Abstract: A method of processing first and second sets of data signals obtained through remotely sensing properties of the same subsurface area at different times comprising the steps of decomposing said first and second data sets into subvolumes of samples and generating subsidence estimates indicating the amount and direction the samples from said first data set need to be translated to obtain a new representation of said first data subvolume that maximally resembles said second subvolume. Preferably, the method further includes the step of derivating said subsidence estimates along the vertical direction in order to generate samples indicating the relative local compaction of the subsurface.

Abstract: A method of gravel packing a wellbore which has at least one aperture therein that provides a fluid flow path between the wellbore and an adjacent subterranean formation. At least a part of the formation adjacent to the open hole has a filter cake coated thereon that comprises a water and oil emulsion. The method of gravel packing comprises injecting into the wellbore a gravel pack composition that comprises gravel and a carrier fluid. The carrier fluid comprises an aqueous liquid having a pH that is outside the range at which the filter cake emulsion is stable. The aqueous liquid is present in an amount effective to invert the water in oil emulsion in the filter cake when the carrier fluid comes into contact with the filter cake. As a result, gravel is deposited at or adjacent to the aperture in the wellbore and some of the filter cake is removed.

Abstract: A linkage apparatus for selectively gripping and releasing the inside walls of a conduit, the apparatus comprising: a first arm; a bi-directional gripping cam rotatably attached to the arm; and an extension and locking device adapted to selectively radially extend the arm from a tool housing to an inside wall of a conduit and adapted to selectively lock the arm in an extended position.

Abstract: A tool generates signals indicative of shear wave slowness of the formation surrounding a borehole. The tool comprises a collar portion adapted for mounting in a drill string, a quadrupole sonic transmitter mounted to the collar portion, and a quadrupole sonic receiver array mounted to the collar spaced apart from the transmitter. A method determines shear wave slowness of the formation. The method includes propagating quadrupole wave energy into the formation and detecting quadrupole dispersive waveforms received at a second location.

Abstract: A shielding method and apparatus for an antenna disposed on an elongated support adapted for disposal within a borehole. The shield providing predetermined attenuation of one or more electromagnetic energy field components as the field components interact with the shield. The shield composed of a flexible strip or cylindrical body and respectively comprising a transverse conductive element or a transverse slot therein. The shields being adapted to cover an antenna mounted on the support. The shields being compatible for use in conjunction with saddle, tilted coils or multi-layered tri-axial coils to produce a pure transverse magnetic dipole electromagnetic field. The shields are also used in methods for shielding an antenna disposed on a support to provide predetermined attenuation of an electromagnetic field component as the field components interact with the shield.

Abstract: A method for aligning measurements of a hostile environment includes synchronizing at least two clocks, wherein at least a first clock is in the hostile environment, measuring characteristics of the hostile environment, aligning time domain curves of the collected measurements, correlating the curves using one or more events recorded by each clock, and correcting the curves by adding one or more time offsets. The offsets may be added to a found resent event or at other locations on the time domain curve. A second clock may be located outside the hostile environment or within a same or similar hostile environment. The collecting the measurements may be taken by a first measurement tool in a first device near the first clock and in at least a second device coupled to a second clock.

Abstract: In order to ensure that at least some of the tools (12-1) to 12-4) in a string of tools that is permanently installed in an oil well (10) are kept in operation even in the event of a localized fault, the link (18) interconnecting the tools and a surface installation (16) is subdivided into segments by switch members (20). More precisely, a switch member is associated with each tool. In addition, the link (18) forms a loop with both ends thereof being connected to the surface installation (16).

Abstract: The invention relates to a method of measuring pressure in which an evacuated capsule (1) containing a resonant element (5) is placed in the fluid whose pressure is to be measured, a vibration characteristic of the element is measured, and the pressure is deduced from said characteristic. A resonant element is used which, during measurement, is to be found in a stress state that is close to buckling. For this purpose, it is possible to use heater means for heating the element and servo-controlled so as to keep the frequency of vibration thereof constant. The resonant element can be made of silicon. The invention is particularly applicable to oil wells.

Abstract: A gravity measuring apparatus is provided comprising a gravitational force detector including a test mass and which produces measurements related to gravitational force exerted on the test mass, characterized in that the gravitational force detector is adapted for use downhole and includes a compensator to compensate for errors in measurements made whilst downhole. The compensator may comprise a guide rail along which the gravitational force detector is moveable over a calibrated distance. Where the test mass is biased toward an equilibrium position about which measurements are made.

Abstract: A method for determining properties of an earth formation surrounding an earth borehole that involves: providing a logging device moveable through the borehole; transmitting sonic energy into the formation; receiving sonic energy that has traveled through the formation; producing signals representative of the received sonic energy; determining whether the formation is anisotropic; determining whether the formation is inhomogeneous; and outputting a characterization of the formation as one of the following types: isotropic/homogeneous, anisotropic/homogeneous, isotropic/inhomogeneous, and anisotropic/inhomogeneous.

