Abstract: A seismic surveying arrangement comprises a vertical source array (26) having at least two sources (27,28) of seismic energy. The source array (26) is disposed such that a first source (28) is located within a weathered layer (35) of the earth's interior and such that a second source (27) is located within the weathered layer at a greater depth than the first source or within a high velocity layer (8) underlying the weathered layer (35). The surveying arrangement also includes a first horizontal receiver array (29) located in the weathered layer, and means for processing seismic data acquired by the first receiver array. The processing means are able to process the acquired seismic data so as to attenuate seismic events involving reflection of seismic energy at at least one boundary face of the high velocity layer. The seismic surveying arrangement may also comprise a second receiver array (30) disposed at a lower depth than the first receiver array (29).

Abstract: A position measurement system for measuring displacement of an observation station viewed from a reference station by receiving radio waves from satellites by these stations, and performing relative position measurement between the stations, having: a short period displacement measurement section for measuring a short period displacement component in each of the stations through independent position measurement; a relative position computing section for performing relative position measurement between said stations; a long period position computing section for inputting a short period displacement component measured by the short period displacement measurement section, a relative position determined by the relative position computing section and an absolute position from the reference station, and determining the absolute position including a long period displacement component by removing the short period displacement component measured by each of the stations; and a radio communication device installed on ea

Abstract: Methods and apparatus for generating a signal with a signal generator comprising a tool body disposed in a tubular member. A first and second electromagnets are disposed within the tool body such that the second electromagnet is opposite the first electromagnet. A power supply selectively provides electrical current to the first and second electromagnets so as to displace the tubular member and generate a signal in the surrounding formation.

Abstract: A downhole receiver for gathering seismic and sonic data from inside a borehole includes a substantially tubular housing adapted for axial connection to a tool string, and one or more sensors. A damping element is provided to flexibly couple each sensor to the tubular housing. An actuator extends the one or more sensors substantially radially with respect to the tubular housing to clamp the sensors against the wall of the borehole. In selected embodiments, the sensors may be one or multiple component geophones, accelerometers, hydrophones, vibrometers, or the like.

Abstract: The present invention provides a method and apparatus for seismic data acquisition. One embodiment of the method includes accessing data acquired by at least two particle motion sensors. The data includes a seismic signal and a noise signal and the at least two particle motion sensors being separated by a length determined based on a noise coherence length. The method may also include processing the accessed data to remove a portion of the noise signal.

Abstract: Acoustic transducers configured with integrated electronics technology are adapted to digitize signal data close to the transducer. The transducers are packaged with a reduced number of elements and sealed for exposure to harsh environments, without oil compensation. A transducer assembly includes a frame, an acoustic transducer element disposed on the frame, and an electronics module disposed on the frame and linked to the acoustic transducer element. The pressure and temperature tolerant electronics module is adapted to process a signal associated with the transducer element.

Abstract: An acoustic logging tool sleeve with a preferably discontinuous, alternating structure that is acoustically opaque in some zones, and acoustically transparent in others. The sleeve may be modular, with several stages connected together. The multiple stages provide a sleeve that may be useful with a variety of borehole logging tools to reduce or eliminate the transmission of noise to the receiving elements.

Abstract: Seismic emission system for use in an underground formation, using at least one seismic source movable successively in a plurality of prepared activation locations and method for implementing same. The system comprises for example a plurality of coupling devices (1) including each for example two anchor elements (12, 9?) tightly coupled with the formation (by cementing for example). These anchor elements are secured to the seismic source (V) such as a vibrator of any type or an impulsive source by transmission elements (10, 13). The seismic source is coupled with coupling device (1) by fast locking means (18, 19). Coupling devices (1) can be preinstalled at a plurality of prepared activation locations above the formation to be monitored. Seismic monitoring operations can be carried out by moving at least one seismic source successively between the different locations where coupling devices (1) are installed.

