Patent Description:
Wells in the oil and gas industry are commonly drilled into the ground to recover natural deposits of hydrocarbons and other desirable materials trapped in subterranean geological formations. Wells are typically drilled by advancing a drill bit into the earth, and the drill bit is attached to the lower end of a "drill string" suspended from a drilling rig or platform. The drill string typically consists of a long string of sections of drill pipe that are connected together end-to-end to form a long shaft for driving the drill bit further into the earth. A bottom hole assembly containing various instrumentation and/or mechanisms is typically provided at the end of the drill string above the drill bit.

During drilling operations, a drilling fluid (or "mud") is typically pumped down the drill string to the drill bit where it is ejected into the forming borehole. The drilling fluid lubricates and cools the drill bit, and also serves to carry drill cuttings back to the surface within the annulus formed between the drill string and the borehole wall.

Once a well is drilled to a desired depth, the wellbore is commonly lined with sections of larger-diameter pipe, usually called casing or liner. Before installing the casing or liner in the wellbore, the drill string is removed from the borehole in a process commonly referred to as "tripping. " The casing or liner is subsequently lowered into the well and cemented in place to protect the well from collapse and to isolate adjacent subterranean formations from each other. After the casing or liner is successfully installed in the wellbore, drilling may continue by again running the drill bit into the wellbore as coupled to the end of the drill string. The process of drilling, tripping, running casing, cementing the casing, and then drilling again is often repeated several times while extending (drilling) a wellbore to total depth. <CIT> discloses a method for drilling a borehole which includes providing a drill string of drill pipe including a center bore; a distal end, a bit assembly at the distal end; hanging a liner from the drill string, thereby forming an annular space between the drill string and the liner and with the bit assembly extending from the lower end of the liner; positioning the drill string with the liner attached thereto in a borehole such that a second annular space is formed between the liner and the borehole wall; operating the bit assembly to proceed with drilling the borehole; and circulating drilling fluid down through the center bore of the drill string out through the bit assembly and down through the second annular space between the liner and the borehole wall, the drilling fluid returning up through the annular space between the drill string and the liner. <CIT> discloses a bottom hole assembly configured for a subterranean drilling operation having a drill bit; a downhole tool deployed above the drill bit, at least a portion of the downhole tool free to rotate with respect to the drill bit about a longitudinal axis of the bottom hole assembly, a sensor sub deployed axially between the drill bit and the downhole tool, the sensor sub configured to rotate with the drill bit about the longitudinal axis of the bottom hole assembly and free to rotate with respect to the downhole tool about the longitudinal axis and a tri-axial magnetic field sensor deployed in the sensor sub.

The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure.

The detailed description set forth below is intended as a description of various implementations and is not intended to represent the only implementations in which the subject technology may be practiced. As those skilled in the art would realize, the described implementations may be modified in various different ways, all without departing from the scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive.

The present disclosure is related to drilling and completing wells in the oil and gas industry and, more particularly, to a drilling system capable of drilling and setting a wellbore liner within the drilled wellbore in a single downhole run.

Conventional drilling can involve drilling, liner placement, and cementing to secure the wellbore liner. The process of drilling, tripping, running casing, cementing the casing, and then drilling again is often repeated several times while extending (drilling) a wellbore to total depth. As can be appreciated, this repetitive process is time consuming and costly.

Drilling systems in accordance with the present disclosure provides a single-trip procedure that enables a well operator to drill the wellbore while simultaneously running in a wellbore liner, and subsequently cement the annulus around the lower wellbore liner. After cementing, a liner hanger can be actuated and a liner running tool released to enable the remaining portions of a downhole assembly to be pulled out of hole while leaving the lower wellbore liner cemented in place. Such drilling systems can reduce operational risks and saving well operators money on reduced non-productive time and increased reservoir exposure.

Referring to <FIG>, illustrated is an exemplary drilling system <NUM> that may employ one or more principles of the present disclosure. Boreholes may be created by drilling into the earth <NUM> using the drilling system <NUM>. The drilling system <NUM> may be configured to drive a downhole assembly <NUM> positioned or otherwise arranged at the bottom of a drill string <NUM> extended into the earth <NUM> from a derrick <NUM> arranged at the surface <NUM>. The derrick <NUM> includes a kelly <NUM> and a traveling block <NUM> used to lower and raise the kelly <NUM> and the drill string <NUM>.

