Abstract: A method and apparatus for deploying seismic detectors and monitoring seismic activity associated with a production well from a down hole location within a well.

Abstract: Methods and systems for acoustically determining reservoir parameters of subterranean formations. A tool comprising at least one seismic source or seismic receiver mounted thereon; a conveyance configured for movement of the acoustic tool in a borehole traversing the subterranean formations; and a source retainer configured or designed for permanent deployment in the borehole to removably retain the acoustic tool in the borehole. The source retainer when deployed provides acoustic coupling with the borehole and removably retains the acoustic tool in the borehole so that, over multiple deployments, the acoustic tool is repeatedly deployed at the same predetermined location and orientation relative to the subterranean formation, and with the same acoustic coupling to the borehole.

Abstract: A technique for processing acoustic waveforms includes: (a) transforming at least a portion of the acoustic waveforms to produce frequency-domain signals; (b) obtaining a model dispersion curve based on a borehole-formation model having a set of borehole-formation parameters; (c) adjusting phases of the frequency-domain signals according to the model dispersion curve to produce back-propagated signals; (d) computing coherence of the back-propagated signals; (e) repeating steps (b)-(d) by varying values of the set of borehole-formation parameters until the coherence reaches a selected criterion; and (f) outputting at least a portion of the set of borehole-formation parameters.

Abstract: Method for identifying one or more fracture clusters in a formation surrounding a reservoir. In one implementation, the method may include generating a P to S image, comparing the P to S image to one or more images from a borehole, and identifying one or more fracture clusters using the P to S image and the borehole images.

Abstract: A magnetically clamped wellbore instrument module includes a substantially non-magnetic housing configured to traverse an interior of the wellbore. At least one electromagnet is disposed at a longitudinally spaced apart position along the housing. The at least one electromagnet has a plurality of circumferentially spaced apart contact points that define a diameter greater than a diameter of the housing. The contact points have circumferential spaces therebetween defining a diameter smaller than the diameter defined by the contact points.

Abstract: A sonde and an apparatus for the deployment thereof against a well casing is described, the sonde comprising a resilient C-shaped member and at least one sensor.

Abstract: Seismic sensor systems and sensor station topologies, as well as corresponding cable and sensor station components, manufacturing and deployment techniques are provided. For some embodiments, networks of optical ocean bottom seismic (OBS) stations are provided, in which sensor stations are efficiently deployed in a modular fashion as series of array cable modules deployed along a multi-fiber cable.

Abstract: A method useful for evaluating the presence and/or the quality of the cement bond of a downhole tubular. The method involves measuring radial resonance modes of the tubular, and comparing those measured values to the unbound tubular resonant values of a calibration ring. For a well bonded tubular, the measured radial resonance should be greater than that of the unbound tubular calibration ring. In regions where a fluid, such as water surrounds the outside of the tubular, or the cement is otherwise not bonded to the outer surface of the tubular, the measured response should be less than the calibrated response. The calibration ring should have the same diameter, wall thickness, and be made of the same material as the tubular.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may include generating attenuation values associated with a set of multiple signals received by multiple receivers from a transmitted signal as a function of reception time and material velocity. The attenuation values may be stored in a memory and/or displayed on a display, perhaps in conjunction with a semblance map.

Abstract: An acoustic borehole logging system for generation and detection of multipole modes used to determine elastic properties of earth formations characterized as inhomogeneous anisotropic solids. The system concurrently generates and senses monopole, dipole, quadrupole and any higher order pole in the borehole/formation system in order to characterize the elastic properties and stress state of material penetrated by the borehole. Multipole modes of all orders are induced simultaneously without the need for separate transmitter and receiver systems. Performance of the logging system is not compromised due to eccentering of the axis of the tool in the borehole, tool tilt with respect to the axis of the borehole, or mismatch of response sensitivity of multiple receivers within the tool.

Abstract: Deploying systems and methods for deploying a plurality of seismic devices into a borehole comprising a cable including a plurality of inter-connected cable segments and ellipsoid seismic units with at least two rows of offset seismic protrusions to establish at least three points of contact between the seismic units and adjacent cylindrical surface of a borehole casing.

Abstract: An acoustic sensor configured to detect sound waves traveling through a substrate in which the acoustic sensor is embedded. The acoustic sensor includes a piezoelectric element and mass configured to receive and react to sound waves in three dimensions. Also, methods of using the acoustic sensor to receive sound waves traveling through a substrate.