Abstract: The present invention provides a method for harmonic noise attenuation in correlated sweep data in seismic exploration. The method includes forming a plurality of correlation data subsets using a plurality of sweep data sets and a correlation reference sequence. The method further includes estimating a noise level in a correlation data set using the correlation data subsets and subtracting the estimated noise level from the correlation data set.

Abstract: A downhole tool for gathering formation data from inside a borehole includes a substantially tubular housing adapted for axial connection to a drill string and multiple sensors coupled to the tubular housing. The sensors include a first pair of sensors aligned along a first axis and adapted to measure a spatial derivative along the first axis, a second pair of sensors aligned along a second axis and adapted to measure a spatial derivative along the second axis, and a third pair of sensors aligned along a third axis and adapted to measure a spatial derivative along the third axis. In selected embodiments, the spatial derivatives are used to differentiate seismic or sonic compression and shear waves measured in a downhole environment.

Abstract: An apparatus and method is provided for transporting, installing, retrieving, and replacing a sensor array of individual sensor pods at a geographically remote location, such as on the sea floor. The apparatus consists of a remotely operated vehicle (ROV), a carousel attached to the ROV, a pod ejector mechanism attached to the carousel, and a manipulator with a manipulator end effector attached to the ROV. The carousel contains a plurality of sensor pod holders, where each sensor pod holder is capable of holding a sensor pod. The pod ejector mechanism is capable of discharging a fresh sensor pod, while the manipulator end effector is capable of lifting a depleted sensor pod and placing the depleted sensor pod in an empty sensor pod holder in the carousel.

Abstract: A gerotor and bearing apparatus for a whirling mass orbital vibrator which generates vibration in a borehole. The apparatus includes a gerotor with an inner gear rotated by a shaft having one less lobe than an outer gear. A whirling mass is attached to the shaft. At least one bearing is attached to the shaft so that the bearing engages at least one sleeve. A mechanism is provided to rotate the inner gear, the mass and the bearing in a selected rotational direction in order to cause the mass, the inner gear, and the bearing to backwards whirl in an opposite rotational direction. The backwards whirling mass creates seismic vibrations.

Abstract: The invention provides methods and apparatus for detecting seismic waves propagating through a subterranean formation surrounding a borehole. In a first embodiment, a sensor module uses the rotation of bogey wheels to extend and retract a sensor package for selective contact and magnetic coupling to casing lining the borehole. In a second embodiment, a sensor module is magnetically coupled to the casing wall during its travel and dragged therealong while maintaining contact therewith. In a third embodiment, a sensor module is interfaced with the borehole environment to detect seismic waves using coupling through liquid in the borehole. Two or more of the above embodiments may be combined within a single sensor array to provide a resulting seismic survey combining the optimum of the outputs of each embodiment into a single data set.

Abstract: Apparatus and methods for reducing ghosts from hydrophone signals in a streamer towed underwater close to the sea surface. A multi-axis micro-electro-mechanical-system (MEMS) accelerometer with attitude sensing is used to reduce the frequency spectral notch in the response of the combined hydrophone-accelerometer system and to reduce the sensitivity to ghost-producing downward traveling acoustic waves that are sea-surface reflections of the primary upward traveling acoustic waves. Multi-axis spring load cells provide high compliance and mechanical isolation between stress members and the accelerometer system. The load cells also provide signals representing the vibration of the stress members. The signals can be used with an adaptive filter estimating the mechanical transfer function between the vibration and the motion of the accelerometer system to remove the vibration-induced noise from the accelerometer signals.

Abstract: A method for deploying and retrieving seafloor equipment modules is disclosed. A conveyor has a fixed end and a free end. The conveyor is deployed into a body of water until the free end reaches, or is proximate to, the seafloor. The conveyor is dragged through the water. The equipment modules are slidably attached to the conveyor. The equipment modules slide along the conveyor to the seafloor, where the equipment modules engage the seafloor and are secured at a fixed position.

