The downhole tool 10 has a drill collar 20, a borehole sensor 50, and an electronics subsection 52. The drill collar 20 has a stabilizer sleeve 30 disposed thereon, and the borehole sensor 50 is mounted at a stabilizer blade 32. Depending on the desired parameters of interest, the borehole sensor 50 measures data in the borehole environs, and the electronics subsection 52 can process and store the data and can telemeter the data uphole for any of the various purposes associated with LWD/MWD.
A surface processor 64 cooperating with the electronic subsection 52 may handle the data and can perform additional mathematical operations associated with standard geological applications. Processed data can then be output to a recorder 66 for storage and optionally for output as a function of measured depth thereby forming an “image” or “log” 68 of one or more parameters of interest. All throughout operations, signals can be sent downhole to vary the direction of drilling or to vary the operation of the downhole tool 10.
There are a few techniques for mounting a sensor on a downhole tool 10 for interaction with a borehole BH. Conventional wisdom in the art has been to either install the sensor externally on a drill collar or stabilizer or to particularly configure the sensor to install on the drill collar or stabilizer. Thus, one technique simply mounts a sensor with a plate on a portion of a drill collar. For example, U.S. Pat. No. 7,250,768 to Ritter et al. discloses a modular cross-over sub for a bottom hole drilling assembly having a stabilizer. Separate from the stabilizer, a resistivity sensor on a plate affixes to the outside of the sub where the sensor and measuring electronics are disposed.
Alternatively, a sensor can be directly part of a stabilizer. For example, U.S. Pat. Pub. No. 2009/0025982 discloses instrumentation devices disposed externally on a blade of a stabilizer using rings attached to the blade with screws or other attachment means.
Finally, a particularized package for a sensor can fit in a recess of a downhole tool and can have a stabilizer fit thereover. For example, U.S. Pat. No. 6,666,285 to Jones et al. discloses a drilling conduit having a cavity particularly sized to receive an instrument package. A portion of the package radially protrudes a distance, and an alignment channel in a stabilizer element is dimensioned to receive the protruding portion of the instrument package. For ease of manufacturing, the alignment channel extends the entire length of the stabilizer element.
As a particular example,
The sensors used for LWD/MWD applications typically measure parameters of the formation traversed by the borehole or of the borehole itself. In typical applications, measurement accuracy is degraded by excessive and/or inconsistent standoff between the sensor and the surrounding borehole wall. To reduce standoff, the sensor 50 may actually be positioned in the drill collar's pocket 24 at a further radial distance than the drill collar's outer surface 23. This allows the sensor 50 to position closer to the borehole wall. To help maintain the consistent standoff and to protect the sensor 50, a stabilizer sleeve 30 is typically employed and is positioned directly on the drill collar's outer surface 23. When the sleeve 30 is pushed into position on the outside of the drill collar 20, one of the stabilizer blades 32 on the stabilizer sleeve 30 fits directly over the sensor housing 40, and the stabilizer sleeve 30 can be retained using a shoulder on the drill collar 20 and a bushing 34 or other features.
Because the housing 40 is physically mounted to the collar 20, the distance between the sensor 50 and the borehole wall will change if the diameter of the borehole BH to be drilled is changed and if the stabilizer sleeve's diameter is also changed accordingly. This impacts the ability to make consistent measurements with the sensor 50 when used in different configurations because the changes in distance from the borehole wall will attenuate the measurements made.
For example,
Yet, in both circumstances, the sensor housing 40 hard-mounted to the drill collar 20 keeps the sensor 50 at the same position on the drill collar 20. As a result, the sensor 50 has a smaller standoff S1 relative to the wall of the smaller borehole BH1, but has a larger standoff S2 relative to the wall of the larger borehole BH2.
For measurement accuracy, the sensor 50 is typically calibrated electronically and with processing algorithms to operate best with a particular standoff from the borehole wall. Due to the different sized stabilizer sleeves 301 and 302 needed in some drilling applications as seen in
As always, changes or modifications made in drilling applications can increase costs, slow down drilling operations, engender unwanted errors, and the like. For these and other reasons, the subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
A sensor and stabilizer arrangement for a borehole drilling tool allows a sensor to be mounted with the same standoff from a borehole wall independent of the size of stabilizer, borehole, and collar involved. The drilling tool has a drilling body, such as a drill collar, defining a receptacle exposed in its outer surface. An electronic sensor component for an LWD/MWD-type sensor or detector disposes in the receptacle, but does not affix in the receptacle. Instead, a stabilizer fits over the drill collar and covers the receptacle and sensor component, and the sensor component mounts directly to the underside of the stabilizer. For example, fasteners affix in openings on the outside surface of the stabilizer and mount the sensor component directly to the underside of the stabilizer so that the electronic component “floats” or “suspends” in the receptacle. Preferably, the sensor component mounts directly to the stabilizer's underside at one of the stabilizer blades so a sensor element exposed on the outside of the stabilizer can be positioned in proximity to the borehole wall to measure parameters of interest.
The drill collar and sensor component can be used in different sized boreholes during drilling, and different sized stabilizer may be positioned on the drill collar to account for the different sized boreholes. Thus, the disclosed arrangement offers a modular system in which the same sensor component and drill collar can be used together and different sized stabilizers can be interchanged thereon depending on the borehole size. Because the same sized drill collar and sensor components may be used to drill larger or smaller sized boreholes, having the sensor component mounted directly underneath the stabilizer maintains the same standoff between the sensor and the borehole wall regardless of the borehole size being drilled. Thus, operators can use the same sensor components for different sized boreholes and do not need to reconfigure or recalibrate the sensor to operate with a different standoff in different sized boreholes.
