Nugget Formation Research Articles

Os solubility in silicate melts: New efforts and results

New experimental results are reported on the partitioning of Os between Ni 94 Os 6 (at) alloys and silicate melt at 1400 °C at one atmosphere total pressure and oxygen fugacities ranging from 10 -6 to 10 -8 atm. Specially designed experiments allowed us to avoid nugget formation, which was responsible for the anomalously high Os solubilities reported by Borisov and Palme (1998). Experimental glasses were analyzed by instrumental neutron activation analysis and by isotope dilution analysis. Results reveal a strong dependence of Os solubility on f O₂ , with Os contents decreasing from about 100 ppb to about 5 ppb as f O₂ decreases. The slope of log (Os solubility) vs. log f O₂ implies that Os 3+ is the dominant Os valence state in silicate melts. The relative geochemical behavior of Os and Pt is also compared. Results suggest that Pt is more siderophile, and may also be more chalcophile than Os under the conditions considered.

Finite element analysis of electrode wear mechanisms: face extrusion and pitting effects

Resistance spot welding is one of the major Joining methods widely used in automotive body fabrication and assembly. Electrode wear has been a major concern in resistance spot welding of galvanised steel and in this paper advanced finite element techniques were used to simulate the thermomechanical interactions between the electrode and the workpiece during welding. First, the coupled electric–thermal–mechanical process associated with nugget formation was studied. The cumulative effects on electrode face deformation were then simulated over a large number of welds. Electrode face pitting effects were also examined. It was found that welding process parameters, such as holding time and pressure trace, played a key role in electrode face extrusion. Any pitting on the electrode tended to accelerate the face extrusion process.

Finite element analysis of electrode wear mechanisms: face extrusion and pitting effects

Resistance spot welding is one of the major Joining methods widely used in automotive body fabrication and assembly. Electrode wear has been a major concern in resistance spot welding of galvanised steel and in this paper advanced finite element techniques were used to simulate the thermomechanical interactions between the electrode and the workpiece during welding. First, the coupled electric–thermal–mechanical process associated with nugget formation was studied. The cumulative effects on electrode face deformation were then simulated over a large number of welds. Electrode face pitting effects were also examined. It was found that welding process parameters, such as holding time and pressure trace, played a key role in electrode face extrusion. Any pitting on the electrode tended to accelerate the face extrusion process.

Experimental determination of the solubility of platinum in silicate melts

We report here new experimental results on the solubility of Pt in silicate melts at one atmosphere total pressure. Experiments were made with two different melt compositions: an anorthitediopside eutectic and a CaO-free system (3SiO2·MgO·Al2O3, by weight). Oxygen fugacities ranged from pure oxygen to 10−8 atm and temperatures from 1300 to 1560°C. Glass samples were analysed after the experiments by instrumental neutron activation analysis (INAA). In experiments with An-Di melts, isotopically enriched 40Ca (and correspondingly depleted 46Ca) was used to reduce the background from 47Sc produced by neutron activation of 46Ca. In this way, the interference was reduced by a factor of 500, allowing the determination of Pt in glass samples by INAA down to a concentration of about 50 ppb.Over five orders of magnitude in oxygen fugacity, from pure oxygen to an fO2 of 10−5 atm, a systematic decrease of the Pt solubility with decreasing fO2 was observed. The slope of the log (Pt solubility) vs. log fO2 correlation suggests a formal valence of +2 for Pt in the silicate melt, independent of temperature. The solubility in the CaO-free melt is about one-fourth of an order of magnitude lower than for the An-Di melt. At oxygen fugacities below 10−5 atm, results show a large scatter. We suspect that formation of Pt nuggests leads to very inhomogeneous distribution of Pt in the melt. A literature survey shows large variations in Pt solubilities determined by various authors. These discrepancies primarily result from the formation of Pt nuggets. A new mechanism of PGE nugget formation is suggested.The formation of PtFe alloys predicted to occur in terrestrial magmatic melts may be important for fractionating Pt from other noble metals.