The downhole assembly <NUM> may include a drill bit <NUM> operatively coupled to a tool string <NUM> which may be moved axially within a drilled wellbore <NUM> as attached to the drill string <NUM>. During operation, the drill bit <NUM> penetrates the earth <NUM> and thereby creates the wellbore <NUM>. The downhole assembly <NUM> provides directional control of the drill bit <NUM> as it advances into the earth <NUM>. The tool string <NUM> can be semi-permanently mounted with various measurement tools (not shown) such as, but not limited to, measurement-while-drilling (MWD) and logging-while-drilling (LWD) tools, that may be configured to take downhole measurements of drilling conditions. In other embodiments, the measurement tools may be self-contained within the tool string <NUM>, as shown in <FIG>.

Fluid or "mud" from a mud tank <NUM> may be pumped downhole using a mud pump <NUM> powered by an adjacent power source, such as a prime mover or motor <NUM>. The mud may be pumped from the mud tank <NUM>, through a stand pipe <NUM>, which feeds the mud into the drill string <NUM> and conveys the same to the drill bit <NUM>. The mud exits one or more nozzles arranged in the drill bit <NUM> and in the process cools the drill bit <NUM>. After exiting the drill bit <NUM>, the mud circulates back to the surface <NUM> via the annulus defined between the wellbore <NUM> and the drill string <NUM>, and in the process returns drill cuttings and debris to the surface. The cuttings and mud mixture are passed through a flow line <NUM> and are processed such that a cleaned mud is returned down hole through the stand pipe <NUM> once again.

Although the drilling system <NUM> is shown and described with respect to a rotary drill system in <FIG>, those skilled in the art will readily appreciate that many types of drilling systems can be employed in carrying out embodiments of the disclosure. For instance, drills and drill rigs used in embodiments of the disclosure may be used onshore (as depicted in <FIG>) or offshore (not shown). Offshore oil rigs that may be used in accordance with embodiments of the disclosure include, for example, floaters, fixed platforms, gravity-based structures, drill ships, semi-submersible platforms, jack-up drilling rigs, tension-leg platforms, and the like. It will be appreciated that embodiments of the disclosure can be applied to rigs ranging anywhere from small in size and portable, to bulky and permanent.

Further, although described herein with respect to oil drilling, various embodiments of the disclosure may be used in many other applications. For example, disclosed methods can be used in drilling for mineral exploration, environmental investigation, natural gas extraction, underground installation, mining operations, water wells, geothermal wells, and the like. Further, embodiments of the disclosure may be used in weight-on-packers assemblies, in running liner hangers, in running completion strings, etc., without departing from the scope of the disclosure.

The drilling system <NUM> may further include computing equipment, such as computing and communications components <NUM> (e.g., a computer processor or firmware, one or more logic devices, volatile or non-volatile memory, and/or communications components such as antennas, communications cables, radio-frequency front end components, etc.). In some embodiments, the computing and communications components <NUM> may be included in the downhole assembly <NUM>, as illustrated. In other embodiments, however, the computing and communications components <NUM> may be provided at the surface and communicably coupled to the downhole assembly <NUM> via known telecommunication means, such as mud pulse telemetry, electromagnetic telemetry, acoustic telemetry, any type of wired communication, any type of wireless communication, or any combination thereof. As described in more detail below, the communication components <NUM> may be used to control the vibration and actuation of one or more vibrational devices or other movable elements on or within the drill bit <NUM> to impart vibrations to the drill bit <NUM> (e.g., by controlling the amplitude and/or frequency of the vibrations). In some embodiments, communication components <NUM> may be used to determine and provide one or more vibrational frequencies for one or more vibrational devices on or within the drill bit <NUM> based on a bending strain and/or a mechanical torsion strain in the drill string <NUM>, as discussed in further detail hereinafter.

<FIG> shows a schematic side view of the drilling system <NUM> according to one or more embodiments of the present disclosure. As illustrated, the drilling system <NUM> can be extended into the wellbore <NUM> drilled through one or more subterranean formations <NUM>. In some embodiments, an upper portion of the wellbore <NUM> may be lined with an upper wellbore liner <NUM> and secured in place using conventional wellbore cementing techniques. The upper wellbore liner <NUM> may comprise a plurality of pipe sections connected end-to-end, and may be referred to in the industry as "casing" or "wellbore liner. " The upper wellbore liner <NUM> terminates at an upper liner shoe <NUM>. Downhole from the upper liner shoe <NUM>, portions of the drilling system <NUM> extend into an uncompleted portion <NUM> of the wellbore <NUM>.

The downhole assembly <NUM> may include several pieces of downhole equipment and tools used to line and cement the uncompleted portion <NUM> of the wellbore <NUM>. More specifically, the downhole assembly <NUM> may include a liner hanger <NUM>, a liner running tool <NUM>, a lower wellbore liner <NUM>, a cementing module <NUM>, a measurement module <NUM>, a steering module <NUM>, and one or more drilling tools <NUM>.