Abstract: The invention provides methods and apparatus for detecting seismic waves propagating through a subterranean formation surrounding a borehole. In a first embodiment, a sensor module uses the rotation of bogey wheels to extend and retract a sensor package for selective contact and magnetic coupling to casing lining the borehole. In a second embodiment, a sensor module is magnetically coupled to the casing wall during its travel and dragged therealong while maintaining contact therewith. In a third embodiment, a sensor module is interfaced with the borehole environment to detect seismic waves using coupling through liquid in the borehole. Two or more of the above embodiments may be combined within a single sensor array to provide a resulting seismic survey combining the optimum of the outputs of each embodiment into a single data set.

Abstract: A seismic sensor, comprising a case, a pre-charged, non-conductive membrane located between two plates that form a capacitor and accommodated inside the case, with one of the plates being immovable relative to the case and the other of the plates being movable relative to the one plate under the action of seismic activity so that the capacitor produces an electrical signal responsive to the seismic activity of a medium in which the sensor is located, and a mass increasing element associated with the movable plate so as to increase mass of the movable plate and therefore to enhance oscillations of the movable plate under the action of the seismic activity, the mass increasing element being formed as a further case which is connected to the movable plate and is located in condition of equilibrium in an inoperative position of the sensor.

Abstract: Provided is a permanent seafloor seismic recording system utilizing Micro Electro-Mechanical Systems seismic sensors. The system includes and expandable backbone, multiple hubs and sensor lines. The sensor lines include multiple sensor modules that include 3-C accelerometers and a hydrophone for providing a 4-C sensor module output signal.

Abstract: The present invention provides an adaptive filtering method for substantially eliminating ground roll noise encountered during seismic data acquisition. An apparatus for acquiring seismic data is provided that includes an adaptive filtering circuit coupled to a multi-axis sensor device.

Abstract: A method and device for seismic exploration of a subsea geologic formation by pickups set on the sea bottom and intermittently connectable to active data acquisition stations (11) brought nearby. Permanent passive reception stations (1) comprising a heavy pedestal provided with housings for seismic pickups (geophones (6), hydrophone (7) which receive acoustic or seismic signals from the underlying formation are arranged at the bottom of the water body. When collection sessions for the signals received by the pickups are scheduled, mobile active acquisition stations (11) connected to permanent passive reception stations (1) are positioned at the bottom of the water body. The signals picked up are then recorded, for the time required to carry out at least one session of acquisition and recording of the acoustic or seismic signals received by the passive stations in response to the emission of seismic waves by one or more seismic sources.

Abstract: Method for operating and testing a sensor assembly (210). The sensor assembly (210) preferably includes accelerometers with axes of sensitivity orthogonal to each other. The method preferably includes determining sensor tilt angle, determining the position of the sensor, and synchronizing the operation of the sensor.

Abstract: An apparatus (10) and method are disclosed for eliminating a noise signal from at least one source during an acoustic measurement of a subsurface geological formation or borehole. The apparatus (10) includes a longitudinal body for positioning in the borehole and a transmitter (22) supported by the body for transmitting acoustic signals into the formation and borehole. A sensor (23), substantially isolated within the body, is used to detect one or more noise signals and a receiver (24) is carried by the body for receiving acoustic signals traversing the formation and borehole, and for receiving one or more noise signals.

Abstract: A method and apparatus for isolating a seismic sensor module from high-g shock loads such as those encountered during handling, deployment and retrieval of the module. The sensor module includes one or more MEMS accelerometers in an electronics package. The electronics package is housed within a module case. And one or more isolators are disposed between the electronics package and the module case to provide shock isolation.

Abstract: A module is described for acquiring geophysical signals. The module includes at least one casing which is individually linked to one track. Each casing houses a processor which operates to digitize the geophysical signals. The module further includes two cable sections associated with each casing. Each cable section includes at a first end, a connector suitable for being coupled up to a complementary connector, and at a second end, an adapted configured to be fixed to a casing and to effect an electrical link with the processor housed in the casing.