亜鉛めっき鋼板のスポット溶接におけるナゲット形成要因の影響

亜鉛めっき鋼板のスポット溶接におけるナゲット形成要因の影響

Study of nugget formation in spot welding of galvanised steel sheet

Study of nugget formation in spot welding of galvanised steel sheet

The solubility of iridium in silicate melts: New data from experiments with Ir 10Pt 90 alloys

Solubilities of Ir in silicate melts of anorthite-diopside eutectic composition were determined by equilibrating IrPt-loops with silicates at a wide range of oxygen fugacities, from air to about 1.7 log units below the iron-wdstite buffer (IW-1.7) at 1300 and 1480°C. Instead of pure Ir metal, Ir 10Pt 90-alloys were used to avoid formation of tiny Ir nuggets in the silicate glass. Although nugget formation was less severe than in experiments with pure Ir metal, some samples were still contaminated as indicated by sporadically high Ir contents. These samples were subdivided and the separates were analysed again. Samples with high Ir were eliminated. The procedure was repeated several times until compositional uniformity of subsamples was achieved. In a log (Ir solubility) vs. log (F O 2 )-diagram the most reliable data plot along a line with a slope of about 1 4 suggesting Ir 1+ as the formal Ir species in the melt, similar to earlier findings for Pd. The Ir solubility was found to be temperature independent within the range of temperatures used in the present experiments. The results with Ir 10Pt 90-alloys were recalculated to solubilities for pure Ir metal. These solubilities are significantly lower than earlier data (e.g., 1.52 ppb at IW-1 and 1478°C). As a result, calculated metal/silicate melt partition coefficients are extremely high (10 8−10 12 at an oxygen fugacity corresponding to IW-2). Because of the uncertainty introduced by the presence of Ir nuggets it cannot be completely excluded that some of the solubility data are upper limits only. This would, however, only increase Ir metal/silicate partition coefficients and thus make arguments against a global core-mantle equilibrium stronger.

Structural Geology of the Circle Ridge Oil Field, Fremont County, Wyoming

Abstract The Circle Ridge Oilfield is located about 60 miles northwest of Riverton, Wyoming, in the Wind River Basin. It was discovered in 1923, and has produced over 28 MMBO from five reservoirs—the Phosphoria, Tensleep, Amsden, Darwin, and Madison. The average surface elevation is 7200 feet above sea level, and the depth of oil production ranges from 300 feet to 1500 feet below the surface. There are over 200 wells in the field. Some of the reservoirs have been on waterflood since 1979; there is an active water drive in others. Waterflood modifications resulting from the present study have so far increased production from about 1475 BOPD to over 1700 BOPD. Circle Ridge is a well expressed doubly plunging surface anticline with exposed section from the Upper Cretaceous Mowry to the Permian Phosphoria Formations. This provides a rare opportunity to integrate surface and subsurface geology in an attempt to obtain a 3D view of a Rocky Mountain foreland structure. As the only pre-existing surface geologic map of the area was published in 1944 at a scale of 1:48000, the author re-mapped the surface geology at the more detailed scale of 1:6000. Much more extensive faulting was recognized, as well as several areas of small scale accomodation folding. In addition, the presence of an erosional remnant of the Jurassic Nugget Formation was discovered. Twenty-two stratigraphic cross sections tie together the extensive well control, and three balanced structural cross sections were constructed and restored to the pre-deformation state. The southwest flank of the structure is overturned, resulting in a complex structural setting. Seismic data are nearly unusable, since the steep to vertical dips are not imaged. Five thrust faults can be recognized in the subsurface, which compartmentalize the reservoirs into six distinct blocks. These blocks are isolated for fluid communication. Understanding the subsurface structural complexity has identified numerous examples of injection into reservoir blocks with no open producers, producing wells in a block with no injectors, and even isolated blocks with reserves which have never been tapped by a producing well. Ongoing efforts to remedy these problems are resulting in increased production rates (by 15%) and reduced injection (by 75%).

