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Collaborating Authors
North America
INTRODUCTION The coal exploration on Far-East have increased up to 1988 when the peak mining (57 mln.t) was achieved. In spite of constant incensement of coal mining the fuel deficiency was constantly observed and coal deliver increased continuously. If up to 1985 the coal deliver was not over 9 mln.t than in 1985 it increased 3 times. At period 1988–1990 the coal mining decreased on 7.2 mln.t and delivery was 7.5 mln.t At period 1976–1986 a problem of atomic power plants in Primorje and Khabarovsk Regions was actively considered. But after Chemobyl catastrophethe the project development was finished. At the same time the coal specific weight in using fuel in Far-East at period 1990–1995 have increased from 55% up to 59% and of black mineral oil have decreased from 25∼ to 21%. Owing to large part of coal and black mineral oil the concentration of dust substances exceed the several times the permissible norms from fuel burning in all large cities. At present time the consumption of boiler-stove fuel in Far- Eastern area (without Amour Region and Republic of Sakha) is 27 mln.t of reference fuel (1994) and at period 1990–1994 have decreased to 1796 and stove black mineral oil - 349∼, natural gas - 12%. CONSUMPTION STRUCTURE OF FAR-EAST The most great consumers of fuel are Khabarovsk and Primorje Regions. The consumer part of stove-boiler black mineral oil decreased and part of Sakhalin Region is 14%, of other regions (Kamchatka and Magadan Regions, Republic of Sakha) - only 18%. Table 1(refer to the full paper) show the consumption structure of main kinds of stove-boiler oil (coal, gas, black mineral oil, other kinds) corresponding to regions.
- Asia > Russia > Far Eastern Federal District > Sakhalin Oblast (0.73)
- Asia > Russia > Far Eastern Federal District > Khabarovsk Krai > Khabarovsk (0.53)
- Geology > Rock Type > Sedimentary Rock > Organic-Rich Rock > Coal (1.00)
- Geology > Mineral (1.00)
- Materials > Metals & Mining > Coal (1.00)
- Energy > Oil & Gas (1.00)
ABSTRACT Crack coalescence by stress-corrosion cracking (SCC) can lead to cracks that eventually are large enough to be fracture-critical (unstable). Up to that point continuing coalescence produces ever longer cracks, which because of coalescence experience significant jumps in their average crack growth rate. Therefore, coalescence can be an important aspect of the SCC failure process. This paper develops a criterion to determine when the conditions between two crack tips, expressed in terms of the linear-elastic fracture mechanics stress-intensity factor, K, will support the onset of coalescence. Whether the loading remains sufficient to support the continuation of the coalescence process can likewise be determined with this criterion. This criterion is based on satisfying the condition between the two tips that K KCoalesce, where KCoalesce is a measure of the material's resistance to cracking due to either SCC or fracture. This criterion is illustrated by its application to field data for the coalescence of SCC that resulted in a leak in a gas-transmission pipeline. INTRODUCTION Stress-corrosion cracking (SCC) occurs occasionally on the outside surface of gas-transmission pipelines. Where failure occurs, this stress-corrosion process produces an axial flaw that can involve the coalescence of many crack segments, which often have similar depths. Coalescence can lead to crack sizes that do not support ductile tearing but can continue to grow stably by SCC until the wall is penetrated (i.e., a leak occurs). This coalescence, which occurs at a rate determined by the kinetics of SCC, begins when the adjacent crack tips sense one another. As shown by Stoneseifer et al (1993), crack tips tend to grow toward each other for interacting colinear crack pairs and away from each other for coparallel pairs.
- North America > United States (0.89)
- North America > Canada (0.89)
ABSTRACT During the next decade, Oil and Gas developments will be from reservoirs in ocean waters down to 4000 feet and beyond. This will require the utilization of more enhanced installation techniques that will be based on welded fabrication of pipelines, risers, and bundles in the vertical (J-lay) rather than the normal horizontal position (S-lay). This paper reviews the recent improvements in Fabrication and Automated inspection technology that are taking place to optimize installation costs for J-Lay techniques. Specifically, the recent improvements in the preferred method of Mechanized Gas Metal Arc Welding (GMAW), which has been used since 1991 in this application, are discussed, in addition to the latest developments in Radial Friction Welding. Correspondingly, the respective Inspection technology, that is currently in use on many Gulf of Mexico projects, where GMAW is utilized, is also detailed. References are made to several recent projects where these improvements in technology have been made to a high degree of success. INTRODUCTION The trend to develop Oil and Gas in deeper water is continuing with the installation of risers, pipelines and flowline bundles. In particular, Shell and its partners are proposing a network of pipelines in the Gulf of Mexico to link all proposed and current deep water production facilities. (Figure I). With 7 billion cubic feet of natural gas per day expected out of the Gulf of Mexico by 2005, these facilities will be used to move gas to market as well as those of other producers. Beyond 800 feet of water there is virtually no infrastructure. In particular, the Mars field is considered the largest Oil and Gas discovery in the Gulf of Mexico in more than 20 years.