The downhole assembly <NUM> may be operatively coupled to the drill string <NUM> at the liner hanger <NUM>. As used herein, the term "operatively coupled" refers to a direct or indirect coupling engagement between two components. Accordingly, in some embodiments, the drill string <NUM> may be directly coupled to the liner hanger <NUM>, but may alternatively be indirectly coupled thereto, such as via one or more other downhole tools (not shown) that interpose the end of the drill string <NUM> and the liner hanger <NUM>. The liner hanger <NUM> may be used to attach or hang the lower wellbore liner <NUM> from the inner wall (surface) of the upper wellbore liner <NUM>. To accomplish this, the liner hanger <NUM> may be configured to expand radially outward until engaging the inner wall of the upper wellbore liner <NUM>. In some embodiments, the liner hanger <NUM> may be a VERSAFLEX® expandable liner hanger available from Halliburton Energy Services of Houston, Texas, USA.

The liner running tool <NUM> may be operatively coupled to the liner hanger <NUM> and the lower wellbore liner <NUM>. The liner running tool <NUM> may be configured to run (carry) the lower wellbore liner <NUM> into the wellbore <NUM> and, more specifically, into the uncompleted portion <NUM> of the wellbore <NUM>. The lower wellbore liner <NUM> may be similar to the upper wellbore liner <NUM>, but of a smaller diameter. The lower wellbore liner <NUM> terminates at a lower liner shoe <NUM>, which may be drillable.

The cementing module <NUM> may be operatively coupled to the liner running tool <NUM> and arranged within the lower wellbore liner <NUM> as the drilling system <NUM> is run into the wellbore <NUM>. In the illustrated embodiment, one or more lengths of inner drill pipe <NUM> may be used to operatively couple the liner running tool <NUM> to the cementing module. The cementing module <NUM> may include upper seal 234a and lower seal 234b that fluidly and structurally isolate the cementing module <NUM> within the lower wellbore liner <NUM>. The cementing module <NUM> may also include one or more cement ports <NUM> (two shown) arranged axially between the upper seal 234a and the lower seal 234b. The cement ports <NUM> may fluidly communicate with one or more liner ports <NUM> (two shown) defined in the lower wellbore liner <NUM>. Consequently, cement <NUM> discharged from the cementing module <NUM> via the cement ports <NUM> may flow into the annulus <NUM> defined between the lower wellbore liner <NUM> and the inner wall of the uncompleted portion <NUM> of the wellbore <NUM> via the liner ports <NUM>.

The measurement module <NUM> may include various measurement tools (not shown) such as, but not limited to, measurement-while-drilling (MWD) and logging-while-drilling (LWD) tools, that may be configured to take downhole measurements of drilling conditions. To allow the measurement tools (e.g., LWD sensors) to function properly, the lower wellbore liner <NUM> may include an electromagnetically transparent portion <NUM> and the measurement module <NUM> may be arranged within the lower wellbore liner <NUM> and axially aligned with the electromagnetically transparent portion <NUM>. The electromagnetically transparent portion <NUM> may comprise any non-magnetic, electrically insulating/nonconductive material such as, but not limited to, a high temperature plastic, a thermoplastic, a polymer (e.g., polyimide), a ceramic, an epoxy material, or any non-metal material. The electromagnetically transparent portion <NUM> may be configured to allow electromagnetic signals emitted by the measurement module <NUM> (e.g., LWD sensors) to pass therethrough generally undisturbed by the lower wellbore liner <NUM>, thereby mitigating any adverse effects on the log quality of the measurement tools. The remaining portions of the lower wellbore liner <NUM> may comprise a metal or any other material.

The measurement module <NUM> may operate in conjunction with the steering module <NUM> and provide real-time measurements of drilling conditions and parameters to help the steering module <NUM> accurately steer the drilling system <NUM> during drilling operations. The steering module <NUM> may comprise any rotary steerable tool. In at least one embodiment, the steering module <NUM> may comprise, for example, a GEO-PILOT® rotary steerable system available from Halliburton Energy Services of Houston, Texas, USA.

The drilling tools <NUM> may be used to drill and enlarge the diameter of the wellbore <NUM>. As illustrated, the drilling tools <NUM> may include the drill bit <NUM> and a reamer <NUM> (altemately referred to as an "underreamer" or "hole enlargement device") axially offset from the drill bit <NUM>. During drilling operations, the drill bit <NUM> drills a pilot hole and the reamer <NUM> enlarges the diameter of the pilot hole. The drilling tools <NUM> are operatively coupled to the drill string <NUM> such that rotation of the drill string <NUM> from the well surface location correspondingly rotates the drilling tools <NUM> to advance the drilling system <NUM> to drill the wellbore <NUM>.

