Near‐surface thermal prospecting: Review of processing and Interpretation

Geophysics ◽  
1994 ◽  
Vol 59 (5) ◽  
pp. 744-752 ◽  
Author(s):  
B. E. Khesin ◽  
L. V. Eppelbaum
Keyword(s):  
Oil And Gas ◽  
Thin Sheet ◽  
Correlation Technique ◽  
Seasonal Temperature ◽  
Noise Sources ◽  
Near Surface ◽  
Geological Features ◽  
Characteristic Points ◽  
Arbitrary Magnetization ◽  
Horizontal Circular Cylinder

Temperature measurements at shallow depths (up to 3 m) contain useful information about features of the geological structures in the areas under investigation; however, the noise caused by seasonal temperature variations and terrain relief effects may significantly distort the observed temperature field. Therefore, procedures are developed for the calculation and removal of these noise sources: (a) seasonal variations are first eliminated by a procedure using repeated observations; (b) terrain relief corrections are calculated by a correlation technique, which facilitates the identification of anomalies associated with concealed geological features. Essential similarities between thermal and magnetic prospecting make it possible to apply to thermal prospecting modifications of the rapid methods of characteristic points and tangents developed for magnetic prospecting. These methods are applicable to conditions of inclined relief, arbitrary magnetization polarization), and an unknown level of the normal field. The methods can be used to locate disturbing bodies by their associated temperature anomalies. Interpretation is made possible by approximating bodies by a dipping thin sheet or a horizontal circular cylinder. The interpretation results obtained both on models and polymetallic (Greater Caucasus) and oil and gas (Middle Kura Depression) deposits testify to the accuracy and reliability of these methods. These methods were also used successfully for interpretation of temperature anomaly over underground cavity in Cracov (Poland).

scholarly journals Formation environments and mechanisms of multistage paleokarst of Ordovician carbonates in Southern North China Basin

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Haitao Zhang ◽  
Guangquan Xu ◽  
Mancai Liu ◽  
Minhua Wang
Keyword(s):  
Carbonate Rocks ◽  
North China ◽  
Oil And Gas ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Geochemical Data ◽  
Near Surface ◽  
Oil And Gas Exploration ◽  
Pore Types ◽  
North China Basin

AbstractWith the reduction of oil and gas reserves and the increase of mining difficulty in Northern China, the carbonate rocks in Southern North China Basin are becoming a significant exploration target for carbonate reservoirs. However, the development characteristics, formation stages, formation environments and mechanisms of the carbonate reservoirs in Southern North China Basin are still unclear, which caused the failures of many oil and gas exploration wells. This study focused on addressing this unsolved issue from the Ordovician carbonate paleokarst in the Huai-Fu Basin, which is located in the southeast of Southern North China Basin and one of the key areas for oil and gas exploration. Based on petrology, mineralogy and geochemical data, pore types, distribution characteristics, and formation stages of the Ordovician paleokarst were analyzed. Then, in attempt to define the origins of porosity development, the formation environments and mechanisms were illustrated. The results of this study showed that pore types of the Ordovician carbonates in the Huai-Fu Basin are mainly composed of intragranular pores, intercrystalline (intergranular) pores, dissolution pores (vugs), fractures, channels, and caves, which are usually in fault and fold zones and paleoweathering crust. Furthermore, five stages and five formation environments of the Ordovician paleokarst were identified. Syngenetic karst, eogenetic karst, and paleoweathering crust karst were all developed in a relatively open near-surface environment, and their formations are mainly related to meteoric water dissolution. Mesogenetic karst was developed in a closed buried environment, and its formation is mainly related to the diagenesis of organic matters and thermochemical sulfate reduction in the Permian-Carboniferous strata. Hydrothermal (water) karst was developed in a deep-buried and high-temperature environment, where hydrothermal fluids (waters) migrated upward through structures such as faults and fractures to dissolve carbonate rocks and simultaneously deposited hydrothermal minerals and calcites. Lastly, a paleokarst evolution model, combined with the related porosity evolution processes, nicely revealed the Ordovician carbonate reservoir development. This study provides insights and guidance for further oil and gas exploration in the Southern North China Basin, and also advances our understanding of the genesis of carbonate paleokarst around the world.