Abstract: A sleeve for an acoustic logging tool has a structure with a window section having fewer bars than a conventional sleeve separated by a slotted region with thin circumferential slots which are stress-relieved at the ends (“dumb-bell” shaped). Steel receiver mounts are provided for hydrophone pressure sensors and this, together with the axially oriented hydrophones makes the tool less susceptible to interfering vibration.

Abstract: The invention is a method for removing trapped water bottom multiples, receiver side peg-leg multiples, and source side peg-leg multiples from dual sensor OBC data, where the data includes both pressure signals and velocity signals. The pressure and velocity signals are compared to determine any polarity reversals between them. Polarity reversals are used to identify and separate up-going and down-going wavefields in the pressure and velocity signals. A matching filter is applied to a portion of the velocity signal where polarity reversals exist. The down-going wavefield is then estimated by calculating the difference between the portion of the velocity signal where polarity reversals exist and the portion of the pressure signal where polarity reversals exist and applying a scaling factor to the result. An attenuated up-going pressure wavefield is then determined by combining the estimated down-going wavefield and the pressure signal.

Abstract: A seismic data acquisition technique comprises laying a seismic data cable having a plurality of spaced apart connection nodes and a plurality of sensor strings connected to the connection nodes along a line of the area to be seismically surveyed. Each sensor string comprises ten or more seismic sensors for producing respective output signals representative of a seismic signal received by them. The sensors of the sensor strings are laid out in at least two sets of groups, each group containing several of the sensors and transmitting at least one seismic signal to a connection node, and the sets of groups being disposed along respective spaced apart lines generally parallel to the line along which the seismic data cable is laid.

Abstract: One or more autonomous devices are deployed in the well to provide a moveable sensor source or obstruction for coupling a tube wave seismic signal into the formation adjacent the well bore. The autonomous devices move in the well and provide moveable obstructions or discontinuities which couple tube waves existing in the well bore or production tubing into the formation adjacent the well bore. Wellbore tube wave energy is converted to body wave energy at minor borehole obstructions or irregularities that become sources of seismic energy. A well bore may contain a plurality of minor obstructions or discontinuities. Each obstruction or discontinuity position along the borehole has an associated unique waveform source coda that may be measured for processing the wavefield radiated into the earth formation surrounding the well bore. A plurality of sensors detects the radiated seismic energy after the seismic energy has transited intervening earth formations.

Abstract: A method and device for seismic exploration of an underwater subsurface zone using seismic receivers coupled with the bottom of the water mass. Acquisition units (1) comprising a spire (2) where seismic receivers (4) are arranged, a measuring compartment (5) for acquisition and storage of the data received by the receivers, as well as removable and selective floating devices (7) are used. The acquisition units (1) are launched and, under the effect of gravity, they attach to the bottom and couple the receivers with the underlying formations. The respective positions thereof are first detected, seismic acquisition operations are carried out using an underwater source so as to collect seismic data on the formation, then the floating devices (7) are actuated so as to bring all or part of acquisition units (1) back up to the surface or a data collection device (vehicle or passive collection unit) is lowered to the neighbourhood of the various units.

Abstract: A measuring device for measuring the elastic properties of a surface structure (3), comprising a probe (2) arranged within a housing (1), a transmitter and at least one receiver, the transmitter transmitting acoustic pulses and the receiver picking up the propagation behavior of the acoustic pulses in the surface structure (3), a control means (16) for generating acoustic pulses and an evaluating means (18) for the measuring signals received by the receiver, at least two adjacent measuring tips (4, 6) being connected as transmitting and receiving elements, the measuring tips being adapted to be set onto the surface structure (3) and having strip-shaped bi-morph elements (12, 14) carried by a holder (8, 10), wherein the measuring tips (4,6) are formed by the holders (8, 10) of the bi-morph elements (12, 14) and the strip-shaped elements (12, 14) have one side of one of their ends fastened to the holder (8, 10).