集束探触子による薄鋼板抵抗スポット溶接部の超音波試験

It is generally impossible to non-destructively inspect spot welds of thin materials by the conventional normal beam technique of ultrasonic testing, because surface and flaw echoes appear so near together on the cathode-ray tube that these echoes can not be distinguished from each other. In this paper, the nugget formation in resistance spot welding of two-plate lap joints of 0.5 mm thick mild steel sheet is examined micrographically, and an improved technique of ultrasonic testing with an immersion-type focusing probe is tried to evaluate the welds. As a result of this study, the welding variables to produce sound fusion or solid-state welds without expulsion during welding process are determined. In the present ultrasonic technique under such a water distance, that the focus of ultrasonic beam locates beneath the weldment, the echoes from back reflection within the weld region and from faying surface reflection within the nonwelded region converge by multiple reflection, and the echo peak appears with an observable delay behind the front surface echo on the A-scan display. By this process, the back and interface echoes can be detected on the scanning inspection too. The scanning graph of the echo height of back and interface reflections versus probe location for each weld mostly records a composite pattern of protrusion and depression from the level of interface echo due to convergence of the back echo and scattering of wave by the indentation of surface respectively. The C-scan display drawn from these scanning graphs indicates shape of the weld region and data corresponding to the indentation.

Presence and Control of Evaporite Top Seals on Occurrence and Distribution of Hydrocarbon Traps: Main Fairway, Central Overthrust Belt, Wyoming and Utah: ABSTRACT

In the Central Overthrust belt fairway, there are 18 known productive formations ranging from Cambrian to Cretaceous in age. Four units - the Ordovician Big Horn formation, Mississippian Mission Canyon formation, Jurassic Nugget formation, and Jurassic Twin Creek Formation - account for 99% of a reported 1.4 billion bbl of oil estimated recoverable reserves discovered to date. A critical factor necessary for significant hydrocarbon accumulations is the presence of effective evaporite seals above these reservoirs. Major accumulations exist in anticlines associated with Paleozoic or Jurassic cutoffs in the hanging wall of the Absaroka thrust with recognized source rocks occurring in the Cretaceous footwall section. Vertical migration is required to source the overlying reservoirs. Migration pathways are via hanging wall cutoffs of these reservoirs or through fractures in the cores of the structures. Hanging wall reservoirs either lacking top seals or having top seals disrupted by extensive fracturing due to folding or faulting, permit vertical migration into higher, more effectively sealed reservoirs. In the Overthrust producing fairway, anhydrites of the Mission Canyon formation and Gypsum Spring Member of the Twin Creek formation as well as the Jurassic Preuss salt are the three effective seal units. Analysis of Overthrust belt traps suggestsmore » that the presence and ductile nature of these evaporite seals are important controlling factors for the significant hydrocarbon accumulations in this highly deformed terrain.« less

Eight-Well Interference Test in the Anschutz Ranch East Field

Summary In many new fields, it is necessary to plan for secondary recovery methods before the field is fully developed or extensive reservoir data have been obtained. Shortly after discovery of the Anschutz Ranch East field, the working-interest owners recognized that planning for an improved recovery program should begin as soon as possible. Knowledge regarding the degree of communication in the reservoir, the magnitude of any directional permeability trend, and the interwell reservoir properties would be needed to select a suitable reservoir management method. A large-scale interference test was chosen as a way to provide part of this information during the early stages of development. This paper describes how the test was planned and executed and includes some of the problems that were encountered during the test performance and interpretation. The results obtained from the test confirmed the geological interpretation of a directional formation flow capacity and indicated that the Nugget formation is at least partially anisotropic.

Resistance spot welding of galvanized steel: Part II. Mechanisms of spot weld nugget formation

Dynamic inspection monitoring of the weld current, voltage, resistance, electrode displacement, and force was performed in conjunction with a detailed study of the effects of material variations and weld process parameter modifications on resistance spot welding of coated and uncoated steels. In order to determine the mechanisms of weld nugget formation and growth, scanning electron microscopy photos were taken of the developing nugget. These physical changes were then related to the dynamic inspection curves and the welding current lobe. The effects of material variations and weld process modifications, the results of which were presented in Part I, can be explained through an understanding of these mechanisms.

