US20180112468A1

US20180112468A1 - Radial Drilling in Horizontal Wells by Coiled-Tubing and Radial Drilling by E-Line and Slick-Line

Info

Publication number: US20180112468A1
Application number: US15/787,913
Authority: US
Inventors: James Mark Savage; Robert L. Morse
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-10-20
Filing date: 2017-10-19
Publication date: 2018-04-26

Abstract

Methods and apparatus are disclosed to overcome problem that are encountered when using coiled-tubing to deploy radial drilling tools in certain wells. In addition, this disclosure provides means and tools by which radial drilling tools can be conveyed and powered by slickline or e-line. To advance the radial drilling tools and/or to apply and control weight on bit (WOB), a chamber is created and is then pressurized to generate a piston-affect. Furthermore, tools and methods are provided to monitor the radial drilling tools' operations and to convey this information to surface personnel. In addition, because the e-line, slickline and certain coiled-tubing strings lack adequate torsional stiffness, torque arresting mechanisms are disclosed. This disclosure further provides for a “zero-discharge drilling” system, a “drill-by-wire” system, and enables radial drilling solutions in horizontal wells using coiled-tubing, e-line or slickline.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This filing claims priority to provisional patent application 62/496,481 filed on Oct. 20, 2016. Certain further improvements, disclosed in provisional patent application 62/603,377 filed on May 30, 2017, are also referenced and claim corresponding priority.

FIELD

The present disclosure generally relates to the arts of radial drilling into subterranean hydrocarbon and geothermal reservoirs. In the art of radial drilling, small boreholes are formed into a target zone from a main wellbore. Presently, this art is practiced in vertical wells with tools deployed by means of coiled-tubing. This disclosure expands the apparatus and method of radial drilling to enable radial drilling by coiled-tubing in horizontal wells. Furthermore, it discloses apparatus and method for performing radial drilling in vertical, deviated and horizontal wells using either e-line or slickline.

BACKGROUND

Natural resources such as oil and gas can be recovered by drilling a well into subterranean formations. Typically, after the well is drilled the tool-string is removed and casing is placed downhole along with a cement slurry. Sometimes however wells are completed without the casing running thru payzone, known as an “open-hole completion”.
In radial drilling procedures, specialized tools are swept around an extremely tight radius, often completing the full change of direction entirely inside the well casing. These tools are then used to form one or more laterals or radials extending in a generally radially-orientation outward from the wellbore. Radial drilling is distinct from more-common coiled-tubing side-track procedures and conventional horizontal drilling in several critical ways. For example, in conventional coil-tubing and horizontal drilling procedures, the drilling tools are swept around a radius or “heel” that is typically hundreds or even thousands of feet in size. By contrast, in radial drilling procedures the change of direction normally occurs entirely within the whipstock, which is situated inside the well casing. As production casing commonly ranges from about 4-½ to 9″—this means the radius or “heel” of the lateral is often completed in the matter of about 2 to 5 inches! Some radial drilling procedures produce boreholes that form a true 90° with the main wellbore, while others form a lesser angle. Because of this small radius, any long tools (e.g. a typical 6-9 ft long mud-motor used in radial drilling), never moves into the radial that is being formed—it is impossible for them to do so! Some procedures entail forming boreholes, but the tools complete a portion of their sweep beyond the wellbore proper. For example, they tools may take a few feet to complete their arc. This size of the heal effectively limits the art of radial drilling; and, stands in contrast to scales found in conventional side-track and horizontal drilling. Radial drilling is characterized by the fact that it generally operates at scale that is 2 to 4 orders of magnitude smaller than conventional horizontal or side-track drilling.
The current paradigm is for radial drilling tools to be deployed by means of a coiled-tubing and in vertical wells. The coiled-tubing not only serves as the control-line for the up/down motion control, but also powers the downhole tools—e.g. a mud-motor or jetting nozzle. While radial drilling tool-strings can comprise various sub-components like filters, weight bars, swivels, etc. a common feature is some form of flexible tool-string. Whether rotating or non-rotating, the flexible tool-string is that portion of the tool-string which transitions around the radius of the whipstock and has a head used to form the hole in the casing and/or the lateral in the formation. Often, but not always, radial drilling is performed in a two-step process: with one tool-strings used to form the hole in the well casing; and, a second used to form the lateral borehole.
Radial drilling procedures can be performed on open-hole completed or cased hole wells. If no opening is present in a cased well, access to the formation to the formation must be gained by milling out a section of the well casing or forming a hole in the casing. Once access to the formation has been gained, tools are then directed at the target formation by the whipstock. Sometimes, radial drilling tools are deployed by means of jointed-tubing, but such methods are not germane to this disclosure.
Perforations typically reach about 1 to 2 feet into the reservoir, essentially bounding what might be called the “near wellbore area”. Conventional sidetrack drilling techniques reach many 100 s or feet and often over 1000 s of feet, essentially to what might be called the “extended drainage well boundary”. By contrast, radial drilling entails forming boreholes that extend to what is perhaps best described as the “well vicinity”—e.g. from about 10 to somewhat over 100 feet from the wellbore. Indeed, given the large differences in size of the heel, it should not be a surprise that the tools used in radial drilling have great difficulty reaching beyond the distance of the well vicinity.
Described more fully in the paragraphs below, there are several shortcomings with current radial drilling apparatus and methods. For example, the continuous nature of coiled-tubing makes it an ideal deployment method for radial drilling tools in vertical wells—where lowering the tools is done with the benefit of gravity. By itself, coiled-tubing, however, is not a good conveyance means in horizontal wells due to its propensity to encounter stick-slips, helically-buckle and, ultimately, encounter helical lock-up. The genesis of these problems stems from the fact that coiled-tubing lacks sufficient axial rigidity or “stiffness” to be pushed into long horizontal wells. In fact, these problems become even more pronounced as one uses progressively smaller diameter and hence less-stiff coiled-tubing. Thus, with known apparatus and methods it is not possible to reliably perform radial drilling in horizontal wells via coiled-tubing.
It is desirable to deploy radial drilling tools by means of e-line and slick-line, but suitable apparatus and methods are not known. Specifically, deploying radial drilling tools in deviated, slant or horizontal wells is not possible without a means to address the e-line or slickline's lack of rigidity. In fact, the problem is even more acute when compared to coiled-tubing, as e-line and slicklines are typically far more flexible than coiled-tubing. Other problems also confront e-line and slickline radial drilling deployment. For example, a slickline unit in and of itself has no means to power a downhole tool; and, neither a slickline nor an e-line provide fluid to wash the cuttings from the head. In addition, known radial drilling practices are unable to offer a closed-loop drilling system, which relies solely upon fluid already present in the formation. Instead, foreign fluids must be introduced, presenting resource and logistics issues, as well as the risk of formation incompatibility.