- North America > United States > Gulf of Mexico > Central GOM (0.34)
- North America > United States > Texas (0.28)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Mississippi Canyon > Block 851 > Mars Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Mississippi Canyon > Block 850 > Mars Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > East Gulf Coast Tertiary Basin > Mississippi Canyon > Block 808 > Mars Field (0.99)
- (5 more...)
ABSTRACT Various types of repairs are discussed for fatigue cracks in marine structures, emphasizing the limited database on the fatigue performance of these repairs. Fatigue tests on full-scale-welded beams show that the original fatigue strength of various types of butt welds are all AWS Category D, regardless of the type of steel, whether they are two-sided or one-sided welds, with and without backing, and with and without the edges ground flush. Continued testing after vee-and-weld repairs of the fatigue cracks indicate that vee-and-weld repairs of through-thickness cracks have the same fatigue strength as the original new butt welds, even after repairing the same location up to four times. The fatigue strength of weld access holes can also be nearly restored with repair welds of cracks. INTRODUCTION Some commercial ships have exhibited extensive fatigue cracking at welded details and cutouts (Liu and Thayamballi, 1996). These fatigue cracks are often repaired by gouging a vee weld preparation along the length of the fatigue crack and welding (Huang and Dexter, 1996). The Tanker Structure Co-operative Forum (TSCF) has published several books which show pictorials of the types of cracks which commonly occur in tankers and the suggested repairs (TSCF, 1986; 1992; and 1995). The restored fatigue life after repair determines the adequacy of these repairs. The few fatigue test data from full-scale specimens with repair weIds indicate that the fatigue resistance of a vee-and-weld repair is equivalent to that of an ordinary butt weld in new construction. Therefore, the basic S-N curve that is used in initial fatigue design of welded ship details may also be used to predict the restored fatigue resistance of the vee-and-weld repairs. However, there is a need for additional test data to support this approach.
- North America > United States (1.00)
- Europe > United Kingdom > England (0.29)
- Energy > Oil & Gas > Upstream (0.95)
- Transportation > Marine (0.88)
- North America > United States > Louisiana > Watson Field (0.89)
- North America > Canada > Alberta > Norris Field > Altair Lloyd Hilliard 1-5-54-17 Well (0.89)
ABSTRACT Fusion welding technology, involving skilled welders has been used extensively offshore. As exploration and exploitation moves to deeper waters, a limit is reached beyond which direct manned intervention is no longer feasible and current welding technology ceases to be viable. This paper explores two alternative arc welding processes for operation in deep water, hyperbaric environments. Although modifications are required to the process control strategies, and the processes are inherently more complex than their shallow water counterparts, it is shown that good quality welds can be produced at pressures up to 100bar. Recent research has shown that welding processes can operate successfully at pressures at least up to 150bar and work is currently under way to extend these limits to 250bar, equivalent to 2,500m (8,200R) water depth. INTRODUCTION There is a general consensus within the oil and gas industry that exploitation of hydrocarbon reserves in water depths significantly greater than those currently being developed will take place within the next decade. Many deepwater reserves world-wide are currently under assessment, including several areas in the Gulf of Mexico, offshore Brazil, in the Philippines, offshore West Africa and in the northern North Sea. Two major projects under way to develop technology for deep water exploitation include "Deep Star" led by Texaco, and "Procap 2000" led by Petrobras. These and others are examining the overall technological concepts needed to commercially extract oil and gas from deep water reserves. In shallow waters, underwater (wet) or hyperbaric (dry) welding techniques are widely used for the joining of pipelines and strictures. There is, however, comparatively little known about the capability of welding processes for operation in deep waters, particularly at depths inaccessible to divers. This paper reports on work carried out to assess the behaviour and suitability of two welding processes for deep water applications.
- North America > United States > Texas (0.28)
- Europe > United Kingdom > North Sea (0.24)
- Europe > Norway > North Sea (0.24)
- (2 more...)