Abstract: The claimed invention is an apparatus, method and system for optimizing bandwidth utilization of demodulators in a system for seismic signal processing, wherein the apparatus comprises demodulators having bandwidths, wherein one demodulator's bandwidth is greater than another demodulator's bandwidth. The apparatus further comprises an optical switch coupled to a fringe rate detector, wherein optical fibers bear seismic signals having fringe rates detected by the fringe rate detector. The optical signals are switched among the demodulators in dependence upon the fringe rates. Further, the claimed invention is an apparatus, method and system for active gain ranging of demodulated signal outputs.

Abstract: An apparatus and method for suppressing multiples in the collection of marine seismic data comprises at least one source positioned in the body of water; at least one receiver positioned in the body of water below the air-water interface and near the sources; a bubble diffuser positioned in the body of water so that the bubbles emitted by the bubble diffuser are positioned between the receivers and the air-water interface, wherein the emitted bubbles provide high acoustic reflection and substantially suppress specular reflection of seismic waves; and a control for activating the bubble diffuser during the collection of seismic data by the sources and receivers.

Abstract: A borehole tool including a tool body having and an anchoring mechanism, the anchoring mechanism having a drive mechanism including a motor, drive shaft, and clutch; an anchor arm moveable between first and second positions relative to the tool body; a push rod connecting the anchor arm to the drive mechanism; and a spring acting to bias the arm into a first position relative to the tool body. The push rod extends through the clutch mechanism and is engaged by the spring to bias the arm into the first position, and is also driven by the drive mechanism through the clutch to move the arm between the first and second position. The push rod may be connected to the anchor arm by a link. Measurement devices may be used to determine the position of the anchor arm or the tool body.

Abstract: A method and system for transferring synchronization data between a central control and seismic recording station and dependent stations in all the cases where the time of transmission through the connection channels between the elements may be liable to too great fluctuations is disclosed. The invention provides a central station (CCU) and intermediate local control and concentration stations (RRS), each connected to local acquisition units (RTU), with a common time reference or clock (H) (that can for example be provided by a satellite positioning network of a well-known type such as the GPS system, or based on the carrier frequency of a radio transmitter) which is picked up by specialized receivers associated with the elements of the seismic device, and in using this common reference to calculate the real transmission time and to local readjust seismic acquisition units (RTU).

Abstract: An acoustic receiver for sensing acoustic waves and generating orthogonal triaxial acoustic response data representative of said acoustic waves is disclosed. The receiver has at least four acoustic sensors oriented in at least four different directions. Each of the acoustic sensors is adapted to produce an electrical signal in response to an acoustic wave impinging thereon. The inventive acoustic receiver also includes means for combining the electrical signals to yield orthogonal triaxial acoustic response data. In one embodiment the means for combining the electrical signals comprises wiring the acoustic sensors in two series pairs to produce a combined output along two of the three orthogonal axes and orienting at least one acoustic sensor substantially parallel to the longitudinal axis of the acoustic receiver.

Abstract: A dynamic force transducer for generating vertically oriented compressional forces and motions at the surface of a solid medium. A frame is rigidly coupled in direct contact with the solid medium surface. At least one pair of identical driver units are mounted to the frame to impart vertically oriented forces to the medium. Compliant springs support the drivers and introduce mechanical resonances. The driver units are excited to produce the vertically oriented pushing and pulling forces along a common collinear vertical direction. The driver units also impart either continuous or pulsed oscillatory forces to produce prescribed seismic compressional waves in the medium.

Abstract: A method of using a seismic detector including four seismic sensors having axes which are in a substantially tetrahedral configuration, each of the sensors being in a respective signal channel, includes one or more of the following steps: combining outputs from the sensors to check that their polarities are correct; testing to ascertain if one of the sensors is not working and, if so, using the outputs from the other three sensors to obtain an indication of motion in three dimensions; if all four sensors are working, using their outputs to obtain an indication of motion in three dimensions on a least squares basis; checking that the outputs from the sensors are coherent; and checking the gains (or sensitivities) of the four channels.

