An example downhole tool may include a first component and a second component. A first seal may be positioned between the first component and the second component, and a first energizer may be positioned between the first seal and the first component. The first seal may comprise a polyaryletherketone (PAEK) material. The first energizer may be a compressible material. The PAEK material may be at least one of polyetherketone (PEK), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyehtheretherketoneketone (PEEKK), and polyetherketoneether-ketoneketone (PEKEKK).

RELATED APPLICATIONS

This application is a U.S. National Stage Application of International Application No. PCT/US2013/076476 filed Dec. 19, 2013, which designates the United States, and which is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates generally to well drilling operations and, more particularly, to energized polyaryletherketone (PAEK) seals.

Hydrocarbon recovery drilling operations typically require boreholes that extend thousands of meters into the earth. The drilling operations themselves can be complex, time-consuming and expensive and may require transportation of fluids through pipes, pipelines, and other fluid conduits under high pressure and temperature conditions. Maintaining pressure within the fluid conduits is important for safety and environmental reasons.

DETAILED DESCRIPTION

To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the disclosure. Embodiments of the present disclosure may be applicable to horizontal, vertical, deviated, or otherwise nonlinear wellbores in any type of subterranean formation. Embodiments may be applicable to injection wells as well as production wells, including hydrocarbon wells. Embodiments may be implemented using a tool that is made suitable for testing, retrieval and sampling along sections of the formation. Embodiments may be implemented with tools that, for example, may be conveyed through a flow passage in tubular string or using a wireline, slickline, coiled tubing, downhole robot or the like.

The terms “couple” or “couples” as used herein are intended to mean either an indirect or a direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection or through an indirect mechanical or electrical connection via other devices and connections. Similarly, the term “communicatively coupled” as used herein is intended to mean either a direct or an indirect communication connection. Such connection may be a wired or wireless connection such as, for example, Ethernet or LAN. Thus, if a first device communicatively couples to a second device, that connection may be through a direct connection, or through an indirect communication connection via other devices and connections.

Modern petroleum drilling and production operations demand information relating to parameters and conditions downhole. Several methods exist for downhole information collection, including logging-while-drilling (“LWD”) and measurement-while-drilling (“MWD”). In LWD, data is typically collected during the drilling process, thereby avoiding any need to remove the drilling assembly to insert a wireline logging tool. LWD consequently allows the driller to make accurate real-time modifications or corrections to optimize performance while minimizing down time. MWD is the term for measuring conditions downhole concerning the movement and location of the drilling assembly while the drilling continues. LWD concentrates more on formation parameter measurement. While distinctions between MWD and LWD may exist, the terms MWD and LWD often are used interchangeably. For the purposes of this disclosure, the term LWD will be used with the understanding that this term encompasses both the collection of formation parameters and the collection of information relating to the movement and position of the drilling assembly.

FIG. 1is a diagram illustrating an example drilling system100, according to aspects of the present disclosure. The drilling system100includes rig102mounted at the surface101and positioned above borehole104within a subterranean formation103. The formation103may be comprised of at least one rock strata. Although the drilling system100is shown on land, a similar drilling system may be used in an offshore drilling environment, where surface101comprises a drilling platform separated by the formation103by a volume of water.

In the embodiment shown, a drilling assembly105may be positioned within the borehole104and coupled to the rig102. The drilling assembly105may comprise drill string106and bottom hole assembly (BHA)107. The drill string106may comprise a plurality of pipe segments threadedly connected at joints, such as joint150. The BHA107may comprise a drill bit108, a measurement-while-drilling/logging while drilling (MWD/LWD) apparatus109, a telemetry system110, and a reamer111. The MWD/LWD apparatus109may comprise multiple sensors through which measurements of the formation103may be taken. The reamer111may comprise extendable arms that contact the wall of the borehole104to increase the diameter of the borehole104behind the drill bit108. The BHA107including the MWD/LWD apparatus109and reamer111may be communicably coupled to the surface through the telemetry system110, which may receive/transmit information between the BHA107and the surface101. Each of the drill bit108, MWD/LWD apparatus109, telemetry system110, and reamer111may be coupled to an adjacent portion of the drilling assembly105at a threaded joint.

The drill string106may extend downward through a surface tubular113into the borehole104. The surface tubular113may be coupled to a wellhead114. The wellhead114may include a portion that extends into the borehole104. In certain embodiments, the wellhead114may be secured within the borehole104using cement, and may work with the surface tubular113and other surface equipment, such as a blowout preventer (BOP) (not shown), to prevent excess pressures from the formation103and borehole104from being released at the surface101.

