Vertical Closure Research Articles

Vertical profiles, aerosol microphysics, and optical closure during the Atlantic Stratocumulus Transition Experiment: Measured and modeled column optical properties

During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud‐free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total‐direct‐diffuse radiometer (TDDR) to the change calculated from measured size‐resolved aerosol microphysics and chemistry. Both profiles included a pollution haze layer from Europe, but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined, and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory sootlike core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3‐km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10–77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (±0.07) and 0.157 (±0.034), respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass (inferred) varied from about 5 to 16 m2 g−1 and was primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4 ± 0.7 m2 g−1. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 ± 0.2 m2 g−1. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded estimated measurement uncertainty (12%). This is attributed to inadequate data on the spatial variability of the aerosol field within the descent region, a critical factor in any validation of this type. Both cases demonstrate that surface measurements may be a poor indicator of the characteristics and concentration of the aerosol column.

Anterior abdominal wall closure in bladder exstrophy

Anterior abdominal wall closure without pelvic osteotomy for bladder exstrophy can be very diffecult and more often than not calls for various reconstructive measures. A technique is described that involves bilateral detachment of the rectus abdominis from the pubic ramus, midline vertical closure, and refixation to the pubic rami after medial and caudal advancement. A relaxing fascial incision may be required. This technique has been used in 15 patients and has obviated the need for pelvic osteotomy, thereby decreasing the postoperative morbidity. It has resulted in good cosmetic repair in all patients in addition to the ease of abdominal wall closure. The healing has been remarkably good. This technique is particularly useful in children coming for primary surgery after the neonatal period.

Differential board/backplane optical interconnects for high-speed digital systems. II. Simulation results

For pt.I see ibid., vol.11, no.7, p.1234-49 (1993). The performance of a DC-coupled fully-differential interconnect is analyzed in terms of the deterministic vertical and horizontal eye closure at Gb/s for different optical power levels and extinction ratios in the two complementary arms. Two types of transmitters are investigated, one based on an ideal optical modulator switch (IOMS) and the other based on conventional modulation of two separate lasers. In general, it is found that the timing jitter increases when the imbalance between the power levels in the two arms increases, when the difference between the laser turn-on delay in the two arms increases, and when the receiver and transmitter bandwidth is reduced. To achieve low latency and to accept a maximum power imbalance of 4-5 dB at the receiver, the IOMS and the lasers should be modulated to produce an extinction ratio of at least 10 dB, and the lasers should be biased above threshold. If low latency is not the main concern, an improvement in the maximum tolerable imbalance can be obtained with regular laser modulation by biasing the lasers below threshold. The fitter can be reduced and the maximum tolerable imbalance be increased if faster receivers and transmitters are employed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The implications of linearly varying eddy viscosity for wind-driven current profiles

A major problem in numerical circulation modelling is the specification of vertical turbulence closure. After the simplicity of a constant eddy viscosity, the next step towards reality appears to be an eddy viscosity described by υ = κ u * z where κ is von Karman's constant, u * is a friction velocity, and z is the distance away from the sea surface or bottom. Applied to the “Ekman problem”, this eddy viscosity results in current profiles that have logarithmic boundary layers. The Ekman depth is replaced by a new depth of influence, κu */ f (where f is the Coriolis frequency). If this depth is less than the water depth, the wind-forced current profile does not reach the bottom, and is unaffected by the bottom conditions. For water depths less than the depth of surface influence, currents through the whole water column are sensitive to the value of the bottom roughness. By contrast, changes to the surface roughness only affect currents in a thin layer near the surface. Numerically, resolution of the log-layers at the sea surface and bottom requires the use of special techniques. The log-layers may be described analytically, or the vertical coordinate may be transformed to expand the near-boundary regions. For modelling the mid-water column, away from the log-layers, a constant eddy viscosity with a linear bottom slip condition represents the currents with reasonable accuracy. Appropriate values of the constant eddy viscosity and bottom friction parameter are determined empirically from the shear stress and bottom roughness by formulae that are consistent over a broad parameter range.