An Analysis of the Transient Nugget Formation in Resistance Spot Welds

An analytical model is presented to describe the transient nugget growth in resistance spot welds. Since an exact analysis of this model is difficult, due to complexities arising from the interaction of heat and electric current flow, and from the melting of the weldment, an approximate solution is proposed by employing the integral method and some previous results obtained by the authors (13). With the aid of this analysis a simplified nugget growth equation is derived, which can be effectively used for the design of an adequate on-line feedback control algorithm. To verify the validity of this model equation, the computed results are compared with those experimentally obtained for the case of welding of mild steels. The comparison shows that the transient nugget behaviour is well predictable by the proposed model for the welding conditions in this simulation study.

Crystalline gold in soil and the problem of supergene nugget formation: Freezing and exclusion as genetic mechanisms

Many of the world's richest gold placer deposits now occur in cold regions despite differences in their climatic history. It therefore seems possible that there may be some fundamental connection between freezing climates and the local chemical behavior of gold in the weathering cycle. This hypothesis, along with the problematical occurrence of gold as euhedral crystals in arctic gravel and soil placers, has led me to review low temperature phenomena that may bear on the geochemistry of gold. Several effects which may influence the weathering of natural gold-bearing rocks, the chemical complexation of gold, and its subsequent mobility and deposition appear to be strongly connected with freeze action. The exclusion of dissolved solutes, solute gases, and particles from ice, subjects rock and soil minerals to increased corrosion from thin, unfrozen, adsorbed water films which remain at particle surfaces throughout the freezing of rocks and soils. The preferential exclusion of cations (over anions) from growing ice crystals creates charge separations and measurable current flow across waterice phase boundaries in freezing soil — a phenomenon which leads to troublesome seasonal electrolytic corrosion of pipelines buried in soil; this phenomenon may also favor the dissolution of normally insoluble metals such as gold during geologic time periods. The ice-induced accumulation of clays, organic acids, bacteria, and other organic matter at mineral surfaces may also speed chemical attack by providing a nearby sink of alternate cation-binding sites and hence rapid removal of liberated cations from solution. The latter mechanism may be operative in both the dissolution and redeposition of gold. These physical, chemical, and electrical effects are favorable to the dissolution of rocks (in addition to frost shattering) and to the dissolution, mobilization, and redeposition of gold and other noble metals and must therefore contribute significantly to the behavior of gold at low temperatures. The occurrence of large numbers of gold placer deposits in northern Canada, Alaska, and Siberia may thus be due in part to the low temperatures common to these regions.

Nugget formation reservoir characteristics affecting production in the overthrust belt of southwestern Wyoming : Lindquist, S J J Pet Technol, V35, N8, July 1983, P1355–1365

The Jurassic-Triassic age Nugget sandstone of the southwestern Wyoming Overthrust Belt is a texturally heterogeneous reservoir with anisotropic directional properties which have been inherited from the depositional environment, modified by diagenesis, and finally overprinted by tectonism. Predominantly eolian processes deposited crossbedded and horizontally-bedded, very fine-grained to coarse-grained sand in dunes, interdunes and associated environments. Original reservoir quality has been somewhat modified by compaction, cementation, dissolution, clay mineralization, and precipitation of hydrocarbon resins. Low-permeability, gougefilled and carbonate-filled fractures potentially restrict hydrocarbon distribution and affect producibility; whereas discontinuous, open fractures enhance permeability in some intervals. Contrast in permeability between dune and interdune intervals ranges over four to five orders of magnitude. Dune and interdune deposits are locally correlatable with the aid of core, conventional log, and stratigraphic dipmeter data. Stratigraphic correlations can then be utilized to model the lateral and vertical extent of directional properties in the reservoir.

