A method for determining properties of rock formations using drill string vibration measurements includes entering into a processor signals corresponding to vibrations detected along a rotating part of a drill string while drilling a borehole. The vibration signals are transformed into transformed signals representing elastic response of the drill string, the rock formations and borehole fluid to a filtered impulse originating at a known location along the drill string. Properties of the rock formations are calculated using the transformed signals.

Some embodiments include an apparatus for determining statistical mean and maximum expected of electromagnetic energy transmission between coupled cavities. Other embodiments of related apparatuses and methods are also disclosed.

A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

An exemplary method of analyzing a well log includes imaging a well log to form a well log image, performing pattern recognition on the well log image to determine pattern data, and determining stratigraphic structure data based on the pattern data. Another exemplary method of improving production from a stratigraphic structure includes performing pattern recognition on a well log image stored in an image format to determine pattern data, determining stratigraphic structure data using a computer-based structure analyzer based on the pattern data, and projecting well parameters based on the stratigraphic structure data. An exemplary system includes a scanner to scan a raster image of a printed well log and a computational system in communication with the scanner to receive the raster image. The computational system includes a pattern recognition analyzer to determine pattern data from the raster image and a structure analyzer to determine stratigraphic structure based on the pattern data.

A multivariate analysis may be used to correlate seismic attributes for a subterranean formation with petrophysical properties of the subterranean formation and/or microseismic data associated with treating, creating, and/or extending a fracture network of the subterranean formation. For example, a method may involve modeling petrophysical properties of a subterranean formation, microseismic data associated with treating a complex fracture network in the subterranean formation, or a combination thereof with a mathematical model based on measured data, microseismic data, completion and treatment data, or a combination thereof to produce a petrophysical property map, a microseismic data map, or a combination thereof; and correlating a seismic attribute map with the petrophysical property map, the microseismic data map, or the combination thereof using the mathematical model to produce at least one quantified correlation, wherein the seismic attribute map is a seismic attributed modeled for the complex fracture network.

The present disclosure relates to detecting subterranean formations using electromagnetic depth sounding. A method for detecting formation properties may comprise of disposing a transmitter at a surface, disposing a receiver at the surface, coupling a high frequency wave to a low frequency wave to form an electromagnetic pulse, transmitting the electromagnetic pulse into a formation from the transmitter, receiving a reflected electromagnetic wave from the formation with the receiver, and determining the depth and nature of the formation from the surface. A formation measuring system may comprise a transmitter, wherein the transmitter is configured to couple a high frequency wave to a low frequency wave to form an electromagnetic pulse. The formation measuring system may further comprise at least one receiver, a data acquisition system, and an analysis unit.

Pipe]parameter determinations from electromagnetic logs can be improved, in accordance with various embodiments, by weighting signals with frequencies below a threshold associated with resolution degradation lower than signals with frequencies above the threshold. The threshold frequency may be determined based on a spatial resolution associated with the logging tool and a logging speed. Further embodiments are described.

A method for estimating reservoir quality from a reflection seismic survey includes determining seismic interval velocity (or their inverse, interval transit time ITT) with respect to depth from the reflection seismic survey. A normal compaction trend of the seismic interval velocity with respect to depth is determined. A fractional amount of sand and a fractional amount of shale at at least one depth is determined based on deviation of the seismic interval velocity (or ITT) at the at least one depth from the normal compaction trend.

A method may include obtaining seismic data for a geological region of interest. The method may further include obtaining geophysical data for the geological region of interest. The method may further includes determining various pressure wavefields using a slowness model and a reflectivity model. The method may further include determining various slowness gradients for the slowness model based on the geophysical data, the pressure wavefields, the seismic data, and a geophysical constraint. The geophysical constraint may correspond to an objective function that determines a misfit between the geophysical data and the slowness model. The method may further includes updating the slowness model using the slowness gradients to produce an updated slowness model. The method may further include generating, based on the updated slowness model and the reflectivity model, a subsurface image of the geological region of interest.

Some embodiments include an apparatus for determining statistics of the current in various wiring systems exposed to diffuse electromagnetic fields. Other embodiments of related apparatuses and methods are also disclosed.