Abstract: The present invention provides a system for, and method of determining an azimuth of a seismic energy source. In one embodiment, the system includes a directional assembly having a mount configured to be coupled to a seismic energy source, a rotatable mass assembly coupled to the mount, a compass rose coupled to one of the mount or the rotatable mass assembly and a direction reference coupled to the other of the mount or the rotatable mass assembly. The compass rose is registered with the direction reference to provide a direction orientation of the rotatable mass assembly with respect to the mount.

Abstract: A seismic acquisition system includes one or more perforating shaped charge modules activable to generate seismic signals into an earth sub-surface. The seismic signals are created by perforating jets formed by the perforating shaped charge modules when activated. The perforating jets produce directional seismic signals that reduce the amount of lateral noise. One or more detectors are employed to receive signals reflected from the earth sub-surface in response to the seismic signals.

Abstract: The present invention discloses a buried object detection system. The detection system has an acoustic emitter capable of generating a non-linear acoustic impulse or a continuous acoustic signal of variable amplitude and frequency. Sensors are deployed on an appropriate surface or surfaces of a granular medium, which are capable of detecting the backscattered and, if possible, forward scattered signals of the original impulse or wave from a buried inclusion or inclusions. The information received by the sensors may be transmitted to a computer for further manipulation and analysis.

Abstract: Measuring device for measuring the elastic properties of a surface structure A measuring device for measuring the elastic properties of a surface structure (3), comprising a probe (2) arranged within a housing (1), a transmitter and at least one receiver, the transmitter transmitting acoustic pulses and the receiver picking up the propagation behavior of the acoustic pulses in the surface structure (3), a control means (16) for generating acoustic pulses and an evaluating means (18) for the measuring signals received by the receiver, at least two adjacent measuring tips (4, 6) being connected as transmitting and receiving elements, the measuring tips being adapted to be set onto the surface structure (3) and having strip-shaped bi-morph elements (12, 14) carried by a holder (8, 10), wherein the measuring tips (4,6) are formed by the holders (8, 10) of the bi-morph elements (12, 14) and the strip-shaped elements (12, 14) have one side of one of their ends fastened to the holder (8, 10).

Abstract: An acoustic receiver for sensing acoustic waves and generating orthogonal triaxial acoustic response data representative of said acoustic waves is disclosed. The receiver has at least four acoustic sensors oriented in at least four different directions. Each of the acoustic sensors is adapted to produce an electrical signal in response to an acoustic wave impinging thereon. The inventive acoustic receiver also includes means for combining the electrical signals to yield orthogonal triaxial acoustic response data. In one embodiment the means for combining the electrical signals comprises wiring the acoustic sensors in two series pairs to produce a combined output along two of the three orthogonal axes and orienting at least one acoustic sensor substantially parallel to the longitudinal axis of the acoustic receiver.

Abstract: A compact, modular sonar assembly for use on the bow of a ship having separate transmitting and receive arrays confined within a single acoustic housing. The narrow and compact design fits much better into the hydrodynamically desirable bulbous bow deign than the typical bow dome sonar design and achieves good performance at a low cost with reduced size and weight.

Abstract: A borehole tool, such as a seismic shuttle-type logging tool, including a tool body having at least one sensor package and an anchoring mechanism, the anchoring mechanism having a drive mechanism including a motor, a drive shaft and a clutch; an anchoring arm moveable between first (extended)and second (retracted) positions relative to the tool body; a push rod connecting the anchoring arm to the drive mechanism; and a spring acting to bias the arm into a first position relative to the tool body. The push rod extends through the clutch mechanism and is engaged by the spring to bias the arm into the first position, and is also driven by the drive mechanism through the clutch to move the arm between the first and second positions. The spring is a coil spring surrounding the drive mechanism and acting on the push rod directly.

