Abstract: An electromagnetic (EM) data acquisition method for a geological formation may include operating EM measurement devices to determine phase and amplitude data from the geological formation. The EM measurement devices may include at least one first EM measurement device within a borehole in the geological formation, and at least one second EM measurement device at a surface of the geological formation. The method may further include processing the phase data independent from the amplitude data to generate a geological constituent map of the geological formation, and identifying different geological constituents in the geological constituent map based upon the measured amplitude data.

Abstract: In one embodiment, a method includes receiving one or more datasets including measured vertical electric and magnetic fields excited by one or more radial and azimuthal electric field antennas from a downtool into one or more processors, wherein each of the one or more datasets corresponds to a different position of the one or more radial azimuthal electric field antennas, simultaneously inverting the one or more datasets using the one or more processors, and as a result of the simultaneous inversion, generating by the one or more processors a three-dimensional (3D) image of a portion of the geological formation.

Abstract: Systems, methods, and apparatuses to generate a crosswell data set are described. In certain aspects, a method includes producing a first electromagnetic field at the earth's surface with a transmitter at a first location, detecting in a first borehole a first field signal induced by the first electromagnetic field, detecting in a second borehole a second field signal induced by the first electromagnetic field, and generating a crosswell data set from the first field signal and the second field signal. A formation model may be created from the crosswell data set.

Abstract: In one embodiment, a method includes receiving one or more datasets including measured vertical electric and magnetic fields excited by one or more radial and azimuthal electric field antennas from a downtool into one or more processors, wherein each of the one or more datasets corresponds to a different position of the one or more radial azimuthal electric field antennas, simultaneously inverting the one or more datasets using the one or more processors, and as a result of the simultaneous inversion, generating by the one or more processors a three-dimensional (3D) image of a portion of the geological formation.

Abstract: A method analyzes a subterranean formation. At least one property of a well casing in the subterranean formation is determined and a plurality of current source vectors at respective positions along a trajectory of the well casing are determined. The effect of the well casing is determined based upon the plurality of current source vectors and the at least one property of the well casing.

Abstract: Various implementations described herein are directed to a method of performing an electromagnetic survey operation. The method may include measuring an electric field of a subsurface area using sensors in a well disposed within the subsurface area. The method may include computing a first current density by multiplying the electric field with a measured electric resistivity in the well. The method may include creating a resistivity model of the subsurface area. The method may include running a simulation on the resistivity model to create a second current density. The method may include calculating a misfit by comparing the first current density to the second current density. The method may also include adjusting the resistivity model based on the misfit.

Abstract: Electromagnetic (EM) survey processing comprising operating an electronic device to model expected EM field components to be measured by an EM apparatus associated with a subterranean formation, wherein the EM apparatus comprises at least one EM source and at least one EM receiver. The electronic device may be operated to determine one or more ratios of the modeled EM field components. The at least one EM source may be operated to emit an EM signal into the subterranean formation, and the at least one EM receiver may be operated to measure actual EM field components of the EM signal. The electronic device may then be operated to compare the one or more ratios of the modeled EM field components with one or more ratios of the actual EM field components. The one or more ratios of the modeled EM field components may then be updated based on the comparison.

Abstract: Electromagnetic (EM) survey processing comprising operating an electronic device to model expected EM field components to be measured by an EM apparatus associated with a subterranean formation, wherein the EM apparatus comprises at least one EM source and at least one EM receiver. The electronic device may be operated to determine one or more ratios of the modeled EM field components. The at least one EM source may be operated to emit an EM signal into the subterranean formation, and the at least one EM receiver may be operated to measure actual EM field components of the EM signal. The electronic device may then be operated to compare the one or more ratios of the modeled EM field components with one or more ratios of the actual EM field components. The one or more ratios of the modeled EM field components may then be updated based on the comparison.

Abstract: Systems, methods, and apparatuses to generate a crosswell data set are described. In certain aspects, a method includes producing a first electromagnetic field at the earth's surface with a transmitter at a first location, detecting in a first borehole a first field signal induced by the first electromagnetic field, detecting in a second borehole a second field signal induced by the first electromagnetic field, and generating a crosswell data set from the first field signal and the second field signal. A formation model may be created from the crosswell data set.