During drilling operations, a pump115located at the surface101may pump drilling fluid from a fluid reservoir116into an inner bore117of the drill string106. The pump115may be in fluid communication with the inner bore117through at least one fluid conduit or pipe118between the pump115and drill string106. As indicated by arrows119, the drilling fluid may flow through the interior bore117of drill string106, the BHA107, and the drill bit108and into a borehole annulus120. The borehole annulus120is created by the rotation of the drill bit108in borehole104, and is defined as the space between the interior/inner wall or diameter of borehole104and the exterior/outer surface or diameter of the drill string106. The annular space may extend out of the borehole104, through the wellhead114and into the surface tubular113. Fluid pumped into the borehole annulus120through the drill string106may flow upwardly, exit the borehole annulus120into the surface tubular113, and travel to the surface reservoir116through a fluid conduit121coupled to the surface tubular113and the surface reservoir116.

According to aspects of the present disclosure, seal assemblies with PAEK seals may be used with the drilling system100and in other aspects of hydrocarbon recovery and production operations to maintain downhole pressures. Maintaining pressure within the bore117and the borehole annulus120may be important to preventing blowouts or other losses of fluid containment. Formation fluids may be held in the formation103under pressure and may escape if the pressure within the annulus120is less than the formation pressure. The drilling fluid may be pumped into the bore117at a particular pressure and flow rate, intended to maintain a pressure within the annulus120above the formation pressure but below a pressure at which the drilling fluid penetrates the formation. Fluid leaks through the joints may cause unwanted pressure fluctuations that can lead to blowouts.

Additionally, seal assemblies with PAEK seals also may be used with the drilling system100and in other aspects of hydrocarbon recovery and production operations to maintain downhole hydraulic fluid systems in which hydraulic fluid is stored and pumped to achieve some purpose or action downhole. For example, the reamer111may have a hydraulic fluid system that is used to extend the reamer arms. When pressure is lost in the hydraulic fluid system (e.g., when a seal is broken), the reamer111, or any other tool with a hydraulic fluid system, may cease to function. When a downhole tool stops functioning, the entire drilling assembly105must be removed from the borehole104and the tool replaced, increasing the time and expense of the drilling operation. Other downhole hydraulic fluids systems may be used, for example, in drill bits, downhole steering systems, LWD/MWD tools, extendable stabilizer systems, inflatable packers, and other downhole elements or tools that would be appreciated by one of ordinary skill in the art in view of this disclosure.

According to aspects of the present disclosure, seal assemblies with PAEK seals also may be used with the drilling system100and in other aspects of hydrocarbon recovery and production operations to protect sensitive equipment from downhole temperatures, pressures, and fluids. Downhole measurement tools may require clean environments in which to operate and take measurements, and seals may be used to prevent sensitive measurements equipment from being exposed to drilling or formation fluids. For example, the bore117through the drilling assembly105may extend through the LWD/MWD apparatus109, which may include sensitive measurement devices, such as magnetometers, accelerometers, antennas, electrodes, etc. Exposure to the drilling fluids may degrade the measurement devices and reduce their useful life, requiring removal of the drilling assembly105from the borehole104in order to replace the LWD/MWD apparatus109.

FIG. 2is a diagram illustrating an example seal assembly200with PAEK seals, according to aspects of the present disclosure. In the embodiment shown, the seal assembly200is positioned between a first component202of a downhole tool and a second component204of the downhole tool. The first component202and second component204may comprise one of adjacent pipe segments in a drill string, adjacent components within a BHA, components of a hydraulic fluid system, and/or components within a downhole tool, such as a LWD/MWD apparatus or a wireline measurement or survey tool. The seal assembly200may provide a hermetic and fluid-resistant seal between a first side250of the components and a second side252of the components. Other configurations for the first and second components202and204are possible, as are different placements and orientations of the seal assembly200with respect to the first and second components202and204.

In the embodiment shown, the seal assembly200comprises a first seal206positioned proximate to the first component202. A first energizer210may be adjacent to the first seal206, between the first seal206and the first component202. The seal assembly200may further comprise a second seal208positioned proximate to the second component204. A second energizer212may be adjacent to the second seal208, between the second seal208and the second component204. The first energizer210and second energizer212may comprise compressible or deformable materials with similar length dimensions to the respective first seal206and second seal208that, when compressed or deformed, exert forces on at least the respective first seal206and second seal208such that there is sufficient force between the seals206and208to engage or “energize” the seal assembly200.