Abstract: The present invention provides a method for forming wellbores. In one method, one or more wellbores are drilled along preplanned paths based in part upon seismic surveys performed from the surface. An acoustic transmitter conveyed in such wellbores transmits acoustic signals at a one or more frequencies within a range of frequencies at a plurality of spaced locations. A plurality of substantially serially spaced receivers in the wellbores and/or at surface receive signals reflected by the subsurface formations. The sensors may be permanently installed in the boreholes and could be fiber optic devices. The receiver signals are processed by conventional geophysical processing methods to obtain information about the subsurface formations. This information is utilized to update any prior seismographs to obtain higher resolution seismographs. The improved seismographs are then used to determine the profiles of the production wellbores to be drilled.

Abstract: A non-destructive method of measuring physical characteristics of a medium, such as uncemented sediment, sandstone, or limestone. A pseudo-random code is generated and is used to generate a pseudo-random acoustic signal. This signal is transmitted into the medium to be measured through the use of a transducer, such as a piezoelectric element, and is received by a plurality of hydrophones. The received signal is then processed to obtain an image of its velocity and attenuation. A universal geoacoustic model of the medium for a given set of measured data is determined, and the model is solved to obtain a pair of permeability-porosity results for the medium. The one of this pair of permeability-porosity results which is correctly indicative of the physical characteristics of the medium is then determined.

Abstract: A method for land seismic data acquisition is provided, together with a seismic cable and a cable spool vehicle for use in the method. In performing the method, the cable spool vehicle mechanically deploys seismic cable with attached sensors according to a desired geophysical spread and at a rate dependent upon the speed of movement of the vehicle substantially without tension in the cable. The cable spool vehicle also allows mechanical pick-up of the seismic cable together with the sensors after the seismic data acquisition.

Abstract: This invention provides near real-time systems and methods for acquiring seismic data in reservoirs at very high resolution such that advancing fluid fronts can be mapped substantially in real time. In one system, one or more autonomous devices are deployed in the well to detect seismic data. Each device includes at least one seismic receiver. An acoustic energy source, preferably at the surface, induces acoustic waves into the subsurface formations. The autonomous devices move in the well and detect seismic waves at selected discrete locations in the well. The seismic data is stored in on-board memory. After the data acquisition, the devices dock at a receiver stations in the well. The receiver stations download the stored data from the memory and transmit such data to a surface control unit via a two-way data link between the receiver and the surface control unit. The surface computer system also sends command signals to the downhole receiver to control the operation of the individual devices.

Abstract: The present invention provides a method for forming wellbores. In one method, one or more wellbores are drilled along preplanned paths based in part upon seismic surveys performed from the surface. An acoustic transmitter conveyed in such wellbores transmits acoustic signals at a one or more frequencies within a range of frequencies at a plurality of spaced locations. A plurality of substantially serially spaced receivers in the wellbores and/or at surface receive signals reflected by the subsurface formations. The sensors may be permanently installed in the boreholes and could be fiber optic devices. The receiver signals are processed by conventional geophysical processing methods to obtain information about the subsurface formations. This information is utilized to update any prior seismographs to obtain higher resolution seismographs. The improved seismographs are then used to determine the profiles of the production wellbores to be drilled.

Abstract: A method and system of dual wavefield reinforcement or increasing the contributions to each image point in the seismic image can be accomplished by aligning the upward traveling energy, U, and the downward traveling energy, D, and then summing U and D in the stacking process. A method of dual wavefield reinforcement includes receiving seismic data having both up going and down going wavefields. The up going wavefields are separated from the down going wavefields. Pre-NMO and post NMO statics for each of said up going and said down going wavefields are calculated. The determined pre-NMO static is applied to each of the up going and the down going wavefields. NMO/DMO stacking velocities for the seismic data on an up going wavefield floating datum is determined.