Abstract: An integrated framework is described for automating some or all of mud slowness estimation for both fast and slow formations. An estimation of fluid slowness based on monopole radial profiling is calculated if conditions permit. Alternatively, an estimation of fluid slowness based on Scholte wave slowness is estimated if conditions do not permit calculation based on monopole radial profiling. Tool standoff may also be estimated based on monopole radial profiling.

Abstract: Correcting seismograms to compensate for absorption or dissipative effects that occur in the earth. In one implementation, a ratio of traveltime (t) to absorption parameter (Q) may be computed for each seismogram. The ratio may be referred to as R. Further, the ratio may be computed for a predetermined set of traveltimes. As a result, a system of linear equations may be generated, where each ratio is represented by a linear equation having a number of unknown components. The system of linear equations may then be solved for the unknown components. The solved components may then be recombined or added to generate an estimate of R. In one implementation, only a portion of the solved components may be added. The seismograms may then be corrected using the estimate of R. As such, the seismograms may be corrected for absorption effects in a surface consistent manner.

Abstract: A measurement package for disposal on an apparatus such as a downhole tool or a tool like device. The measurement package including an enclosure, a first acoustic transducer housed within the enclosure, a second acoustic transducer housed within the enclosure and electronics housed within the enclosure that is in communication with the first and second transducers. Further, an acoustic transmitter and receivers can be disposed at an angle with respect to a longitudinal axis of the enclosure. The enclosure can contain attenuative material surrounding the transmitter and receivers, and electronics for controlling the transmitter and receivers and communicating with the downhole tool.

Abstract: An improved energy efficient intelligent pulser driver used for generating a mud pulse in a MWD (measurement while drilling) application. In the pulser driver, a direct current (DC) powered control circuit activates a three-phase DC brushless motor that operates a servo-valve. Opening of the servo-valve equalizes pressure in a plenum causing the operation of a main valve reducing flow area and causing a pressure spike in the mud column. Closing of the servo-valve creates a reduction in mud pressure that operates the main valve and increases the flow area causing an end to the pressure spike. The servo-valve is powered both in opening and closing operations by the motor.

Abstract: An acoustic borehole logging system for generation and detection of multipole modes used to determine elastic properties of earth formations characterized as inhomogeneous anisotropic solids. The system concurrently generates and senses monopole, dipole, quadrupole and any higher order pole in the borehole/formation system in order to characterize the elastic properties and stress state of material penetrated by the borehole. Multipole modes of all orders are induced simultaneously without the need for separate transmitter and receiver systems. Performance of the logging system is not compromised due to eccentering of the axis of the tool in the borehole, tool tilt with respect to the axis of the borehole, or mismatch of response sensitivity of multiple receivers within the tool.

Abstract: An acoustic isolator for use with downhole subterranean exploration and production operations, where the operations transmit acoustic signals into a subterranean formation. The acoustic isolator comprises a series of threaded fittings and is disposed on a downhole tool between a transmitter and a receiver. The acoustic isolator substantially attenuates the acoustic signal along the body and minimizes its effect on the receiver.

Abstract: A downhole logging tool is equipped with a modified Helmholtz resonator for facilitating acoustic formation evaluation and reservoir characterization. The resonator permits calculation of sound speed and viscosity of the fluid in the resonator cavity. The presence of gas bubbles in the fluid may also be detected. The modified Helmholtz resonator includes at least two openings so that fluid can flow through the resonator cavity. Because fluid can flow through the resonator cavity, local fluid can be measured under local conditions, e.g., downhole temperature, pressure, and gas influx from formations. Further, the modified Helmholtz resonator utilizes an acoustic signal at or near the frequency of interest for at least some acoustic logging tools.

Abstract: When a static magnetic field and a crossed oscillating field are applied, the deformation rate at a boundary between a fluid and a porous medium depends on the amplitudes of the applied magnetic fields (to be exact, on their product), electric conductivity, porosity, and permeability. Knowing two of the three enables determination of the third. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Abstract: Embodiments of the present invention relate to a caliper and method for mapping the dimensions and topography of a formation such as the sidewall of a borehole. Examples of formations in which embodiments of the invention can be used include, but are not limited to, an oil, gas, pile borehole or barrette that has been drilled or excavated into the earth.

Abstract: A method and apparatus for enhancing the moveout between a direct wave and a reflected wave. The method involves transmitting imaging signals into a body to be imaged and receiving the resulting signals propagated from the signal source. The step of receiving the propagated signals includes selectively adjusting the distance between the signal source and the signal receivers between successive signals. The method further comprises separating the reflected signals from the total received signals and enhanced stacking of the measured reflected signals.