At least one of the first seal206and the second seal208may comprise a PAEK seal. As used herein, a PAEK seal may comprise a seal that is at least partially composed of a PAEK material. PAEK material comprises a family of semi-crystalline thermoplastics characterized by robust mechanical and chemical resistance properties that are retained at high temperatures and pressures. Materials in the family of PAEK materials include but are not limited to polyetherketone (PEK), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyehtheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK). PEEK, for example, may have a Young's modulus on the order of about 3.6 gigapascals, a tensile strength on the order of about 90 to 100 megapascals, a glass transition temperature at around 143° C. (289° F.), and a melting point at around 343° C. (662° F.). Downhole environments normally have high temperatures and pressures and contain caustic fluids, all of which may degrade typical seals. Accordingly, the use of PAEK material may improve the useful life of the seal due to the material's highly resistance to thermal degradation as well as attack by both organic and aqueous environments.

At least one of the first energizer210and the second energizer212may comprise a compressible material such as rubber which exerts outward forces on the surfaces with which they are in contact when compressed. In the embodiment shown, the first seal206may contact the second seal208when the first component202and the second component204are positioned proximate to each other. When the first component202is urged toward the second component204, the first seal206may contact the second seal208, and the force used to urge the first component202toward the second component204may cause the first energizer210to compress. The force further may cause the second energizer212to compress. Once compressed, the first energizer210may exert outward forces on the first component202and the first seal206, forcing the first seal206toward the second seal208. Likewise, the second energizer212, once compressed, may exert an outward force on the second component204and the second seal208, forcing the second seal208toward the first component202and the first seal206. Notably, PAEK material may be resistant to compression, and the force provided by one or more of the first energizer210and second energizer212may ensure sufficient contact between the first seal206and the second seal208to maintain a hermetic and fluid-resistant seal.

In certain embodiments, at least one of the first seal206and the second seal208may comprise at least one planar or flat surface. In the embodiment shown, each of the first seal206and second seal208comprise six flat surfaces. At least one flat surface on each of the first seal206and second seal208may be aligned when the first seal206and the second seal208are in contact with each other. A first flat surface206aof the first seal206may be in contact with a second flat surface208aof the second seal208.

In certain embodiments, the first seal206may comprise a PAEK material and the second seal208may comprise a non-PAEK wear resistant material, such as metal or diamond. For example, the second seal208may comprise a steel ring positioned proximate to the second component204, with the second energizer212positioned between the steel ring and the second component204. The steel ring may have at least one planar surface to contact the first seal206to form a seal between the first component202and the second component204.

FIG. 3is a diagram illustrating an example seal assembly300with a PAEK seal, according to aspects of the present disclosure. In the embodiment shown, the seal assembly300is positioned between a first component302of a downhole tool and a second component304of a downhole tool. The first component302may comprise the body of a downhole measurement tool, such as a LWD/MWD apparatus or a wireline measurement or survey tool, and the second component304may comprise a hatch or cover positioned over a recess312within the first component302. The hatch or cover may be comprised of metal or other wear resistant material. In certain embodiments, one or more measurement devices314may be positioned within the recess312, and the hatch304may be positioned over the recess312to protect the measurement device314from exposure to particulates and fluids316outside of the hatch304. The particulates and fluid316may comprise drilling fluids, formation fluids, and particulates generated during the drilling process.

The seal assembly300may be positioned between the hatch304and the body302and at least partially disposed in a seal gland316of the first component302, and may provide a hermetic and fluid-resistant seal between the recess312and the particulates and fluids316outside of the tool. In certain embodiments, the seal glad316may be located on the hatch304. In the embodiment shown, the seal assembly300comprises a first seal306and a first energizer308. Although only one seal and energizer are shown, others may be included within the seal assembly300, similar to the seal assembly200. Likewise, seal assembly200may have only one seal and energizer.

The first seal306may comprise a PAEK material and the first energizer308may comprise a compressible material. The notched area316may have a depth “d” within the first component302. In certain embodiments, the first seal306and first energizer308in an uncompressed state may have a combined height greater than the depth “d”, so that the first seal306extends outside of the seal gland316. When the hatch304is in place with respect to the first component302, the hatch304may compress the first energizer308and cause the first energizer308to exert force on the first seal306and the first component302. The force from the first energizer308may cause the first seal306to engage with and seal against the hatch304. The first seal306may comprise at least one flat or planar surface. In the embodiment shown, the first seal306comprises six planar surfaces, and at least one planar surface306aof the first seal306may contact and engage with the second component304.