SUMMARY

This disclosure solves several short-coming related to known radial drilling tools and methods. Most notably, it expands upon the types of wellbores and deployment systems that can be used with radial drilling tools. Specifically, this disclosure enables radial drilling to be performed in horizontal wells by coiled-tubing. In addition, it provides method and apparatus to enable radial drilling by e-line or slickline systems, including in slant and horizontal wells. Notably, this disclosure addresses the inadequate longitudinal stiffness of these control lines, while also solving the problem of the reverse torque created by mechanical, rotating drilling tools. Other notable features of this disclosure include: a zero-discharge drilling solution; the ability to utilize an electric motor for radial drilling; the ability to power a mud-motor in e-line and slickline deployments; and, reporting of key radial drilling operating parameters like weight on bit (WOB), torque and pressures via a fiber optic or conductor cable in the coiled-tubing or via the e-line conductor cable.
In most methods of deployment, a sealing member or “seal” between the upset tubing and the radial drilling tool-string (or the control-line, itself) is used to form a chamber in the upset tubing annulus above the seal. Several types of sealing mechanisms are disclosed, including certain preferred cup-seals. The seal and the chamber formed thereby (with the wellhead) are used in conjunction with fluid or gas to generate a differential pressure across the seal in order to create a piston-affect. The piston-affect is then used to drive the radial drilling tool-string further into the well. By providing slack in the control-line, the tool-string can thus be propelled down slant or deviated wells or along horizontal wells. Furthermore, this same approach can be utilized to apply or increase WOB, such as is needed for mechanical drilling procedures. With these apparatus and methods, one can overcome the problem of stick-slips and helical buckling/lock-up in horizontal wells.
In slickline and e-line deployments, the disclosure provides for one or more inlets on the radial drilling tool-string, whereby fluid from the wellbore can enter the tool-string. This fluid can be used to power a downhole tool (e.g. a mud-motor or jetting nozzle) and/or serve as the drilling fluid. This disclosure allows mechanical radial drilling to be performed without the need for a coiled-tubing powered mud-motor. Instead, the mud-motor can be deployed on e-line or slick-line. Alternatively, a downhole electric motor can be deployed via e-line. Furthermore, as e-lines and slicklines, as well as some coiled-tubing deployments are not capable of resisting torque, various torque arresting means are also disclosed. These prevent twisting and damage to the control-line, when using rotating tools.
In certain e-line deployments, one or more intake ports are positioned between the wellbore annulus and the upset tubing. These intake ports allow fluid from the casing annulus to enter the upset tubing. This fluid can then enter the tool-string via an inlet port(s), where it can to the head. After exiting the head, the fluid returns to the wellbore and repeats the same circulation path. Described more fully, below, this system enables a highly-desirable zero-discharge radial drilling solution. Certain e-line deployments utilize a one-way valve at the intake port. This configuration allows fluid from the wellbore annulus to freely enter the upset tubing, but prevents flow in the opposite direction. With such a valve, if more WOB were needed or the tool-string were having problems passing a sticking point in the well, additional fluid could be pumped into the chamber to increase the force of the piston-affect acting on the tool-string.
It is a further aspect of this invention to utilize an electrical conduit, fiber optic cable, or changes in the pressure/flow of the fluid pumped downhole to convey (to surface personnel) key operating parameters of the radial drilling tools. For example, one can monitor the loads via an e-line to determine operating torque and RPM. Similarly, one can use transducers or load/torque cells on the tools which report their values via an electrical or fiber optic cable positioned inside a coiled-tubing string. Additionally, one might monitor items such as flow rates or differential pressures across the opposing sides of the seal to better understand the forces created by the piston-affect.
Finally, it is a principal feature of this invention to enable radial drilling in horizontal wells, something not presently feasible with known art. That is, this disclosure provides apparatus and methods to overcome the stick-slip and helical buckling issues that preclude the use of e-line, slickline and coiled-tubing units to perform radial drilling in horizontal wells. Notably, this disclosure even allows small diameter coiled-tubing, which is especially susceptible to such problems, to be deployed in extended horizontal wells.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying figures are incorporated into and form a part of the specification, illustrating several aspects and examples of the present disclosure. These figures together with their descriptions explain the general principles of the disclosure. The figures are only for the purpose of illustrating preferred and alternative example and are not to be construed as limiting the disclosure to only the illustrated and described examples. The various advantages and features of the various aspects of the present disclosure will be apparent from a consideration of the figures along with this text.

FIG. 1 illustrates an e-line deployment of a radial drilling tool-string that uses a downhole electric motor and pump to rotate a flexible drill-string, which ejects fluid out the attached cutting-head. As can be seen, additional fluid will need to be placed in the well to “flood” the intake ports on the upset or production tubing.

FIG. 2 illustrates an e-line system employing several optional features including an anti-torque tool, cup-seals and a one-way intake valve positioned on the upset tubing. Fluid enters the upset tubing via the intake valve and then enters the radial drilling tool via an inlet. The fluid is then pumped down the flexible tool-sting and out the head—where it returns to the main wellbore, rises again and repeats the circuit.

FIG. 3 illustrates a whipstock sitting atop an anchor with upset tubing running only part way to the surface. This radial drilling tool-string uses a rotating jetting nozzle to erode the borehole. The jetting nozzle is powered by an electrical pump that is powered by the e-line. As the drilling fluid does not need to be brought back to the surface (to be pumped again), this is a zero-discharge radial drilling system.

FIG. 4 illustrates a closed-loop mechanical radial drilling system deployed by slickline. In this case, a surface-based pump creates high pressure fluid that is pumped down the upset tubing. The fluid enters the radial drilling tool-string and rotates a mud-motor, which rotates the flexible drill-string. The fluid exits the head, which is a mechanical cutting-head, to wash the cutting away.

FIG. 5 illustrates a slickline deployed system that uses pressurized fluid in the chamber atop a labyrinth style seal. This system allows: the tool-string to be advanced into the well; WOB to be applied during drilling; and, directs fluid into a mud-motor and through the flexible drill-string to the head.

FIG. 6 illustrates a slickline deployed system wherein seals have been positioned along the upset tubing to allow the tool-string to be driven into the well. The fluid is then directed into the radial drilling tool-string and out the head, which in this case is a self-rotating jetting nozzle. The system is powered by a pump located at the surface.

FIG. 7 illustrates a radial drilling system deployed by coiled-tubing in a horizontal well. A ring style seal allows fluid to be pumped down the upset tubing to create the piston-affect used to apply WOB. Fluid pumped down the coiled-tubing is used to power the downhole tools, which form the radial. In this case, the tools comprise a downhole motor that rotates a flexible drill-string and attached head defining a drill bit.

FIG. 8 illustrates a radial drilling tool-string deployed by a coiled-tubing unit in a horizontal well. This configuration is similar to that shown in FIG. 7, expect this time, cup-seals are used to enable the piston-affect used to overcome stick-slips and helical buckling of the coiled-tubing. In this case, the flexible tool-string used to form the lateral tunnel comprises a form of conduit (hose) and jetting nozzle.

