. Firstly, the paper describes the procedure and results of an early initial structural assessment procedure on the basis of an American Bureau of Shipping (ABS) Phase A analysis, past tanker voyage history and a review of past survey records and thickness gauging data. Secondly, the paper describes the procedure and results of a detailed structural finite element analysis of the two vessels considering past tanker service and future FPSO or FSO service, including the effects of on-and offloading of crude oil. Since the abstract was first written, a third FPSO of similar configuration to the 1980s FPSO described in this paper has been analysed with the same procedure.

Operations in 4000 m Water Depth: Prestige Wreck Fuel-Recovery Project

This article, written by Technology Editor Dennis Denney, contains highlights of paper OTC 17557, "Operations in 4000-m Water Depth for the Prestige Wreck Fuel-Recovery Project," by G. Corbetta, Sonsub A/S; A. del Corral, Repsol YPF; J. Ewen, Sonsub Ltd.; and R. Paez and I. Rodriguez, Repsol YPF, prepared for the 2005 Offshore Technology Conference, Houston, 2-5 May. The tanker Prestige, carrying 77 000 tonnes of heavy fuel oil, sank in 3850 m of water 240 km off the northwestern coast of Spain in November 2002. The ship broke apart, and, for several months afterward, large quantities of spilled fuel oil washed ashore in the Gallaecia region of Spain and elsewhere. Repsol YPF, although in no way connected to the vessel or its cargo, was appointed by the Spanish government to recover the fuel oil remaining in the wreck. This paper describes operations performed during the fuel-oil-recovery project, focusing mainly on deepwater and offshore operations. Innovative deepwater equipment and procedures were used in tapping into the wreck's tanks, transferring extremely viscous fuel oil into specially designed shuttles, recovering these shuttles to surface, and offloading them into a dynamically positioned floating storage and offloading (FSO) vessel. Introduction Initial studies indicated that the innovative content of any solution adopted to solve the Prestige incident would require a substantial verification phase to ensure feasibility. At the same time, fuel oil was still leaking from the wreck, and it was apparent that a survey would be required at the site to verify the actual conditions. Also, for reasonable availability of offshore operations, activities would have to be concentrated between May and September, when the meteo-oceanographic conditions were most suitable. Therefore, a two-phase operational plan was implemented, with the most urgent activities being targeted for the summer of 2003 and the complete remedial operations being targeted for the summer of 2004. 2003 Campaign. The first offshore operations started in the spring of 2003. The scope of this first campaign included the following.Verify that the equipment for the operations on the wreck, as well as for the extraction and recovery of the fuel oil, was suitable to the task.Prepare a suitable working spread to operate in diverless construction mode in 4000 m water depth.Repair any remaining sources of leakage.Assess the remaining fuel-oil quantity in the cargo tanks.Implement a comprehensive survey and data-acquisition program.Execute a prototype fuel-oil extraction (target 100 m3) to qualify the selected method for fuel-oil extraction. The second phase of the project began in December 2003 to design, fabricate, and test all tools and equipment by no later than the end of April 2004. This tight schedule, to allow the start of the offshore operations by the beginning of May 2004, was one of the key challenges of the project. It was mandatory to complete the mobilization of the whole spread during the first half of May 2004. The extracting of more fuel oil than the planned 11 100 m3 was described in the article "The Prestige Wreck Fuel-Recovery Project" JPT (June 2005) page 58.

The Prestige Wreck Fuel-Recovery Project

This article, written by Technology Editor Dennis Denney, contains highlights of paper OTC 17534, "The Prestige Wreck Fuel-Recovery Project," by R. Hernan, A. del Corral, C. Berenguer, SPE, R. Paez, J. Sparrowe, and J. Moro, Repsol YPF, originally prepared for the 2005 Offshore Technology Conference, Houston, 2-5 May. This article is an overview of the recovery project to extract the hydrocarbons remaining in the wreck of the Prestige tanker. The ship, carrying approximately 77 000 tonnes of heavy fuel oil, broke up and sank in 3850-m-deep water in November 2002, 240 km off the northwestern coast of Spain. During the sinking, and for a period of several months afterward, a large amount of fuel was spilled, ending up mainly on the shores of Galicia. Repsol YPF, though in no way connected to the vessel or its cargo, was appointed by the Spanish government to recover the fuel remaining inside the wreck. Extraction of the remaining fuel was carried out in 2004 by use of large-volume aluminum shuttles. An innovative core-flow technique was used to extract this extremely viscous fuel (500 kPa·s at the shuttle offloading conditions) from the shuttles and offload it into a floating storage and offloading (FSO) vessel. Finally, bioremediation was used to accelerate the biodegradation of the remaining immobile fuel. Project Summary On 19 November 2002, the oil tanker Prestige broke up and sank in two parts. Approximately 37 000 tonnes of heavy fuel was believed to remain in the wreck, which continued leaking. The Spanish government commissioned a permanent solution for stabilizing the wreck and neutralizing its cargo. Potential solutions included the use of shuttle tanks to transport oil from the wreck to a surface container, pumping the oil to the surface by use of a riser system, and enclosing the whole wreck in a sarcophagus. Fuel viscosity at the wreck conditions was extreme (3 to 4×106 kPa·s), which, at this depth, precluded the use of conventional techniques. Repsol YPF (with technical assistance from BP, Eni, Petrobras, Statoil, and Total) outlined an action plan to be completed in 2003. The plan approved by the Spanish government consisted of the following. - Develop work-class remotely operated vehicles (ROVs) to operate at 4000 m water depth. - Seal all remaining leaks. - Carry out data acquisition on the wreck and its fuel composition and mobility, as well as on the environment and the marine soil, to assist future interventions. - Test a batch-extraction scheme that used shuttle bags. - Perform basic engineering studies of confinement solutions as an alternative if the above scheme did not work. Sonsub was hired as the main contractor, and, in the spring and summer of 2003, it carried out an offshore campaign for the above program to establish the basis for the actual fuel recovery planned for 2004.