AlthoughFIG. 3is described above in relation to a LWD/MWD apparatus, the seal assembly300and the configuration shownFIG. 3, or a similar configuration, may be equally applicable to other downhole applications. For example, the first component302may comprise the body of a downhole tool with hydraulic fluid system, such as a reamer, and the second component304may comprise a hatch or cover positioned over a hydraulic fluid chamber312within the first component302. The seal assembly300may function substantially as described above, with the purpose being to ensure that pressure within the hydraulic fluid system and chamber312is maintained.

In addition to the seals described above, PAEK seals may also be used as dynamic seals, according to aspects of the present disclosure. Specifically, a PAEK seals may be used between first and second components where there is relative motion between the first and second components. The relative motion may comprise, for example, axial motion or radial motion.FIG. 4is a diagram of an example PAEK seal assembly400, according to aspects of the present disclosure. The PAEK seal assembly400may be positioned between a first component401of a downhole tool and a second component402of a downhole tool in a seal gland403in the first component401. In certain embodiments, the seal glad403may be within the second component402. The PAEK seal assembly400may comprise a PAEK seal405and energizer404that engages with an outer surface of the second component402. The second component402may comprise a shaft or portion of a piston that moves axially with respect to the first component401, which may be fixed. The PAEK seal405may remain in a sealing engagement with the surface of the second component402, as the second component402moves with respect to the first component401.

FIG. 5is a diagram of the example PAEK seal assembly400, according to aspects of the present disclosure, where the first component401and the second component402move radially with respect to one another. Specifically, the second component402may comprise a rotating shaft that rotates radially as indicated by arrow450, with respect to the first component401, which remains fixed. In other embodiments, the shaft402may remain fixed while the first component401rotates. In both instances, the PAEK seal405may remain in a sealing engagement with the second component402

According to aspects of the present disclosure, an example downhole tool may include a first component and a second component. A first seal may be positioned between the first component and the second component, and a first energizer may be positioned between the first seal and the first component. The first seal may comprise of a polyaryletherketone (PAEK) material. The first energizer may comprise a compressible material. The PAEK material may be at least one of polyetherketone (PEK), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyehtheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK).

In certain embodiments, the downhole tool may further include a second seal positioned between the first seal and the second component. A second energizer may be positioned between the second seal and the second component. The second seal may also comprise a PAEK material. The first seal further may comprise a planar or flat surface that is in contact with the second component. Where a second seal is present, both the first seal and the second seal may have planar or flat surfaces. The planar or flat surfaces of the first seal and second seal may be in contact with each other.

In certain embodiments, the first component may be a first pipe segment of a drill string and the second component may be a second pipe segment of a drill string. The first seal may be positioned proximate to a threaded joint between the first component and the second component. In other embodiments, one of the first component and the second component may be a tool body for a downhole tool that includes a recessed portion. The other one of the first component and the second component may be a hatch or cover positioned over the recessed portion.

According to aspects of the present disclosure, and example method may include positioning a first component proximate to a second component and positioning a first seal between the first component and the second component. The first seal may comprise a polyaryletherketone (PAEK) material. A first energizer may be positioned and compressed between the first seal and the first component. In certain embodiments, the first energizer may comprise a compressible material. The PAEK material comprises at least one of polyetherketone (PEK), polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyehtheretherketoneketone (PEEKK), and polyetherketoneetherketoneketone (PEKEKK).

In certain embodiments, the method may further include positioning a second seal between the first seal and the second component. A second energizer may be positioned and compressed between the second seal and the second component. The second seal may at least one of a PAEK material and/or metal. The first seal may comprises at least one planar or flat surface, and compressing the first energizer may comprise causing the at least one planar or flat surface to contact the second component. Where there is a second seal, the second seal may comprise at least one second planar or flat surface, and compressing the first energizer may comprise causing the at least one first planar or flat surface to contact the at least one second planar or flat surface

In certain embodiments, positioning a first component proximate to a second component may comprise positioning a first pipe segment of a drill string proximate to a second pipe segment of a drill string. And positioning the first seal between the first component and the second component may comprise positioning the first seal proximate to a threaded joint between the first pipe segment and the second pipe segment. In other embodiments, positioning the first component proximate to the second component may comprise positioning a hatch or cover over a recessed portion in a downhole tool body.

Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. The indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the component that it introduces.