The invention relates generally to methods and apparatus for obtaining formation evaluation logs. More specifically, the invention relates to a body for protecting sources and sensors used in measuring formation properties in a borehole environment.
Various well logging techniques are known in the field of hydrocarbon exploration and production. These techniques typically employ logging instruments or sondes equipped with sources adapted to emit energy through a borehole traversing the subsurface formation. The emitted energy interacts with the surrounding formation to produce signals that are detected and measured by one or more sensors on the instrument. By processing the detected signal data, a profile or log of the formation properties is obtained. Logging techniques known in the art include wireline logging, logging while drilling (LWD), measurement while drilling (MWD), and logging while tripping (LWT). Wireline logging involves lowering the instrument into the borehole at the end of an electrical cable to obtain the subsurface measurements as the instrument is moved along the borehole. LWD/MWD involves disposing the instrument in a drilling assembly for to obtain subsurface measurements while a borehole is drilled through subsurface formation. LWT involves disposing sources or sensors within the drill string to obtain measurements while the drill string is withdrawn from the borehole.
Sources and sensors used in making subsurface measurements are typically disposed in cylindrical sleeves or housings. The housing protects the sources and/or sensors from the borehole environment. For example, U.S. Pat. No. 4,873,488 (assigned to the present assignee) discloses a logging sonde including a support having a generally tubular shape. The support is made of a metal that is preferably non-magnetic and has excellent electrical conductivity. Transmitter and receiver coil units are located along the axis of the support. The coil units are insulated from the metallic material of the support by insulating sleeves. Holes are provided in the support for passage of electrical conductors connected to the coil units. The coils and support are installed in an insulating sleeve made of non-conductive material, such as fiberglass-reinforced epoxy, to protect the coil units from the mud in the borehole. U.S. Pat. No. 7,026,813 (assigned to the present assignee) describes a semi-conductive sleeve for subsurface use.
Throughout the development and advances in subsurface measurements, there continues to be a desire for a robust and inexpensive methodology for protecting sources and/or sensors in a borehole environment.
In one aspect, the invention relates to a composite encased tool for making subsurface measurements in a borehole traversing a subsurface formation which comprises a conductive mandrel, a first composite layer wrapped around the conductive mandrel, the first composite layer having one or more slots, a source or sensor disposed in each of the one or more slots, and a second composite layer wrapped around the first composite layer with the source or sensor in the one or more slots.
In another aspect, the invention relates to an apparatus for use in a borehole formed in a subsurface formation which comprises a conductive mandrel and a composite body formed on the conductive mandrel. The composite body comprises a first composite layer wrapped around the conductive mandrel an a second composite layer wrapped around the first composite layer. The apparatus further includes an antenna embedded in the composite body. The antenna is adapted to transmit or receive the electromagnetic energy.
In yet another aspect, the invention relates to a method for forming a logging tool for use in a subsurface formation which comprises wrapping a first composite layer around a conductive mandrel, forming a slot in the first composite layer, disposing a source or sensor in the slot formed in the first composite layer, and wrapping a second composite layer around the first composite layer with the source or sensor in the slot.
In another aspect, the invention relates to a system for subsurface measurement in a borehole traversing a subsurface formation which comprises a logging tool comprising a composite encased tool supported in a borehole. The composite encased tool comprises a conductive mandrel, a first composite layer wrapped around the conductive mandrel, the first composite layer having one or more slots, a source or sensor disposed in each of the one or more slots, and a second composite layer wrapped around the first composite layer and over the source or sensor.
Other features and advantages of the invention will be apparent from the following description and the appended claims.
The accompanying drawings, described below, illustrate typical embodiments of the invention and are not to be considered limiting of the scope of the invention, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale, and certain features and certain view of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.
The invention will now be described in detail with reference to a few preferred embodiments, as illustrated in the accompanying drawings. In describing the preferred embodiments, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that the invention may be practiced without some or all of these specific details. In other instances, well-known features and/or process steps have not been described in detail so as not to unnecessarily obscure the invention. In addition, like or identical reference numerals are used to identify common or similar elements.
Referring to
A variety of conventional sources/sensors 110 may be disposed in the slots 108 to obtain a variety of measurements. The number of slots 108, the number of sources/sensors 110, and the arrangement of the sources/sensors 110 would depend on the type of subsurface measurement being made using the sources/sensors 110. For electromagnetic (EM) tools, the sources/sensors 110 may be antennas. The antennas may be solenoid-type coil antennas, loop antennas, or any coil construction resulting in a longitudinal magnetic dipole (LMD) or transverse magnetic dipole (TMD) as known in the art. An antenna may have one or more coils. LMD antennas typically have one coil, while some TMD antennas may have multiple coils. Where the sources/sensors 110 are solenoid-type coils, the slots 108 may be circumferential slots and the coils may be disposed in the slots 108 by winding the coils directly on and around the circumference of the first composite layer 106 within the slots 108 using, for example, a coil winding machine. Corresponding to an induction tool, a transmitter antenna coil 110a and a receiver antenna coil 110b are disposed in two of the slots 108. A bucking antenna coil 110c may also be disposed in one of the slots 108, near the transmitter antenna coil 110a or the receiver antenna coil 110b, to eliminate direct transmitter-to-receiver coupling. The transmitter antenna 110a transmits electromagnetic energy when energized, while the receiver antenna 110b receives electromagnetic energy which has been modified by the surrounding formation or borehole.
Filler material 116 may be added to the slots 108 to lock the sources/sensors 110 in place and eliminate air pockets that may be trapped underneath the sources/sensors 110 in the slots 108. The filler material 116 may be a curable material such as resin. The filler material 116 may be disposed in the slots 108 such that the filler material 116 is flush with the outer surface 106a of the first composite layer 106. This may include first overfilling the slots 108 with the filler material 116 and then machining down or otherwise filing away the filler material 116. In one example, as illustrated in
The stabilizing composite layer 109 may be made of any composite material suitable for use in a borehole environment. Examples of composite materials include, but are not limited to, fiber-resin composite and polyaryletherketone, such as polyetheretherketone and polyetherketone. The sealant layer 107 may be made of an elastomer or a rubber material. Examples of materials for the sealant layer 107 include, but are not limited to, Neoprene (RTM), Viton (RTM), and Nitrile (RTM). The sealant layer 107 prevents borehole fluids from entering the slots 108 and reaching the sources/sensors 110. The stabilizing composite layer 109 when present provides a stabilizing layer for the sealant layer 107. For example, the stabilizing composite layer 109 may prevent the sealant layer 107 from collapsing into the slots in cases where air pockets are not completely eliminated from the slots 108. The second composite layer 105 may also be made of suitable composite material. In one example, the second composite layer 105 is made of fiber-resin composite. In another example, the second composite layer 105 includes one or more layers of fabric, e.g., glass cloth or graphite cloth, impregnated with resin.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. For example, embodiments of the invention may be implemented with various types of sources/sensors as known in the art (e.g., temperature, pressure, gravity, nuclear, acoustic, microphone sensors, etc.). It will also be understood by those skilled in the art that embodiments of the invention may be implemented with the various EM antenna configurations as known in the art and activated to transmit/receive at any desired frequency or frequency range (e.g., for propagation or induction type measurements).
This application claims priority to U.S. Provisional Application No. 60/690,328, entitled “Composite Shelled Tools for Subsurface Measurements” filed on Jun. 14, 2005, which is hereby incorporated in its entirety.
Number | Date | Country | |
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60690328 | Jun 2005 | US |