Uncertainty in microseismic monitoring sensor data can be reduced. A computing device can receive information about at least one sensor that is monitoring a subterranean formation, including a location, after a fracturing fluid is introduced into the formation. The computing device can also receive information about a microseismic event and determine a seismic ray bath between a location of the event and the at least one sensor, and an uncertainty value of the location based on information about the formation and the information about the event. The computing device can determine a total uncertainty value associated with the locations of a plurality of microseismic events, including the microseismic event. The computing device can determine a solution to an objective function based on the total uncertainty value and a number of sensors. The computing device can determine a new location of the at least one sensor based on the solution.

A nodal seismic unit for acquiring seismic information includes an enclosure, a GPS receiver disposed in the enclosure; a motion sensor disposed in the enclosure; a LPWAN radio transceiver disposed in the enclosure; and a control unit disposed in the enclosure. The control unit is configured to transmit an unplanned movement signal to a remote operator using the LPWAN radio transceiver if the control unit receives a signal from the motion sensor indicative of an acceleration greater than a preset level. Additionally, he control unit may be configured to change an operating state of the nodal seismic unit in response to detecting a predetermined pattern of motion using the motion sensor.

A method for determining an internal multiple attenuated seismic image is disclosed. The method includes obtaining a seismic dataset composed of a plurality of seismic traces and for each seismic trace determining an internal multiple trace based, at least in part, on a nested truncated correlation and a bounded convolution of the seismic trace with itself. The method further includes determining an internal multiple attenuated seismic trace based, at least in part, on subtracting the internal multiple trace from the seismic trace and combining the internal multiple attenuated seismic trace to form the internal multiple attenuated seismic image. A system including a seismic source, a plurality of seismic receivers, and a seismic processor for executing the method is disclosed.

The disclosure generally relates to a method, apparatus and system to deploy aquatic sensors to obtain oceanographic data. In an exemplary embodiment, a free-floating or untethered sensor receives signals from different transmitters. The signals may be configured to travel through air and/or water. The sensor records each signals' time of arrival and determines its location in relationship to known transmitters based on the signal travel time. The position of each sensor may be determined by triangulation to several devices whose positions are known. The distances from the sensor in question to each device is measured by means of time-of-flight measurements for a wireless signal from the sensor to each known-position device. Other methods such as trilateration or dead-reckoning may also be used. The sensor may additionally collect and record oceanographic or other environmental data.

An embodiment of a method of stimulating an earth formation includes: disposing a stimulation device at a borehole in an earth formation, the earth formation having been stimulated by an initial stimulation operation; subsequent to the stimulation operation, performing a probe operation configured to cause movement of existing fractures in the formation; and measuring microseismic events occurring in the formation by one or more seismic receivers. The method further includes: identifying one or more target zones in the formation based on the measuring, the one or more target zones exhibiting a reduced micro seismicity relative to another zone in the formation; and designing a re-stimulation operation configured to stimulate the one or more target zones to increase hydrocarbon production from the formation.

A method includes receiving, via a processor, input data based upon received seismic data, migrating, via the processor, the input data via a pre-stack depth migration technique to generate migrated input data, encoding, via the processor, the input data via an encoding function as a migration attribute to generate encoded input data having a migration function that is non-monotonic versus an attribute related to the input data, migrating, via the processor, the encoded input data via the pre-stack depth migration technique to generate migrated encoded input data, and generating an estimated common image gather based upon the migrated input data and the migrated encoded input data. The method also includes generating a seismic image utilizing the estimated common image gather, wherein the seismic image represents hydrocarbons in a subsurface region of the Earth or subsurface drilling hazards.

A kinetic penetrator for multistatic geophysical sensing includes a tubular body having a first end and a second end, a nose coupled to the first end of the tubular body, and a sensing element coupled to at least one of the tubular body and the nose. The nose is configured to penetrate a ground surface and subsurface materials of a subterranean ground volume. The sensing element is configured to interface with an external geophysical sensing system.

Imperfect separation at the higher frequencies has been observed and was eventually was tracked down to the poor GFE signal that is normally used in the inversion. The invention thus uses a “derived GFE” for each source, obtained by comparing the shot records and remove the differences, instead of the prior estimated GFE signal put out by the controller, thus accurately maximizing the separation of the data.

Apparatus, methods, and systems for determining acoustic velocity behind casing or tubing in a subterranean wellbore. A method may include obtaining a plurality of waveform data sets corresponding to a plurality of propagation path regimes and obtaining a total wavefield across the receiver array. The method may also include determining a Green's function representing each of the plurality of propagation path regimes and determining a noise wavefield by convolving the Green's functions and a known transmitted pressure signal corresponding to the plurality of waveform data sets. The method may also include generating a reduced-noise wavefield by subtracting the noise wavefield from the total wavefield and estimating the acoustic velocity of a formation behind the casing or tubing from the reduce-noise wavefield.

An apparatus for acquiring seismic wave data includes a network of geophones and a seismic wave data receiving device coupled to the network and configured to receive the seismic wave data as an optical signal and process the seismic data in real time to provide locations and corresponding sizes of fractures in an earth formation. The network of geophones includes: a plurality of geophone channels, each channel having an array of geophones coupled to a field digitizer unit; an array of geophone patches having geophone channels connected in series by a metallic conductor; a plurality of geophone branches having a metallic conductor and a branch digitizer unit to connect geophone patches in series; a plurality of electrical to optical signal converters for converting signals received from branch digitizer units for transmission using an optical fiber; and a plurality of optical fiber segments for transmitting optical signals to the receiving device.