DESCRIPTION OF EMBODIMENTS

This disclosure enables radial drilling by an expanded array of deployment systems and in a broader array of well types. As with existing radial drilling practices, this disclosure entails a whipstock positioned on upset tubing. The radials of this disclosure can be formed be formed by any number of methods. For example, the radials may be formed by: a jetting nozzle used to erode the rock; acid ejected from a nozzle to dissolve the rock; lasers that vaporize the rock; heat that spalls the rock; or, a motor that rotates a flexible tool-string to mechanically drill the casing and/or formation. It warrants mention that this disclosure expands the range of suitable deployment apparatus and methods, as wells as the types of tools that can be used to form the hole in the casing and/or formation. Finally, it is worth noting that most current radial drilling procedures involve two tool-strings: a first to form the hole in the casing; and, a second to form the lateral.
The benefits of this disclosure are particularly suited to mechanical radial drilling tools, which utilize rotation and compressive forces to generate WOB required for drilling. Current systems comprise a sort of flexible tool-string and attached cutting-head, rotated by a mud-motor and controlled by coiled-tubing. This disclosure enables such tools to also be deployed by a motor run on a slickline or conveyed by e-line. Moreover, by virtue of the sealing apparatus and piston-affect disclosed herein, these e-line and slickline systems can be deployed in slant, deviated and horizontal wells!
To expand the types of wellbores and control-lines suitable for deploying radial drilling tools, pressurized fluid is created above a seal (or seals) position between the upset tubing and the radial drilling tool-string. These seals are used to create a pressurize-able chamber bounded by the wellhead at top, the upset tubing on the sides and the seal(s) at bottom. By then pressurizing this chamber, a piston-affect is created which can be used to advance the radial drilling tool-string down the wellbore and/or apply greater WOB. To insure the desired piston-affect is created, the pressure below the seal(s) must be less than that above the seal(s). This can be done by assuring the fluid below the seal freely drains (from the upset tubing) to the annulus of the wellbore and that the fluid in the wellbore annulus is vented (e.g. returns to an open-tank at the surface). Notably, this same sealing apparatus can also be used for the further purpose of directing fluid from the upset tubing into the tool-string (via the inlet) used in certain e-line and slickline systems.
Again, by pumping—or, more specifically by pressurizing—the fluid in the chamber, one can create a piston-affect that drives the tool-string further into the well. Moreover, because one can know beforehand the net surface area over which the pressurized fluid acts and can determine the differential pressure (acting across the seal), one can determine the net force acting on the tool-string. As described more fully below, one can determine the differential pressure by monitoring downhole pressure transducers (on the opposite sides of the seal); or, one can infer the differential pressures by monitoring the pressure in the casing annulus and upset tubing annulus at the surface. For example, if the effective piston area were 1.5 square inches and the differential pressure was 1,000 psi, then the force of the piston-affect acting on the tool-string would be 1,500 lbs. The operator would then slacken (or advance) the control-line, allowing this piston-affect to pull the tool-string further into the well. Furthermore, by now monitoring (and changing) the tension in the control line, the operator could now control the amount of WOB applied. For example, if the control-line had a net tension of 1,000 lbs (after factoring in its weight and any buoyancy offset) than the applied WOB would be 500 lbs (i.e. 1,500 lbs−1,000 lbs). Similarly, in instances where fluid returns to the surface via the annular area in the wellbore, the operator can increase or decrease the back-pressure (e.g. choke on the return flow line), thereby increasing or decreasing the differential pressure across the seal and hence the net force of the piston-affect. A pump (or, in the case of gas, a compressor) at the surface can be used to generate the pressure in the chamber for this piston-affect.
With the apparatus and method described above, one can now advance and apply WOB by control-lines and in wells not previously feasible to radial drilling. We now turn to a discussion of features of this disclosure, beginning with methods and apparatus to power the tools.
Certain e-line and slickline embodiments have one or more inlet ports that allow fluid from the upset tubing to enter the tool-string. Optionally, this inlet defines a filter that prevents contaminants from entering the tool-string. Certain e-line and slickline deployments entail fluid pumped (from the surface) down the upset tubing, where it enters the tool-string via the inlet port(s). The fluid entering these ports can be used for several purposes. For example, it can be used to rotate a mud-motor or to power a jetting nozzle; or, it can be used as drilling fluid to wash the cuttings from the lateral. In instances, this fluid may be over pre-pressurized (compared to the ambient downhole pressure) by virtue of surface pumping equipment or by a downhole pump powered by the e-line. In some embodiments, the fluid entering the tool-string via the inlet port(s) first enters the upset tubing from the annulus of the wellbore via the intake port(s), described below.
In certain preferred e-line deployments, an intake port is positioned along the upset tubing. This intake port allows fluid to move from the wellbore annulus into the upset tubing. In operation, the intake port is situated above the inlet port of the radial drilling tool-string, thereby assuring the inlet port remains submerged in fluid. Optionally, the intake port may incorporate a filter to prevent contaminants from entering the upset tubing. Optionally, the intake port may comprise a one-way valve, the purpose of which is to prevent the reverse flow of fluid into the casing annulus—i.e. the one-way valve prevents the fluid that is pumped into the upset tubing annulus from immediately equalizing with the fluid in the wellbore annulus (and thereby negating the piston-affect).
In certain by e-line deployments, the disclosure defines a zero-discharge drilling system. In these embodiments, the e-line powers an electric pump used to pressurize the fluid that exits the flexible tools-string. In zero-discharge embodiments, the circulation path of the fluid: travels from the wellbore into the upset tubing via an intake port; enters the tool-string via an inlet port; and is then pumped down the flexible tool-string and out the head (e.g. jetting nozzle). This same fluid then returns to the wellbore (washing out the cuttings); rises in the casing annulus until it re-enters the upset tubing via the intake port. The cuttings (which are relatively small in volume), exiting the lateral, can simply fall to the bottom of the wellbore. This cycle can be repeated, forming a “zero-discharge drilling” drilling system where neither the cuttings nor the drilling fluid are returned to the surface. Moreover, this system can utilize fluid already in the wellbore, potentially eliminating any water procurement and treatment issues.
Having explained the creation and control of the piston-affect in e-line applications, we now turn to a discussion of slickline deployments. As described above, slickline deployments also utilize the seal(s) in the upset tubing. Unlike e-line deployments, however, slickline deployments lack an immediate means to power a downhole tool. With slickline only the longitudinal position of the tool-string can be controlled—and this only by virtue of gravity pulling the tool-string downward. To power the downhole radial drilling tools in slickline deployments, fluid is again directed into the tool-string via an inlet port(s). However, instead of an electric motor, a positive displacement motor (e.g. mud-motor or vane motor) is used. Fluid is thus pumped from the surface down the upset tubing, where it enters the tool-string via an inlet. The fluid then runs through the motor (producing the necessary rotation) and travels down the flexible drill-string where it exits the drilling-head. The fluid then returns to the surface, where it is again pumped down the upset tubing. In yet other slickline deployed embodiments, the flexible drill-string comprises a jetting hose and jetting nozzle. In these embodiments, the pressurized fluid pumped from the surface—and directed into the tool-string by the seals and inlet—is then used by the jetting nozzle to erode the formation. In this fashion, whether using mechanical or jetting tools, one is using a “drill by wire” form of radial drilling.
A principal feature of this disclosure is to allow radial drilling deployed by coiled-tubing in horizontal wells. In these embodiments, the coil itself serves as the pressurized fluid supply line used to power the downhole tools. As with certain e-line and slickline deployments, optional sealing members or seals are placed between the tool-string and the upset tubing. The requisite piston-affect is again created by pressurizing the chamber atop the seal(s); and is again used to propel the tool-string (and coiled-tubing) along the horizontal well and/or to increases the WOB at the tool-string head.
In most embodiments, to generate the required piston affect, surface pumping equipment can be used to pressurize the chamber. However, in certain embodiments, the pressure is created by porting-off a portion of the fluid pumped down the coiled-tubing. In these embodiments, the ported-off fluid enters and pressurizes the chamber to create the desired piston affect. To control the pressurization of the chamber and hence the magnitude of the piston affect, a spring-loaded check valve or other pressure drop device could be utilized. For example, with the annulus of the well vented and with both the annulus of the wellbore and the annulus of the upset tubing full of fluid, hydrostatic equilibrium would be attained. By now pumping (i.e. pressurizing) fluid into the chamber, one would create an over-pressurization situation and hence the desired piston-affect. Moreover, one could limit the force of this piston affect by limiting the over-pressurization in the chamber. For example, if the pressure inside the coiled-tubing were 1000 psi over the hydrostatic equilibrium, but a 500 psi check valve were installed in the port-off apparatus, than a maximum of 500 psi of differential could be applied to the chamber. Knowing the area over which this pressure acts, one could know the drive force of the piston affect. As before, by now slackening the coiled-tubing one can advance the tool-string and/or apply WOB.
In various embodiments, the seals may be affixed to or made part of the radial drilling tool-string. In addition, the seals may be affixed to the control-line rather than the radial drilling tool-string, proper. In these embodiments, the seals move with the radial drilling tool-string. In other embodiments, the seals may be affixed to the upset tubing. The seals in these embodiments are thus essentially fixed . . . with the tool-string being moving through them. In certain embodiments, multiple seals are spaced longitudinally along the tool-string or along the upset tubing. By emplacing multiple members, a robust seal can be assured regardless of downhole conditions and whether a particular seal fails (e.g. becomes ripped or fails to seal such as when passes-over a tubing collar). Whether “moving” or “fixed” and whether single or many, the seals help create the chamber that allows for the desired piston-affect.
Having discussed the reason and placement of the seals, we now turn to a discussion on the types of seals. This disclosure envisions two general seal types: positive engagement seals, where no or virtually no leakage occurs; and, virtual or proximity seals where some leakage is allowed. Within the first category, examples include ring seals, o-ring seals and style cup-seals. Within the second category are labyrinth seals and “virtual seals” formed by the close proximity of the radial drilling tool-string and the upset tubing.
The seals or sealing members are defined by a variety of types, shapes and materials. In certain embodiments not requiring high drive forces from the piston-affect, one can use a “leaky” labyrinth seal or similar “close-fit” between the outside diameter of the tool-string and the inside of the upset tubing. Moreover, even in these applications, one can increase the piston affect by increasing the pump rates into the chamber. Certain preferred embodiments entail an o-ring or ring-style seal. Other preferred embodiments, use a cup-seal that easily flexes to pass obstructions, yet provides robust sealing on account of the expanding cups. As with the labyrinth and close-fit style seals, in the event of leakage, additional fluid could be pumped into the chamber to maintain or increase the piston affect.
Certain preferred embodiments of this disclosure enable critical downhole operating parameters to be reported to surface personnel. The means of conveying this information to the surface may vary depending upon whether the control-line being used is e-line, slickline or coiled-tubing. Before discussing how this information is communicated, let us first talk about what information is gathered from downhole and why?
In certain embodiments, pressure sensors are placed downhole in the tool-string. For example, pressure sensors can be positioned above and below the seals, so as to measure the pressure acting across the seal—and hence the magnitude of the piston-affect. In certain embodiments, a torque cell is positioned in the radial drilling tool-string to measure the torque loads of a rotating tool-string. This information can be useful to surface personnel, who can adjust the electrical power supply or pump rates to better control the downhole tool (e.g. motor). In embodiments, a load cell or pressure sensor is used to measure and report the WOB, allowing surface personnel to modify drilling parameters for a more favorable rate of penetration (ROP). Indeed, by directly measuring the WOB from this downhole sensor, operating personnel can eliminate inaccuracies when deriving this value from calculations on the piston-affect and counter-acting line tension.
Having discussed various downhole sensors, we now turn to a discussion of how this information is conveyed to the surface. In e-line unit deployments, the conductor cable itself is used to convey the information to surface personnel. In slickline deployments, one or more ports on the tool-string can be alternately opened or closed thereby introducing identifiable pressure changes in the fluid column in the upset tubing annulus above the radial drilling tool-string. These pressure changes can be read by personnel using surface-based pressure transducers. In the instance of coiled-tubing, the conveyance mechanism need not be the fluid in the annulus of the upset tubing, but instead can be the fluid in the coiled-tubing itself. Indeed, this is a preferred pathway as personnel typically already monitor this pressure. In yet other embodiments, the coiled-tubing contains a concentric conductor cable or a fiber optic cable to convey this information. Indeed, electrical and fiber optic conductor are desirable to the extent that the readings can be more accurate and multiple sensors can be time coded or otherwise multiplexed into a single cable.
By virtue of the systems described above and perhaps more evident from the illustrations below, with this disclosure one can deploy and power radial drilling tool-strings via e-line, slickline or coiled-tubing unit; and, in an expanded range of well types—including even horizontal wells.