The Site Tilt and Lander Transfer Function from the Short-Period Seismometer of InSight on Mars

2021 ◽  
Author(s):  
Alexander E. Stott ◽  
Constantinos Charalambous ◽  
Tristram J. Warren ◽  
William T. Pike ◽  
Robert Myhill ◽  
...  
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Dust Devils ◽  
Total Change ◽  
Noise Sources ◽  
Element Analysis ◽  
Near Surface ◽  
Seismic Experiment ◽  
Short Period ◽  
Sensitivity Changes

ABSTRACT The National Aeronautics and Space Administration InSight mission has deployed the seismic experiment, SEIS, on the surface of Mars, and has recorded a variety of signals including marsquakes and dust devils. This work presents results on the tilt and local noise sources, which provide context to aid interpretation of the observed signals and allow an examination of the near-surface properties. Our analysis uses data recorded by the short-period sensors on the deck, throughout deployment and in the final configuration. We use thermal decorrelation to provide an estimate of the sol-to-sol tilt. This tilt is examined across deployment and over a Martian year. After each modification to the site, the tilt is seen to stabilize over 3–20 sols depending on the action, and the total change in tilt is <0.035°. Long-term tilt over a Martian year is limited to <0.007°. We also investigate the attenuation of lander-induced vibrations between the lander and SEIS. Robotic arm motions provide a known lander source in the 5–9 Hz bandwidth, yielding an amplitude attenuation of lander signals between 100 and 1000 times. The attenuation of wind sensitivity from the deck to ground presents a similar value in the 1.5–9 Hz range, thus favoring a noise dominated by lander vibrations induced by the wind. Wind sensitivities outside this bandwidth exhibit different sensitivity changes, indicating a change in the coupling. The results are interpreted through a finite-element analysis of the regolith with a depth-dependent Young’s modulus. We argue that discrepancies between this model and the observations are due to local compaction beneath the lander legs and/or anelasticity. An estimate for the effective Young’s modulus is obtained as 62–81 MPa, corroborating previous estimates for the top layer duricrust.

scholarly journals ADAPTATION OF THE METHOD OF CHROMATOGRAPHIC ANALYSIS OF GASOLINE TO ACHIEVE PURPOSES OF GEOCHEMICAL PROSPECTING FOR OIL AND GAS

2019 ◽  
pp. 16-23
Author(s):  
A. R. Kurchikov ◽  
R. I. Timshanov ◽  
E. A. Ustimenko
Keyword(s):  
Chromatographic Analysis ◽  
Oil And Gas ◽  
Seismic Survey ◽  
Near Surface ◽  
Petroleum Potential ◽  
Geological Interpretation ◽  
Gasoline Hydrocarbons ◽  
Snow Water ◽  
Individual Hydrocarbons ◽  
Background Content

Geochemical survey is commonly applied during geological exploration to predict petroleum potential of large areas and to estimate the content of traps identified by the results of seismic survey. C1-C6 hydrocarbon concentrations in samples of surface and subsurface air, soil, snow, water, etc. are used as predictive indicators. At the exploration stage the capabilities of geochemical methods can be significantly expanded by comparing the content of gasoline hydrocarbons in samples of formation fluids and in samples of near-surface sediments. The method of chromatographic analysis of gasolines Chromatec Gazolin has been adapted for sample analysis. The taken measures to increase the sensitivity allowed us to register individual hydrocarbons C1-C10 in concentrations up to 0,01 ppb, which is obviously lower than their background content in the oil prospect areas. The revealed patterns are used in the geological interpretation of geochemical distributions based on theoretical ideas about the subvertical migration of hydrocarbons from the reservoir to the surface.

scholarly journals GEOLOGICAL AND GEOPHYSICAL CHARACTERISTICS OF THE ANABAR‐KHATANGA OIL AND GAS PROVINCE; NUMERICAL MODELING OF THE PROCESSES OF FORMATION OF SALT DOMES (SIBERIAN SECTOR OF THE RUSSIAN ARCTICS)

2019 ◽  
Vol 10 (2) ◽  
pp. 459-470
Author(s):  
V. A. Kontorovich ◽  
В. V. Lunev ◽  
V. V. Lapkovsky
Keyword(s):  
Cross Sections ◽  
Oil And Gas ◽  
Numerical Models ◽  
Sedimentary Cover ◽  
Ground Surface ◽  
Geological Structure ◽  
Salt Domes ◽  
Software Packages ◽  
Geological Features ◽  
Gas Bearing