Abstract: The present invention provides a method and apparatus for using an acoustic logging tool conveyed in a borehole in an earth formation for determining a characteristic of the formation. The method comprises using a first acoustic source for generating an acoustic signal in the earth formation at a first frequency. A second acoustic source spaced apart from the first source is used for generating an acoustic signal in the earth formation at a second frequency different from the first frequency. An acoustic receiver is used for receiving a third acoustic signal indicative of said characteristic. The third acoustic signal has a frequency substantially equal to a difference between the first frequency and the second frequency. The third acoustic signal is produced by a nonlinear interaction between the first signal and the second signal in a portion of said earth formation.

Abstract: Acoustic transducers configured with transducer elements disposed on an arch or arcuate shaped member adapted to fit in juxtaposition around a tubular. The arcuate shaped member is adapted with conductors to provide a voltage to the transducer elements. One embodiment uses a metallic arcuate shaped member. Embodiments implemented as sources are used to excite borehole acoustic modes. Some embodiments provide phased array acoustic energy excitation/signal reception. The transducers are covered with a sealer in a liquid-free configuration and shields are used to protect the transducers.

Abstract: An apparatus for logging a formation traversed by a borehole includes a plurality of logging tools adapted for conveyance inside the borehole. The plurality of logging tools includes a tool body, a sensing pad responsive to a density property of the formation coupled to the tool body, a current emitting measure electrode responsive to a lateral resistivity property of the formation incorporated on the sensing pad, a mechanism for urging the sensing pad in contact with a side of the borehole coupled to the tool body, and a pair of mass isolation bands disposed about the tool body to isolate a mass of the tool body adjacent the measure electrode.

Abstract: The disclosure relates to methods and apparatus for determining the velocity of an ultrasound pulse in drilling fluids in downhole environments. A method for determining a velocity of ultrasound propagation in a drilling fluid in a downhole environment includes emitting an ultrasound pulse into the drilling fluid in a borehole using a first ultrasound transducer (37); detecting the ultrasound pulse after the ultrasound pulse has traveled a distance (d); determining a travel time (t) required for the ultrasound pulse to travel the distance (d); and determining the velocity of ultrasound propagation from the known distance (d) and the travel time (t).

Abstract: An acoustic isolator section for an acoustic well logging tool, the isolator section comprising: an isolator comprising: (i) an isolator body; (ii) a mass; (iii) a resilient portion formed integrally with the isolator body; (iv) a movement limiter.

Abstract: Methods and an apparatus for determining at least one characteristic of an environment are disclosed. A vibrational energy may be imparted into an environment and a magnitude of damping of the vibrational energy may be measured and at least one characteristic of the environment may be determined. Particularly, a vibratory source may be operated and coupled to an environment. At least one characteristic of the environment may be determined based on a shift in at least one steady-state frequency of oscillation of the vibratory source. An apparatus may include at least one vibratory source and a structure for positioning the at least one vibratory source proximate to an environment. Further, the apparatus may include an analysis device for determining at least one characteristic of the environment based at least partially upon shift in a steady-state oscillation frequency of the vibratory source for the given impetus.

Abstract: A method for interpreting transient electromagnetic survey data includes measuring transient response of a medium over a plurality of switching events. The measured transient response to a first one of the current switching events is modeled. Transient response to the model for at least one current switching event prior in time to the at least a first current switching event is calculated. The calculated transient response is summed with the first event measured response and the sum is compared to the electromagnetic survey measurements. The model is adjusted and the calculating summed transient responses is repeated until a difference between the summed calculated responses and the survey measurements falls below a selected threshold.

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: A formation logging tool having a substantially continuous central mandrel with regularly spaced mass blocks disposed thereon, at least some of the mass blocks carrying sensors such as receivers. By adopting this structure, the tool can be made to behave as a mass-spring structure and its flexural and extensional behaviour controlled such that its dispersion curve does not extend into the dispersion curve of the formation to be logged. The structure can be applied to the whole of the logging tool or just to the receiver section and/or any spacer section between the receiver and the transmitter section.

Abstract: The present invention is directed to overcoming analog transmission difficulties by digitizing transducer signals at or near the transducer of an acoustic pulse gun and then transmitting the transducer signals in a digital form so that the signals can be recovered with greater fidelity by a remote computer or recorder. System, apparatus and method aspects of the invention are provided. Advantages of the present invention include better transmission of the acoustic signal from the pulse gun assembly to the computer or recorder, reduced noise and electronic interference, and better data capture.

