Air Motor Assembly

This application is a continuation of U.S. Nonprovisional patent application Ser. No. 19/084,298, filed on Mar. 19, 2025, which claims priority to U.S. Provisional Patent Application No. 63/567,575, filed on Mar. 20, 2024, entitled “AIR MOTOR ASSEMBLY,” the disclosure of which is herein incorporated by reference in its entirety.

The present disclosure relates to an air motor for air drilling and other borehole operations, such as wellbore cleanout. More particularly, the disclosure provides an air motor that may be used with an air hammer, the air motor configured to protect sensitive electrical components and allow for real time monitoring of a borehole operation.

Underground directional drilling has been largely limited to drilling with roller cone or polycrystalline diamond compound (PDC) type bits with mud or air-mist rotary drilling motors utilizing rotor-stator or similar technologies. These technologies use liquid-based drilling fluids, which are not conducive to wireless telemetry for real time monitoring of the drilling operation. Portions of the drilling industry use air hammer drilling tools, also known as drill hammers, for conventional straight-hole drilling that strictly use air as the drilling medium. However, rotor-stator technology is not suitable for air hammer drilling tools. Consequently, the air hammer drilling industry has had limited access to the benefits of directional drilling.

The following descriptions are provided to explain and illustrate embodiments of the present disclosure. The described examples and embodiments should not be construed to limit the present disclosure.

Turning to, apparatusincludes a filter assemblyat an uphole end thereof, a motor assemblyadjacent the filter assembly, an adjustable bent sub assemblyadjacent the motor assembly, and a bearing assemblyat the downhole end thereof. The filter assemblyis configured to connect to a drill string and to receive compressed air therethrough from, e.g., a compressor positioned at the surface of a well. The bearing assemblyis configured to connect to an air hammer. The apparatuscan be operated with dry compressed air, nitrogen, other gases including, but not limited to, natural gas, or combinations thereof (referred to herein as “compressed air”) without the need for liquids to cool and lubricate the motor components, a requirement for most positive displacement motors (PDMs). The ability for air and nitrogen to be used for the drilling process allows for the deployment of a microwave-based communication system that can send and receive data to and from the downhole assembly through the drill pipe. A suitable microwave-based communication system is disclosed in U.S. Pat. No. 9,856,730, which is hereby incorporated by reference in its entirety. The communication link provides for massive amounts of data to be sent up and down the borehole between downhole assemblies and the surface in real time. The tools, systems, and methods described herein may be applicable to a variety of borehole operations, such as mining operations, geothermal well operations, Horizontal Directional Drilling (HDD), oil and gas operations, construction, water well drilling, and others.

Referring to, the filter assemblyincludes an inletfor receiving compressed air. The inletmay be part of a regulator subattached to the filter assembly housingvia thread. The regulator submay also include wrench flatsfor easy attachment to the rest of the drill string. For instance, the wrench flatsallow for small top drive rigs to hold the apparatusin place with forks during makeup or tripping without the need for bowls and slips. This results in an increased saving of time and increased safety for rig personnel during those operations.

In operation, the compressed air stream flows to the filter canisterand initially impacts a filter cone. In some embodiments, the filter canisterincludes cyclone generating featuresto rotate and accelerate the compressed air. The featuresmay include spiral vanes or grooves configured to generate a cyclone. The effect of the featuresis to spin the air stream, thereby ejecting particulate matter within the air stream outward and away from the air inlet portsleading to the filter. This action reduces the buildup of grit on the filter, extending its life.

The filter canister, which is shown in isolation in, serves as a shield between the filterand the air stream, and can serve as housing for a communication hub, which is shown in. The communication hubmay include, for example, a batteryand a communication link between sensors within the apparatusand the surface. In some embodiments, the communication link includes a processorand a transmitter. In some embodiments, one or more sensors may be included in the communication hub, such as a pressure sensor, a temperature sensor, an accelerometer, an inclinometer, or combinations thereof. In some embodiments, the communication hubmay include a microwave transmitteror other suitable communication devices. In some embodiments, the communication link within the communication hubis wireless and wirelessly communicates up the drill string to the surface. In other embodiments, the communication hub may include a wired link to the surface. In some embodiments, the filter coneis formed of a material that can withstand the violent compressed air stream directed through the apparatusyet be invisible to microwaves (or other wireless communication frequencies) linking to the telemetry system. For example, in some embodiments, the filter coneis formed of TEFLON® (a polytetrafluoroethylene-based composition from The Chemours Company).

