Airborne Reconnaissance Research Articles

Next Generation High Resolution Airborne Gravity Reconnaissance in Oil Field Exploration

Simple modelling studies of gravity fields using elementary structural forms, oilfield-type structures and geological reconnaissance situations, show that gravity gradiometry technology offers significant petroleum exploration potential. In geological environments of interest, gravity gradients are primarily due to density displacement along (near) vertical boundaries. Gradient images therefore reveal the edges and corners of intrusions, faults, fault intersections, and other such structures often associated with hydrocarbon migration pathways and traps, and/or significant basinal trends. Recent technological advances may make gravity gradiometry an airborne reconnaissance tool capable of providing sensitivity and resolution superior to the best gravimetry available today. This capacity, and the array of gradient components that may be measured, will embellish aspects of the gravity field important to developing regional geologic interpretations. While the potential advantage of gravity gradiometry is greater lateral resolution and sensitivity from a moving platform, the disadvantage is the high sensitivity to topographic and shallow buried irregularities unrelated to the deeper geological structures of interest. A further difficulty is the complex gravity field representations produced for density structures of certain geometries. Buried features that have near surface expressions will be easiest to map. However, full use of gravity gradient technology will require application-focused data processing techniques and new interpretation skills. When the technology becomes commercially available it could find application in preseismic reconnaissance, structural (and possibly stratigraphic) mapping, acreage management and assessment, and in the evolution and mapping of controls on oilfield distribution. The technology could help develop exploration in remote and inaccessible areas, and provide a new look at well-explored regions. An immediate practical implementation appears to be in offshore exploration applications, possibly linked to deepwater exploitation strategies.

Maps and Charts for Visual Air Navigation

Back in 1914, an army surveyor who was carrying out an airborne reconnaissance of potential sites for a new military aerodrome to the west of London is alleged to have held his map upside down – and that, consequently, RAF Northolt was built to the south of what was then called the Great Central Railway Line instead of about a mile to the north-east near where South Ruislip is now. A short apocryphal story perhaps, undoubtedly distorted by the mists of history, but it serves to illustrate the need for aeronautical charts that are designed with the requirements of visual air navigation firmly in mind.

Combined Geological and Surface Geochemical Methods Discovered Agaritta and Brady Creek Fields, Concho County, Texas

From December 1987 to March 1991, 25 prospects in the lower King sand (Upper Pennsylvanian Cisco) play in Concho County, Texas, were tested by several operators. They used combinations of subsurface geology, reconnaissance airborne gas sensing, surface radiometrics, soil magnetic susceptibility, and soil-gas hydrocarbon measurements to define prospects. Six new King sand discoveries or extensions and three deeper Goen discoveries resulted in a 36% exploratory success rate. The total exploration and development cost was approximately $0.67/bbl of proven producing oil reserves. Final locations for the discovery wells on each of the nine successful prospects were selected primarily on the basis of combined subsurface geology and surface geochemical data. As examples, we present information about the discovery of Brady Creek and Agaritta fields. Agaritta field is one of the two largest of the new-field discoveries, with estimated proven producing recoverable reserves of 6 million bbl of oil. Its discovery was based on a combination of (1) regional subsurface geologic projection, (2) airborne hydrocarbon sensing, (3) interstitial soil-gas hydrocarbon data, (4) soil magnetic-susceptibility measurements, and (5) surface potassium and uranium concentrations measured by gamma-ray spectrometry.

Monitoring marine oil pollution using AVHRR data: observations off the coast of Kuwait and Saudi Arabia during January 1991

Abstract In support of a United Nations Environment Programme (UNEP) initiative to assess the impact of marine oil pollution during the conflict over Kuwait, a time series of five Advanced Very High Resolution Radiometer (AVHRR) scenes recorded during January 1991 was analysed. Evidence of the oil slick was observed adjacent to the Mina al Ahmadi oil terminal at Sea Island and close to the Kuwaiti coastline. The identification of the slick was supported by negative results from cloud tests, by the observation that it was warmer than the sea at night and cooler by day, and by its juxtaposition with the known source at Sea Island. The extent of the slick was determined using a thermal threshold, and its trajectory mapped over one week. The slick appeared to extend over 144 km2 on 29 January. This experience suggests that AVHRR can be a useful data source for slick monitoring, particularly when airborne reconnaissance is difficult.

Variable frame rate analysis in the ARM continuous speech recognition system

The application of a simple variable frame rate analysis to the RSRE Airborne Reconnaissance Mission System, a continuous speech recognition system based on phone-level hidden Markov models, is described. Results are presented which show that performance using the variable frame rate technique and triphone models can be better than that obtained using triphone models and full frame rate data. The variable frame rate technique requires considerably less processing time.

The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

Introduction

The advent of aircraft to arctic exploration heralded a new age in North Greenland geology. Exactly 45 years elapsed from the time that Lauge Koch first conducted airborne reconnaissance over eastern North Greenland until the Geological Survey of Greenland (Grønlands Geologiske Undersøgelse, GGU) launched the major regional geological programme, the North Greenland Project (1978-80, 1984-85), which has provided the bulk of the geological information upon which this present volume is based.