Abstract: A method may include modeling a bulk electromagnetic (EM) characteristic of a composite material including a fracturing fluid, a proppant, and a sensing additive. The method may further include generating a modeled propped fracture pattern for a subterranean formation having the composite material injected therein, and generating a three dimensional (3D) arrangement of cells based upon the bulk EM characteristic and the modeled propped fracture pattern using an effective medium theory (EMT) model, with each cell having a modeled localized EM characteristic associated therewith. The method may also include injecting the composite material into the subterranean formation to cause an actual propped fracture pattern, collecting EM data based upon the sensing additive within the actual propped fracture pattern, and determining a respective actual EM characteristic for each cell based upon the modeled localized EM characteristics and the collected EM data.

Abstract: Methods and related systems are described for measuring naturally occurring electromagnetic fields both at the earth's surface as well as downhole. These fields originate from currents in the ionosphere above the earth, and are the same fields as employed by known magnetotelluric geophysical methods based on surface measurements. Some embodiments are especially useful in horizontal wells that are uncased at depth, although some embodiments are also useful in normal vertical wells that are both uncased or cased with a conductive liner. The method includes receiving downhole electromagnetic survey data of the naturally occurring electromagnetic fields obtained using a downhole receiver deployed at a first location in a borehole. A second set of electromagnetic survey data of the naturally occurring electromagnetic fields is also received that has been obtained using a receiver deployed at a second location.

Abstract: An electromagnetic (EM) data acquisition method for a geological formation may include operating EM measurement devices to determine phase and amplitude data from the geological formation. The EM measurement devices may include at least one first EM measurement device within a borehole in the geological formation, and at least one second EM measurement device at a surface of the geological formation. The method may further include processing the phase data independent from the amplitude data to generate a geological constituent map of the geological formation, and identifying different geological constituents in the geological constituent map based upon the measured amplitude data.

Abstract: A method analyzes a subterranean formation. At least one property of a well casing in the subterranean formation is determined and a plurality of current source vectors at respective positions along a trajectory of the well casing are determined. The effect of the well casing is determined based upon the plurality of current source vectors and the at least one property of the well casing.

Abstract: To perform a marine survey of a subterranean structure, a vertically oriented electromagnetic (EM) source is positioned in a body of water, where the EM source is coincident with an EM receiver. The EM source is activated to cause transmission of EM energy into the subterranean structure. After deactivation of the EM source, an EM field affected by the subterranean structure is measured by the EM receiver. In an alternative implementation, a survey system is provided that has a continuous wave EM source, a main EM receiver, and an auxiliary EM receiver.

Abstract: A survey module includes at least one sensing element to measure a first electromagnetic (EM) field along a first direction, and circuitry to derive a second EM field along a second, different direction based on the first EM field.

Abstract: To perform a marine survey of a subterranean structure, a vertically oriented electromagnetic (EM) source is positioned in a body of water, where the EM source is coincident with an EM receiver. The EM source is activated to cause transmission of EM energy into the subterranean structure. After deactivation of the EM source, an EM field affected by the subterranean structure is measured by the EM receiver. In an alternative implementation, a survey system is provided that has a continuous wave EM source, a main EM receiver, and an auxiliary EM receiver.

Abstract: A system to perform a marine subterranean survey includes at least one vertical electromagnetic (EM) source and at least one EM receiver to measure a response of a subterranean structure that is responsive to EM signals produced by the vertical EM source. At least one tow cable is used to tow the EM source and EM receiver through a body of water.

Abstract: Methods and related systems are described for measuring naturally occurring electromagnetic fields both at the earth's surface as well as downhole. These fields originate from currents in the ionosphere above the earth, and are the same fields as employed by known magnetotelluric geophysical methods based on surface measurements. Some embodiments are especially useful in horizontal wells that are uncased at depth, although some embodiments are also useful in normal vertical wells that are both uncased or cased with a conductive liner. The method includes receiving downhole electromagnetic survey data of the naturally occurring electromagnetic fields obtained using a downhole receiver deployed at a first location in a borehole. A second set of electromagnetic survey data of the naturally occurring electromagnetic fields is also received that has been obtained using a receiver deployed at a second location.

Abstract: A survey module includes at least one sensing element to measure a first electromagnetic (EM) field along a first direction, and circuitry to derive a second EM field along a second, different direction based on the first EM field.

Abstract: A method of determining an orientation of a data acquisition system deployed on a seafloor includes measuring horizontal magnetic fields using detectors on the data acquisition system while the data acquisition rotates and descends to the seafloor or rises from the seafloor. Resting horizontal magnetic fields are measured after the data acquisition system is on the seafloor. A heading of the data acquisition system on the seafloor may be determined based on maximum and minimum horizontal magnetic fields measured during the descent and the resting horizontal magnetic fields.