Nugget Formation Reservoir Characteristics Affecting Production in the Overthrust Belt of Southwestern Wyoming

Lindquist, Sandra J., Amoco Production Co. Summary The Jurassic/Triassic Age Nugget sandstone of the south western Wyoming over thrust belt is a texturally heterogeneous reservoir with anisotropic properties that have been inherited primarily from the depositional environment but also have been modified by diagenesis and overprinted by tectonism. Predominantly eolian processes deposited cross bedded, low-angle to horizontally bedded and rippled, very- fine- to coarse-grained sand in dunes, interdune areas, and associated environments. Original reservoir quality has been somewhat modified by compaction, cementation, dissolution, clay mineralization, and the precipitation or emplacement of hydrocarbon asphaltenes or residues. Low-permeability gouge- and carbonate-filled fractures potentially restrict hydrocarbon distribution and negatively affect producibility whereas discontinuous open fractures enhance permeability in some intervals. Contrast in air permeability between dune and inter dune deposits ranges over four to five orders of magnitude. Dune and inter dune intervals are correlatable locally with the aid of core log, conventional log, and stratigraphic dipmeter data. Stratigraphic correlations then can be utilized to model the lateral and vertical extent of directional properties in the reservoir. Introduction A large proportion of the sizable hydrocarbon reserves in the Utah/Wyoming over thrust belt are within the Jurassic/Triassic Age Nugget formation. Upper Nugget data were obtained from three fields in Uinta County, southwest Wyoming-Clear Creek, East Painter, and Glass cock Hollow-all of which are closed anticlinal structures on the upper plate of the Absaroka thrust (Fig. 1). Nugget pay fluids are probable retrograde gas condensates and volatile oils. In the producing trend, the Nugget sandstone is primarily a clastic eolian deposit ranging (north to primarily a clastic eolian deposit ranging (north to south) from 800 to greater than 1,000 ft (250 to greater than 300 m) in thickness. It probably is conformable with the underlying Triassic Ankareh formation and certainly unconformable with the overlying Jurassic Twin Creek formation. Lithology is predominantly sandstone, with some siltstone. Siltier lithologies are more abundant toward the base of the formation, concurrent with probable increased influence of moisture, water tables, and/or water processes in the depositional environment. Many eolian sandstone reservoirs mistakenly have been considered homogeneous from a reservoir performance standpoint because the importance of subtle, facies-related performance standpoint because the importance of subtle, facies-related controls on reservoir properties within these thick sandstone sequences has been overlooked. Textural heterogeneity results from bedding variations in grain size and sorting, which are directly related to the geometry of eolian facies. Within the Nugget formation, these primary depositional heterogeneities are amplified by diagenesis and further modified by tectonic stresses that folded and faulted the region. JPT p. 1355

めっき鋼板のスポット溶接性

This report is concerned with the weldability, especially the characteristic of the nugget formation in the spot welding of metal plated steel. The factors which determine the characteristic of the nugget formation are as follows, i) the melting point of plated material, ii) the surface condition of plated material and base material.In case of one side plated steel, the influence of the melting point of plated material on the characteristic of the nugget formation depends upon the combination of the plated film; that is, the plated sides face to face or the plated sides face with electrodes. For instance, in case of the plated sides face with electrodes, the plated film with 800°C melting point doesn't melt during welding because electrode is cooled by water. In case of the plated sides face to face, the same film melts because interface is the nugget formation area. As a result, the current density during welding depends upon the combination of the plated film.In case of the both side plated steel, the nugget formation is more difficult than that in one side plated steel.In addition, nugget formation is also influenced by the surface condition of the plated material. In case of the base material, the same tendency is obtained. This surface condition means the amount of oxides on the surface of the plated material or the base material. For instance, the increasing of the amount of oxides means the increase of the resistivity, and thus current path is restricted. As a result, the nugget is easily formed.

Real-time control of nugget formation in spot welds

In the mass production of resistance spot welds for commercial use, several uncontrollable variables tend to produce welds of varying quality. We describe a microprocessing technique which is used with an infrared thermal sensing method to ensure weld uniformity. An optical fiber bundle “pipes” infrared radiation from a heated zone near the weld. A detection system provides a thermal signature of this zone, which reflects the progress of the heating inside the weld. A “standard” weld is made by trial and error, its thermal signature to serve as a model for all later welds of the same type. By controlling the welding-machine power in real time, the microprocessor ensure that all such welds will have the same thermal signature and, thus, the same quality.

