The Gas-Liquid Cylindrical Cyclone (GLCC ©* ) is a simple, compact and low-cost separator, which provides an economically attractive alternative to conventional gravity-based separators over a wide range of applications. More than 6,500 GLCC © 's have been installed in the field to date around the world over the past 2 decades. The GLCC © inlet section design is a key parameter, which is crucial for its performance and proper operation. The flow behavior in the GLCC © body is highly dependent on the fluid velocities generated at the reduced area nozzle inlet. An earlier study (Kolla et al. [1]) recommended design modifications to the inlet section, based on safety and structural robustness. It is important to ensure that these proposed configuration modifications do not adversely affect the flow behavior at the inlet and the overall performance of the GLCC © . This paper presents a numerical study utilizing specific GLCC © field application working under 3 different case studies representing the flow entering the GLCC, separating light oil, steam flooded wells in Minas, Indonesia. Commercially available Computational Fluid Dynamics (CFD) software is utilized to analyze the hydrodynamics of flow with the proposed modifications of the inlet section for GLCC © field applications.

First oil production from a deep-water oil field is to be achieved by the installation of an initial development system (IDS). Well testing is required for field development and reservoir management. The well testing system requires high-accuracy oil and water rates to provide the data needed for decision analysis in ongoing drilling programs. The well testing system must also be integrated with other platform operations, such as well cleanup after drilling. We introduce here, the concept of a multiphase meter in series with conventional separation technology for improved process control. This feedback control loop configuration is simulated in MATLAB and shown to extend the capabilities of both technologies. The principle of gas volume fraction control in two-phase separator liquid lines is shown to be supplementary to conventional level control systems for performance enhancement of oil field well testing. Concepts demonstrated here can also be easily applied as retrofits to existing separation facilities, which show accuracy or upset problems.

Characterization of formation while drilling continues to be a challenge to the engineers. When a well kicks while drilling, evaluation of pore pressure and the corresponding kill mud density is of critical importance for the safety of the drilling crew and mechanical integrity of the wellbore. Besides the estimation of these parameters, it will be beneficial to estimate the thickness of the kicking formation prior to drilling. This helps to drill safely and carefully through the potentially active kicking formation. In this paper, it is shown how to calculate the thickness of the kicking zone with the limited information available at the time of an oil/gas kick. A method of data analysis (obtained on a kicking well) to estimate the formation thickness of the kicking zone is presented. Illustrative examples including actual field cases are described and analyzed.

Drill string safety valves (DSSVs) are used to prevent blowouts up the drillpipe when unexpected subsurface pressures are encountered in oil and gas drilling. Several case history reviews of well control events have recently shown evidence of poor reliability with DSSVs. Of the problems reported, valve lock-up was most significant, resulting in failure to open or close due to high actuation torque. This paper describes an experimental apparatus and experimental procedures used to quantify the actuating torque of DSSVs under a variety of common operating conditions. Experimentally obtained torque curves are presented for both commercially available and prototype DSSVs, and the results are discussed. Results show the benefit of using special low-torque DSSV designs under certain operating conditions.

The need for alternative fuels to replace liquid petroleum-based fuels has been accelerated in recent years by environmental concerns, concerns of shortage of imported liquid hydrocarbon, and congressional prompting. The fact is accepted that natural gas is the cheapest, most domestically abundant, and cleanest burning of fossil fuels. However, socio-economical and technical handicaps associated with the safety and efficiency of on-board fuel storage inhibit its practical use in vehicles as an alternative fuel. A concept is presented for safely storing fuel at low pressures in the form of hydrates in natural gas vehicles. Experimental results lead to gas storage capacities of 143 to 159 volumes/volume. Vehicle travel range could be up to 204 mi. Controlled decomposition rate of hydrates is possible for feeding an automotive vehicle. Upon sudden pressure decrease in the event of a vehicle accident, the rate of release of hydrocarbons from the hydrates at constant temperature is 2.63 to 12.50 percent per min, slow enough to prevent an explosion or a fireball. A model is given for predicting the rates of gas release from hydrates in a vehicle wreck. A storage tank design is proposed and a process is suggested for forming and decomposing hydrates on-board vehicles. A consistent fuel composition is obtained with hydrates.

