1. Technical Field
The present disclosure relates in general to methods of operating downhole jars used during drilling, completing, or producing products from wellbores, for example, but not limited to, wellbores for producing hydrocarbons from subterranean formations, and more particularly to methods of controlling the charging, firing, amount of force, and/or direction of force exerted by one or more downhole jars.
2. Background Art
Drilling jars are tools used to free stuck drill pipe or drill collars (herein referred to generically as “drilling apparatus”) by storing energy through application of axial load to an end of the jar, then releasing that energy in rapid motion to jar the pipe free from the point where it is stuck. “Jarring” is the process of trying to free a stuck drill string through delivery of impact loads to the stuck components. Drilling jars aid the process. The jarring direction, impact intensity and jarring times can be controlled from the rig floor. In one known apparatus, two jars are arranged in a series, with collars or drill pipe therebetween, on a drill string. The jars can be selectively fired to effect a stress wave in the wellbore. By using an electronically actuated jar, a series of jars could be set off at slightly different times to maximize the stress wave propagation and impulse.
So-called “downhole transmission systems” for transmitting power and/or signals from the surface to downhole components (including jars) and vice versa are known. Certain of these known apparatus and methods for integrating transmission cable into the body of selected downhole tools, such as drilling jars, can have variable or changing lengths. Certain wireless systems used in a different context (time-lapsed seismic data acquisition system) are also known.
Jars are most effective at freeing stuck pipe when located above and yet close to the point where the pipe is stuck. The further the jars are located above the stuck point, the more the jarring force is diminished. Furthermore, as far as is known to the inventors herein, when a jar is below the stuck point the jar cannot be cocked or fired. Even more problematic, however, is that even with the recent capabilities of downhole transmission systems to offer real time data, and even if multiple jar sets are employed in making up a drill string, jars are rarely if ever optimally positioned with respect to the stuck point(s), which of course cannot be known in advance. It would be advantageous if multiple jars could be disposed on a drillstring, and their cocking (charging), firing, amount of force and/or direction of force controlled from the surface in a coordinated manner, to satisfy many drilling and well workover needs, including helping to locate stuck points and accomplish the goal of unsticking stuck drill string components in a logical, efficient manner. The methods of the present disclosure are directed to these needs.
In accordance with the present disclosure, it has now been determined that one or more of charging, firing, the amount of force exerted, and/or the direction of the forces exerted by multiple downhole jars and/or jar accelerators can be digitally controlled from the surface, and many advantageous operations are available to the driller or well operator that heretofore have not been described.
These and other needs are addressed in the art by a method of jarring. The method of jarring can include communicating between a surface command device and communication components in two or more jars of a drill string, the drill string comprising a plurality of spaced jars positioned in a corresponding plurality of wired pipe sections; and selectively controlling at least one of charging, firing, amount of force, and direction of force, and two or more of these parameters, of two or more of the jars via at least one of the surface command devices.
According to various embodiments, the present teachings can also include a method of freeing stuck components of a drill string in a subterranean borehole. The method can include drilling a borehole using the drill string, the drill string comprising a plurality of spaced apart jars and a plurality of wired drill pipe sections, the drill pipe section and jars each comprising electromagnetic components allowing communication at least between the jars and a surface command device; communicating between the surface command device and the communication components in two or more of the jars; and selectively controlling at least one of charging, firing, amount of force, and direction of force, of two or more of the jars via the surface command device.
According to various embodiments, the present teachings can further include a method of jarring. The method can include communicating between a surface command device and communication components in one or more jars of a drill string, the drill string comprising a plurality of spaced apart jars positioned in a corresponding plurality of wired pipe sections; digitally selectively controlling at least one of charging, firing, amount of force, and direction of force, of one or more of the jars with the surface command device; firing a sub-set or all of the jars in a digitally controlled manner and determining depth of a stuck drill string section through analysis of behavior or performance of the fired jars; and subsequently digitally selectively controlling firing one or more of the jars below the stuck drill string section via the surface command device.