DETAILED DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an e-line unit (2) near a wellbore (22) wherein a whipstock (60) has been positioned on the end of upset tubing (40) and is facing a target zone (21). An upper portion of the upset tubing (40) has intake ports (46), allowing fluid to enter from the casing annulus (26). At present, the fluid level (28) in the wellbore (22) is too low to allow fluid to enter the upset tubing (40) via the intake ports (46). A fluid tank (12) and surface pump (10) will fill the wellbore (22) with fluid for the formation drilling procedure. The whipstock (60) is used to direct the radial drilling tool-string (70) toward the casing (24). This radial drilling tool-string (70) has an electric motor (87) and flexible drill-string (80) with attached cutting-head (82) used to drill through the casing (24). The radial drilling tool-string (70) has been equipped with torque arresting ears (102) that engage mating slots (45) along the upset tubing (40). This has been done to prevent torque from being conveyed up the e-line cable (3). There is no inlet port on the radial drilling tool-string (70) as the casing milling procedure does not require fluid to exit the cutting-head (82).
FIG. 2 illustrates another e-line (2) deployment. A return line (14) connects the casing annulus (26) to a fluid tank (12). The fluid level (28) is near the top of the wellbore (22), allowing fluid to enter the upset tubing annulus (42) via intake ports (46). In this case, the intake ports (46) have been equipped with a one-way valve (48) that prevent any fluid pumped down the upset tubing annulus (42) from directly passing into the casing annulus (26). A series of cup-seals (110), positioned on the radial drilling tool-string (70), prevent fluid from draining down the upset tubing annulus (42), past the radial drilling tool-string (70). The radial drilling tool-string (70) comprises an inlet port (108), filter (106), torque arresting ears (102) that engage mating slots (45) along the upset tubing (40), and electric motor (87) that rotate the flexible tool-string (80) and attached cutting-head (82). A downhole pump (88) pumps fluid down the flexible tool-string (80) and cutting-head (82). A relief port (47) allows fluid below the cup seals (110) to equalize with the fluid in the casing annulus (26). In this configuration, the surface pump (10) can be used to fill and/or pressurize the upset tubing annulus (42), if the fluid level (28) in the wellbore (22) drops below the intake port (46) or in the event that additional WOB needs to be applied.
To create additional WOB, the surface pump (10) is engaged so as pressurize the fluid in the upset tubing annulus (42) above the cup-seals (110), creating a differential pressure across the cup-seals (110). This differential pressure creates a piston-affect that tends to push the radial drilling tool-string (70) downward. By allowing slack in the e-line cable (3), the radial drilling tool-string (70) moves downward and/or WOB can be applied. The cutting-head (82) is forming a lateral borehole (76) in the target zone (21)—i.e. the earthen formation. As shown by the set of curved arrows, this is a zero-discharge radial drilling system whereby the fluid pumped out the cutting-head (82) returns to the casing annulus (26), rises to the intake ports (46), enters the upset tubing annulus (42), enters the inlet port (108) of the radial drilling tool-string (70) and then re-pressurized by the downhole pump (88), where it flow through the flexible tool-string (80) and out the cutting-head (82).
FIG. 3 illustrates a whipstock (60) resting atop an anchor (68) with upset tubing (40) running only part way up the wellbore (22). The fluid level (28) in the wellbore (22) allows the fluid to enter the top of the upset tubing (44). Weight bars (78) have been installed above the radial drilling tool-string (70) to assure adequate WOB at the cutting-head (82) as it drills into the target zone (21). In this case, the flexible tool-string (80) has been equipped with a cutting-head (82) that works by jet drilling (high pressure fluid). As such, no torque arresting apparatus is required. This radial drilling tool-string (70) has a downhole pump (88) powered by the e-line unit (2). The downhole pump (88) pressurizes the fluid, which then travels through the flexible tool-string (80) and out the cutting-head (82), which in this case is a jetting nozzle. The fluid exiting the cutting-head (82) returns to the casing annulus (26), where it then enters the top of the upset tubing (44) and re-enters the radial drilling-tool-string (70) via the inlet port (108). The fluid flow path is shown by the set of curved arrows.
FIG. 4 illustrates a slick-line unit (4) being operated in conjunction with a surface pump (10) and a radial drilling tool-string (70) comprising a mud-motor (86). The activation of the surface pump (10) pressurizes the fluid (29) in the chamber (43) atop the radial drilling tool-string (70) by virtue of labyrinth seals (111), which restrict (but do not completely eliminate) the flow past the labyrinth seals (111). This allows for a piston-affect with the radial drilling tool-string (70), whereby WOB can be applied to the cutting-head (82) via the flexible tool-string (80). Inlet ports (108) direct the pressurized fluid (29) into the radial drilling tool-string (70) and through a filter (106). The fluid then powers a mud-motor (86) used to rotate flexible drill-string (80) and attached cutting-head (82) which are will now be used to drill a hole in the casing (24) and proceed to form the borehole in the target zone (21). Torque arresting ears (102) on the radial drilling tool-string (70) engage mating slots (45) on the upset tubing (40) to resist the torque induced by the cutting-head (82). Unlike the flow constriction created by the labyrinth seals (111), the torque arresting ears (102) do not meaningfully prevent flow down the upset tubing annulus (42). The space (63) between the flexible toolstring (80) and J-path (62) of the whipstock (60) allows leakage of fluid to the casing annulus (26) as shown by arrow. The fluid exiting the cutting-head (82), as shown by the arrow, returns to the fluid tank (12) via the casing annulus (26) and is again pressurized by pump (10) and pumped down the upset tubing annulus (42). The fluid flow-paths are manifestly evident by the curved arrows.
FIG. 5 illustrates a slickline unit (4) used with a surface pump (10), fluid tank (12) and return line (14) used to deploy and power a radial drilling tool-string (70). In this case, the outside diameter of a mud-motor (86) creates a virtual seal (113) with the inside diameter of the upset tubing (40). This virtual seal (113) induces most of the pressurized fluid (29) atop the mud-motor (86) to enter the inlet port (108) of the radial drilling tool-string (70). The fluid then passes through a filter (106) before rotating a mud-motor (86). The mud-motor (86) rotates the flexible tool-string (80) and attached cutting-head (82) to form a borehole (76). Fluid (as shown by arrow) exiting the cutting-head (82) returns to the fluid tank (12) via the casing annulus (26)). The pump (10) again pumps the fluid (shown by curved arrow) down the upset tubing (40) and into the inlet port (108), whereby the circuit is repeated.
FIG. 6 illustrates a slick-line unit (4) performing a radial drilling procedure. In this case, fixed position seals (112) have been set along the upset tubing (40). Fluid from a surface pump (10) travels down the upset tubing (40) where it enters an inlet port (108) and passes through a filter (106) before traversing thru the flexible tool-string (80) and exiting the cutting-head (82), which in this case, is a rotating jetting nozzle. Fluid from the surface pump (10) moves down the upset tubing annulus (42) and encounters the fixed-position seals (112) bounding the chamber (43). This causes the pressure in the chamber (43) to build to 250 psi. As the pressure below the seals (112) is only 100 psi, a piston-affect is created, which allows the radial drilling tool-string (70) to be advanced down the upset tubing (40) and out the borehole (76) as slack is allowed in the slickline (4). The fluid exiting the cutting-head (82) returns to the fluid tank (12) via the casing annulus (26) and is re-pressurized by the surface pump (10) to again repeat the described circulation path.
FIG. 7 illustrates a coiled-tubing unit (6) deployed system with an injector head (16) positioned above a wellbore (22) having a horizontal section (25). A whipstock (60) is positioned on a scrapper (69) and upset tubing (40) running to the surface. A fluid tank (12) and pump (11) supply fluid to the coiled-tubing (8). A port-off apparatus (75) diverts a portion of this flow into the chamber (43) created by a ring seal (109) that has been affixed to a radial drilling tool-string (70) and the sealed wellhead (27), This configuration allows for the creation of the piston-affect, which propels the coiled-tubing (8) into the horizontal section (25) and applies WOB at the cutting-head (82) via the flexible tool-string (80). A mud-motor (86) powered by the coiled-tubing (8) rotates the flexible drill-string (80), which has transition through the whipstock (60). In this case, the cutting-head (82) mechanically drills the borehole (76) into the target zone (21). The fluid (as shown by arrow) exiting the cutting-head (82) returns to the fluid tank (12), via the casing annulus (26). As this particular coiled-tubing (8) is of a small diameter and cannot resist the torque generated by the action of the cutting-head (82), torque arresting ears (102) engage mating slots (45) on the upset tubing (40) to prevent twisting of the coiled-tubing (8).
FIG. 8 illustrates a similar embodiment to that of FIG. 7 except that the whipstock (60) is set on an anchor (68). In addition, cup-seals (110) are used so that the fluid (shown by curved arrows) pumped down the upset tubing annulus (42) drive the radial drilling tool-string (70) down the horizontal section (25) of the wellbore (22) as slack is allowed in the coiled-tubing line (8). In this instance, the flexible drill-string (80) does not rotate as the cutting-head (82) is a jetting nozzle. As shown by arrows, the fluid exiting the cutting-head (82) returns to the fluid tank (12) via the casing annulus (26).