Description Of A Dry Film Tactical Laser Beam Recorder

This article describes a laser beam image recorder, which has been designed and fielded for a minimum amount of flexibility for the operator and a maximum amount of control by a remote sensor minimizing the operator duties and requirements. It is also designed for the shelter environment of a tactical and field operation, where the environment is not so benign. With the advent of recent electronic sensors, the capability for data linking information directly to ground with immediate image production is now feasible. The laser beam recorder, which RCA chose to call the Tactical Laser Beam Recorder because of its application, has been designed to meet three general types of applications which are somewhat similar. They are systems with electronic sensors and data link capability, where images can be immediately produced, all in high resolution. The information from an Air Force remote sensor system is directed to the Tactical Laser II earn Recorder which records a latent image, immediately processes the film on a continuous in-line basis, and slides the film automatically across the photo-interpreter's tables. Simultaneously, a tape recorder records the information in the airborne reconnaissance plane in the event that a data link is not maintained,

Automatic tracking improved performance for electro-optical imaging and target acquisition system

Real time electro-optical imaging devices, especially those sensors having standard television format compatibility, have previously been adapted for use in various airborne reconnaissance and fire control systems. Performance requirements of these systems have become particularly stringent in such applications as aircraft-mounted laser designator platforms which are needed to assure a high probability of first-pass target acquisition and engagement. This paper discusses a new generation of microprocessor based digital tracker modules for electro-optical fire control systems.

Applied geology in the discovery of the Spokane Mountain uranium deposit, Washington

In 1975, Western Nuclear, Inc. discovered a blind uranium deposit on the north flank of Spokane Mountain approximately 38 miles (61 km) northwest of Spokane, Washington, after extensive geologic, geophysical, and geochemical programs had been conducted over a five-year period to locate the target area. The Spokane Mountain deposit was discovered in a northeast (Midnite) geophysical trend defined by airborne magnetic and reconnaissance induced polarization surveys. Regional and detailed soil and stream sediment geochemical programs helped narrow the target area. The deposit averages 8 ft (2 m) thick with a grade of 0.25 weight percent eU 3 O 8 *, lies at 150 to 500 ft (46 to 152 m) depths, has a linear trend of N 70 degrees -80 degrees E with a 1,000-ft (305 m) minimum length and 150-ft (46 m) average width. Pitchblende in veinlets or as coatings on fractures is associated with iron sulfides and is located mainly in the unoxidized zone of the graphitic phyllite and chloritic schists of the Precambrian Togo Formation within 100 ft (30 m) of its contact with the intrusive Cretaceous Loon Lake Porphyritic Quartz Monzonite. Preliminary studies indicate the deposit may have been of penesyngenetic(?) and hydrothermal origins with remobilization and late-stage supergene enrichment and is related to regional and local structural features. Although the Spokane Mountain deposit has many of the same characteristics of those of the Midnite mine, it differs in the following features: (1) the mineralized body strikes east-northeast; (2) mapable carbonate beds are absent; (3) mineralization penetrates the quartz monzonite; (4) the ore seems to have some stratigraphic control; (5) most of the uranium mineralization is reduced and below the present water table; and (6) ore grades and thicknesses appear to be lower than that of the Midnite but have wider distribution.

On airborne wave tilt measurements

The relationship between the wave tilt and the local surface impedance for ground waves propagating over a nonhomogeneous surface has been studied. It is shown that a sufficient condition for their equivalence is that the normal (vertical) electric field and the tangential (horizontal) magnetic field be simply related by the intrinsic impedance of free space. The “phase quadrature” airborne method of measuring the imaginary part of the wave tilt is modified to allow measurement of the imaginary part of the surface impedance. A second method for airborne measurement of the wave tilt is also proposed. It uses two orthogonal electric dipoles lying in the plane of incidence, oriented so that errors resulting from small mechanical misalignment are second order. Both the magnitude and imaginary part of the wave tilt can be measured. The system is best suited for airborne reconnaissance mapping of poorly conducting areas, giving basic information concerning the electrical properties and structure of the uppermost few meters of ground. The basic instrumentation is described but the tasks of development and testing remain.

Stereoscopic viewing with PLZT ceramics

Abstract A new electro-optic shutter viewing device is described for use with stereoscopic real-time television and computer-driven CRT display systems. The high speed electronic shutters employ lead lanthanum zirconate titanate (PLZT) ferroelectric ceramics. The PLZT stereoscopic viewer represents significant improvements in performance and physical implementation over existing shutter viewing devices. Operational principles of PLZT stereoscopic viewers examined included CRT viewing geometry, synchronous PLZT shutter operation, and perceived visual effects. Also, pertinent PLZT shutter operating parameters are presented. Numerous application areas are identified, including airborne reconnaissance, remote vehicle control, and analysis of processed computer data.

Radar: Some personal recollections

Wartime radars used by all three Services are briefly described and their contributions towards post-war development indicated. The second part of the paper deals with proximity fuzes, army radars, and airborne reconnaissance equipment.

Aeromagnetic survey over lower palaeozoic andesites in the Parkes-Daroobalgie area N.S.W.

Detailed and reconnaissance airborne magnetic data over a 150 square mile tract in the Parkes area N.S.W. have been compared and used to investigate the magnetic response and distribution of Ordovician volcanics and metasediments which occur in the area.