The disclosed stabilizer and sensor arrangement is in contrast to the typical hard-mounting of sensor components to the drill collar in the prior art. Being coupled to the stabilizer, the sensor maintains a consistent standoff from the borehole wall, and the sensor can be calibrated to obtain the best measurements with this particular standoff. The disclosed arrangement can offer a number of benefits in the operation of a drilling tool having a sensor because the arrangement maintains a consistent distance between the borehole wall and any sensors, independent of tool body size, stabilizer size, or borehole size. As a result, there will be less measurement attenuation in comparison to the current collar mounted scheme.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.
The tool's sensor housing 140 disposes in a receptacle or pocket 124 formed on the outer surface 123 of the drill collar 120. The sensor housing 140 holds the borehole sensor 150 beyond the collar's outer surface 123 so the sensor 150 can be positioned in closer proximity to a borehole wall (not shown) for measuring parameters of interest. As will be appreciated, the sensor 150 can be any LWD/MWD sensor, detector, or other device used in the art, including, but not limited to, a resistivity imager, a gamma sensor, an extendable formation testing sensor, a transducer, a transceiver, a receiver, a transmitter, acoustic element, etc. To provide strength and to reduce electrical interference, the sensor housing 140 can be made from a suitable alloy.
The drill collar 120 has a stabilizer 130 disposed thereon to stabilize the drill collar 120 during operation and to position the sensor 150 closer to the borehole wall. Although not shown, the stabilizer 130 can affix to the drill collar 120 using any of the common techniques known in the art. For example, the stabilizer 130 can be heat shrunk onto the collar 120, and/or ends 136 of the stabilizer 130 can be affixed by welding, fasteners, or the like.
Rather than hard-mounting the sensor housing 140 to the drill collar 120 as in the prior art, the sensor housing 140 mounts directly to the underside or undersurface 134 of the stabilizer 130 and preferably mounts at one of the extended stabilizer blades 132. By mounting directly to the undersurface 134, the sensor housing 140 is essentially supported at its circumferential distance on the drill collar 120 independent of the receptacle 124. Accordingly, the housing 140 “floats” or “suspends” in the drill collar's receptacle 124. As shown in
The sensor housing 140 has a central passage or compartment 144 in which electronic components 154 of the sensor 150 mount. Typically, the electronic components 154 include a circuit board, power supply, and other elements needed for operation of the sensor 150. The internal components 154 can operatively couple to one or more external sensor elements 152 exposed on the surface of the stabilizer 150, but this depends on the sensor 150 used as some sensors may not require such an exposed element 152. The sensor element 152 is intended to interact with the borehole wall, annulus, etc. to obtain measurements of interest.
End caps 148 affix to open ends of the housing 140 to seal the housing's compartment 144 so the electronic components 154 can be protected from pressures and drilling fluid. These end caps 148 can have passages to communicate electric wiring, hydraulics, or the like between the sensor components 154 and other parts of the tool 100, such as memory or telemetry components.
Finally, the end-section of
With a general understanding of the stabilizer and sensor arrangement, assembly of the disclosed arrangement is discussed with reference to
The sensor housing 140 is a pressure housing, and as shown in
As shown in
During assembly, the sensor housing 140 is outfitted with the components and electronics of the sensor 150, end caps 148, etc. Assemblers then set the housing 140 temporarily in the collar's receptacle 124. Assemblers then slide the stabilizer 130 shown in
The advantages of the sensor and stabilizer arrangement of the present disclosure are best illustrated with reference to
To account for the difference in borehole size relative to the same sized drill collar 120, different sized stabilizers 1301 and 1302 are used when drilling. The first stabilizer 1301 (
Yet, in both circumstances, the sensor housing 140 mounted to the undersurface 134 of the stabilizer 130 keeps the sensor 150 at similar standoffs S3 and S4 from the borehole wall. The similar standoffs S3 and S4 are preferably the same, although they may vary to some degree dependent on the sensitivity and calibration of the sensor 150. Having the similar standoffs S3 and S4 is possible because the sensor housing 140 “floats” or “suspends” in the collar's receptacle 124 as noted above and sits at different radii R3 and R4, respectively, for the different sized boreholes BH1 and BH2.
As noted previously, the sensor 150 is calibrated electronically with processing algorithms to operate best with a particular standoff from the borehole wall. Using the disclosed arrangement, the particular standoff S for the sensor 150 can be maintained despite the different sized stabilizers 1301 and 1302 needed in some drilling applications. Accordingly, operators do not need to recalibrate the sensor 150 to operate with a different standoff and do not need to use an entirely different sensor as required in the prior art. Thus, the disclosed arrangement offers a modular system in which the same component, including sensor 150 and housing 140, and the same drill collar 120 can be used together and in which different sized stabilizers 1301 and 1302 can be interchanged on the drill collar 120 depending on the borehole size.
In addition to the above, there are other advantages of the disclosed sensor and stabilizer arrangement.
The sensor element 152 is installed in the sensor opening 135 of the blade 132 and extends down into the sensor opening 145 in the sensor housing 140. Various features, such as fasteners, threads, bushings, welds, etc. are not shown, but can be used to retain the sensor component 150 in these openings 135 and 145. In addition to (or as an alternative to) such features, one or more sealing members 170 can be disposed between the interface of the sensor component 150 and the housing's opening 145. Thus, the sensor element 152 is exposed on the surface of the blade 132 and extends into the housing's sealed compartment 144 where the element 152 operatively couples to the electronic components 154.
When the drill collar 120 is deployed downhole in a borehole, fluid pressure Fp from the borehole as shown in
As shown in
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.
This application claims the benefit of U.S. Provisional Appl. No. 61/551,609, filed 26 Oct. 2011, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61551609 | Oct 2011 | US |