The article discusses the geological structure, oil‐and‐gas‐bearing capacities and salt tectogenesis of the Anabar‐Khatanga saddle located on the Laptev Sea shore. In the study area, the platform sediments are represented by the 14‐45 km thick Neoproterozoic‐Mesozoic sedimentary complexes. The regional cross‐sections show the early and middle Devonian salt‐bearing strata and associated salt domes in the sedimentary cover, which may be indicative of potential hydrocarbon‐containing structures. Diapirs reaching the ground surface can be associated with structures capable of trapping hydrocarbons, and typical anticline structures can occur above the domes buried beneath the sediments. In our study, we used the algorithms and software packages developed by A.A. Trofimuk Institute of Petroleum Geology and Geophysics (IPGG SB RAS). Taking into account the structural geological features of the study area, we conducted numerical simulation of the formation of salt dome structures. According to the numerical models, contrasting domes that reached the ground surface began to form in the early Permian and developed most intensely in the Mesozoic, and the buried diapirs developed mainly in the late Cretaceous and Cenozoic.

scholarly journals Environmental monitoring of soil pollution in urban areas (a case study from Heraklion city, Central Crete, Greece)

2017 ◽  
Vol 47 (2) ◽  
pp. 963
Author(s):  
E. Kokinou ◽  
C. Belonaki ◽  
D. Sakadakis ◽  
K. Sakadaki
Keyword(s):  
Magnetic Susceptibility ◽  
Urban Areas ◽  
Magnetic Measurements ◽  
Topographic Map ◽  
Near Surface ◽  
Thermomagnetic Analysis ◽  
Geological Features ◽  
Digital Elevation ◽  
Elevation Model

Main scope of the present study is to combine topographic and geological data, magnetic susceptibility and thermomagnetic analysis in order to investigate the magnetic properties of the near surface soils in possible polluted urban areas. For this purpose, a power plant with a dense traffic net around it, located in the NW section of Heraklion city in Crete was selected to be the study area. Surface soil samples have been collected from the area under investigation and they were analyzed in order to estimate the spatial distribution of the magnetic susceptibility. Loci of high values of the magnetic susceptibility within the study area gave rise to further proceed to thermomagnetic analysis of the selected samples. GIS techniques were used for mapping the magnetic measurements on the various topographic and geological features of the area. The digital elevation model was created by the digitization of the topographic map contours (1:5000 scale maps). The combination of the above techniques indicate high values of the magnetic susceptibility especially in the northeastern part of the investigated area, possibly related to pollution due to the presence of heavy metals.

Thermal-diffusivity measurements by the converging-thermal-wave technique

1986 ◽  
Vol 64 (9) ◽  
pp. 1172-1177 ◽  
Author(s):  
P. Cielo ◽  
L. A. Utracki ◽  
M. Lamontagne
Keyword(s):  
Thermal Diffusivity ◽  
Thermal Wave ◽  
Infrared Detector ◽  
Thermal Flux ◽  
Thin Sheet ◽  
High Amplitude ◽  
Practical Implementation ◽  
Noise Sources ◽  
Wave Technique ◽  
Effect Of Surface

A converging-thermal-wave technique is described for the measurement of thermal diffusivity in bulk or thin-sheet materials. An annular-shaped area is heated by a pulsed laser beam focused on the material's surface through a combination of spherical and conical lenses, and the surface temperature is monitored by an infrared detector focused on the center of the annulus. The converging action of the thermal flux results in a high amplitude of the detected signal with little overheating of the irradiated material. An analysis of such a technique is presented, as well as some experimental results obtained on heterogeneous materials. Several aspects relevant to the practical implementation of such a technique in an industrial environment, such as the effect of surface losses and different noise sources, are discussed.

Southern Hemisphere Continental Temperature Responses to Major Volcanic Eruptions Since 1883 in CMIP5 Models

2021 ◽  
Author(s):  
Pamela J Harvey ◽  
Stefan W Grab
Keyword(s):  
Southern Hemisphere ◽  
Temperature Response ◽  
Volcanic Eruptions ◽  
Lag Time ◽  
Cmip5 Models ◽  
Seasonal Temperature ◽  
Near Surface ◽  
Santa Maria ◽  
Temperature Responses ◽  
Austral Autumn