- Research Report (0.66)
- Overview (0.66)
ABSTRACT Recent developments in reliability analysis to aid structural design and reassessment during use as well as inspection planning are reviewed. Data and methods applied to calculate the probability of ultimate and fatigue failure of structural components and systems, considering the effect of inspection, are critically examined. Target reliability levels are briefly discussed. INTRODUCTION The harsh environmental conditions and other hazards associated with offshore structures as well as the significant consequences of failure make safety an important consideration for such structures. Offshore platforms are designed for a service life of 20 years or more, with criteria for serviceability and safety against structural failure and overall instability or possible sinking (see e.g. ISO 1994-). Adequate structural safety is achieved by applying ultimate (ULS) and fatigue (FLS) limit state criteria for components. Fatigue is an important consideration for structures in areas with more or less continuous storm loading (such as the North Sea) and especially for dynamically sensitive structures. Progressive collapse limit state (PLS) criteria are applied to avoid catastrophic accidents, i.e., due to a small damage. In addition to design measures inspection and monitoring, and repair, if necessary, are important measures for maintaining safety, especially with respect to fatigue, wear and other deterioration phenomena. But their effect on the reliability depends upon the quality of inspection, e.g., in terms of detectability vs. size of the damage. Hence, an inspection and repair measure can contribute to the safety only when there is a certain damage tolerance. This implies that there is an interrelation between design criteria (fatigue life, damage tolerance) and the inspection and repair criteria. Up to now, however, this interrelation has not been explicitly considered, due to lack of methods tO deal with this problem in a rational way.
- North America > United States (0.94)
- Europe > Norway > North Sea (0.35)
- Europe > United Kingdom > North Sea (0.25)
- (2 more...)
UOE-Formed Tendon Pipes For Deep Water Oil & Gas Exploration In the Gulf of Mexico
Ikeda, Tomoaki (Sumitomo Metal Industries, Ltd.) | Ohnishi, Kazushi (Sumitomo Metal Industries, Ltd.) | Yamamoto, Akio (Sumitomo Metal Industries, Ltd.) | Nagase, Makoto (Sumitomo Metal Industries, Ltd.) | Takeuchi, lzumi (Sumitomo Metal Industries, Ltd.) | Smith, James D. (Shell Offshore Inc.)
This paper describes the development, pre-qualification testing and production properties of heavy wall-thickness TLP tendon pipes for the TLP projects in the Gulf of Mexico, X-60, 26" O.D. x 1.300"W.T. (AUGER), X-70, 28"O.D.X1.200"W.T. (MARS, RAM/POWELL), X-65, 32"O.D. X 1.500"W.T. (URSA). The AUGER TLP, installed in 2,860 ft of water in 1994, was the first step-wise development of deep water Gulf of Mexico discoveries. This success in subsea field exploitation accelerated the consecutive deep water TLP construction, MARS, RAM/POWELL, and URSA, was based on the lessons obtained. The thick-walled tendon pipes were also developed in this stream with the TLP construction projects. The tendon pipes for AUGER TLP was the first thread, manufactured by UOE process using proprietary TMCP-practiced steel plate with double-submerged arc seam welding (DSAW). The development of tendon pipes for MARS, RAM/POWELL, and URSA TLP's went on stream. Although the steel grade or wall thickness was increased more than for AUGER tendons, its excellent weldability with low carbon equivalent had to be maintained in order to keep the fabrication cost equivalent to the application of no-preheat easy welding methods. From these points of view, the same control ranges in chemical compositions were applied for all grades and thicknesses but with some modification in the TMCP parameters and reinforcement in the UOE press machine for higher grade and heavier wall thickness. The evaluation test results and production history show the superb weldability and excellent fracture toughness for every tendon pipe and within tight production tolerance. This also enabled the rapid consecutive construction TLP's in the Gulf of Mexico setting world records. For the success of all these TLP construction projects were a result of the concentrated efforts of TLP design engineers, construction fabrication contractor, and the steel maker.