Having reviewed the figures, we now continue our discussion of various preferred embodiments and the methods for deploying the radial drilling tools. In certain preferred embodiments, the invention comprises a radial drilling tool-string deployed by means of a e-line unit. These embodiments entail a whipstock positioned in the wellbore on upset tubing, with the e-line serving as the control-line. The tool-string comprises a flexible tool-string and head, which are configured to penetrate casing and/or formation. The flexible tool-string and head are run through the upset tubing and whipstock. Optionally, the radial drilling tool-string may comprise a form of drilling tool that penetrates the casing, but does not require fluid to traverse the flexible tool-string. In other embodiments, the flexible tool-string and head may be configured to allow for the passage of fluid out the head. In e-line embodiments where fluid is utilized one or more inlets are positioned along the tool-string allowing for the entry of fluid. Optionally, the tool-string comprises a downhole motor that rotates the flexible tool-string and which defines a cutting bit that mechanically drills the casing and/or formation. This motor may define an electric motor (powered by the e-line) or it may comprise a positive displacement motor (powered by fluid). In instances where the flexible tool-string is rotated by a positive displacement motor, the fluid that powers the motor comes from the annulus of the upset tubing via the inlet(s) on the tool-string. In e-line embodiments where fluid is used a pump pressurizes the fluid. This pump may be a surface-based pump used to pump the fluid down the annulus of the production tubing; or, it may be a downhole pump powered by the e-line. In e-line embodiments, where the tools used to form the hole in the casing and/or formation are rotating tools, a torque arresting mechanism may be used. This apparatus prevents the reverse torque from being induced into the e-line. One such version of this torque resisting mechanism is defined by ears on the tool-string and extended mating slots on the upset tubing. Another embodiment defines a camming mechanism in the tool-string, which engages the upset tubing and prevents the further rotation of the radial drilling tool-string (and attached e-line). Either of these embodiments can allow for the arresting of torque during the extended drilling of the lateral borehole. It should be noted, however, that not all e-line deployed systems require the arresting of torque. For example, certain embodiments employ a jetting nozzle to erode the formation, and generate no appreciable torque needing to be resisted.
In certain preferred embodiments, the invention comprises a radial drilling tool-string deployed by means of a slick-line. Such systems entail a whipstock positioned in a wellbore on upset tubing, with the slickline serving as the control-line for the tool-string. The tool-string comprises a flexible tool-string and head, which are configured to penetrate casing and/or formation. The flexible tool-string and head are run through the upset tubing and whipstock. The flexible tool-string and head may be configured to allow for the passage of fluid, such as by a hose positioned in the flexible tool-string and one or more passageways in the head, itself. Slickline embodiments utilize one or more inlets, positioned along the tool-string, thereby allowing fluid to enter and power the tool-string. Optionally, the tool-string comprises a downhole motor that is used to rotate the flexible tool-string and which defines a cutting bit that mechanically drills the casing and/or formation. In these embodiments, a positive displacement motor (e.g. vane motor or mud-motor) is used. The motor is powered by the fluid pumped down the upset tubing annulus and which enters the radial drilling tool-string via the inlet(s) on the tool-string. The pump that supplies this fluid is surface-based. In slickline embodiments, where the tools used to form the hole in the casing and/or formation are rotating tools, a reverse torque may be induced into the torsionally-weak slickline. To prevent this reverse torque from twisting-up and damaging the slickline, a torque-resisting mechanism is used. One such version of this torque resisting mechanism is defined by ears on the radial drilling tool-string and extended mating slots on upset tubing. Another embodiment defines a mechanism that locks the tool-string to the upset-tubing (which is able to resist the torque) by virtue of a camming device. It should be noted, however, that not all slickline deployed systems require the arresting of torque. For example, if one deploys a jetting nozzle to erode the formation, no problematic torque is created by the nozzle and hence the torque arresting feature is not required.
In certain preferred embodiments, the invention comprises a radial drilling system deployed by means of coiled-tubing in a horizontal well. The coiled-tubing may be of a large diameter (e.g. 2″+), which generally has high axial and torsional stiffness; or, it may be small diameter tubing (e.g. ⅝″) which has limited axial stiffness and low resistance to torque (i.e. twisting). These systems entail a whipstock positioned in a wellbore on upset tubing, with the coiled-tubing serving both as the retrieval line for the radial drilling tool-string, but also the power supply line for the tool-string. The radial drilling tool-string comprises a flexible tool-string and head, which are configured to penetrate casing and/or formation. The flexible tool-string and head are run through the upset tubing and whipstock. In some embodiments, the flexible tool-string and head are configured to allow for the passage of fluid, such as by a hose positioned in the flexible tool-string and one or more passageways in the head, itself. In other embodiments, the flexible tool-string does not pass fluid to the head, e.g. such as if only cutting the wellbore casing. Optionally, the tool-string comprises a downhole motor that rotates the flexible tool-string and attached cutting-head. The motor is a positive displacement motor (e.g. vane motor or mud-motor) and is powered by the fluid pumped down the coiled-tubing from a surface-based pump. In coiled-tubing applications, where the tools used to form the hole in the casing and/or formation are rotating tools, a torque arresting mechanism, like that described elsewhere herein, may be used to resist the reverse torque. Such a device may not be required in all instances, however. For example, when deploying such tool by large diameter coiled-tubing (e.g. 1.5″ diameter), the low torque values generated by the rotating tools (typically below about 150 ft-lbs) can be resisted by the tubing itself. On smaller diameter coiled-tubing (e.g. ¾″), however, such torque values could twist and damage the coiled-tubing—and hence, the torque resisting apparatus would be used. It should be noted that not all ‘small diameter’ coiled-tubing applications require the torque arresting apparatus. For example, if one were deploying a jetting nozzle in a horizontal well on the end of a small diameter coiled-tubing unit, no appreciable torque would be created and the torque arresting feature would not be required.
Having discussed the general deployment control-lines and how these tools are deployed, we now continue our discussion of optional embodiments and methodologies.
In certain e-line and slickline embodiments, the system comprises a downhole motor in the tool-string. This motor is used to rotate the flexible tool-string and attached head. In e-line embodiments, the downhole motor may be either an electric motor, powered by the e-line; or, it may be a fluid-powered motor, such as a mud-motor. When the motor is fluid-powered, the fluid is pumped down the upset tubing from the surface and enters the tool-string via the inlet(s). The pressurized fluid then runs through the motor, generating rotation, which is transferred to the attached flexible tool-string and head. In slickline embodiments where the means to cut the casing and/or formations is via a rotating tool, then the downhole motor is a fluid motor is powered by a surface pump. Similar to certain e-line embodiments, in these slickline embodiments, the fluid is sourced from a surface-based pump, travels down the upset tubing and enters the tool-string via an inlet(s).
In e-line embodiments employing a downhole motor, the motor may comprise a dual-purpose assembly that also serves as pump. In these embodiments, the dual-purpose assembly would serve to both pump fluid to the head and act as a motor that rotates the flexible tool-string. Such a system enables mechanical radial drilling of boreholes by e-line.
Optionally, e-line embodiments, may have one or more entry points or intake ports along the upset tubing. The purpose of the intake port(s) is to allow fluid to pass from the annulus of the wellbore into the upset tubing, where it can then enter the tool-string via the inlet(s). The purpose of these intake ports is to allow for a closed loop drilling system whereby fluid exiting the head returns to the wellbore, rises in the wellbore, enters upset tubing form the intake port and then enters the tool-string, where the fluid can then be pumped down the flexible tool-string and out the head.
Optionally, the e-line, slickline or coiled-tubing embodiments may further comprise a seal between the upset tubing and the radial drilling tool-string or between the upset tubing and the respective control line. The purpose of this sealing apparatus is to allow for the creation of a piston-affect by virtue of differential pressure across the seal. By this method of applying higher pressure above the seal (than below), the piston-affect can be created to advance the tool-string further into the well or to apply WOB. In some embodiments, the sealing apparatus is formed by a positive seal, which negates flow from above the seal to below the seal; while in other embodiments the seal is a virtual seal created by the close-proximity of the tool-string and the upset tubing. Suitable seal for this purpose may be selected from the following list: a labyrinth seal; a ring or o-ring style seal; a cup seal; or, a virtual seal, created by the close proximity of the tool-string to the upset tubing.