An enlarged view of the communication hubaccording to an embodiment is shown in. As shown, the communication hubincludes a power source, such as a battery, for powering one or more components of the communication hub. The communication hubmay include one or more sensors, such as a pressure sensor, a temperature sensor, an accelerometer and/or inclinometer, or any combinations thereof. In the embodiment shown, the communication hubfurther includes a processorconfigured to receive data from sensors within the communication huband/or from sensors elsewhere in the apparatus. The communication hubalso includes a transmitterfor wirelessly transmitting data from the processor(e.g., data from the sensors) to the surface. A receiver at the surface (not shown) may receive the data from the transmitter. The received data may provide real time information about the borehole operation, and operators may adjust parameters of the operation in response to the information. In some embodiments, the communication hubincludes wiringextending down the apparatusto one or more additional sensors, which are described in more detail below.

Referring again to, a portion of the air stream flows into the filtervia air inlet portsof the filter canisterwhile the remainder of the air stream bypasses the filtervia filter bypass. In some embodiments, the filtermay be a 100-micron stainless steel air filter. Filtered air from the filteris directed to the motor assembly, as shown in, via filter outlet.

In some embodiments, the filter assembly housingor the regulator submay include one or more jet portsupstream of the motor assemblyto allow for additional air volume and pressure to be transmitted down the drill pipe and be exhausted into the borehole above the hammer and motor assemblyfor better bore hole cleaning. Most air drilling rigs operate air compression systems at 350 psi or less, and 1250 cfm or less. When encountering fluids in the well bore, many drillers will increase their air volume and pressure with air boosters in order to help clean out the hole. This increase will often exceed the recommended air flow and pressure requirements for the air hammer causing damage to the hammer and bit. Jet ports, in the form of built-in pressure relief valves set at 350 psi, may be built into the top sub apparatus. The jet portswill only open when the air pressure inside the drill pipe exceeds the set pressure of the valves. This allows most of the additional air, provided by the booster, to be exhausted above the motor. This exhausted air will bypass the air hammer yet still provide for the additional hole cleaning.

In some embodiments, the filter assemblymay include one or more sensorsin communication with the communication hub. The sensorsmay include accelerometers and/or inclinometers or other low power sensors such as a Micro Electromechanical System (MEMs) gyroscope placed to measure tilt and roll of the apparatus. The sensorscan be fixed at a precise tilt angle and oriented with the adjustable bent sub assemblyso the face direction of the apparatuswill always be known relative to the drill string orientation. This is particularly useful during the initial kickoff phase of the drilling, so the bit direction at the bottom of the hole can be accurately oriented. The sensorsmay also measure the rotation of the entire bottom assembly both for RPM and smoothness of the rotation when the driller is rotating the entire drill string. This is particularly useful when the drill string is long and the driller is unable to sense these parameters.

Turning to, an embodiment of the motor assemblyincludes a motor housingthat may include threaded portionsandfor attachment to the filter assemblyand the adjustable bent sub assembly, respectively. Immobilizers(such as set screws) are provided to prevent rotation of the vane motorand/or gear assemblyrelative to the motor housing. The motor housingmay further include a pressure relief valve. The valvemay be a check valve that is openable when a pressure inside the motor housingexceeds a borehole pressure. Release of air though the valvemay aid in cleanout of the borehole.

Filtered air from the filter outletpasses to a regulator. The regulatorcan be set to a desired pressure, e.g., about 90 psi, and thereby provides a constant pressure to the vane motorvia a manifold, which can in turn provide steady rotation speed to the air hammer regardless of the incoming compressed air pressure (though inlet). Power generated by the motoris transferred to the gear assembly(e.g., a planetary gear assembly) which in turn drives an output(e.g., a square drive or universal joint) that is linked to the adjustable bent sub assembly.

Rotation speed for pneumatic hammer operations may be capped between 30 to 50 RPM. Maximum rotational speed is pre-determined by the regulatorsetting inside the motor assemblyand the initial vane motorand gear assemblyconfiguration. This rotation is independent of fluctuations in air volume or pressure (from inlet). Only a small, fixed portion of the air that flows down the drill pipe is required for the power section of the vane motor, while the remaining air is bypassed down to the hammer and bit via bypass tubes, which are in communication with filter bypassof the filter assembly. The bypass tubesare further in communication with motor bypass, which guides the air stream to the adjustable bent sub assembly(and eventually to the hammer).