According to various embodiments, the present teachings can also include a method of jarring. The method can include communicating between a surface command device and communication components in two or more jars of a drill string, the drill string comprising a plurality of spaced apart jars positioned in a corresponding plurality of wired pipe sections; digitally selectively controlling at least one of charging, firing, amount of force, and direction of force, of two or more of the jars via the surface command device; selectively firing, using one or more digitally controlled signals from the surface command device, two or more jars sequenced in time so that their forces meet in one of a constructive and destructive manner at a preselected point in the drill string.
According to various embodiments, the present teachings can also include a method of jarring including communicating between a surface command device and communication components in one or more jars of a drill string, the drill string comprising a plurality of spaced apart jars positioned in a corresponding plurality of wired pipe sections; selectively controlling at least one of charging, firing, amount of force, and direction of force, of one or more of the jars using the surface command device; charging one or more of the jars from the surface command device by actuating a digitally-controlled valve in the jar which directs hydraulic pressure from within the drill string to charge the jar.
According to various embodiments, the present teachings can also include a method of jarring including electromagnetically communicating between a surface command device and electromagnetic communication components in one or more jars of a drill string, the drill string comprising a plurality of spaced apart jars positioned in a corresponding plurality of wired pipe sections; and selectively controlling at least one of charging, firing, amount of force, and direction of force, of two or more of the jars using the surface command device; wherein the electromagnetically communicating is selected from the group consisting of i) sending a wireless electromagnetic signal from the surface command device to two or more of the jars, or from two or more jars to the surface command device, ii) sending an electromagnetic signal through wired connections from the surface command device to two or more of the jars, or from two or more of the jars to the surface command device, and iii) combinations thereof.
As used herein, the term “digital” when applied to the term “signal” means signals that have outputs of only two discrete levels. Examples: 0 or 1, high or low, on or off, true or false. The phrases “digital control” and “digitally controlled signals” mean that controllers used have the advantages and disadvantages of digital controllers. Advantages can include flexibility, multiplicity of function, the ability to make use of advanced design and analysis techniques (as further explained herein), and implementation of hierarchal control schemes. The main disadvantages in digital control are that the signals are sampled and quantized. Also, digital control implies that a model of the system being controlled is available, or may be generated by observing similar processes. The model is used for extracting more information from the process being controlled, and predicting the result of taking certain actions and then being able to choose values of inputs to achieve particular outputs. Digital signals may be selected from electronic (wired and/or wireless), optical, and acoustic (for example, mud-pulse techniques, and through-pipe acoustic signals). Certain methods of this disclosure can include generating a drill string model, including the jars, and using the model to digitally control the cocking, firing, direction, and/or amount of force used in the various jars.
These and other features of the methods of the disclosure will become more apparent upon review of the brief description of the drawings, the detailed description, and the claims that follow.
The manner in which the objectives of this disclosure and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:
It is to be noted, however, that the appended drawings are not to scale and illustrate only typical embodiments of this disclosure, and are therefore not to be considered limiting of its scope, for the methods and apparatus described may admit to other equally effective embodiments.
In the following description, numerous details are set forth to provide an understanding of the exemplary disclosed methods and apparatus. However, it will be understood by those skilled in the art that the methods and apparatus may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. Identical reference numerals are used throughout the several views for like or similar elements.
As noted above, it has now been determined, and will be described in the exemplary embodiments herein, that multiple jars can be connected together (either electromagnetically (via wired pipe, or wirelessly connected), optically, or acoustically through mud-pulse or through-pipe communication) to control cocking (charging), firing, adjusting the amount of force, or the directions of force (either applied to and imparted by) of the jars. Multiple jars can be placed in the drillstring, and digital signals can be used to select which jar is to be fired, which direction to jar the pipe, and the amount of force to be exerted by the jars alone or added together, either constructively or destructively. In certain embodiments, the methods can include redirecting hydraulic pressure inside a drill pipe to the jar cocking mechanism using digital command, allowing jars below the stuck point to be cocked and actuated. This same hydraulic mechanism is used in certain embodiments to control the amount of energy the jars will store thereby allowing the force exerted to be digitally controlled from the surface with greater precision than previously possible.
