Abstract:
Systems and methods for detecting faults in the active damping of a logging tool are disclosed herein. A wellbore logging tool system comprises a processor, a memory, a wellbore logging tool comprising an acoustic transmitter, and a logging tool control module. The logging tool control module is operable to receive sensor signals from one or more sensors coupled to the wellbore logging tool after a damping control signal has been transmitted to the acoustic transmitter. The logging tool control module is also operable to determine one or more expected sensor signals, determine error values using the expected sensor signals and the sensor signals received from the one or more sensors, and compare the error values with one or more thresholds.
Abstract:
The disclosure addresses acoustic receivers including an acoustic isolator structure, and an acoustic logging tool which incorporates the acoustic receiver. The acoustic receiver isolation structure is configured to minimize acoustic transmissions which could otherwise adversely affect acoustical measurements being made by an acoustic receiver. The described acoustic receiver includes a plurality of longitudinally arranged mass members coupled to a central supporting structure, in a configuration to reduce acoustic transmissions in at least selected frequency ranges.
Abstract:
Various systems and methods for implementing and using a variable stiffness downhole tool housing include cylindrical segments positioned along a common axis, with a pair of segments each coupled to a bulkhead and positioned at either axial end of the tool housing. The housing also includes a flexible cylindrical sleeve, positioned along the common axis between two of the plurality of cylindrical segments, that includes a first and second region with an outer diameter no larger than a common segment inner diameter and a third region located between the first and second regions and with an outer diameter no larger than a common segment outer diameter (the first and second regions each at least partially inserted into an end of one segment). A stiffness controller controls the stiffness of the tool housing by controlling at least part of an axial force exerted between the two segments.
Abstract:
Methods and apparatus for reducing the impact of guided (or “tube”) waves in permanently installed seismic systems are provided. By utilizing passive acoustic absorbers, the impact of tube waves may be reduced, leading to improved performance of permanently installed seismic systems that are installed onto production tubing when the well is completed.
Abstract:
An acoustic attenuator assembly for an acoustic tool for performing acoustic investigation of a subterranean formation is disclosed. The acoustic attenuator assembly includes a first end portion (205) and a second end portion (215) having a bore therethrough to enable passage of an electrical line. The acoustic attenuator assembly further includes a fiber portion (230) disposed between the first and second end portion so that the fiber portion attenuates at least a portion of acoustic energy when the acoustic energy is received by one or both of the first (205) and second (215) end portions.
Abstract:
An acoustic isolator for use with tubular assemblies such as drillpipe or production tubing comprising an acoustic wave transmitter, the acoustic isolator comprising, in series connection, an odd integer λ/4 multiple tuning bar of first acoustic impedance adjacent the acoustic wave transmitter, an odd integer λ/4 multiple reflector tube of second acoustic impedance, and a snubber of third acoustic impedance, wherein there is an acoustic impedance mismatch between the odd integer λ/4 multiple tuning bar and the odd integer λ/4 multiple reflector tube and an acoustic impedance mismatch between the odd integer λ/4 multiple reflector tube and snubber, such that a ‘down’ wave propagated toward the isolator is reflected back substantially in phase with an ‘up’ wave propagated from the acoustic wave source away from the isolator. Furthermore, the acoustic isolator is similarly effective in reflecting ‘up’ propagating waves originating from below the isolator, hence further protecting the acoustic wave source from possible deleterious interference.
Abstract:
An acoustic isolator for attenuating through-tool acoustic signals comprises a plurality of u-shaped link members, where each link member has two sets of ears. A plurality of yoke members are adapted to fit between cooperating sets of ears. A plurality of pins connect the plurality of u-shaped link members to the plurality of yoke members for providing limited flexural compliance. The isolator may be made from metallic and/or composite materials.
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:
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:
An acoustic attenuator includes a housing having an inner side surface which defines an interior chamber and at least one dampening member both physically and acoustically coupled to the housing and projecting into the interior chamber. Acoustic energy propagating within the housing is deflected into the dampening members for acoustically dispersal within the interior chamber. In various aspects thereof, the dampening members may include one or a group of two or more generally cylindrical sleeves having one end both physically and acoustically coupled to the housing and a second end projecting into the interior chamber. Preferably, when a group of two or more cylindrical sleeves are employed, the sleeves are nested within one another. The dampening members may further include a second, oppositely disposed, group of two or more acoustic attenuators nested within one another and interdigitated with the first group of cylindrical sleeves.