Operation of the apparatusis distinct from positive displacement motors (PDMs), which will speed up or slow down their rotation speed with increases or decreases of air pressure and air volume. This is because all of the air that flows down the drill pipe and through the bit flows through the power section of the PDM. High air flows will cause high rotation speeds that can cause excessive damage or damage to drill bits and can wear out or damage the elastomer inside the PDM. When a PDM stalls on the bottom of a hole, air flow is halted, and air pressure increases inside the drill string. A rapid and excessive runaway rotation can occur when the tool is lifted off the bottom. This can cause damage to the assembly. More damage can occur when the motor touches back down on the bottom of the hole when the motor is rotating excessively. The motorof the present disclosure will rotate gradually up to speed to its set maximum rotation speed (e.g., approximately 30 RPM) when lifting off the bottom after a stall. Any air flow increase due to the release of pressurized air inside the drill string during a stall passes through to the hammer and aids in hole cleaning which is a positive result.

The motor assemblymay include one or more sensors for monitoring drilling conditions. For example, a speed sensormay be positioned downhole of the motor(e.g., between the motorand the gear assembly) to monitor the rotational speed of the motor. Wiringmay connect the speed sensorto the communication huband may utilize spaces between the bypass tubesto protect the wiringfrom the air stream. That is, bypass tubessend the high velocity air past the vane motor chamber. The design provides for additional space for sensors and wiring to be located inside the vane motor chamberso that they are protected from the violent compressed air stream flowing down to the hammer. Sensors that measure air pressure, temperature, shock and vibration, and motor rotation speed can be placed within this chamberor adjacent to the chamber. These sensors will provide the driller with instantaneous critical information regarding the motor performance.

For example, in some embodiments, one or more pressure and/or temperature sensors may be positioned within the motor assemblyand in communication with the communication hub, e.g., via wiringor via wireless communication. For example, a pressure sensorcan be positioned within the motor housingto measure a borehole pressure or an ambient pressure and a pressure sensorcan be positioned within the air stream bypassing the filter(i.e., the air pressure to be delivered to the air hammer). The communication hubcan relay information from the sensors,,to the surface to provide real time monitoring of the drilling operation, and the data transmitted may be accurately time stamped. Should a failure occur, the moment of failure can be accurately noted with the sensor data. This can greatly aid both the driller and manufacturer with the ability to diagnose the failure and take corrective steps to either continue on with drilling, or to modify future components to mitigate future failures.

With reference to, an embodiment of the motor assemblyis shown. In this embodiment, the motor assemblydoes not include bypass tubes. Rather, the vane motoris contained within a motor canister, which forms a plurality of slotswith the motor housingto allow high velocity air to bypass the motor canisteren route to the air hammer. In some embodiments, the slotsmay be isolated from one another or partially connected by circumferential vias. As with the bypass tubes, the motor canistercan isolate sensitive equipment, such as sensors and wiring, from high velocity air and also provide space for housing the same. In some embodiments, the slotsmay be substantially connected to one another to form an annulus between the motor canisterand the motor housing. In some embodiments, the slotsmay provide greater cross-sectional area as compared with the bypass tubes, thereby allowing increased airflow and lower air pressure and friction pressure.

An additional view of the motor canisteris shown in, wherein the motor canistermay include one or more annular portsproviding fluid communication between an interior of the motor canisterand the slots, e.g., via valves. In some embodiments, the vane motormay exhaust into the motor canisterand then into the slotsvia check valves at the annular ports. The motor canistermay also include one or more borehole portsthat are aligned with motor housing portsproviding fluid communication between an interior of the motor canisterand the borehole, e.g., via valves. In some embodiments, the borehole portsmay be used to sample borehole gas and/or exhaust air or sampled borehole gas into the borehole. In some embodiments, the motor housing portsmay be used to house immobilizers, such as set screws, to prevent rotation of the vane motorrelative to the motor housing.