Specialist on-site machining saves offshore vertical pump

One of Marathon Oil's floating storage and offloading (FSO) vessels, operating off the West Coast of Africa, recently suffered a leak on a critical vertical pump used for the transfer of sweet crude oil. Facing prohibitively expensive downtime the company called in Metalock Engineering to see if they could affect a repair.

Cargo Oil Heating Requirements for an FSO Vessel Conversion

Highly viscous crude oil stored in a floating-storage-and-offloading (FSO) vessel can provoke cargo pumping and remain-on-board (ROB) problems. Cargo oil heating in the vessel to reduce the viscosity and minimize the problems is studied in this paper as well as heating requirements. An operating scenario is introduced for a vessel of 300 kdwt with assumed data. Heat dissipation from warm cargo to ambient, heat addition to incoming cold cargo, and heat depletion during cargo offloading are analyzed for the vessel. A simplified but robust heat loss analysis for the vessel is presented. Using the readily available product crude as the boiler fuel to heat cargo is a logical decision. Fuel consumption is estimated for the vessel. Boiler loads for heating steam generation and heating devices are discussed. The cargo offloading configurations between the vessel and shuttle tanker are investigated for heated and unheated cargo to determine its deliverability. The configuration dictates the length of offloading hoses from the vessel to the tanker. High pressure losses within long hoses may prevent unheated cargo from being delivered at the design rate to the tanker. Alternatives to cargo heating are postulated. Addition of heating coils to an ultra-large crude carrier (ULCC) built in the 1970's or 1980's is considered during the vessel conversion. The cost estimates of addition and conversion for cargo heating are assessed. The transportational considerations are discussed. Conclusions and recommendations are presented.

Economic Evaluation of Subsea Development Options in the North Sea

Summary New fields in the northern and central North Sea are decreasing in size as this major oil- and gas-producing region matures. This paper analyzes technical options and costs to develop these smaller fields. Introduction The northern and central North Sea are major oil and gas producing areas and will continue to be for some time, with undiscovered reserves estimated to be between 4 and 13 billion bbl. As the region matures, however, the sizes of the fields are decreasing, and it seems that it will be necessary to use subsea development techniques to develop the fields economically. This paper presents technoeconomic evaluation of the application of such techniques to develop small fields. The number of undiscovered fields and their fundamental characteristics (reserves, distance to existing facilities, and water depth) are identified from historical and statistical data. These characteristics are used to model typical fields, and then a range of potential subsea development schemes are evaluated for cost with typical (1989) cost data for the North Sea. Potential development schemes include fixed platforms, subsea tiebacks, semisubmersibles with a catenary anchor-leg moored buoy (CALM) and a floating storage and offloading (FSO) unit, semisubmersibles with pipeline export, and floating production, storage, pipeline export, and floating production, storage, and offloading (FPSO) units. After base costs are established for each development, sensitivity analyses are performed t show the importance of the various technical and economic parameters involved in the cost estimation. Analysis of Field Characteristics In this section, we analyze published data for undeveloped fields and discoveries in the northern and central North Sea. From these data and the estimated undiscovered reserves, we develop an approximation for the numbe of undiscovered fields and their fundamental characteristics. Reserves. An estimated 4 to 13 billion bbl oil still remain undiscovered in the sedimentary basins of the northern and central North Sea. This estimate, of course, is updated continually and is based on analysis of exploration data and an ever-increasing understanding of the basins' geology. Analysis of discovered but undeveloped reserves data for the North Sea gives the distribution of small field sizes shown i Table 1. For the purposes of this paper, "small reservoirs" are purposes of this paper, "small reservoirs" are reservoirs containing less than 100 million bbl recoverable reserves. Table 1 shows that 75% of the undeveloped fields have less than 100 million recoverable oil, which corresponds with predictions 6 that 80% of future discoveries predictions 6 that 80% of future discoveries will have reserves of less than 100 million bbl. To obtain an approximation of the frequency distribution of future field sizes, and therefore a prediction of the total number of fields, the current field-size distribution was projected onto the estimated amount of undiscovered reserves. From the current statistics, 75% of the estimated reserves (3 to 9.75 billion bbl) will be found in reservoirs with less than 100 million bbl. Table 2 shows the projected reserves distributions for the minimum (3 billion bbl) and maximum (9.75 billion bbl) cases. These simple projections indicate that 69 to 226 small undiscovered fields exist in the northern and central North Sea, with 55% of these fields having recoverable reserves less than 60 million bbl. Depending on the type of analysis used, these estimates may vary widely, but on the basis of statistical analysis of the frequency distribution of reservoir size, the size of the fields predicted is, if anything, optimistic. Distance to Nearest Platform. One of the most popular methods of developing small reservoirs popular methods of developing small reservoirs in the British sector of th North Sea is to use satellite wells tied back to existing facilities with excess production capacity. Currently, 11 miles (between Don and Thistle oil fields) is the longest distance (in the British sector) over which an oil-producing satellite has been tied back with no primary processing of the well fluids. Thus, the proximity of a new field to existing facilities can hava large effect on its potential development. Table 3 shows that >50% of undeveloped fields (and discoveries) are >9 miles from a producing platform.