In certain embodiments, the seals used to generate the piston-affect are cup-seals, i.e. seals that produce a mild interference fit with the inside diameter of the upset tubing and readily flare outward to produce an even more robust seal with increasing differential pressure. In embodiments, the cup-seal are integrated into the tool-string and comprise an assembly with two parts: a main body and the cup-seals themselves. In certain embodiments, the main body has a recess that is narrower about its center than its ends. This recess serves as a space into which part of the sealing element can move or collapse. For example, the recess can also serve as a space into which the cup-seal may collapses, when the tool-string is retrieved from the well. The concave side of the cup-seal(s) face toward the top of the well to “catch” the fluid pumped down the upset tubing. In certain preferred embodiments, the thickness of the cup is about ¼″ to 1.2″ and the overall length of the cup is about 1-½″ to 3″ long. In embodiments, the forward and back edges of the cup-seal are rounded or chamfered so as to prevent damage to the seal edges when being run into or retracted from the well. This rounding or chamfering of the cup-lip, helps assure they cup seal does not become folded over when being retracted from the well. In certain embodiments, the main body has an inner passageway through which drilling fluid can pass toward the flexible tool-string. In some preferred embodiments, the two ends of the main body make a “close fit” (e.g. less than about ⅜″), to the inside diameter of the upset tubing, so as to assure that the cup seal remains centralized along the upset tubing axis.
Optionally, the slickline and e-line embodiments described herein which entail fluid entering the radial drilling tool-string, may incorporate a filter. This filter would be part of the tool-string and would serve to prevent contaminants from entering: the radial drilling tool-string; the downhole pump and/or the flexible tool-string.
Optionally, in e-line embodiments using a downhole pump or motor, the upset tubing may entail a one-way valve. By virtue of this one-way valve fluid can enter the upset tubing from the wellbore annulus but is prevented from moving from the upset tubing to the wellbore annulus. The purpose of this one-way valve is to allow for the creation of the piston affect by virtue of the differential pressure across the seals. It is a further purpose of the one-way valve to allow a closed-loop drilling system, by virtue of the fact that the circulation path does not necessitate that fluid be brought to the surface.
The various embodiments described herein are intended to allow for the deployment of a variety of heads used to form the hole in the casing and/or formation. For example, the head may define a form of mechanical drill bit that is rotated by a motor. Alternatively, the head may define a jetting nozzle that ejects pressurized fluid to erode the formation. Likewise, the head may define an apparatus that works by means of jet-assisted mechanical drilling or is defined by a form of jet-assisted mechanical drilling.
In the various embodiments utilizing a seal(s) for the creation of the chamber and piston-affect, one can use fluid or gas to generate the requisite differential pressure. Moreover, the piston-affect can be aided by the slackening or loosening of the control line. It should also be noted that the control lines have a natural stretch to them, so it is not always mandatory to deliberately slacken the control line. For example, if a cutting-head is already drilling the wellbore casing on a horizontal well, the operator can apply more WOB by merely increasing the pressure on proximal (or top) side of the seal. In this case, the increased force of the piston-affect can slightly stretch the coiled-tubing, e-line or slickline, thereby allowing for an increased in WOB. Of course, for continuous drilling of an extended borehole, it will be necessary to advance the control line with maintaining the piston-affect.
We now turn to a discussion of the placement of the seal(s). In various embodiments, the seal(s) of this disclosure can be placed in either a fixed position along the upset tubing; or, they may be placed along on the downhole tool-string. In the cased where the seals are placed in a fixed position, the radial drilling tool-string essentially moves through the seal as it traverses the upset tubing. Typically, in these fixed location embodiments, multiple seals are positioned along the upset tubing forming a series of successive series, whereby the piston-affect can remain uninterrupted as the tool-string moves down the well. Notably, these fixed position seals may only be necessary in slant or horizontal section of a wells, as force of gravity alone is likely sufficient in the vertical portion; and, if not, the weight bars can be added to generate higher downward forces. In other embodiments, the seal(s) would be attached to the tool-string itself; and, would thereby move along the upset tubing as the tool-string is moved in and out of the wellbore.
In e-line embodiments, the e-line conductor may serve as a pathway for communicating the parameters or values of certain downhole tool. In embodiments, the value reported to the surface will be the torque value, such as by may be determined by a downhole position sensor, transducer or load cell. In certain embodiments, the e-line may be used to convey the WOB value, such as might be attained from a pressure transducer or position sensor. And, in embodiments, the value reported through the e-line may be the annular pressure in the upset tubing above, below and/or across the seal(s). In embodiments, reported value may be the pressure reading may be of the fluid being pumped down the flexible tool-string. Obviously, multiple values may be reported by the e-line conductor.
Optionally, in coiled-tubing embodiments the means to create the pressure in the chamber above the seal is a port-off apparatus. In such embodiments, the port-off apparatus is part of the radial drilling tool-string and would discharge a portion of the flow from inside the coiled-tubing to the chamber. In this fashion the chamber could be pressurized to generate the piston-affect, without the need for pumping fluid from the surface down the upset tubing. Moreover, in some embodiments, this port-off apparatus would define a spring-loaded check valve or similar pressure drop device that would limit the maximum pressure that could be built in the chamber. For example, if the line pressure in the coiled-tubing exceed the hydrostatic pressure by 750 lbs and the spring-loaded check valve did not open until 375 lbs were applied, then the pressure in the chamber could be regulated to only exceed hydrostatic pressure by 375 psi. In this fashion, one can limit the magnitude of the piston-affect.
In coiled-tubing embodiments the radial drilling system may entail a conductor or fiber optical cable positioned in the coiled-tubing. Alternatively, one may incorporate fluid pulses into the fluid stream in the coiled-tubing. This can be done be changing opening or closing a port and thereby changing the back-pressure on the fluid—a value which can be measured at the surface. In embodiments, the value reported from the downhole tool to the surface will be the torque value such as by a may be reported by a downhole position sensor, transducer or load cell. In embodiments, this conductor cable or fiber-optic line may convey the WOB value, such as might be attained from a pressure transducer or position sensor. And, in embodiments, the value reported through the conductor or fiber optic cable may be the pressure reading above the seal, below the seal or across the seals.
In the narrative above, we have discussed various apparatus and methods to deploy radial drilling tool-string using the piston-affect to advance the tool-string into a well and/or apply WOB. However, a similar piston-affect can also be used to help retrieve the tool-string from a well in the event that it becomes stuck or in order to reduce the amount of line-pull (tension) required in the control-line. This can be done by bleeding-off the pressure in the chamber above the seals (e.g. returning this fluid to an open tank), while pumping fluid into the annulus of the wellbore. By this method, once essentially creates the same piston-affect, but in the opposite direction.
As evident from the figures, descriptions, and narrative, the various embodiments of the present disclosure can be joined in combination with other embodiments without deviating from the spirit of this disclosure. Moreover, the figures and narrative are not meant to limit the disclosure. That is, all combinations of various embodiments of the disclosure are enabled, even if not given in a particular example.
While illustrative embodiments have been depicted and described, modifications thereof can be made by one skilled in the art without departing from the scope of the disclosure. Moreover, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces. For purposes of brevity and grammatic style, in certain instances, the longer term “radial drilling tool-string” is simplified by usage of the simpler term “tool-string”. Similarly, the term “head” may be used herein to denote a form of mechanical cutting-head, jetting nozzle or other apparatus by which a hole in the casing and/or earthen formation are formed. Furthermore, while this disclosure typically utilizes the term “fluid”, it is to be understood the fluid may be fluid or gas. For example, one can power the mud-motor with a gas such as nitrogen. If there is a conflict in the usages of a word or term in this specification and one or more patent or other documents, the definitions that are consistent with this specification should be adopted. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly defined by the patentee.
Depending on the context, all references herein to the “disclosure” may in some cases refer to certain specific embodiments only. In other cases, it may refer to subject matter recited in one or more, but not necessarily all, of the claims. While the foregoing is directed to embodiments, versions and examples of the present disclosure, which are included to enable a person of ordinary skill in the art to make and use the disclosures when the information in this patent is combined with available information and technology, the disclosures are not limited to only these particular embodiments, versions and examples.
Numerous other modifications, equivalents, and alternatives, will become apparent to those skilled in the art once the above disclosure is fully appreciated. While embodiments of the disclosure have been shown and described, modifications thereof can be made by one skilled in the art without departing from the teachings of this disclosure. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the disclosure disclosed herein are possible and are within the scope of the disclosure.
Use of the term “optionally” with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. It is intended that the following claims be interpreted to embrace all such modifications, equivalents, and alternatives where applicable. Other and further embodiments, versions and examples of the disclosure may be devised without departing from the basic scope thereof and the scope thereof is determined by the claims that follow.