Although not shown in, the motor assemblyincludes a gear assembly, outputand thread portionsas described above and shown in. In some embodiments, the motor housingmay comprise two or more connected segments. For example, as shown in, the motor housingmay include a threaded portionsandconnecting a first motor housing segment about the vane motorwith a second motor housing segment about the gear assembly. Likewise, any of the housing elements described herein may be unitary or comprised of two or more connected segments. Such configurations may allow for greater flexibility in construction and/or maintenance of the apparatus, wherein added threaded portions may provide access to internal components positioned within the respective assemblies. Referring to, in some embodiments, the immobilizerscomprise splines formed in a gear housingcontaining the gear assembly. As shown, the splines may include a groove in the gear housingwith corresponding protrusions in the motor housingpositioned therein to prevent rotation of the gear assemblyrelative to the motor housing.

Returning to the embodiment shown in, the motor assemblyincludes a pressure sensorconfigured to measure air pressure within the manifold, a shock or vibration sensor, and a temperature sensorto measure a temperature within the motor canister, each of which may be in wired (via wiring) or wireless communication with the communication hub. The motor assemblyfurther includes a gas sensorfor identifying borehole gas content, the gas sensorbeing in fluid communication with the borehole via borehole portsand motor housing ports. The gas sensoris shown in additional detail in. The gas sensoris provided with high pressure air from the manifold, which accelerates through a venturi nozzleand decelerates past the end of the nozzlecreating a vacuum. The vacuum draws in sample borehole gases from a sensor inlet(through borehole portand motor housing port), which is in fluid communication with a sensor chambervia a sensor chamber inlet. The sensor chambermay include one or more gas sensors, such as a combustible gas sensorand an HS gas sensor, configured to measure gas content of the sample borehole gas drawn into the sensor chamber. The sensor chamberis in fluid communication with the nozzle(or the vacuum created thereby) via a sensor chamber outletand the sample borehole gases that have been measured are removed and exhausted via sensor outlet(through borehole portand motor housing port). In some embodiments, the sensor inletmay be positioned about 10 feet above the bit (e.g., air hammer) and be free from contamination from uphole gas entries. The gas sensormay be in wired (via wiring) or wireless communication with the communication hubto provide instantaneous transmission of gas content data to the surface with precise entry point and time of entry information. According to embodiments of the present disclosure, gases such as methane and HS can be detected almost immediately when encountered by the drilling operation. The HS sensorwill warn the driller and crew of a hazard immediately and provide valuable time for safety actions to take place before the dangerous gas reaches the surface. Additionally, combustible gasses can be logged immediately when encountered as to the depth and content. Increases and decreases in borehole temperature could indicate the entrance of formation gas into the borehole and serve as an indirect indication of natural fracturing in the formation.

In any embodiment, additional sensors can be placed within the motor housingand be in communication with the communication hub. Any combination of the sensors and sensor positioning described inmay be employed, optionally, with additional sensors such as those described above. Any of the sensors may include sampling ports for measuring conditions within the borehole (outside of the apparatus).

The various sensors disclosed herein in combination with the communication hubcan provide critical information to drillers allowing them to understand downhole conditions in real time and to optimize drilling. This sensor capability can enhance the drilling efficiency and warn of potential motor failure conditions before a failure occurs. Some sensors can also detect borehole conditions and serve as early warnings when dangerous gas is encountered. Several components of the apparatusdisclosed herein serve a dual function, being a component for the motorto function and as a location for the placement of sensors and other electronics. Sensors measuring motor rotation, air pressure both inside and outside the motor, temperature both inside and outside the motor, and shock and vibration may be placed within the apparatus.

The apparatuscomprises a gear and vane driven motorthat rotates nearly vibration free. PDMs combined with air hammers can cause excessive vibration on the downhole assemblies. Excessive vibration also leads to the failure of the electrical components for many types of downhole measurement devices such as EM and GR tools. The design of the apparatusprovides low vibration while also shielding electrical components from compressed air, thereby enabling reliable, real time monitoring of drilling operations.

Turning to, the outputof the gear assemblyis connected to a bent sub jointwithin the adjustable bent sub assemblyat uphole joint. The uphole jointmay be a constant velocity or universal joint which allows for a shaft bend between the motor assemblyand the adjustable bent sub assembly. The adjustable bent sub assemblyincludes a housingwith threaded portions,for attachment to the motor assemblyand the bearing assembly, respectively. A downhole joint, which may be the same type as the uphole joint, is configured to connect to a shaftof the bearing assembly, as shown in. In some embodiments, the adjustable bent sub assemblyis configured to be adjustable from 0 to 3 degrees, allowing the apparatusto be used in straight or directional drilling. Air from the motor bypassmay flow into the adjustable bent sub assembly, past the bent sub jointand into the bearing assembly.

