摘要:
Apparatus and methods for establishing electrical communication between an instrument subsection disposed below a mud motor and an electronics sonde disposed above the mud motor in a drill string conveyed borehole logging system. Electrical communication is established via at least one conductor disposed within the mud motor and connecting the instrument sub section to a link disposed between the mud motor and the electronics sonde. The link can be embodied as a current coupling link, a magnetic coupling ling, an electromagnetic telemetry ling and a direct electrical contact link. Two way data transfer is established in all link embodiments. Power transfer is also established in all but the electromagnetic telemetry link.
摘要:
A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna. The antenna can also be embodied to be more sensitive to resitivity in a particular azimuthal direction.
摘要:
An electromagnetic antenna for Measurement-While-Drilling (MWD) applications is disclosed. The antenna can include several array elements that can act alone or together in various measurement modes. The antenna elements can be disposed in tool body recesses to be protected from damage. The antenna elements can include a ferrite plate crossed or looped by independent current carrying conductors in two or more directions forming a bi-directional or crossed magnetic dipole. Although disclosed as a MWD system conveyed by a drill string, basic concepts of the system are applicable to other types of borehole conveyance.
摘要:
An electromagnetic borehole telemetry system for transmitting information between a borehole transceiver and a surface transceiver located at or near the surface of the earth. Tubulars, such as steel casing and liners, are typically set within the well borehole to stabilize the wall of the borehole and to assist in hydraulically isolating penetrated formations. The invention utilizes these tubulars cooperating with one or more signal wires to reduce attenuation and noise in signals transmitted between the borehole and surface transceivers. The one or more signal wires are typically disposed within an annulus formed by the borehole wall and the outside surface of the casing. The one or more signal wires are connected at one end to one or more connection terminals positioned preferably near the bottom a tubular string. Opposing ends of the one or more signal wires are connected to one or more terminals of the surface transceiver. By minimizing signal attenuation and noise, the telemetry system can be effectively used at greater depths in the borehole. The telemetry system can be embodied in a measurement-while-drilling system, a formation testing system, a production monitoring system and other system requiring communication between a downhole assembly and the surface of the earth.
摘要:
The present invention is a propagation resistivity system that utilizes one or more transmitter coil antennas, or “transmitters” and at least two receiver coil antennas, or “receivers”. The system uses a wellbore resistivity tool which may be embodied as a MWD tool or as a wireline tool. Two or more transmitters may be spaced equally on either side of two or more spaced-apart receivers. Two or more frequencies are transmitted and received simultaneously. Multiple frequencies may be transmitted from each transmitter or from separate transmitters at the same time. Multiple frequencies are simultaneously received and analyzed by the receiver electronics, thereby reducing the measurement time for multiple frequency measurements. In one embodiment each of two transmitters transmits simultaneously. One transmitter operates on a high frequency. The second transmitter operates at a lower frequency. The higher frequency signal penetrates a relatively shallow radial distance into the formation and the lower frequency penetrates to a radial depth which exceeds the higher frequency. Composite measurements made at two radial depths are used to compensate for factors having adverse effects on resistivity measurements in the immediate region of the borehole. Such factors include invasion, variations in borehole size, variations in borehole fluid, and the like.
摘要:
An NMR apparatus includes permanent magnets oppositely polarized in the axial direction and suitably arranged along the axis of the apparatus to produce a nearly radial static magnetic field in a toroidal examination region within the rock formation surrounding the wellbore. A first coil is wound around a cylindrical annulus core coaxial with the magnets, the core including high magnetic permeability material. The first coil produces pulsed RF magnetic fields oriented parallel to the axis of the apparatus and thus perpendicular to the static magnetic field in the toroidal examination region. This reorients certain nuclear spins and the bulk magnetization of the formation within the examination region resulting from them. The first coil picks up on component of the spin-echo signals of the precessing nucleii. A second coil toroidally wound around the same cylindrical annulus core in the form of a torus with windings in planes parallel to the axis of the apparatus detects a second component of the spin-echo signals. The apparatus also includes a third coil spaced apart from the first coil and having a geometry similar to that of the second coil. An electrically conducting collar shields the third coil from the magnetic fields produced elsewhere in the apparatus. A processor combines the signals from the three coils to give spin-echo signals with improved signal-to-noise ratio.