Claims

1. A coiled-tubing deployed system for radial drilling from a horizontal well comprising:

a surface based pump capable of supplying fluid through coiled-tubing;

a whipstock placed in a wellbore on upset tubing;

the coiled-tubing serving as a control-line for a radial drilling tool-string positioned in the upset tubing;

the radial drilling tool-string comprising:

a flexible tool-string and head wherein fluid can traverse the flexible tool-string and exit the head;

the head configured to penetrate casing and/or earthen formation;

a chamber formed by: the wellhead; the annulus in the upset tubing; and, a sealing apparatus between the upset tubing and the radial drilling tools-string;

said chamber able to be pressurized so as to create a piston-affect capable of driving the radial drilling tool-string and coiled-tubing down the horizontal well and/or of applying weight on bit.

2. The sealing apparatus of claim 1 either attached to the control-line, the radial drilling tool-string or to the upset tubing; and, selected as one from the following list:

a labyrinth seal;

a ring or o-ring style seal;

a cup-seal; or,

a virtual seal created by the close proximity of the radial drilling tool-string to the inside of the upset tubing.

3. The sealing apparatus of claim 1 defining a cup-seal assembly attached to the radial drilling tool-string or the control-line and having one or more of the following characteristics:

a cup which faces toward the top of the well;

a recess into which a portion of the cup can fold or collapse as it is moved in the upset tubing; or,

a cup-lip having a radius or chamber.

4. The radial drilling tool-string of claim 1 further comprising a torque arresting apparatus used to resist the reverse torque generated by a positive displacement motor powered by the coiled-tubing and used to rotate the flexible tool-string and head.

5. The system of claim 1 further comprising a sensor apparatus that can indicate at least one of the following radial drilling tool-string operating parameters:

the torque load on a downhole motor;

the pressure generated by a downhole pump;

the weight on bit;

the pressure above the sealing apparatus;

the pressure below the sealing apparatus; or

the differential pressure across the sealing apparatus.

6. The system of claim 1 further comprising apparatus to communicate one or more radial drilling tool-string operating parameters to the surface via one of the following methods:

an electrical conductor line running through the coiled-tubing;

a fiber-optic line running through the coiled-tubing; or,

via changes in the back-pressure of the fluid in the coiled-tubing.

7. The radial drilling tool-string of claim 1 further comprising a port-off apparatus, which directs a portion of the flow down the coiled-tubing into the chamber allowing for the creation of the piston-affect used to advance the radial drilling tool-string and/or apply weight on bit.