Turning to, the bearing assemblyincludes a bearing housingwith a threaded portionfor connecting to the adjustable bent sub assembly. A downhole end of the bearing assemblyis configured to connect to an air hammer and to deliver the air stream that has bypassed the filterto the air hammer. The shaftis connected to the bent sub jointat the downhole jointand is configured to rotate the air hammer. The shaftincludes a hollow conduit therethrough for delivering the air stream to the air hammer. The shaftmay include wrench flatsfor case of assembly and installation. A bearing deviceis included to allow for rotation of the shaftrelative to the bearing housing.

Referring to, an additional view of the bearing assembly, adjustable bent sub assembly, and a portion of the motor assemblyis shown. The view shown provides additional detail regarding the threaded connections between the various assemblies according to an embodiment of the present disclosure. In the embodiment shown, the motor assemblyincludes two gear assemblies. In any embodiment, an appropriate number of gear assembliesmay be utilized based on the operational requirements of the apparatus.

In one or more embodiments, the apparatusof the present disclosure may have an outer diameter of about 3″, about 4″, about 6″, about 8″, about 10″, about 12″, between about 4″ and about 8″, between about 3″ and about 10″, or between about 3″ and about 12″. Any other suitable size may be employed and the apparatusmay be appropriately scaled. In some embodiments, the apparatusis configured to fit within a 5.5″ cased well (e.g., a 4″ outer diameter). In some embodiments, the apparatusmay be used for cleanout operations, such as well cleanout. In this regard, one of the main reasons for low productivity over time from older wells is the buildup of very hard scale inside the casing. Operators need to clean out this scale to increase or restore productivity. Coiled tubing units are typically employed for this task. The PDC and PDM combination used with coiled tubing can often breach the casing since significant weight on the bit must be applied in order to cut through the hard scale. Unfortunately, PDC bits can drill into and possibly through the wall of the softer casing when this bit weight is applied. The loss of the well is possible when this happens. Since the air hammer and air motor combination described herein requires very little weight on the bit for effective drilling, the drilling action can be confined inside the casing and not breach the casing. Also, down the hole (DTH) hammers are very effective in hard formations. Consequently, the air motor and air hammer combination has the ability to drill out this hard scale while not breaching the casing.

Additionally, the apparatusdisclosed herein may provide for low rotational and makeup torque and may have a short length. The short tool length allows for the apparatusto be made up within short tower conventional rigs and small horizontal directional drilling (HDD) rigs. Large fleets of small top drive rigs routinely and exclusively drill with air hammers. The short length apparatusallow small rigs to drill deviated and horizontal holes with conventional air hammers. Further, drill rigs may not need high torque makeup tools to employ the apparatusof the present disclosure. The bottom hole assembly can be made up with the equivalent torque that is routinely applied during drill string makeup. That torque is typically generated by the top drive for most pull down rigs. High rotational torque is not required for DTH pneumatic hammers to operate. The cutting action for the DTH bit is supplied by the impact of the buttons of the bit on the formation and not by a scraping mechanism employed by PDC bits. Rotational torque for DTH hammers is only necessary to ensure the buttons on the bit are striking in new spots on the bottom of the hole. The short length and low rotational and makeup torque in combination with the low weight on the bit make the apparatusideal for small HDD rigs, particularly in very hard rock drilling situations.

The apparatusmay also be used in high temperature drilling (e.g., geothermal) because the components thereof can withstand or be insulated from high borehole temperatures. This ability allows for the use of the apparatus in high temperature geothermal drilling applications. On the other hand, PDMs have temperature limitations due to the elastomers used in the power section of the motor.

Although mechanical valves have been disclosed herein, any one or more of the valves of the apparatusmay be a remotely controlled valve (e.g., a solenoid valve). The sensors and telemetry system disclosed may be used to communicate with and control such valves.

Although the present disclosure has been described using preferred embodiments and optional features, modification and variation of the embodiments herein disclosed can be foreseen by those of ordinary skill in the art, and such modifications and variations are considered to be within the scope of the present disclosure. It is also to be understood that the above description is intended to be illustrative and not restrictive. Many alternative embodiments will be apparent to those of ordinary skill in the art upon reviewing the above description. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the future shown and described or any portion thereof, and it is recognized that various modifications are possible within the scope of the disclosure.