Abstract: Methods and apparatus are adapted for acquiring seismic data from an array of sensors deployed along a section of a deviated, including horizontal, wellbore for monitoring seismic and microseismic activity. The sensors may be permanently deployed in the wellbore.

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: Apparatus and methods for acoustically isolating logging tool receiver and transmitter sections. One or more modular isolators is arranged between the receiver and transmitter sections. The modular isolators comprise a high tensile strength while also providing for a high wave attenuation level. The modular isolators are mechanical mass-spring systems capable of absorbing acoustic waves propagating along the logging tool. The mass is a swinging sleeve, and the spring includes a Belleville spring stack. The use of the strong modular isolators provides acoustic isolation between the transmitters and receivers for the complete sonic frequency band at multiple modes.

Abstract: A casing sensor and methods for sensing using a casing sensor are disclosed. The casing sensor includes a casing shoe and a sensor coupled to the casing shoe. A casing data relay includes a downhole receiver coupled to a well casing and a transmitter coupled to the receiver. The casing sensor may be coupled to the transmitter. A drill string actuator may be controllable through the downhole receiver.

Abstract: A plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings secured to the inner surface of the collar by neck pieces, extending outwardly from the outer circumference of the ring. The mass irregularities may be made of steel or tungsten and are between six and ten in number. The spacing of the irregularities may lie between twelve and fourteen centimeters. A center pipe may be included to isolate the irregularities from the fluid flow associated with the drilling operation. The pipe may be of a soft material such as rubber to reduce transfer of acoustic noise along the drill string. The irregularities may be in an oil based fluid with the pipe fitting closely in the center of the rings.

Abstract: An apparatus for performing acoustic investigations while drilling a borehole in a subsurface geological formation comprises a longitudinally extending assembly conveyed in the borehole on a drilling tubular. The assembly and the drilling tubular have a drilling fluid flowing through a longitudinally extending passage therein. An acoustic transmitter is supported by the assembly. The transmitter generates acoustic signals in the assembly, the borehole and the subsurface formation. An acoustic receiver is spaced apart from the transmitter and receive the acoustic signals. An attenuator is located in the assembly between the acoustic transmitter and the acoustic receiver for attenuating the acoustic signals in the assembly within a predetermined frequency range. The attenuator comprises a tubular element of a composite material having a substantially cylindrical outer surface. The outer surface has a plurality of spaced apart masses having a predetermined spacing, mass and length firmly attached thereto.

Abstract: The invention relates to a source block with a downhole seismic source for use in seismic acquisition during production, comprising: a device for locking the block in a first position spaced from the well casing, a device for releasing the locking device, a device for urging the source block against the casing. The source block is characterized by comprising, a fluid circuit for controlling the operation of the locking and releasing devices, this fluid circuit comprising a rupture disc.

Abstract: A method, apparatus and system for detecting seismic waves. A sensing apparatus is deployed within a bore hole and may include a source magnet for inducing a magnetic field within a casing of the borehole. An electrical coil is disposed within the magnetic field to sense a change in the magnetic field due to a displacement of the casing. The electrical coil is configured to remain substantially stationary relative to the well bore and its casing along a specified axis such that displacement of the casing induces a change within the magnetic field which may then be sensed by the electrical coil. Additional electrical coils may be similarly utilized to detect changes in the same or other associated magnetic fields along other specified axes. The additional sensor coils may be oriented substantially orthogonally relative to one another so as to detect seismic waves along multiple orthogonal axes in three dimensional space.

Abstract: A sonde and an apparatus for the deployment thereof against a well casing is described, the sonde comprising a resilient C-shaped member (22) and at least one sensor (23).

Abstract: Methods and apparatus for attenuating waves in a bore hole, and seismic surveying systems incorporating the same. In one embodiment, an attenuating device includes a soft compliant bladder coupled to a pressurized gas source. A pressure regulating system reduces the pressure of the gas from the gas source prior to entering the bladder and operates in conjunction with the hydrostatic pressure of the fluid in a bore hole to maintain the pressure of the bladder at a specified pressure relative to the surrounding bore hole pressure. Once the hydrostatic pressure of the bore hole fluid exceeds that of the gas source, bore hole fluid may be admitted into a vessel of the gas source to further compress and displace the gas contained therein. In another embodiment, a water-reactive material may be used to provide gas to the bladder wherein the amount of gas generated by the water-reactive material may depend on the hydrostatic pressure of the bore hole fluid.

