Abstract: A seismic source is positioned at the surface of a geologic formation and a plurality of seismic receivers is positioned in a wellbore of the geologic formation. Seismic wavefield data is obtained based on the seismic source outputting seismic energy into the wellbore and the plurality of seismic receivers receiving the seismic energy. A velocity profile is determined along the wellbore based on the seismic wavefield data. P and S wave data in a downgoing direction is separated from the seismic wavefield data based on an inversion and the velocity profile. The P and S wave data in the downgoing direction is adaptively subtracted from the seismic wavefield data to form residual wavefield data. The P and S wave data in a upgoing direction is separated from the residual wavefield data based on the inversion and an updated velocity profile. The P and S wave data in the upgoing and downgoing direction is output.

Abstract: A system and method for predicting the front arrival time in seismic monitoring is disclosed The method includes measuring or computing a physical property reference signature at a calibration point, the physical property reference signature based on a change in a physical property over time due to a well injection; computing a seismic attribute reference signature at the calibration point based on the physical property reference signature; identifying a reference marker, the reference marker corresponding to a change in the seismic attribute reference signature at the calibration point over time; detecting a measured marker, the measured marker corresponding to a change in a seismic attribute of a recorded dataset over time; calibrating the measured marker; and calculating a marker arrival time for a location other than the calibration point.

Abstract: Methods and apparatus are provided related to seismic sensor data. Seismic sensor signaling is digitally sampled in accordance with a local clock and without synchronization to standardized time. Timestamp data is used to synthesize data correspondent to an artificial stimulus waveform. Cross-correlation of the synthesized data with the seismic sensor data yields a correlation result. The correlation result can be scaled to an original starting time for the seismic data sampling. The scaled correlation result can be stored in computer-accessible media and subject to further processing or interpretation.

Abstract: Methods and systems for digital control utilizing oversampling.

Abstract: A technique includes monitoring acquisition activity of a plurality of seismic vibrators. The technique includes receiving signals from the seismic vibrators during the monitoring. Each of the signals indicates that at least one of the seismic vibrators is available for an associated seismic operation. The technique includes, in response to the signals, regulating the operations based on the monitored acquisition activity.

Abstract: Presented are systems and methods for wireless data acquisition. The wireless data acquisition may involve synchronizing modules within a data acquisition array. The synchronized data acquisition array may be used to facilitate a seismic survey. Synchronization may be facilitated by receipt of a reference time event such that a clock is synchronized based on the reference time event.

Abstract: Methods and systems for digital control utilizing oversampling.

Abstract: In various embodiments, seismic receivers may detect seismic energy and transmit digital signals representative of the seismic energy to an S-line interface module (SLIM) and/or a smart antenna module (SAM) for collection. A SLIM may be used to connect two or more seismic receivers together. A SAM may include a memory medium for storing digital signals from seismic receivers (e.g., received directly from the seismic receivers or received through a connection to a SLIM) and a wireless transmitter to transmit data stored on the memory medium. The SAM may further include a Global Positioning System (GPS) receiver for receiving and storing timestamps, clock data, and/or positional data relative to the seismic receivers. The timestamps, clock data, and/or positional data may be transmitted along with the digital signal data to an external source (e.g., a laptop) for analysis to detect characteristics of subterranean formations.

Abstract: A system and method for microseismic fracture mapping using seismic source timing measurements for velocity calibration is disclosed. The system may include a seismic source coupled to a wireline and a seismic source trigger, a sensor capable of detecting a first signal from the seismic source trigger, a transmitter coupled to the sensor, capable of transmitting a time value associated with the first signal, a receiver capable of detecting an event generated by the seismic source; and an analyzer capable of calculating a microseismic velocity of the event. In one embodiment, a first signal is transmitted through a wireline to trigger a seismic source. The first signal is detected, and a first time value associated with the first signal is transmitted. An event associated with the seismic source is detected and a second signal associated with the event is transmitted to an analyzer.