Abstract: The effect of various chemical or biological agents in well treatment fluids can be delayed by sequestering the agents in the discontinuous phase of an emulsion for a period of time, before the emulsion is destabilized by exposure to at least one of: (1) a change in temperature, (2) a change in pH, (3) a change in salinity, (4) a change in alcohol concentration, (5) a change in stabilizing surfactant concentration, (6) a change in organic ion concentration, (7) a change in destabilizing surfactant concentration, (8) a change in surfactant adsorbent material concentration, (9) an ultrasonic pulse, and (10) an electrical field. Upon exposure to the emulsion destabilizing condition, the agent sequestered in the discontinuous phase of the emulsion is released into the continuous phase of the fluid composition, where it can have its intended effect.

Abstract: A method for determining a radial profile of sonic shear velocity of formations surrounding a fluid-containing borehole, including: suspending a logging device in the borehole; transmitting sonic energy from the logging device to establish flexural waves in the formation; receiving sonic energy from the flexural waves and producing, from the received sonic energy, measurement signals at a number of frequencies; determining, at each frequency, the flexural wave velocity in the formation; deriving sonic compressional and shear velocities of the substantially undisturbed formation; deriving sonic compressional velocity of the borehole fluid; and determining the radial profile of sonic shear velocity from the derived compressional and shear velocities of the substantially undisturbed formation, the derived compressional velocity of the borehole fluid, and the flexural wave velocities.

Abstract: A method of forming a stator for a positive displacement motor. The method includes forming a liner that includes at least two resilient layers and at least one fiber layer, and the at least two resilient layers are positioned so as to enclose the at least one fiber layer. The liner is positioned in a stator tube, and the stator tube includes a shaped inner surface including at least two radially inwardly projecting lobes extending helically along a selected length of the stator tube. The liner is cured in the stator tube so that the liner conforms to the radially inwardly projecting lobes formed on the inner surface and to the helical shape of the inner surface. The curing forms a bond between the liner and the inner surface and between the at least two resilient layers and the at least one fiber layer.

Abstract: A system is disclosed for communication from an instrument disposed in a wellbore. The system includes a flow diverter selectively operable to conduct fluid flow between a first path along the interior of a housing and a second path along the interior of the housing. The system includes an initiator operatively coupled to the flow diverter to cause selective operation thereof in response to an event.

Abstract: A cable includes an electrical conductor, a first insulating jacket disposed adjacent the electrical conductor and having a first relative permittivity, and a second insulating jacket disposed adjacent the first insulating jacket and having a second relative permittivity that is less than the first relative permittivity. A method includes providing an electrical conductor, extruding a first insulating jacket having a first relative permittivity over the electrical conductor, and extruding a second insulating jacket having a second relative permittivity over the electrical conductor, wherein the second relative permittivity is less than the first relative permittivity.

Abstract: A magnetic receiver with a magnetically permeable core is positioned inside a wellbore casing and operated in a feedback mode to reduce attenuation of a measurable magnetic field. The receiver employs a feedback device to reduce mutual coupling between the core and the casing, which reduces the otherwise normal attenuation of em signals inside the casing. The feedback device may be provided in the form of an extra or feedback winding that effectively cancels the inducing field inside the core and reduces the attenuation otherwise caused by the core-casing interaction. Alternatively, the magnetic receiver may employ, as the feedback device, a current feedback amplifier circuit to cancel the inducing field inside the core. Specifically, the circuit is operated to produce a secondary magnetic field that essentially cancels the inducing field inside the core.

Abstract: Nuclear magnetic resonance methods for extracting information about a fluid in a rock are described. A system of nuclear spins in the fluid are prepared in a driven equilibrium, and a series of magnetic resonance signals generated from the fluid. The series of magnetic resonance signals is detected and analyzed to extract information about the fluid in the rock.

Abstract: A method is disclosed for determining a position of a wellbore with respect to layer boundaries in earth formations. The method includes projecting a trajectory of the wellbore onto an initial model of the earth formations, selecting a segment of the trajectory and calculating along the segment expected responses of a well logging instrument. Differences between the expected responses and responses measured by the instrument along the segment are determined. The model is adjusted, the expected responses are recalculated and the differences are again determined. These are repeated until the differences fall below a selected threshold. In one embodiment, the trajectory of the wellbore can be adjusted to remain within a selected distance of a selected one of the layer boundaries.

Abstract: The disclosure describes a system and method for dynamically matching a source impedance to a load impedance or the complex conjugate of the load impedance. An embodiment of the present invention is a device for active impedance matching comprising a current driver having an output connected to a load, means for detecting an output voltage from the current driver to the load, means for scaling the detected output voltage by a scaling value, and means for subtracting a value representing the scaled detected output current from an input signal of the voltage driver.

Abstract: A method of and apparatus for determining a physical property of a material. The method includes: attaching nanoparticles to a substrate; positioning the substrate near the material; illuminating the nanoparticles with photons having wavelengths that stimulate surface enhanced Raman emissions; detecting photons emitted as a result of the illumination; and determining said physical property of said material using said detected photons. The apparatus includes: a substrate; nanoparticles attached to the substrate; a light source, connected to the substrate, for illuminating the nanoparticles with photons having wavelengths that stimulate surface enhanced Raman emissions; a photodetector, connected to the substrate, for detecting photons emitted as a result of illumination of the nanoparticles; and a processor, connected to the photodetector, for determining a property of material near the nanoparticles from the detected photons.