摘要:
The present invention provides a drilling assembly with a stabilization system that stabilizes at least a section of the drilling assembly as a function of one or more downhole measured parameters or parameters of interest. One or more sensors carried by the drilling assembly measure the desired parameters of interest and a control system controls the stabilizer system in response to one or more determined parameters of interest to provide desired stabilization of a section of the drilling assembly. Measurement-while-drilling sensors whose measurements are affected by the parameters of interest are preferably disposed in the stabilized section. In one embodiment, the stabilization system includes at least two axially spaced apart stabilizers. Each such stabilizer includes a plurality of independently adjustable members that radially extend from the drilling assembly to exert force on the wellbore inside. A control circuit processes the signals from the sensors and in response thereto causes a power unit to independently adjust the force applied by the adjustable members so as to maintain a parameter of interest below a predetermined value. The measurement-while-drilling sensors take measurements while the stabilization system is activated, which may be during the drilling of the wellbore or during retrieval of the drilling assembly from the wellbore. In an alternative embodiment, the stabilization system includes only one stabilizer that may contain a plurality of independently adjustable members.
摘要:
An NMR logging tool has a conducting permanent magnet with its axis parallel to the borehole axis to produce a static field in a portion of the formation surrounding a borehole that is parallel to the borehole axis. A dipole RF antenna with the dipole axis orthogonal to the borehole axis is used to produce an RF magnetic field orthogonal to the static field. The same antenna is used to receive the echo signals from excited nuclei in the formation. A number of gapped ferrite strips on the permanent magnet shield the permanent magnet from the RF field and enhance the RF field. Another form of the tool may be used for making Measurement-While-Drilling measurements with the permanent magnet set in a recess on a drilling collar.
摘要:
The present invention is directed to a measurement-while-drilling logging tool which includes a minimum number of analog electrical and electronic components, and which instead utilizes digitally-controlled electronic and electrical components to obtain an accuracy which is not possible utilizing prior art measurement-while-drilling logging tools. Additionally, the present invention allows for calibration operations to be conducted before, during, and after logging operations. Preferably, the calibration operations are performed periodically or intermittently during logging operations, and recorded, to be utilized later in explaining any irregularities in the log data. This calibration operation during drilling operations is not found in prior art devices, and is rendered practical by the utilization of digitally-controlled electrical and electronic components in lieu of analog components which are traditionally utilized in logging tools. The logging tool of the present invention also allows for the periodic calculation of the undesirable magnetic field mutual coupling between particular receiving antennas. Once the value of the magnetic mutual coupling is calculated, it may be recorded for future use, or automatically subtracted from particular measurements, greatly enhancing the accuracy of logging operations. Finally, the measurement-while-drilling logging tool of the present invention can perform for the first time accurate borehole calipering operations, due in large part to the great accuracy associated with the particular components selected of the preferred embodiment of the present invention.
摘要:
A method for detecting and sensing boundaries between strata in a formation during directional drilling so that the drilling operation can be adjusted to maintain the drillstring within a selected stratum is presented. The method comprises the initial drilling of an offset well from which resistivity of the formation with depth is determined. This resistivity information is then modeled to provide a modeled log indicative of the response of a resistivity tool within a selected stratum in a substantially horizontal direction. A directional (e.g., horizontal) well is thereafter drilled wherein resistivity is logged in real time and compared to that of the modeled horizontal resistivity to determine the location of the drill string and thereby the borehole in the substantially horizontal stratum. From this, the direction of drilling can be corrected or adjusted so that the borehole is maintained within the desired stratum.