Accidental leakages of liquefied propane from high-pressure pipelines may occur despite the use of sophisticated safety equipment and following strict monitoring procedures. Environmental impact of steady and transient leakages were considered from toxicity and flammability viewpoints for two specific scenarios of full pipe ruptures. For each case, calculated mass flow rate, velocity, and temperature of leaking gas were utilized in an EPA-based dispersion model to predict the ground level concentration profiles in the downwind and crosswind directions. For the specific pipeline conditions considered here, the first scenario of a nonjet release (a cloud) produced steady toxic and flammable zones which were about 20 times bigger than those produced in the transient case. The second scenario of a free vertical jet resulted in the formation of a flammable vertical plume, while at ground level it did not produce flammable nor toxic zones. A parametric study of the first scenario confirmed the expected effects of both the gas release time and the atmospheric stability on the size of the dangerous zones. Within the typical range, the wind speed was found to have opposite effects for steady and transient releases. For a steady release, the dangerous zone was wider for slower winds and vice versa for a transient case. Moreover, the size of the dangerous zone was found to be an exponential function of the pipe diameter, while the effect of the initial pipe pressure was insignificant.

The flame flashback limit represents the minimum concentration of the fuel in the stream of homogeneous mixtures of fuel and air at which a flame can propagate upstream against the direction of the flow. Information about these limits is important in the assessment of the safety of operation in situations where a flowing homogeneous fuel-air mixture is present. The present work examines the flame flashback in turbulent homogeneous fuel-air streams with Reynolds number up to 16,000. The flashback limits were established for a number of common gaseous fuels, such as methane, propane, hydrogen, ethylene, and their binary mixtures. Taking into consideration the wide use of low heating value fuels, the effect of the presence of diluents (nitrogen and carbon dioxide) in the fuel on the flashback limit was also investigated. Correlations were proposed to calculate the flashback limits of fuel mixtures and their accuracy is discussed.

Concern over the environment and a potential oil shortage has resulted in an intensified research for alternative fuels for the transportation sector. Two fuels given strong consideration are methanol and compressed natural gas (CNG). This paper is a comprehensive comparative study of methanol and CNG as transportation fuels. The physical properties of methanol and CNG are discussed. The various concerns, such as source and potential fuel supply, safety, toxicity and health hazards, engine performance and emissions, fuel storage, fuel tank and refueling of these alternative fuels are addressed briefly in this paper. We find that no single alternative fuel is best in all categories. The merits and drawbacks of each fuel are tabulated and the vehicle characteristics are compared with gasoline. The study concludes that the neat methanol may be considered as an alternative for passenger cars and CNG may be considered for fleets, light and heavy-duty vehicles as the best near-term solution.

The background knowledge of jackup structures, current methods and procedures for moving and positioning of jackups practiced by the industry and related safety performance (analysis of accident records) are reviewed. Floating stability and motion response are identified as important factors contributing to fatal accidents and weather is found to be, in general, responsible for delays in ocean transit. An improved criterion is suggested for assessing the capability of jackup structures to be moved and positioned safely. This also includes the procedure for selection of towing power in order that a move not be unduly delayed by its mobility to make desired speed.