Abstract: A network distributed seismic data acquisition system comprises seismic receivers connected to remote acquisition modules, receiver lines, line tap units, base lines, a central recording system and a seismic source event generation unit synchronized to a master clock. One or more high precision clocks is added to the network to correct for timing uncertainty associated with propagation of commands through the network. Seismic receivers and seismic sources are thereby synchronized with greater accuracy than otherwise possible. Timing errors that interfere with the processing of the seismic recordings are greatly reduced, thus enabling an improvement in subsurface geologic imaging.

Abstract: Methods and systems are provided for acquiring seismic data. Data are collected representing acoustic signals received from the Earth at distinct geographic locations. Data representing an ambient signal at the distinct geographic locations are also collected. For each of the geographic locations, a known time dependence of the ambient signal is correlated with a time dependence of the collected acoustic-signal data to define time-correlated acoustic signal data. The collected acoustic-signal data for the distinct geographic locations are synchronized from the time-correlated acoustic-signal data.

Abstract: A method and system for simulating and optimizing land seismic survey operations. The method and system utilizes spatially referenced data and nonspatial data relevant to land seismic survey operations such as high resolution satellite and airborne imagery and uses discrete event information about land seismic survey operation to simulate a land seismic survey. The output of the simulation is a detailed list of survey events. Mathematical optimization techniques are used to enhance the efficiency of the survey execution via optimal route planning and optimal allocation of survey logistical components. The invention uses a discrete event simulator which is an object-oriented software program with survey geometry objects that represent the survey design, resources objects that represent resources needed to conduct survey operations and manager objects to coordinate the resource objects within the specified survey geometry.

Abstract: A system for synchronizing a seismic system having multiple subsystems. A control system transmits a message to selected subsystems and an internal subsystem counter is zeroed to a selected epoch. Depending on the message or on an internal instruction code, each subsystem initiates an event or sequence of events synchronized to the selected epoch. The system is based on the relative occurrence of cyclic events and does not depend on the transmission of an absolute time signal. The system is self rectifying, reduces systemic errors, and reduces the data transmission required for system control and operation. The system permits autonomous, asynchronous operation by a subsystem without continuous control by a central controller as a function of time, and can interactively respond to events without intervention from the central controller.

Abstract: A seismic data acquisition system is featured that utilizes a series of nearly identical seismic shots (SISS) to synchronize and to communicate with novel data acquisition units (NDAU) located in the field. Each SISS seismic shot is carefully timed to provide synchronization to each NDAU, and to allow the NDAU to correct for the time drift of its internal clock. Further, each NDAU is programmed with a number of menus, which are used to interpret the seismic shots received from a seismic source. Thus, communication from a central or headquarter site to each NDAU is facilitated, allowing for a change in production schedule and other variables. In addition, the disclosed seismic data acquisition system features movable SISS source sites and overlapping production and SISS shots.

Abstract: As a means for determining the preferred azimuthal alignment of a horizontal borehole, the reflection travel time vectors between an acoustic source and a plurality of equidistant seismic receivers are measured along a plurality of directional wavefield trajectories. The travel time vectors are resolved to measure the angular orientation of the strike of vertical stress patterns. The alignment of the horizontal borehole is directed perpendicularly to strike.

Abstract: Described are methods of and systems for seismic exploration wherein a master station and a plurality of slave stations are utilized in conjunction with remotely located seismic sources. The system includes apparatus at the master station for generating a start signal and transmitting that signal over single frequency radio link to each of the slave stations. Upon receipt of the start signal at the slave stations the seismic sources are energized in a preprogrammed mode. The field time-break and signature of the seismic energy is acquired and transmitted via the same radio link to the master station. The time-break of one of the sources is transmitted in real time and thereafter each slave station is polled or interrogated by the master station to transmit via the same radio link the time-break and amplitude data representative of the signature of each of the sources before the generation of the next start signal.