Results from Simulated Remote-Handled Transuranic Waste Experiments at the Waste Isolation Pilot Plant (WIPP)

ABSTRACTMulti-year, simulated remote-handled transuranic waste (RH TRU, nonradioactive) experiments are being conducted underground in the Waste Isolation Pilot Plant (WIPP) facility. These experiments involve the near-reference (thermal and geometrical) testing of eight full-size RH TRU test containers emplaced into horizontal, unlined rock salt boreholes. Half of the test emplacements are partially filled with bentonite/silica-sand backfill material. All test containers were electrically heated at about 115 W/each for three years, then raised to about 300 W/each for the remaining time. Each test borehole was instrumented with a selection of remote-reading thermocouples, pressure gages, borehole vertical-closure gages, and vertical and horizontal borehole-diameter closure gages. Each test emplacements was also periodically opened for visual inspections of brine intrusions and any interactions with waste package materials, materials sampling, manual closure measurements, and observations of borehole changes. Effects of heat on borehole closure rates and near-field materials (metals, backfill, rock salt, and intruding brine) interactions were closely monitored as a function of time. This paper summarizes results for the first five years of in situ test operation with supporting instrumentation and laboratory data and interpretations. Some details of RH TRU waste package materials, designs, and assorted underground test observations are also discussed. Based on the results, the tested RH TRU waste packages, materials, and emplacement geometry in unlined salt boreholes appear to be quite adequate for initial WIPP repository-phase operations.

Alleviation of vertical closure in longwall gateroads : Matsui, K Proc MMIJ/IMM Joint Symposium, Today's Technology for the Mining and Metallurgical Industries, Kyoto, 2–4 October 1989P271–277. Publ London: MMIJ/IMM, 1989

Alleviation of vertical closure in longwall gateroads : Matsui, K Proc MMIJ/IMM Joint Symposium, Today's Technology for the Mining and Metallurgical Industries, Kyoto, 2–4 October 1989P271–277. Publ London: MMIJ/IMM, 1989

The Indefatigable Field, Blocks 49/18, 49/19, 49/23, 49/24, UK North Sea

Abstract The Indefatigable Field was discovered in June 1966 by the Amoco Operated Group well 49/18-1. The field is located 55 miles northeast of Great Yarmouth in the central part of the Southern North Sea Basin in water depths of 100 ft. The field lies in Blocks 49/18, 19 and 49/23 and 24. The reservoir section is Lower Permian Rotliegendes sandstones comprising a mixed sequence of aeolian and fluvial sediments at an average depth of 8500 ft subsea. Maximum reservoir thickness is in excess of 420 ft; however, the average pay thickness is of the order of 150 ft. The main reservoir trap is a complexly faulted NW-SE-trending anticlinal horst with a maximum vertical closure of 1300 ft. The field is approximately 17 miles long and 6 miles wide and has an areal extent of some 60 square miles. Recoverable reserves in the Field are estimated to be 4418 BCF of gas. The field is not unitized and is jointly operated by Amoco and Shell.

Geology and reservoir characteristics of Lower Cretaceous Kharaib Formation in Zakum Field, Abu Dhabi, United Arab Emirates

Abstract The Zakum oil field is an east-west plunging anticline, located in offshore Abu Dhabi, UAE. The field was discovered in 1963 by seismic survey, and came on production in 1967 at an initial rate of 50 000 bopd from the Lower Cretaceous carbonate sediments. The Zakum structure is a broad asymmetric anticlinal feature characterized by gentle dips throughout; the steepest dips occur in the north and northeast where the average dip is about 2.5°. The structure is about 45 km long and 28 km wide, and has a vertical closure in excess of 1200 ft. At Zakum field the Lower Cretaceous Thamama Group is a thick shallow-marine carbonate sequence with an average thickness of about 2300 ft, and is divided into four formations: Shuaiba, Kharaib, Lekhwair and Habshan (in descending order). An informal reservoir-oriented classification was set up for this group. It was subdivided into six zones given a numerical notation from top to bottom (Zones I to VI). The Kharaib Formation represent shallowing upward cycles formed in very shallow epicontinental seas. The energy level grades from low-energy subtidal to high-energy setting at or above wave base. It is characterized by dense-argillaceous pyritic bioclastic lime mudstones/wackestones, peloidal-ooidal packstones/grainstones, dolomitic limestones and thin black shale laminae. The reservoir quality of the formation is controlled by vertical and lateral distribution of porosity, permeability and stylolites. The porosities ranges from 5 to 28%, and permeabilities from less than 1 to 100 Md. The influence of initial environment of deposition, diagenesis and petrophysical properties on the reservoir characteristics is evaluated.