Abstract: The invention relates to an apparatus for receiving downhole acoustic signals, processing the signals into electric signals, then transmitting the signals wirelessly to a remote above-surface monitoring station. The apparatus is mountable to an above-surface rotatable component used in borehole application. The apparatus includes an instrument housing, and a clamping assembly attached to the housing and having sufficient length and flexibility to enable the apparatus to surround the perimeter of the rotatable component.

Abstract: Array quadrupole data obtained in a LWD environment are processed to determine the shear velocity of an earth formation taking into account dispersion effects caused by the logging tool. When this processing is done in an azimuthally anisotropic formation, the shear velocity that is obtained is the slow shear velocity. When 4C (cross-dipole) data are also obtained, then both the fast and slow shear velocities of an azimuthally anisotropic formation can be obtained.

Abstract: A plurality of heavy mass irregularities attached to an inner wall of the drill collar attenuate waves traveling through the collar. The plurality of heavy mass irregularities are spaced and sized for the maximum attenuation of acoustic pulses in a predetermined frequency range. The mass irregularities may be rings firmly coupled to the outer surface of the collar. Alternatively, the mass irregularities may be rings firmly coupled to the outer collar surface by neck pieces, extending inwardly from the inner circumference of the ring. The mass irregularities may be made of steel or tungsten. In another preferred embodiment, the mass irregularities are asymmetrically coupled to an outer collar wall for providing preferential directional attenuation.

Abstract: An acoustic logging tool including an elongated body, one or more acoustic transmitters, one or more acoustic receivers, and a broadband acoustic absorption region. A substantial portion of the broadband acoustic absorption region is between the transmitter and the receiver. The acoustic energy absorber includes a first absorber for absorbing a first mode of acoustic energy and a second absorber for absorbing a second mode of acoustic energy. The acoustic absorption material used to make the acoustic absorbers has an acoustic impedance between 20% and 120% of the material used to construct the acoustic logging tool. The acoustic logging tool includes an elongated hollow tool body, an insert configured to be inserted into the tool body, and a ring configured to be inserted onto the insert. A first element is supported by the ring and exposed to a pressure field, and a second element is supported by the ring and exposed to a pressure field.

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: A method and apparatus suitable for coupling seismic or other downhole sensors to a borehole wall in high temperature and pressure environments. In one embodiment, one or more metal bellows mounted to a sensor module are inflated to clamp the sensor module within the borehole and couple an associated seismic sensor to a borehole wall. Once the sensing operation is complete, the bellows are deflated and the sensor module is unclamped by deflation of the metal bellows. In a further embodiment, a magnetic drive pump in a pump module is used to supply fluid pressure for inflating the metal bellows using borehole fluid or fluid from a reservoir. The pump includes a magnetic drive motor configured with a rotor assembly to be exposed to borehole fluid pressure including a rotatable armature for driving an impeller and an associated coil under control of electronics isolated from borehole pressure.

Abstract: The acoustic isolator assembly of the present invention comprises a elongated cylindrical body suited for connection to an acoustic array and subsequent disposition within a wellbore. According to one embodiment of the present invention, the acoustic isolator comprises a plurality of cylindrical isolator modules that are coaxially arranged to form the body of the tool. Each isolator module comprises a spring disposed within an outer housing. The separate isolator modules are attached to one another by connecting rods around which are disposed a plurality of metal spacers. The isolator module further comprises mechanical stops that limit the deflection of the spring during high axial loading. These features enable the acoustic isolator assembly to withstand the high loading that may be applied during logging operations. Therefore, the isolator modules are capable of supporting high compressive and tensile loads without suffering permanent deformation of the springs.

Abstract: A telemetry system involving a shear-type mud pulser valve as the preferred embodiment is described. The control system includes a motor driver for the mud pulser which, in essence, moves one movable plate with respect to a stationary plate to create openings of various sizes. Pressure is sensed uphole of the pulser valve and is compared in real time to the desired pressure pulse amplitude. By allowing different relative rotational positions of the rotatable plate with respect to the stationary plate, different amplitudes can be achieved to further enhance the transmission of data to the surface. The control system compensates for wear in the mud pulser valve itself as well as drastic changes in mud flow and pressure. The configuration is simple and not prone to fouling from grit or other particles in the mud.