Digital control of multiple jars can enable firing of two or more jars in synchronization so that jarring forces can be either constructive or destructive when the pulses from multiple jars meet.
Constructively summed forces can be non-exclusively used to (1) reinforce one with another to deliver stronger impacts at the stuck point; (2) simultaneously apply jarring loads from below and above the stuck point; (3) time-delay the firing of multiple jars one slightly behind the other to deliver a lengthier impulse to the stuck point; and (4) generate buckling loads which will create lateral forces which can dislodge materials that have bridged around the pipe or can be used to lift the pipe away from a point where it is differentially stuck due to wellbore fluid pressures being much greater than formation fluid pressures.
The firing of two or more jars in a phased sequence can be used to concentrate forces in a particular area of the drill string or to prolong the duration of the application of the force. By configuring the timing sequence of the firing of two or more jars, the drill string can be used to create a buckling load which can in turn be used to lift the drill pipe off of a differentially stuck area or to compact drill cuttings which have packed off around the drill pipe, creating space between the drillpipe and those cutting to allow the operator to re-establish circulation and to restore movement of the pipe so that the hole can be properly cleaned and the drill string safely withdrawn or to continue to drill further.
The extension of the duration of the firing by using multiple jars fired in sequence can enhance the success of freeing differentially stuck drill pipe. A single firing can begin to free a portion of the interval stuck as the pipe is effectively peeled off the wall of the hole where it is exposed to the differential pressure. However, if the pipe is stuck at multiple sands down the well or over lengthy sand, then the force decays before it can reach those deeper intervals, while the upper portion is working free. By firing in phases or from opposite directions, the energy can be made available to work rapidly on the additional stuck areas.
Additionally, the jars that are fired can be either on the same side of the stuck point or on opposites of the stuck point which allows forces to be applied to the stuck point from two directions, allowing the problem to be worked from both sides at the same time or by alternating sides, which will be more effective than simply working the stuck point from the top as existing jars work.
Destructively summed forces can be used to create high tension in the drill pipe at the point where the forces meet, which can then be used to separate the pipe at a tool joint thereby eliminating the need to trip wireline into the well to fire a “string” charge to jump a drill pipe connection.
The depth of a stuck point, points or length of stuck area can be determined by selectively firing a jar or jars at certain depth(s) then monitoring the drill string response at the surface or downhole via accelerometers.
Jars can also be fired in sequence to concentrate their forces at a particular tool joint which will allow the operator to jump that joint and separate the drill sting into two parts. Traditionally, this has been done with explosives (string shots) to create the force that allow the pin to “jump” a box without damaging the box. Then the operator is able to pull the upper half of the drill string and change components to aid in retrieving the lower stuck sting and then trip back in the well and screw back into the same box and continue the fishing operation. Phased firing can be conducted where one jar above and another below are fired such that the energy arrives at the connection where the operator wants to jump the pin at precisely the same moment.
Certain method embodiments can include coordinated firing of two or more independent jars in a phased firing arrangement so that energy arrives from two directions at the same time at a particular targeted point in the drill string. Due to the very high speed of the shock wave in the pipe, timing precision may not always be available on digital communication networks used along drillpipe due to noise on the network. An untimely miscommunication due to delays created in the bit checking protocols of the network could create an improper sequence of firings. In accordance with certain exemplary method embodiments, the methods described herein can include synchronizing the firing clocks in the individual jars. The individual clocks can continually synchronize themselves to a network clock and then be instructed to fire themselves at some predetermined time (in some embodiments determined by a signal from the surface, in other embodiments, pre-loaded while making up the drill string) to assure that all bit checking protocols are assured to have been completed before any of the jars are actually fired. In certain embodiments, two or more jars can communicate between each other on the network to ensure that they have all received and understood the same firing time with a checking scheme directly between them.