Petroleum Geology of Heavy Oil in the Oriente Basin of Ecuador: Exploration and Exploitation Challenge for the 1990s: ABSTRACT

Published Ecuadorian government forecasts suggest that Oriente basin light oil (21-32{degree} API) production may start to decline in the early to mid-1990s. To maintain stabilized production into the next century, heavy oil reserves (10-20{degree} API) will have to be aggressively exploited. The Oriente's undeveloped proven plus probable heavy reserves are substantial and are expected to exceed 0.5 billion bbl. A recent discovery made by Conoc Ecuador Ltd., operator of Block 16 for a group which consists of O.P.I.C., Maxus, Nomeco, Murphy and Canam, is a good model for future exploration and exploitation of heavy oil in the remote eastern regions of the basin. Amo-1 tested a low-relief anticline (less than 100 ft vertical closure) and encountered 10-20{degree} API oil in five Cretaceous sandstone reservoirs (8,000-10,000 ft depth). Cumulative test production was 1,062 BOPD. Subsequent drilling along the trend resulted in three additional discoveries. The Cretaceous sands were transported from the Brazilian shield by the westward flowing proto-Amazon River and were deposited in fluviodeltaic, tidal, and high-energy marginal marine environments. Air permeabilities are high and geometric mean values approaching several darcies. Porosities average 18-22% in generally well-consolidated sands. The heavy oils are the result of mild biodegradation and/or expulsion from amore » thermally immature source. Oil-to-oil correlations suggest that all of the basin oils have the same or similar origin, probably marine calcareous shales of the Cretaceous Napo formation. The Block 16 project will provide a major step toward the strategic exploitation of the Oriente basin's heavy oil reserves, when it comes on stream in the early 1990s.« less

採炭坑道の維持に関する研究 （第２報） 穿孔・発破および機械掘進による坑道の変形挙動の比較

In an attempt to clarify the effectiveness of machine drivage on roadway deformation, field measurements of vertical closure were carried out both in the roadway driven with a roadheader and with drill and blast. A theoretical discussion considering the interaction between support and rock mass was also made.The results show that there is no significant difference in the deformational behaviour of roadway driven by each method. This is related to the deterioration of the surrounding strata by the presence of water and the setting conditions of the support. A suitable support system to the strata conditions should be used to obtain the effectiveness of machine drivage on roadway deformation. However, if the magnitude of deformation of the roadway driven with machine and supported with the traditional system is within an allowable limit, the validity of using machine cutting can be found in the rapid drivage rate leading to the total cost reduction in formation and maintenance of roadway.

The Glabellar Transposition “Banner” Flap

The frontoglabellar skin has long served in reconstruction of certain nasal and canthal defects. The glabellar transposition "banner" flap is relatively simple and efficient. It can be designed either on a curved glabellar line or as a vertical midline closure, depending upon requirements and aesthetic variables.

Shuaiba Reservoir Geological Study, Yibal Field, Oman

The Yibal oil field in west central Oman is a large dome created by deep-seated salt movement. The maximum oil column is 370 ft (112.8 m) and the productive area is about 4.3 x 6.2 mile (7 x 10 km). The structure is complicated by extensive tensional faulting. The main oil accumulation is in the Shuaiba chalk overlain disconformably by the Nahr Umr shale. The Shuaiba reservoir is in pressure communication with the underlying Kharaib formation. It is speculated that early accumulation of oil played a major role in preserving the high porosity and greater crestal reservoir thickness by inhibiting diagenetic processes. This field study provided the reservoir simulation engineer with a viable geological and petrophysical model of the Shuaiba reservoir to aid in understanding observed phenomena.

採炭切羽の接近・通過に伴う風道およびゲート坑道の変形について

A simple and inexpensive method is adopted to measure the gate roadway deformation with advancing longwall coal face in Ikeshima Collieries of Matsushima Coal Mining Co., Ltd.Vertical closure of the gate roadway is much greater than sides closure. It is characterized that vertical closure reaches a certain value at about 100m distance behind longwall face.The effects of strata and mining conditions on the gate roadway deformation are studied by laboratory tests and elastic numerical analysis. It is shown that the deeper the depth of coal seam is and the weaker the strength of the floor rock is, the greater the gate roadway deformation becomes.It is difficult to get an empirical equation to preestimate the gate roadway deformation by statistical treatment of measuring data because of a shortage of the precise data. It becomes clear, however, that relating the results of elastic numerical analysis presented by Everling to measuring data makes it possible to preestimate the gate roadway deformation with a considerable accuracy.

The closure of tidal basins

The closing of tidal basins generally serves a combination of various purposes, such as land reclamation, protection against floods, creation of fresh-water reservoirs, etc. Closure works in tidal areas will change the tidal conditions on the sea side of the closure, while desalination will be the main problem in the enclosed area. A comparison between some closure methods is given. A distinction is made between sudden and gradual closure methods, the latter being subdivided into vertical, horizontal and combined methods. Some attention is paid also to the seabed protection, which is needed in order to reduce the risk of instability of the closure dam during construction. As an illustration of a large-scale closure operation, a case study has been worked out briefly. From a comparison between a vertical and a combined horizontal and vertical closure method, the latter appears to be less appropriate in the case of large-scale closure works.