- North America > United States (1.00)
- North America > Mexico (1.00)
- Materials > Metals & Mining > Steel (1.00)
- Energy > Oil & Gas (1.00)
The current state-of-the-practice in the global performance design verification of tension leg platforms (TLP) relies on conventional short-term response analysis techniques to estimate the extreme platform responses during a prescribed design storm environment (e.g. a 100 year hurricane) with collinear wind, waves and current conditions. However, the TLP responses are sensitive to non-aligned wind, wave and current, which may result in significant variations in extreme airgap (minimum under deck wave clearance) and extreme tendon tensions. In the Gulf of Mexico such conditions can occur during the passage of the eye of a hurricane. Their effect on the global performance of TLP's can be evaluated by investigating the long-term response characteristics. The paper discusses a simple and efficient long-term response analysis method, which can be used to derive consistent design criteria and can be readily incorporated in the design process. The method is applied to TLP in deep water. The 100 year long-term extreme responses are compared with the short-term 100 year hurricane design estimates. Moreover, for a given storm at a particular site, the temporal variations of extreme airgap and tendon tension are explored to provide enhanced insight into the sensitivity of TLP responses to varying wind, waves and current. INTRODUCTION Some extreme responses (e.g. minimum airgap and tendon tension) of tension leg platforms are sensitive to non-aligned wind. waves and current conditions as discussed, for example, by Schott et al (1994). The global response design verification often relies on conventional short-term response analysis techniques to estimate the extreme platform responses in an extreme design storm event (e.g. 100 year hurricane) with collinear wind. waves and current, see API (1987). In the Gulf of Mexico such non-collinear conditions are often associated with the passage of a hurricane. Their combined effect on global platform responses may be assessed by means of a proper long-term response analysis.
We present a model of natural gas hydrate occurrence that incorporates capillary effects arising from the co-existence of liquid water, gaseous hydrocarbons and solid hydrate phases in porous media. Based on a review of recent gas hydrate observations and on our model, the maximum amount of gas hydrates residing in sediments above a bottom simulating reflector (BSR) mapped on the Niger Delta front is suspected to be only 4% by volume. The accompanying free gas volume in sediments below the BSR is suspected to be only about 6% by volume. Because these resources are most probably occurring inhomogeneously and finely dispersed in the sediments, there is currently no commercial potential for recovering and exploiting this trapped energy source. INTRODUCTION A vast reservoir of methane is undoubtedly trapped in the form of natural gas hydrates residing in submarine sediments of the continental margins (Kvenvolden, 1993). Gas hydrates recovered from beneath the sea floor display a wide range of growth habits and tend to be patchily distributed within the host sediment (Booth et al., 1996a). Even though there is a very extensive zone of potential stability in the subsurface, the occurrence is evidently limited either by the availability of sufficient quantities of guest gases or the in-situ availability of liquid water (Clennell et al., 1995). Little attention has so far been paid to the distribution of hydrate on a small scale, or to the role played by the host sediment physical properties on the stability and habitat of these minerals. We have developed a model incorporating capillary effects arising from the co-existence of liquid water, gaseous hydrocarbons, and solid hydrate phases in porous media.
- North America > United States (1.00)
- Europe (1.00)
- Africa > Niger (1.00)
- Africa > Nigeria > Niger Delta (0.62)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- (2 more...)
The amount of natural gas within the gas hydrate accumulations of the world is believed to greatly exceed the volume of known conventional natural gas reserves. The hydrocarbon production history of the Russian Messoyakha field, located in the West Siberian Basin, has been used as evidence that gas hydrates are an immediate source of natural gas that can be produced by conventional means. Re-examination of available geologic, geochemical, and hydrocarbon production data suggests, however, that gas hydrates may not have contributed to gas production in the Messoyakha field. More field and laboratory studies are needed to assess the historical contribution of gas hydrate production in the Messoyakha field. INTRODUCTION The Messoyakha gas field in the northern part of the West Siberian Basin is often used as an example of a hydrocarbon accumulation from which gas has been produced from in-situ natural gas hydrates. Production data and other pertinent geologic information have been used to document the presence of gas hydrates in the Messoyakha field (Makogon and others, 1972; Makogon, 1981, 1988; Cherskiy and others, 1985; Krason and Ciesnik, 1985; Krason and Finley, 1993). It has also been suggested that the production history of the Messoyakha field demonstrates that gas hydrates are an immediate producible source of natural gas and that production can be started and maintained by conventional methods. Recently, however, several studies suggest that gas hydrates may not be contributing to gas production in the Messoyakha field and that the potential resource significance of gas hydrates may have been overestimated (Verkhovsky and others, 1988; Ginsburg and others, 1990; Ginsburg, 1993). In this paper we re-examine the evidence for gas hydrates in the Messoyakha field and critically review the available geologic data in order to determine if gas hydrates have contributed gas production in the Messoyakha field. This paper begins with a technical review of gas hydrate physical properties and description of known gas hydrate occurrences, which is followed by a description of the geologic setting of the Messoyakha field.
- Geology > Geological Subdiscipline (1.00)
- Geology > Sedimentary Basin > Cratonic Basin (0.82)
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.47)
- North America > United States > Oregon > Washington > North Pacific Ocean > Cascadia Basin (0.99)
- North America > United States > Oregon > North Pacific Ocean > North Pacific Ocean > Cascadia Basin (0.99)
- North America > United States > California > Eel River Basin (0.99)
- (6 more...)