8. The head on the end of the flexible tool-string in claim 1 that is used to form the hole in the casing and/or in the earthen formation, selected from the following list:

a rotating mechanical drilling bit;

a non-rotating jetting nozzle;

a cavitation or pulsating nozzle;

a rotating jetting nozzle; or,

a jet-assisted mechanical drilling head.

9. A system for radial drilling in vertical, slant or horizontal wells deployed by e-line or slickline comprising:

a whipstock placed in a wellbore on upset tubing;

the e-line or slickline serving as a control-line for a radial drilling tool-string positioned in the upset tubing;

the radial drilling tool-string comprising:

a flexible tool-string and attached head configured to allow fluid to traverse the flexible tool-string and exit the head;

the head configured to penetrate casing and/or earthen formation;

an inlet port for fluid to enter from the upset tubing annulus into the radial drilling tool-string;

a pump capable of providing pressurized fluid to the radial drilling tool-string;

10. The systems of claim 9 further comprising a downhole filter that is part of the radial drilling tool-string and which filters fluid that moves from the upset tubing into the radial drilling tool-string.

11. The system of claim 9 further comprising one of the following:

a surface-based pump system that moves fluid down the upset tubing, where it enters the radial drilling tool-string through the inlet port;

a downhole pump that is powered by the e-line and is part of the radial drilling tool-string; or,

a dual-purpose downhole assembly that is powered by the e-line and which both pumps fluid through the flexible tool-string and comprises a motor used to rotate the flexible tool-string.

12. The system of claim 9 further comprising a torque arresting apparatus used in conjunction with one of the following:

an electric motor powered by the e-line and used to rotate the flexible tool-string and/or head; or,

a positive displacement motor powered by fluid pumped down the upset tubing from the surface and which enters the radial drilling tool-string via the inlet port, and is used to rotate the flexible tool-string and/or head.

13. The sealing apparatus of claim 9 either attached to the upset tubing; the control-line or the radial drilling tool-string; and, selected as one from the following list:

a labyrinth seal;

a ring or o-ring style seal;

a cup-seal; or,

14. The sealing apparatus of claim 9 defining a cup-seal assembly attached to the radial drilling tool-string or to the control-line and having one or more of the following characteristics:

a cup that is oriented so as to expand outward when fluid is pumped into the chamber;

a recess into which a portion of the cup can fold or collapse as the cup-seal assembly is moved along the upset tubing; and/or,

a cup-lip having a radius or chamber.

15. The upset tubing of claim 9 having an intake port allowing fluid to pass from the annulus of the wellbore into the annulus of the upset tubing.

16. The apparatus of claim 9 further comprising a one-way valve that allows fluid to enter the upset tubing from the wellbore annulus, but prevents fluid from moving from the upset tubing to the wellbore annulus via this valve.

17. The system of claim 9 further comprising one or more sensor apparatus that indicate at least one of the following radial drilling tool-string operating parameters:

the torque load on a downhole motor;

the pressure generated by a downhole pump;

the weight on bit;

the pressure above the sealing apparatus;

the pressure below the sealing apparatus; or

the differential pressure across the sealing apparatus.

18. The system of claim 9 further comprising apparatus to communicate one or more radial drilling tool-string operating parameters to the surface via one of the following methods:

an electrical conductor line running through the e-line; or,

via changes in the pressure of the fluid in the annulus of upset tubing.

19. The head on the apparatus of claim 9 that is used to form the hole in the casing and/or in the earthen formation, selected as one from the following list:

a rotating mechanical drilling bit;

a non-rotating jetting nozzle;

a cavitation or pulsating nozzle;

a rotating jetting nozzle; or,

a jet-assisted mechanical drilling head.

20. A method to performing radial drilling from a horizontal well by means of coiled-tubing comprising the steps of:

positioning a whipstock in a horizontal well on upset tubing;

connecting the coiled-tubing to a radial drilling-tool-string comprised of:

a flexible tool-string having a conduit for conveying fluid to a head; wherein,

the head is attached: to the flexible tool-string; allows for the ejection of fluid; and, is configured to form a hole in casing and/or earthen formation;

lowering the radial drilling tool-string through the upset tubing;

forming a chamber atop the upset tubing by means of a sealing apparatus situated between:

the upset tubing and the radial drilling tool-string; or,

the upset tubing and the coiled-tubing;

activating a surface-based pump in fluid communication with and capable of powering the radial drilling tool-string;

generating a piston-affect used to advance the radial drilling string and/or apply weight on bit by virtue of pressurizing the chamber; and then,

advancing the radial drilling tool-string so as to form a hole in the wellbore casing and/or earthen formation by virtue of the head.

21. The method of claim 20 further comprising the steps of pressurizing the chamber to generate the piston-affect by:

porting-off a portion of the fluid pumped down the coiled-tubing; or,

pumping fluid directly into the chamber from the surface.

22. The method of claim 20 further comprising the steps of supplying pressurized fluid to the radial drilling tool-string, thereby allowing the formation of the hole in the casing and/or earthen formation by virtue of one of the following types of head:

a non-rotating nozzle;

a head defining a rotating nozzle;

a self-rotating mechanical drilling head; or,

a mechanical cutting-head that is rotated by a motor that rotates the flexible tool-string.

23. The method of claim 20 further comprising the steps of using a torque arresting apparatus to resist the reverse torque generated by a rotating head used to drill the casing and/or earthen formation.

24. The method of claim 20 further comprising an electrical cable or fiber optic cable;

or changes in the fluid pressure within the coiled-tubing to report at least one of the following radial drilling tool-string operating parameters:

the torque on a downhole motor;

the weight on bit;

the pressure above the sealing apparatus;

the pressure below the sealing apparatus; and/or

the differential pressure across the sealing apparatus.

25. A method for radial drilling into earthen formation with an e-line unit comprising:

placing a whipstock in a wellbore on upset tubing;

connecting the e-line to a radial drilling tool-string comprising:

a flexible tool-string and attached cutting-head wherein fluid can traverse the flexible tool-string and exit the cutting-head;

an electric motor powered by the e-line and capable of rotating the flexible tool-string and cutting-head; and,

a torque-resisting apparatus to counter-act the reverse torque generated by the action of the cutting-head;

activating the electric motor to rotate the radial drilling tool-string;

activating a pumping system capable of supplying fluid through the flexible tool-string and out the cutting-head;

using the flexible tool-string and attached cutting-head to drill a hole in the wellbore casing and/or earthen formation; while engaging the torque-resisting apparatus to prevent any reverse torque generated by the cutting-head from twisting the e-line.

26. A method for deploying radial drilling tools from vertical, deviated or horizontal wells by means of a slickline or e-line unit comprising:

positioning a whipstock in a wellbore on upset tubing;

connecting the slick-line or e-line to a radial drilling tool-string comprising:

a flexible tool-string capable of delivering fluid to a head, which is configured to form a hole in the casing and/or earthen formation;

an inlet port for fluid to enter from the wellbore into the radial drilling tool-string, wherein the fluid can traverse through the flexible tool-string and exit the head;

positioning a sealing apparatus between the radial drilling tool-string and the upset tubing so as to create a chamber atop the sealing apparatus;

activating a surface-based pumping system that pumps fluid down the upset tubing whereby it encounters the sealing apparatus and generates a piston-affect that is used to advance the radial drilling string and/or apply weight on bit; and, wherein at least some of the fluid enters the radial drilling tool-string and powers the head; and, then,

forming a hole in the casing and/or earthen formation by virtue of the flexible tool-string and head.

27. The method of claim 26 further comprising the steps of using the fluid to power a motor that is part of the radial drilling tool-string and which rotates the flexible tool-string and the head so as to mechanically drill the casing and/or earthen formation while engaging a torque-resisting apparatus that counter-act any reverse torque generated by the head.

28. The method of claim 26 further comprising the formation of the hole in the earthen formation by conveying pressurized fluid down the flexible drill-string and ejecting the pressurized fluid out a nozzle