Sacha Oil Field of Ecuadorian Oriente

The Sacha oil field in the Ecuadorian Oriente was discovered in early 1969. Production began in July 1972, and at the end of 1980 had exceeded 190 million bbl. Drilling through 1980 had resulted in 91 oil wells and 2 dry holes. Estimated original primary recoverable reserves surpass 632 million bbl. The field is on a very low-relief anticline about 17.5 mi (28 km) long and averaging 4 mi (6.5 km) wide. Vertical closure amounts to 200 ft (60 m) and there are 41,000 acres (16,600 ha.) of areal closure on top of the principal reservoir. The Cretaceous sandstones, at drilled depths between 9,300 and 10,100 ft (2,835 and 3,080 m) provide excellent reservoirs. The Hollin Formation, the basal Cretaceous sandstone, is the principal reservoir, having produced 80% of the oil through 1980 and containing about 68% of the original reserves.

Sacha Field of Ecuadorian Oriente: ABSTRACT

The Sacha oil field was discovered in early 1969 about 112 mi (180 km) east-southeast of Quito, Ecuador. It lies in the present-day axial region of the sub-Andean basin which in Ecuador is filled with Upper Silurian to Holocene sediments. Sacha field is on a low-relief, faulted anticline about 17.5 mi (28 km) long. At the principal reservoir there are approximately 41,000 acres (16,400 ha.) under a vertical closure of 200 ft (61 m). Principal reservoirs are sandstones of the Lower Cretaceous Hollin formation and the middle to Upper Cretaceous Napp formation. The Hollin sands, the main reservoir, are marine-fluvial, whereas the Napo sandstones are largely continental deposits. The basal sandstone of the Upper Cretaceous-Paleocene Tena formation is a secondary reservoir. Production from the field commenced in July 1972 and, at the end of September 1979, over 164,000,000 bbl of oil had been produced. Gross recoverable reserves in the field are estimated at 633,784,000 bbl. Through September 1979, 89 wells had been drilled in the field, two of which were dry holes. End_of_Article - Last_Page 687------------

Recent Huge Gas Discoveries in Kangan Area, Iran: ABSTRACT

The Kangan area is located in the Fars Province of Iran and is a part of the Zagros foothills belt. It differs from the northwestern Disful embayment, which holds the main oil reserves of Iran, by its situation on the Fars high which, together with Qatar arch, separated the Mesopotamian basin from the Rub Al Khali basin during Mesozoic times. The discovery in Kangan was made in 1973 by Societe Francaise des Petroles d'Iran which acted as the operator for a European consortium (Elf Aquitaine, AGIP, Hispanoil, Fina, OEMV) in a service contract for National Iranian Oil Co. Since then, several other discoveries have been made in Fars Province in structures such as Pars, Dalan, Mar, Varavi, and Aghar, among which Pars and Nar are presently undergoing development drilling. The gas-bearing zones are in the Lower Triassic to Permian Khuff Formation (Kangan and Dalan Formations according to NIOC nomenclature) constituted mainly of heavily fractured dolomitic and oolitic carbonate rocks of intertidal environment. Thin layers of anhydrite form the caprock. Huge east-west elongate anticlines (up to 80 km long, with vertical closure up to 2,500 m) were folded during late Tertiary and Quaternary movements to form traps, some holding more than 18 Tcf of wet gas. The role of tear faults is important as a cause of possible gas migration. The gas originates either from the organic-rich Permian carbonate rocks or from older Paleozoic source rocks. Most of the traps are full to the spill point, and gas entrapment seems very recent if not in progress. End_of_Article - Last_Page 520------------

PETROLOGICAL AND PETROPHYSICAL STUDY OF PERMIAN ARENITES FOR POTENTIAL SUBSURFACE STORAGE OF NATURAL GAS, SYDNEY BASIN, NEW SOUTH WALES, AUSTRALIA