Abstract: A method and apparatus for indicating the time-break on a seismic record wherein the time-break is marked in response to the rupture of an electric circuit by the explosive charge used to generate the seismic waves. The preferred rupturable electric circuit is connected to the same energy source as the electric detonator used to initiate the explosive charge and the preferred electric detonator is one connected to a high frequency A.C. firing energy source through a transformer, the rupturable electric circuit being the primary or secondary circuit of the transformer.The method is more accurate than the present method of marking the time-break at the initial application of current to the detonator.

Abstract: Individual seismic source units of a surface array activated simultaneously for cumulative reinforcement may initiate seismic waves at slightly different times despite efforts at synchronization. These variations are measured and used to compute an inverse operator which is applied to the summed uncorrected seismic recording so as to undo the distortion they produce.

Abstract: A method for determining the effective or apparent firing time of a seismic source. The seismic detectors positioned at known distances from the source, but outside the non-linear acoustic region, are used to detect arrivals of energy from the source. The arrival times and known distances are used to determine effective source firing time which is in turn used to calibrate the source for actual seismic operations.

Abstract: A process for better defining first break seismic energy travel times for correlated seismic return signals that consists of constructing a minimum phase bandpass filter having bandwidth narrower than the vibrational seismic return signals and convolving the filter with the return signals to convert the seismic return signals to a causal wave form.

Abstract: An ocean bottom seismometer unit records refraction waves from a seismic source. The refraction waves are digitzed and stored in a magnetic memory. Periodically, a tape recorder is started and digital samples are transferred from digital memory to tape during a time in which operation of the tape recorder will not generate spurious noise signals which interferes with the detection of the refraction waves. The water break is detected and the time of its occurrence is digitized. Only the digitized time of the water break occurrence is recorded thereby permitting shortened record length and increased record storage capacity.

Abstract: The present invention relates to a method and apparatus for conditionally updating source-detector array parameters related to a seismic exploration system, especially during generation and collection of seismic data using a vibratory source detector array positioned at known locations along a line of survey at the earth's surface. The updated array and source parameter are generated as bits of digital data in a microcomputer system of a ground position controller housed in a recording truck associated with the exploration system of interest.

Abstract: A device for the sequential transmission of information elements from a sensor arrangement receiving acoustic waves at different locations and a system for recording or processing these information elements. The device includes means for generating information signals representative of the instant of reception at one of said sensor means of a directly transmitted acoustic wave emanating from a source, in the form of at least two discrete values of a continuously varying voltage which begins to be generated at the instant of reception of the direct wave, and means for determining the instant of reception from said discrete values are provided, after their transmission to the recording or processing system by a sequential transmission of the discrete values.

Abstract: A rotating eccentric weight apparatus and method for generating coded shear wave signals for use in seismic exploration. The apparatus includes a rotatable eccentric and a position sensor capable of detecting each instant that the eccentric passes a particular angular position about its axis of rotation and generating a code signal for use in correlating the raw seismic data obtained. In one embodiment, the apparatus includes an outrigger shovel which transmits a sinusoidal shear wave signal generated by the rotating eccentric while the rest of the apparatus is caused to alternately decouple from and impact against the earth surface to transmit a coded train of pressure wave impulses into the earth.

Abstract: A seismic exploration method in which a rotating eccentric weight seismic source is employed to transmit a coded energy signal into the earth. A position sensor mounted on the source directly detects the instants at which the rotating eccentric passes a particular angular position about its axis of rotation, and generates a code signal which is used to correlate the raw seismic data. Preferably the source is allowed to decouple from the earth surface such that the coded energy signal transmitted into the earth is a coded impulse train.

Abstract: Multiplexed seismic data representing a plurality of seismic channels intensity modulates each sweep of the electron beam of a cathode-ray tube. Each successive sweep of the electron beam is photographically reproduced on a rotating drum plotter to provide a seismic record section. The modulation of the cathode-ray tube is further controlled to provide for various seismic trace presentations on the record section, including wiggle traces, variable area traces, wiggle-variable area traces, and symmetrical-variable area traces.