The outer diameter of the drill bit <NUM> and reamer <NUM> may be smaller than the inner diameter of the lower wellbore liner <NUM> to allow the drilling tools <NUM> to pass through the interior of the lower wellbore liner <NUM>. In some embodiments, the reamer <NUM> may be radially actuatable to enable adjustment of the outer diameter of the reamer <NUM> for drilling operations or passing through the interior of the lower wellbore liner <NUM>.

As illustrated, the drilling tools <NUM> may extend axially out the distal end of the lower wellbore liner <NUM> a short distance <NUM>. In some embodiments, the short distance <NUM> may range between about <NUM> meters to about <NUM> meters, but could alternatively range between <NUM> meters and <NUM> meters, without departing from the scope of the disclosure. The short distance <NUM> may be sufficient to allow the drilling tools <NUM> to engage the underlying rock formation to increase the length (depth) of the wellbore <NUM>.

The drilling system <NUM> may be first built or assembled at the well surface location. This can be accomplished by first lowering the entire length of the lower wellbore liner <NUM> into the wellbore <NUM> and "hanging" the lower wellbore liner <NUM> at the well surface location. In some embodiments, the lower wellbore liner <NUM> may be coupled to and otherwise "hung off" a rotary table forming part of the drilling rig or platform at the well surface location. The drilling tools <NUM>, the steering module <NUM>, the measurement module <NUM>, and the cementing module <NUM> may then be extended into the interior of the lower wellbore liner <NUM> and the liner running tool <NUM> may then be coupled to the lower wellbore liner <NUM>. In some embodiments, the entire downhole assembly <NUM> (minus the lower wellbore liner <NUM>) may be coupled to the lower wellbore liner <NUM> using a false rotary table forming part of the drilling rig or platform at the well surface location.

While assembling the downhole assembly <NUM>, the length of the inner drill pipe <NUM> may be adjusted (i.e., lengthened or shortened) to axially align the measurement module <NUM> with the electromagnetically transparent portion <NUM> of the lower wellbore liner <NUM>. The inner drill pipe <NUM> may then be operatively coupled to the liner running tool <NUM> and the cementing module <NUM>. The liner hanger <NUM> may then be operatively coupled to the liner running tool <NUM> to complete the assembly of the downhole assembly <NUM>. Once properly assembled at the well surface location, the downhole assembly <NUM> is then ready to be detached (released) from the rotary table at the well surface location and run downhole into the wellbore <NUM> through the upper wellbore liner <NUM>.

An exemplary operation is shown in <FIG>. In the operation <NUM>, the drilling system <NUM> is run into the wellbore <NUM> on the drill string <NUM> until locating ("tagging") the bottom of the wellbore <NUM> below the upper liner shoe <NUM>. Once the bottom of the wellbore <NUM> is located, drilling operations may commence to extend the length of the wellbore <NUM>. This may be accomplished by circulating drilling fluid through the drilling system <NUM> from the well surface location and to the drilling tools <NUM> while simultaneously rotating the drilling tools. At the drilling tools <NUM>, the drilling fluid is ejected from the drill bit <NUM> and the reamer <NUM> and into the annulus <NUM> to cool the drilling tools <NUM> and carry drill cuttings out of the wellbore <NUM> via the annulus <NUM>. The direction of the drilling system <NUM> is controlled by the steering module <NUM> in communication with the measurement module <NUM>. The measurement module <NUM> provides real-time measurements of drilling conditions that can be processed by the steering module <NUM> to update the direction, speed, and general operation of the drilling tools <NUM>.

Drilling continues until the wellbore <NUM> is extended to a desired wellbore depth and the uncompleted portion <NUM> of the wellbore <NUM> is generated. Once reaching the desired wellbore depth, the wellbore <NUM> may be cleaned by circulating a fluid through the wellbore <NUM> that serves to remove remaining debris.