The 2×981 MW, GE-BWR/6-Mark III Montalto plant was commissioned in the late 1970s by the Italian Public Utility (ENEL), in a context—the “Nuclear Option Plan,” “PUN” 1 —which called for the construction of about 10 nuclear powerplants of various types in several sites across Italy, to cover approximately a 15 percent share of the baseload requirements by the year 2000. For several reasons, both technical and political, the ambitious PUN failed, to a point in which, following a National Conference on Energy Generation Systems and Strategies (Feb. 1987), the citizens were called to decide in a national ballot whether they wanted such a plan to be discontinued or enforced (Nov. 1987). The decision having been to discontinue the PUN (by a 66-percent to 34-percent margin), the problem arose about the destination of the two plants which were under construction: “Trino 2”—midway between Torino (Turin) and Milano (Milan)—and “Montalto”—about 70-km from Roma (Rome). Trino, being in the initial construction stages, was promptly halted. The decision about Montalto (70 percent completed) was a more difficult one. Six alternatives were formally presented to a specially appointed Government Committee: (i) the original nuclear option as envisioned by the PUN; (ii) and (iii) two different reconversions to a gas-fired, combined cycle plant, both of which have been proposed earlier (1986) on the basis of objections to the safety procedures related to the reactor’s operation; (iv) a substitution with a series of 7 modular, gas-fired combined cycle plants (also proposed before the national ballot); (v) a reconversion to a multi-fuel, custom-design steam powerplant (also proposed before the national ballot); (vi) a substitution with four modular units, each standard steam multi-fuel (proposed by the Public Utility as the only valid alternative to the completion of the nuclear plant). This paper presents an independent, comparative analysis of the six alternatives, taking into account both technical and economical issues. On the basis of a cost structure deduced by the Public Utility’s published data, an average cost for the kilowatthour is determined for each of the six options, and compared to that corresponding to the completion of the nuclear plant. The final decision of the Italian Government was made public in June 1988 and is also discussed in this final version of the paper.

Design of cross-country hydrogen pipelines is still uncommon. No industry-accepted codes and standards have been developed to guide the engineering and design of such facilities. A hydrogen pipeline was required to connect a hydrogen purification plant to an anhydrous ammonia production facility. Since no pipeline standards were available, special considerations were required during the design and engineering stages. The small molecular size and reactivity of hydrogen presented unique problems. So do the hydrogen embrittlement/attack/delayed failure phenomena, inverse Joule-Thomson effects and special concerns for commissioning, operation and maintenance. This paper will review world experience, the research, economics, design and safety considerations for hydrogen gas pipelines, as well as the engineering, design and construction methods which were considered necessary by Novacorp International Consulting Inc. for successful completion of the project.

Many of the offshore structures used for oil exploration and exploitation are built of tubular members. The repeated damages in tubular joints have clearly shown that the safety of these structures depends on the safe fatigue design of the joints. The fatigue life of the joint depends very much on the Stress Concentration Factor, SCF. The current practice is to use semi-empirical formulas proposed by various investigators to determine SCF. While some of the formulas give the maximum SCF, others give the SCFs at both the crown and saddle points. The design of fatigue life using the value of maximum SCF is conservative, while using SCFs at crown and saddle is unsafe. The main aim of this paper is to propose a set of formulas for T and Y-joints, which gives not only the magnitude of maximum SCF as in the presently available formulas, but also the variation of SCF around intersection.

Over the recent years, following the very rapid increase in the construction and installation of offshore structures, there has been a considerable growth of interest in the assessment of the probabilities and consequences of collision and damage of such structures. This is reflected by the very large number of papers published over the last 15 yr and the multitude of conferences and meetings held on the subject. Many research programs have been completed or are in progress at many centers and institutions over the world. Accidental loading and damage are now accepted design parameters recommended for consideration in a number of Codes for the design in offshore structures. This paper reviews the state-of-the-art with respect to the probabilities and consequences of collisions and accidental loading in general, and methods for the assessment of the design of steel offshore structures against damage. Most of the available information in the field of offshore collisions and accidental loading emanates from research and experience related to ship safety. However, in this paper emphasis is placed on research activity and available information concerned with offshore structures, such as platforms, semisubmersibles, etc. There is a considerable amount of information available on methods for evaluating the extent and effects on damage of these structures and in estimating their residual strength in the damaged condition. As this is an area currently of major interest in the offshore industry, the paper presents comprehensive information and some new results relating to all major structural components. The state-of-the-art with regards to methods and principles for design against damage is also reviewed and commented upon. The paper concludes with general recommendations and indications of areas where future research could be most usefully directed.