Methods of the present disclosure are applicable to both on-shore (land-based) and offshore (subsea-based) drilling.
In order to better understand the methods of the present disclosure; a discussion of one useable downhole network (or downhole transmission system) is presented in relation to
A bottom-hole assembly may include drill bit 20, sensors, and other downhole tools such as logging-while-drilling (“LWD”) tools, measurement-while-drilling (“MWD”) tools, diagnostic-while-drilling (“DWD”) tools, or the like. Other downhole tools may include heavyweight drill pipe, drill collar, stabilizers, hole openers, sub-assemblies, under-reamers, rotary steerable systems, drilling jars, drilling shock absorbers, and the like, which are all well known in the drilling industry. Note that in prior art systems as illustrated, it is not known to utilize multiple jar sets spaced apart in the drill string, as heretofore it would have been a large expense to do so without any return on investment.
While drilling, a drilling fluid is typically supplied under pressure at drill rig 10 through drill string 14. The drilling fluid typically flows downhole through a central bore of drill string 14 and then returns uphole to drill rig 10 through an annulus 9 formed between borehole 11 and drill string 14. Pressurized drilling fluid is circulated around drill bit 20 to provide a flushing action to carry the drilled earth cuttings to the surface.
Other intermediate nodes 18b-d may be located or spaced along network 17 to act as relay points for signals traveling along network 17 and to interface to various tools or sensors (but not jars) located along the length of drill string 14. Likewise, a top-hole node 18a may be positioned at the top or proximate the top of drill string 14 to interface with an analysis device 26, such as a personal computer 28.
Communication links 24a-d may be used to connect the nodes 18a-e to one another. Communication links 24a-d may include cables or other transmission media integrated directly into the tools configuring the drill string 14, routed through the central bore of drill string 14, or routed externally to drill string 14. Likewise, in certain embodiments, communication links 24a-d may be wireless connections. In selected embodiments, downhole network 17 may function as a packet-switched or circuit-switched network 17.
To transmit data along drill string 14, packets 22a, 22b may be transmitted between nodes 18a-e. Packets 22b may carry data gathered by downhole tools (but not heretofore jars) or sensors to uphole nodes 18a, or may carry protocols or data necessary to the function of network 17. Likewise, some packets 22a may be transmitted from uphole nodes 18a to downhole nodes 18b-e. For example, these packets 22a may be used to carry control signals or programming data from a top-hole node 18a to tools or sensors interfaced to various downhole nodes 18b-e. Thus, downhole network 17 may provide a high-speed path for transmitting data and information between downhole components and devices located at or near the earth's surface 19, but as yet has not been used as taught herein for methods of jarring including electromagnetically communicating between at least one surface command device and electromagnetic communication components in one or more jars of a drill string comprising a plurality of spaced apart jars positioned in a corresponding plurality of wired pipe sections; and selectively controlling at least one of charging, firing, amount of force, and direction of force, and two or more of these parameters, of one or more of the jars using at least one of the surface command devices.
As used herein the phrase “surface command device” means an apparatus such as a personal computer, server computer, hand-held computer, laptop computer, and the like, which may have data manipulation, data storage, and data acquisition software, as well as computation algorithms and software models accessible and usable by humans, or by another device accessible by humans, and is does not include surface devices such as pipes, BOPs, pumps, top drives, compressors, rigs, tanks, and other surface or downhole tools.