Once the wellbore is cleaned, cement <NUM> may then be pumped into the annulus <NUM> to secure the lower wellbore liner <NUM> within the uncompleted portion <NUM> of the wellbore <NUM>. To facilitate pumping of the cement <NUM> into the annulus <NUM>, a wellbore projectile (not shown), such as a dart, a ball, or a plug, may be pumped into the downhole assembly <NUM> and land on a seat (not shown) provided within the cementing module <NUM>. Landing the wellbore projectile on the seat provides a fluid seal within the cementing module <NUM> that isolates lower portions of the downhole assembly <NUM> from upper portions thereof. The cement <NUM> may then be pumped into the downhole assembly <NUM> from the well surface location via the drill string <NUM>. The fluid seal provided by the wellbore projectile forces the cement <NUM> to be discharged from the cementing module <NUM> via the cement ports <NUM> and subsequently into the annulus <NUM> via the liner ports <NUM> defined in the lower wellbore liner <NUM>. The upper seal 234a and the lower seal 234b prevent the cement <NUM> from entering the axially adjacent lengths of the lower wellbore liner <NUM> and instead force the cement <NUM> into the annulus <NUM> via the liner ports <NUM>.

Once the cement <NUM> is deposited in the annulus <NUM>, the liner hanger <NUM> may then be actuated to operatively couple the lower wellbore liner <NUM> to the upper wellbore liner <NUM>. Actuation of the liner hanger <NUM> may be accomplished by pumping a second wellbore projectile (not shown), such as a dart, a ball, or a plug, into the liner hanger <NUM> to land on a seat (not shown) provided within the liner hanger <NUM>. Landing the wellbore projectile on the seat within the liner hanger <NUM> provides a fluid seal within the downhole assembly <NUM>. Fluid pressure within the drill string <NUM> may then be increased to hydraulically actuate the liner hanger <NUM> and thereby secure it to the upper wellbore liner <NUM>.

Once the liner hanger <NUM> is properly actuated and the lower wellbore liner <NUM> is effectively coupled to and otherwise "hung off" the upper wellbore liner <NUM>, the liner running tool <NUM> may then be released from the lower wellbore liner <NUM>. Releasing the liner running tool <NUM> allows the remaining portions of the downhole assembly <NUM> to be removed from the wellbore <NUM>, alternately referred to as "pulled out of hole. " More specifically, once the liner running tool <NUM> is released, the drill string <NUM> may be retracted back uphole towards the well surface location and simultaneously retract the cementing module <NUM>, the measurement module <NUM>, the steering module <NUM>, and the drilling tools <NUM>.

Accordingly, the drilling system <NUM> provides a single-trip system that enables a well operator to directionally drill the wellbore <NUM> while simultaneously running in the lower wellbore liner <NUM>, and subsequently cement the annulus <NUM> around the lower wellbore liner <NUM>. Once the cement <NUM> is deposited, the liner hanger <NUM> may be actuated and the liner running tool <NUM> released to enable the remaining portions of the downhole assembly <NUM> to be pulled out of hole while leaving the lower wellbore liner <NUM> cemented in place. In some applications, the drilling system <NUM> may be referred to as a "steerable liner drilling system. " The drilling system <NUM> may prove advantageous in reducing operational risks and saving well operators money on reduced non-productive time and increased reservoir exposure.

A phrase "at least one of" preceding a series of items, with the terms "and" or "or" to separate any of the items, modifies the list as a whole, rather than each member of the list.

It is understood that the specific order or hierarchy of steps, operations, or processes disclosed is an illustration of exemplary approaches. Unless explicitly stated otherwise, it is understood that the specific order or hierarchy of steps, operations, or processes may be performed in different order. Some of the steps, operations, or processes may be performed simultaneously. The accompanying method claims, if any, present elements of the various steps, operations or processes in a sample order, and are not meant to be limited to the specific order or hierarchy presented. These may be performed in serial, linearly, in parallel or in different order. It should be understood that the described instructions, operations, and systems can generally be integrated together in a single software/hardware product or packaged into multiple software/hardware products.

In one aspect, a term coupled or the like may refer to being directly coupled. In another aspect, a term coupled or the like may refer to being indirectly coupled.

Terms such as top, bottom, front, rear, side, horizontal, vertical, and the like refer to an arbitrary frame of reference, rather than to the ordinary gravitational frame of reference. Thus, such a term may extend upwardly, downwardly, diagonally, or horizontally in a gravitational frame of reference.

Claim 1:
A downhole assembly (<NUM>) comprising:
a liner hanger (<NUM>);
a liner running tool (<NUM>) operatively coupled to the liner hanger (<NUM>);
a lower wellbore liner (<NUM>) operatively coupled to the liner running tool (<NUM>), comprising an electromagnetically transparent portion (<NUM>), and defining one or more liner ports (<NUM>);
a cementing module (<NUM>) operatively coupled to the liner running tool (<NUM>), arrangeable within the lower wellbore liner (<NUM>), and defining one or more cement ports (<NUM>) that are positionable in fluid communication with the one or more liner ports (<NUM>); and
one or more drilling tools (<NUM>) extendable axially out a distal end of the lower wellbore liner (<NUM>).