A method for surface estimation of reservoir properties, wherein location of and average earth resistivities above, below, and horizontally adjacent to the subsurface geologic formation are first determined using geological and geophysical data in the vicinity of the subsurface geologic formation. Then dimensions and probing frequency for an electromagnetic source are determined to substantially maximize transmitted vertical and horizontal electric currents at the subsurface geologic formation, using the location and the average earth resistivities. Next, the electromagnetic source is activated at or near surface, approximately centered above the subsurface geologic formation and a plurality of components of electromagnetic response is measured with a receiver array. Geometrical and electrical parameter constraints are determined, using the geological and geophysical data. Finally, the electromagnetic response is processed using the geometrical and electrical parameter constraints to produce inverted vertical and horizontal resistivity depth images. Optionally, the inverted resistivity depth images may be combined with the geological and geophysical data to estimate the reservoir fluid and shaliness properties.

Remote reservoir resistivity mapping

http://directory.umm.ac.id/Data%20Elmu/jurnal/J-a/Journal%20Of%20Applied%20Geophysics/Vol44.Issue2-3.2000/1246.pdf

Geoelectrical investigation of old/abandoned, covered landfill sites in urban areas: model development with a genetic diagnosis approach

A marine seismic exploration method and system comprised of continuous recording, self-contained ocean bottom pods characterized by low profile casings. An external bumper is provided to promote ocean bottom coupling and prevent fishing net entrapment. Pods are tethered together with flexible, non-rigid, non-conducting cable used to control pod deployment. Pods are deployed and retrieved from a boat deck configured to have a storage system and a handling system to attach pods to cable on-the-fly. The storage system is a juke box configuration of slots wherein individual pods are randomly stored in the slots to permit data extraction, charging, testing and synchronizing without opening the pods. A pod may include an inertial navigation system to determine ocean floor location and a rubidium clock for timing. The system includes mathematical gimballing. The cable may include shear couplings designed to automatically shear apart if a certain level of cable tension is reached.

Method and apparatus for seismic data acquisition

This paper presents a tutorial review of electrical and electromagnetic(herein collectively called geoelectromagnetic) methods as applied in the search for natural resources. First, the paper discusses the technical problems and advances in geoelectromagnetic methods in the last decade. A scheme for integrating electrical and electromagnetic depth sounding data is suggested.Then, for natural resources exploration, it focuses on three themes: (1) understandinggeological models of resource targets, their physical properties, and the development of conceptual geoelectromagnetic exploration models, (2) overview of geoelectromagnetic case studies in resourceexploration, and (3) outstanding challenges in exploration. For brevity, model development is restricted to groundwater, geothermal and hydrocarbon resources, metallic ore-bodies (exemplified byvolcanogenic massive sulphides, porphyry coppers, and epithermal and Archaean greenstone belt gold deposits) and diamonds. In the treatment of resource exploration in this paper, the unifying themeis that geochemical processes of weathering and hydrothermal alteration form clayey products that may render natural resource targets directly or indirectly detectable by their resistivity characteristics.Since hydrated clays are an important feature of most resource types and are major causes of low resistivity anomalies in geoelectromagnetic exploration, they may be taken as providing detectable marker horizons or pathfinders and a basis for developing a consistent investigative approachfor natural resources. However, it is recognised that no single resource model or standard approach may be universally applicable. Natural resource systems are inherently 3D and require large numbers of depth soundings at high station densities to image adequately. Thus, developing methodsof increasing the productivity of data acquisition, the development of better 3D software tools and lowering costs are seen as the major challenges facing the use of geoelectromagnetic methods for naturalresource exploration.

https://link.springer.com/content/pdf/10.1023/a:1015052419222.pdf

Geoelectromagnetic exploration for natural resources: models, case studies and challenges

A method for calibrating impedance includes coupling at least first, second, and third electrodes at respective locations to a surface of a body of a subject. A first current passing through the body between the first and second body-surface electrodes is measured, and a second current passing through the body between the first and third body-surface electrodes is measured. From the first and second currents, a contact factor is derived that is indicative of the impedance between at least one of the body-surface electrodes and the surface of the body. Also described are methods for sensing the position of a probe and for detecting tissue contact based on a relation between currents from the probe to body-surface electrodes.

Relative impedance measurement

Method and apparatus for high accuracy simultaneous calibration of electrical measuring systems wherein a calibration signal which has frequency spectra which interleave but do not interfere with the data spectra is injected into the electrical system during data acquisition to simultaneously correct for the response of the particular detection system. In a particular geophysical application, a calibration signal at a source system or receiver system, or both, is injected into each individual system as the data and calibration signals are measured so that an overall system response can be applied to the data signals in order to remove system response effects therefrom.

Method and apparatus for obtaining high accuracy simultaneous calibration of signal measuring systems

A method and apparatus for electromagnetic hydrocarbon exploration which is accomplished by implanting at least two pairs of electrodes into the ground. One pair transmits a signal into the earth, and the other pair receives the signal. With proper processing the polarization and resistivity of the ground can be calculated. The components are arranged in a manner to insure that the electromagnetic coupling can be determined and can be removed from the measurements. Electrode spacing can be varied to focus on the anomalous stratum. If an anomalous stratum is discovered, it is cored to determine the nature of the material creating the anomaly.

Hydrocarbon prospecting method with changing of electrode spacing for the indirect detection of hydrocarbon reservoirs

An apparatus includes a logging tool having electrodes for introducing a current into a downhole formation and for detecting a voltage produced in the formation by the current. The current is provided by a transmitter circuit, and the voltage is received and processed by a receiver circuit including a computer programmed to provide induced polarization and resistivity measurements based on the detected voltage. The electrodes are equidistantly spaced but are adjustable (either on a single logging tool or as between different logging tools) so that various logging runs can be made to obtain different measurements whereby the intrinsic complex resistivity (induced polarization) of formation layers can be suitably resolved. The apparatus also includes a contact resistance measurement circuit for making measurements used by another computer means to determine the contact resistance of each of the electrodes. The contact resistance measurements are used to compute the coupling phase angles for correcting the data at the output of the initial computer means. The logging tool is constructed to reduce water, and therefore electrical, leakage.

Ben K. Sternberg

Papers

Method and apparatus for obtaining high accuracy simultaneous calibration of signal measuring systems

Hydrocarbon prospecting method with changing of electrode spacing for the indirect detection of hydrocarbon reservoirs

Method and apparatus for complex resistivity measurements with elimination of electromagnetic coupling effects

Electrode prospecting method providing calculable electromagnetic coupling for the indirect detection of hydrocarbon reservoirs

Induced Polarization For Hydrocarbon Exploration: Geochemical/Geological Interpretation