Planning and Progress on Drilling a Record-Depth Well in the Rocky Mountains

Introduction Rainbow Resources Inc., as operator for the Pacific Creek Deep Unit, has drilled a record-depth well in the Rocky Mountains. The Pacific Creek structure, which was defined by seismic techniques, is about 200 miles (322 km) southwest of Casper, WY, and 60 miles (97 km) north of Rock Springs, WY.The well was spudded March 14, 1978, and breached a total depth of 25,764 ft (7853 m) on May 9, 1979. This surpassed the previous depth record of 23,081 ft (7035 m) held by American Quasar Petroleum Co. in their Sellers Draw Unit 2, Well 1, in Petroleum Co. in their Sellers Draw Unit 2, Well 1, in Park County, WY. This paper discusses the planning Park County, WY. This paper discusses the planning for this record-depth well including the casing design, mud program, cementing of the deep strings, and drilling progress and techniques used to total depth. Geology and Structure Fig. 1 is a generalized columnar section of the Green River basin. Superior Oil Co. originally drilled this structure to 20,521 ft (6255 m) in 1949 and held the world's depth record until 1952. Terra Resources Inc. drilled a 13,500-ft (41 15-m) test on the structure in 1974. The Superior well bottomed in the top of the Frontier formation, and Terra bottomed in the Rock Springs formation. This left all the possible productive formations from the Frontier to the productive formations from the Frontier to the Madison untested on the Pacific Creek structure. Fig. 2 shows the structure contoured on top of the Nugget formation. As shown, the structure encompasses two large anticlinal closures. The northern structure has not yet been tested. The drilling of Pacific Creek Deep Unit Federal 1-34 has confirmed Pacific Creek Deep Unit Federal 1-34 has confirmed that the Superior and Terra wells were not drilled on the top of the southern structure. Drilling History Drilling Rig Parker Drilling Co.'s Rig 166 was used to drill Parker Drilling Co.'s Rig 166 was used to drill Federal 1-34. It is a diesel-electric rig and has an OIME Inc. Hercules E-3000 drawworks driven by two General Electric Co. 752 [1,000-hp (746-kW)] electric motors. The Lee C. Moore Corp. derrick is 142 X 30 ft (43 X 9 m) with 1.3 million lbm (589 670 kg) static hook load and 800,000 Ibm (362 874 kg) setback capacity. Prime movers consist of three Waukesha 5792's rated at 1,000 hp (746 kW), each of which drive generators that are fed through an SCR system.Mud pumps are two Continental-Emsco Co. FA-1600's. Two 6 X 8 in. (15.24 >< 20.32 cm) and two 5 x 6 in. (12.7 X 15.24 cm) centrifugal pumps are used for mud mixing. The rig is equipped with four 400-bbl (63.59-m3) mud pits and a 100-bbl (15.90-m3) trip tank.Drillpipe is 5-in. (12.7-cm) OD, 19.5-lbm (885-kg) Grades E and 5-135. Drill collars arc 9 1/2-in. JPT

プロジェクション高さのナゲット形成におよぼす影響―プロジェクション溶接現象についての研究 Ｖ

The effect of projection height on nugget formation and growth has been examined using projections with the constant diameter, embossed on a cold rolling sheet of low carbon steel of 1 mm in thickness (SPCC).Using the high projection, the splash during the collapse of projection occurs extensively under the low electrode force, and causes to decrease the tensile shear strength. Using the low projection, the current shunting occurs in the other part near the projection. A rate of occurrence of the current shunting in the weld specimens. is found to increase with the electrode force. This shunting also causes the tensile shear strength to decrease the value near the critical weld current.Under the high electrode force, the bonding part like a torus is formed at the initial period of weld time by using high projections. The tensile shear strength is related to the nugget diameter and the saturated diameter of nugget depends only on the weld current above the critical current as a function of the cold collapsed area and the electrode force.