Referring now to
Referring first to
As illustrated schematically in
In certain embodiments, two or more jars may be fired in quick succession. This is illustrated in
The location of the stuck point can be determined by monitoring the reaction of one or more accelerometers 110a, 110b, and 110c, as illustrated in embodiment 200 of
Embodiment 300 of
Referring to
The flow-through position of valve 514 illustrated in
Embodiment 600 of
Referring now to
In accordance with the present exemplary embodiments, a primary interest lies in digitally controlling, from the surface, the charging, firing, and/or setting the amount of impact force and/or direction of those forces of a plurality of jars positioned along a drill string, in order to more efficiently and effectively free stuck drill strings. The skilled drilling operator or designer will determine which method and apparatus is best suited for a particular well situation and formation to achieve the highest efficiency without undue experimentation.
In actual operation, the status and/or operation of the jars (and jar accelerators, if present) can be presented in paper format, or more likely today, in electronic format on surface command device 28, or a device communicating with surface command device 28. The change in one or more of the charging, firing, amount of impact force, and direction of impact force of each jar, as well as other parameters, such as mud parameters, drilling parameters, formation parameters, and the like and properties can be tracked, trended, and changed by a human operator (open-loop system) or by an automated system of sensors, controllers, analyzers, pumps, mixers, agitators (closed-loop system).
Any of the jars and jar accelerators currently in use in the drilling industry can be used in practicing the methods of this disclosure, including bumper jars, mechanical jars, hydraulic jars, mechanical-hydraulic jars, electro-mechanical jars, and so on. The only requirement is that the jars be able to, or can be modified to be able to interface electromagnetically with nodes in wired, wireless, or a combination of wired and wireless downhole transmission networks as described herein. The jar is basically a telescopic slip joint including a hammer, anvil and internal trigger that resists movement until the desired tension or compression has been applied. Potential energy stored in the drill string is suddenly released when the jar fires. The slip joint then accelerates rapidly until it shoulders, delivering an impact blow. A related device called a jar accelerator can be used in combination with a drilling jar to intensify the jarring impact.
To jar upward, the drill pipe is stretched via an axial tensile load applied at the surface. This tensile force is resisted by the jar trigger mechanism long enough to allow the pipe to stretch and store potential energy. When the jar trips, this stored energy is converted to kinetic energy causing the hammer and anvil to come together rapidly. To jar downward, the pipe weight is slacked off at the surface and, if necessary, additional compressive force is applied to put the pipe in compression. This compressive force is resisted by the jar trigger mechanism to allow the pipe to compress and store potential energy. When the jar trips, the potential energy of the pipe weight and compression is converted to kinetic energy, causing the impact surfaces to come together rapidly. Upon impact, some of the jarring kinetic energy is transmitted to the stuck point. If the resultant force at the stuck point is great enough, the stuck drill string will slide during the impulse period and eventually be freed after a sufficient number of jarring cycles. “Impact” is the initial instantaneous force generated by the jar. “Impulse” is a residual force of the impact, including of reverberations occurring in milliseconds following impact. The objective of a jar is to create a sufficiently strong impact and sufficiently strong and long impulse.
There are many types of drilling jars, and all may be useful in carrying out methods of this disclosure. The types include, but are not limited to, bumper, mechanical, hydraulic, mechanical-hydraulic, electro-mechanical, and so on. The bumper jar is used primarily to provide a downward jarring force. The bumper jar ordinarily contains a splined joint with sufficient axial travel to allow the pipe to be lifted and dropped, causing the impact surfaces inside the bumper jar to come together to deliver a downward jarring force to the string. Mechanical, hydraulic, mechanical-hydraulic, and electro-mechanic jars differ from the bumper jar in that they contain some type of tripping mechanism which retards the motion of the impact surfaces relative to each other until an axial strain, either tensile or compressive, has been applied to the drill string. Mechanical jars have a mechanical latch mechanism with a preset release force. The release force cannot be adjusted downhole, except for one particular type of mechanical jar whose release force can be adjusted by torque. The jar fires (moves from latched position into the free stroke) as soon as the applied load exceeds the jar release force. Hydraulic drilling jars provide a wide variety of possible triggering loads, determined by the actual tensile or compressive load at the jar. This can be accomplished by a hydraulic mechanism and so-called metering stroke in which oil is forced to flow through a small orifice. At the end of the metering stroke, oil bypasses the orifice causing the hydraulic resistance to drop to a very low value (free stroke). The metering stroke creates a delay time, allowing the jarring operator to set the desired release force. This selective, wide operating range of jar release force is the major advantage of hydraulic jars. Disadvantages can include unintended jar firing during normal drilling operations, long metering times for low overpull, overheating the oil during repeated jarring and risk of overloading the jar during the metering stroke.