A decision-theoretic approach to the problem of optimizing strategies for the protection of submarine pipelines against ice scour is presented. The model simultaneously considers twinning, deep trenching, and valve segmentation. The opitmal solution is dependent on the uncertainty regarding the frequency of pipeline damage and the associated consequences. Two sources of uncertainty are considered, namely the rate and the depth of scour. Consequences of pipeline damage are represented by their impact on economy and enviornmental safety. An example is presented and the model is used to check the sensitivity of the optimal solution to different input parameters.

In order to investigate the mechanisms and the factors to govern the brittle fracture initiation during the fatigue crack propagation at low temperatures, fracture toughness tests under wide range of loading rates, fatigue tests at low temperatures and fracture toughness tests after having been given pre-loading were performed on steels and weld junctions. The fatigue fracture toughness K fc was estimated as equivalent as the fracture toughness K c under the monotonic tensile loading if they were compared at the same loading rate, since the residual stress due to the cyclic loading was less effective on the brittle fracture initiation. The calculated fatigue life based on Paris’s formula taken into consideration of the crack closure phenomena showed a good one-by-one agreement with the observed fatigue life up to the brittle fracture initiation. Therefore, a design curve was preliminarily drawn to determine the fatigue life at low temperatures.

The stability of jack-up rigs with spud-cans, particularly during the jacking-up and preloading operations, has always been critical in soft soil conditions. In the offshore areas opened to prospection in Cameroon, unconsolidated clays and silts are frequent, and therefore the need to conduct these critical operations with maximum safety is of utmost importance. The monitoring of soil reactions at the spud-cans and of structural loads at the jack-houses enabled jacking operations to be conducted safely, in an area where other rigs previously encountered severe difficulties (capsizing). Data recorded by instrumentation have shown that leg maneuvering with soil penetrations of up 40 m (131 ft) may induce dangerous overloads to the structure. The continuous monitoring and control of soil reaction forces and structural loads during drilling ensured the safety of the rig. For jacking-down, the monitoring of the loads was necesary to control the structural stresses induced by the legs pulling out. To the authors’ knowledge, no similar measurements have been reported in the past.

A reasonably safe reliability approach to a fatigue damage theory can be based on the fact that, in most cases involving the public safety, the designer can accept only very low probabilities of failure by fatigue. Thus we must be almost exclusively concerned with the lower left-hand tails of the associated distribution functions. An approach to damage theory is presented based on this concept and its possible utility reviewed. The Weibull distribution is utilized with three parameters. Suggestions are made as to needed fatigue testing.

A modified method of producing composite-holed, safety-rupture diaphragms is suggested. The influence of the proposed manufactring approach on predoming, bursting pressure, and venting action is examined.

Loop testing of safety devices during operation improves plant performance, reduces downtime of process-dependent rotating equipment, and enhances training of personnel. Designers, manufacturers, staff engineers, and plant personnel are always concerned with improving the efficiency and reliability of process equipment. An unscheduled shutdown caused by breakdowns or accidents involving machinery may result in millions of dollars in unrecoverable losses, because the capacity of rotating equipment has increased to a point where temporary replacements to enable the plants to continue their production are hard, or even impossible, to find. The paper will discuss how accidents may be prevented and outline a systematic approach to checking alarm and trip circuits.

This paper presents a procedure on the finite element method for analyzing a bolted flange connector and compares this method with three traditional approaches. The finite element method considers such effects as flange interface separation, nonlinear and nonconstant flange stiffness, and bolt bending. A comparison of the finite element model with the three traditional methods (each employs a formula for flange stiffness) shows a fairly close correlation for total bolt force versus applied load, but a wide discrepancy for maximum bolt stress versus applied load. The discrepancy between the finite element model analysis and the three other methods (empirical by Weiss and Wallner, truncated conical area by Roetscher, and the classical hollow cylinder approach) can be attributed to the change in flange stiffness during separation and the occurrence of bolt bending. The selected method of analysis was shown to significantly affect the results of a bolt fatigue analysis, but was shown to have little effect on a static analysis. In offshore applications, the environment creates dynamic stresses which make a fatigue analysis essential for long-term safety.