The expanding natural gas market in New South Wales during the next decades will require guaranteed back-up supplies in the event of insufficient deliverability through the Moomba-Sydney pipeline and/or cut-off of the pipeline. Subsurface storage of natural gas in natural reservoirs near the market area offers one solution for ensuring continuity of supply to this market.A petrological, wireline log, structural and reservoir-engineering study has been conducted of water-bearing arenites of the Permian Nowra Sandstone, Muree Sandstone and Snapper Point Formation in the Sydney Basin. This has resulted in the delineation of seven potential natural gas storage reservoirs near Sydney.The cap-rocks to the seven reservoirs are Permian impermeable arenites, siltstone, claystone and shale beds of the Berry Formation, Mulbring Siltstone, Wandrawandian Siltstone and Snapper Point Formation.Porosity in the Nowra and Muree Sandstone ranges from 5.5 to 12.2 percent and in the Snapper Point Formation from 5.4 to 6.8 per cent. Permeability is estimated to range from 0.47 to 5.00 millidarcies.The structures of these potential reservoirs include both faulted and unfaulted, gently folded anticlines, and an irregular dome. Their areal extent and vertical closure range from 1 to 45 sq km and 20 to 225 respectively.Total potential storage capacity for the seven reservoirs is estimated to be 21.3 x 109m3 of natural gas, and their deliverability potential, based on permeabilities of 1.0 and 5.0 millidarcies, ranges from 0.002 to 0.103 x 106m3 of natural gas per day per well.

Handil Field, East Kalimantan, Indonesia: ABSTRACT

Handil field is located in the swamp area of the present delta of the Mahakam River in East Kalimantan, Indonesia, in the central part of the Tertiary Kutei basin. The anticlinal feature was found by seismic work in 1973, the discovery well being drilled in April 1974. An east-west fault perpendicular to the axis of the anticline (10.5 km long, 4.5 km wide) divides the field into two blocks of equivalent area. Areal closure is 35 sq km. Vertical closure increases with depth through the hydrocarbon-bearing section. Most of the 120 reservoir sands between 500 and 2,900 m are tidal to fluvial delta-plain sediments (middle to late Miocene). Most of them are oil bearing with a gas cap. Their types of deposition can be identified as channel fills, offshore bars, etc. A high pressure zone is encountered below 2,900 m, where deeper prospects remain for investigation. More than 50 significant markers (lignite, carbonate streaks) are used to correlate the sand bodies. Vertically, the field has been divided into six zones corresponding to End_Page 545------------------------------ changes in environmental conditions and/or oil characteristics. Isobath maps show a displacement to the southwest (approximately 2.5 km) of the top of the anticline from deeper horizons to surface. In the upper and shallow zones, hydrocarbons are found in the south block only, divided into smaller blocks by an east-west fault pattern. Daily production is 160,000 bbl. Cumulative production is 125 million STB (October 1978). End_of_Article - Last_Page 546------------

RECENT SEISMIC STUDIES UPGRADE THE PETROLEUM PROSPECTS OF THE TOKO SYNCLINE, GEORGINA BASIN

The Georgina Basin covers an area of 325,000 sq km in the Northern Territory and Queensland. Most of the basin contains less than 500m of Palaeozoic sediments, but the Toko Syncline, in Queensland, contains up to 5000m of Middle Cambrian to Middle Ordovician shallow marine carbonate, sandstone and shale. The syncline is bounded on its western margin by the Toomba-Craigie Fault systemHydrocarbon shows are known within the Middle Cambrian to Middle Ordovician strata and some of the rocks have fair source rock potential. Potential reservoir rocks are vuggy dolostones and sandstone. Ordovician siltstones and shales may provide cap-rocks. The southern, deepest part of the syncline appears to have been protected from flushing. AOD Ethabuka-I well, drilled in the southern part, encountered gas in the Ordovician, but drilling problems prevented penetration of the deeper section.A Bureau of Mineral Resources (BMR) seismic survey in 1977, linked lines shot on earlier surveys, tied to wells and examined the Toomba Fault system. The results show that two previously unidentified reflectors represent the top of Upper Cambrian Georgina Limestone and the base of the Middle Cambrian section. Substantial thickening of Ordovician and slight thinning of Middle and Upper Cambrian strata occurs southeast along the axis of the syncline. Southeast progradation of some Middle Cambrian strata and possible bioherms were observed. The Toomba Fault is a high-angle reverse fault and several possible anticlines are present in the adjacent folded and faulted zone. The two largest ones, the Ethabuka and Mirrica Structures, were partially outlined by Alliance Oil Development (AOD). They are shown to lie within a larger structure which has a minimum vertical closure of 700m over a minimum area of 130 sq km. Possible stratigraphic traps are located on the northeastern flank and along the axis of the syncline.The seismic work has better defined the prospective section and confirmed closure on a large structure. The next step in exploration should be to drill the Mirrica-Ethabuka Structure, where about 1500m of section remains to be tested.