Many hydraulic drilling jars have a disadvantageously long metering stroke. The metering stroke is the amount of relative movement between the mandrel and the housing that must occur for the jar to trigger after it is cocked by application of an axial load. When an ordinary hydraulic drilling jar is cocked by application of axial load, fluid is pressurized in a chamber to resist relative movement of the mandrel and the housing. One or more metering orifices in the jar allow the compressed fluid to bleed off at a relatively slow rate. As the fluid is bleeding off, there is some relative axial movement between the mandrel and the housing. The amount of relative axial movement between the mandrel and the housing that occurs after the jar is cocked, but before the jar triggers, is known as bleed off. The bleed off represents lost potential energy that might otherwise be converted to additional jarring force. Many hydraulic drilling jar designs have a relatively long metering stroke of 12 inches of more and, therefore, a significant amount of bleed off. A long metering stroke leads to heat buildup in the hydraulic fluid, which may require costly intervals between firings and lead to degradation of fluid. Electro-mechanical jars utilize a magnetorestrictive material that responds to a predetermined pressure to open one or more orifices in a shoulder of a mandrel to allow rapid pressure communication between the upper and lower chambers.
Mechanical-hydraulic (aka hydro mechanical) jars are hybrid jars that combine initial mechanical release (to avoid uncontrolled firing) with hydraulic action to provide flexibility and adjustable release force.
In certain embodiments more jarring force than is obtainable from jars alone is desired. Shallow depths can limit the available pipe stretch or compression to obtain strong jarring impacts. Friction in high angle and horizontal wells can impede drill string rebound when the jars are tripped, thus damping the jarring impacts. In such cases a “jar accelerator” (sometimes referred to herein as “jar intensifier”) is placed above the jar, normally with a few drill collars between the jar and accelerator. The telescoping accelerator serves as an elastic ‘spring’ to store energy until the jar is triggered. When the jar is triggered, the accelerator quickly releases its stored energy and accelerates the hammer of the drilling jar to a relatively high speed. The impact force is related to the square of the velocity, thus, the accelerator greatly increases the hammer force. The spring medium can be steel (mechanical accelerator), compressible oil (hydraulic accelerator) or nitrogen (gas accelerator). Jar accelerators can be single- or double-acting.
Those of ordinary skill in the hydrocarbon exploration and drilling arts will already be familiar with some aspects of wired and wireless downhole networks.
Wireless systems used in a different context (time-lapsed seismic data acquisition system) are known. Electromagnetic transmission of signals to and from surface command devices and jars, and other optional components such as sensors, may be “completely wireless”, wherein all wires, cables, and fibers (such as optical fibers) for communication are substantially eliminated. This does not rule out the use of wires, cables, or optical fibers for example in recording station equipment and jars, for example for power. Wireless systems and methods can offer improvements over systems and methods that use wire or optical fiber for communications in terms of one or more of robustness, scalability, cost, and power-efficiency. Electromagnetic signals can be used to transfer data to and/or from the jars, to transmit power, and/or to receive instructions to charge and/or fire jars.
Systems and methods described in the present disclosure can employ a wireless data network comprising one or more surface command units transmitting commands to one or more surface nodes 18a via first wireless links, which in turn transmit commands to downhole nodes and then jars 102 via second wireless links. Commands can be sent from node to node via wireless links, and, to the extent data is exchanged between nodes and surface command units, wireless links may also be considered part of the wireless data network.