Abstract Although global and Northern Hemisphere (NH) temperature responses to volcanic forcing have been extensively investigated, knowledge of such responses over Southern Hemisphere (SH) continental regions is still limited. Here we use an ensemble of CMIP5 models to explore SH temperature responses to four major volcanic eruptions: Krakatau (1883), Santa Maria (1902), Agung (1963) and Pinatubo (1991). Focus is on near-surface temperature responses over southern continental landmasses including southern South America (SSA), southern Africa (SAF) and Australia and their seasonal differences. Findings indicate that for all continents, temperature responses were strongest and lasted longest following the Krakatau eruption. Responses in Australia had the shortest lag time, strongest maximum seasonal response, as well as the most significant monthly anomalies. In contrast, SSA records the longest lag time, weakest maximum seasonal temperature response, and lowest number of monthly negative anomalies following these eruptions. In most cases, the strongest single-season response occurred in austral autumn or winter, and the weakest in summer or spring. We tentatively propose that cooler temperature responses are likely caused, at least in part, by the intensification of the westerlies and associated mid-latitude cyclones and anti-cyclones.

Interpretation of 3-D effects in long‐offset transient electromagnetic (LOTEM) soundings in the Münsterland area/Germany

Geophysics ◽  
1992 ◽  
Vol 57 (9) ◽  
pp. 1127-1137 ◽  
Author(s):  
Andreas Hördt ◽  
Vladimir L. Druskin ◽  
Leonid A. Knizhnerman ◽  
Kurt‐Martin Strack
Keyword(s):  
Integral Equation ◽  
Thin Sheet ◽  
Three Dimensional ◽  
Equation Modeling ◽  
Data Sets ◽  
Sign Reversal ◽  
Near Surface ◽  
Transient Electromagnetic ◽  
Long Offset ◽  
Geological Situation

The interpretation of long‐offset transient electromagnetic (LOTEM) data is usually based on layered earth models. Effects of lateral conductivity variations are commonly explained qualitatively, because three‐dimensional (3-D) numerical modeling is not readily available for complex geology. One of the first quantitative 3-D interpretations of LOTEM data is carried out using measurements from the Münsterland basin in northern Germany. In this survey area, four data sets show effects of lateral variations including a sign reversal in the measured voltage curve at one site. This sign reversal is a clear indicator of two‐dimensional (2-D) or 3-D conductivity structure, and can be caused by current channeling in a near‐surface conductive body. Our interpretation strategy involves three different 3-D forward modeling programs. A thin‐sheet integral equation modeling routine used with inversion gives a first guess about the location and strike of the anomaly. A volume integral equation program allows models that may be considered possible geological explanations for the conductivity anomaly. A new finite‐difference algorithm permits modeling of much more complex conductivity structures for simulating a realistic geological situation. The final model has the zone of anomalous conductivity aligned below a creek system at the surface. Since the creeks flow along weak zones in this area, the interpretation seems geologically reasonable. The interpreted model also yields a good fit to the data.

MAPPING EARTH CONDUCTIVITIES USING A MULTIFREQUENCY AIRBORNE ELECTROMAGNETIC SYSTEM

Geophysics ◽  
1978 ◽  
Vol 43 (3) ◽  
pp. 563-575 ◽  
Author(s):  
H. O. Seigel ◽  
D. H. Pitcher
Keyword(s):  
Thin Sheet ◽  
Radar Altimeter ◽  
Electromagnetic System ◽  
Near Surface ◽  
Quantitative Estimates ◽  
Simple Geometry ◽  
Airborne Electromagnetic ◽  
Groundwater Mapping ◽  
Actual Field ◽  
Depth Of Burial

The Tridem vertical coplanar airborne electromagnetic system provides simultaneous in‐phase and quadrature information at frequencies of 500, 2000 and 8000 Hz. The system can map a broad range of earth conductors of simple geometry and provide quantitative estimates of their conductivities and dimensions. Computer programs have been developed to automatically interpret the six channels of Tridem data, plus the output of an accurate radar altimeter, to determine the depth of burial, conductivity and thickness of a near‐surface, flat‐lying conducting horizon. In limiting cases, the interpretation provides the conductance (conductivity‐thickness product) of a thin sheet (ranging from 100 mmhos to 100 mhos) or the conductivity of a homogeneous earth (ranging from 1 mmhos/m to 10 mhos/m). Two actual field examples are presented from Ontario, Canada; one relating to the mapping of overburden conditions (sand, clay and rock, etc) and the other to the mapping of the distribution of a buried lignite deposit. Other areas of potential application of the system to surficial materials would include groundwater mapping, permafrost investigations, and civil engineering studies for roads and pipelines.

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