The first wireless links can be characterized as Wireless Personal-Area Networks (WPAN). A “WPAN” is a personal area network (PAN) using wireless connections. WPAN is currently used for communication among devices such as telephones, computers and their accessories, as well as personal digital assistants, within a short range. The second and third wireless links between nodes can be individually selected from any wireless communication protocol that supports point to multi-point (PMP) broadband wireless access.
As used in the context of the present disclosure (coordinated charging and firing of downhole jars), the nodes and surface command devices can be compared to a metropolitan area networking (MAN), as given in the 802.16 standard, sometimes referred to as fixed wireless. In fixed wireless, a backbone of base stations is connected to a public network. As with a MAN, each node 18 supports many “fixed subscriber stations” (jars, sensors, and the like), which are akin to either public WiFi hot spots or fire walled enterprise networks. Nodes 18 can use a media access control (MAC) layer, and allocate uplink and downlink bandwidth to “subscribers” (jars, sensors, etc.) as per their individual needs. This is basically on a real-time need basis. The MAC layer is a common interface that makes networks interoperable.
Systems and methods of this disclosure can include provision of multi-antenna signal processing (MAS) software architectures for implementation of the second and/or third wireless links employing WiMAX. The WiMAX profiles support both adaptive antenna system (AAS) and multiple-input/multiple-output (MIMO) architectures in baseline form.
“Drilling” as used herein can include, but is not limited to, rotational drilling, directional drilling, non-directional (straight or linear) drilling, deviated drilling, geosteering, horizontal drilling, and the like. Rotational drilling can involve rotation of the entire drill string, or local rotation downhole using a drilling mud motor, where by pumping mud through the mud motor, the bit turns while the drillstring does not rotate or turns at a reduced rate, allowing the bit to drill in the direction it points. A turbodrill may be one tool used in the latter scenario. A turbodrill is a downhole assembly of bit and motor in which the bit alone is rotated by means of fluid turbine which is activated by the drilling mud. The mud turbine is usually placed just above the bit.
First, as indicated in box 402, the drilling supervisor, probably in conjunction with a mud engineer, geologist or other person in charge can choose downhole network components, jars, and optionally jar accelerators; and assemble the drill string, either on-site or at a site removed from the well.
In box 404, drilling is then begun, drilling toward a target formation at a known azimuth and dip angle using the selected drilling mud, drill bit, and assembled drill string.
At box 406, upon sticking of the drill string at one or more unknown locations in the wellbore, locate sticking point using one or more digitally-controlled jars using one or more surface command devices. The step also includes charging selected jars and selecting force magnitude and direction using one or more surface command devices, and firing the jars.
At box 408, upon locating the sticking point, charge selected jars and select force magnitude and direction using one or more surface command devices.
At box 410, fire the charged jars using one or more surface command devices, selecting constructive or destructive addition of the forces.
At box 412, analyze results using one or more surface command devices. If drill string is unstuck, continue drilling. If drill string is not unstuck, repeat steps 408-412 until drill string is unstuck.
From the foregoing detailed description of specific embodiments, it should be apparent that patentable methods and apparatus have been described. Although specific embodiments of the disclosure have been described herein in some detail, this has been done solely for the purposes of describing various features and aspects of the methods and apparatus, and is not intended to be limiting with respect to the scope of the methods and apparatus. It is contemplated that various substitutions, alterations, and/or modifications, including but not limited to those implementation variations which may have been suggested herein, may be made to the described embodiments without departing from the scope of the appended claims. For example, drilling jars, jar accelerators, and downhole transmission systems other than those specifically described above can be employed, and are considered within the scope of the disclosure.
This application claims priority to U.S. Provisional Application No. 61/351, 177, filed on Jun. 3, 2010, which is incorporated herein by reference in its entirety for all purposes.
Number | Date | Country | |
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61351177 | Jun 2010 | US |