Large numbers of older oil wells in the U.S. bypassed relatively thin oil-bearing formations, whose recovery was not economical at the time those wells were drilled. Production of oil from formations that were thus bypassed represents a significant opportunity in an era of higher oil prices. Many of these previously bypassed zones are now being reworked. Oil production from thin zones and depleted older producing zones is commonly accompanied by substantial water production. Hydraulic fracturing is the principal technique for stimulating production from thin zones and depleted fields. This technique typically results in a pair of vertical wing fractures extending into the formation. In thin zones or depleted formations, the fractures commonly intersect water-bearing formations, resulting in the recovery of oil cut with water. The cost of separating the oil from the recovered oil and water mixture, and disposing of the water, is significant.
Jet drilling rotors are capable of drilling porous rock such as sandstone, with low thrust and zero mechanical torque. These tools can be made very compact, enabling the tools to conform to a small bend radius. Ultra-short radius jet drilling offers the potential to drill production holes entirely within the oil- or gas-bearing volume of a producing formation, or within a previously bypassed formation, such as those noted above. This approach should minimize the amount of water recovered with the oil, while simultaneously enabling the recovery of oil from a relatively large area.
Lateral completion wells in thin producing zones with good vertical permeability provide the greatest potential for increased production relative to vertical wells. The target formations for lateral drilling are typically relatively thin (i.e., ranging from about 2 to about 10 meters in thickness) formations that were bypassed in existing production wells. Jet drilling tools provide effective drilling at minimal thrust in permeable oil and gas producing formations, but may not effectively drill through impermeable cap-rock. The objective when drilling such formations is to drill a curved well within the formation thickness, implying the need to drill around a short radius curve having a minimum radius of about 1 meter (40 inches). Working within such a tight radius cannot be achieved using small diameter steel or titanium coiled tubing without exceeding the elastic yield of the tubing and generating a set bend that prevents subsequent straight hole drilling. Composite tubing capable of elastic bending through a small bend radius is available (for example, from Hydril Advanced Composites Group of Houston, Tex.). Unfortunately, such composite tubing generally exhibits maximum pressure ratings of about 35 MPa (˜5000 psi), which is too low for many jet drilling objectives. Wire-wound high-pressure hose capable of bending though a short radius is also available (for example, from the Parflex Division of the Parker Hannifin Corporation in Ravenna, Ohio). Unfortunately, such wire-wound high-pressure hose is very flexible, and will buckle if employed to drill lateral completion wells. It would therefore be desirable to provide a hose assembly configured to deliver high-pressure jetting fluid to a jet drilling tool, where the hose assembly is sufficiently flexible to pass through a short radius curve without damage or acquiring a permanent set, yet is stiff enough to drill a long lateral extension without buckling or locking up in the hole.
Disclosed herein is a sleeved hose assembly configured to facilitate the drilling of a long lateral extension through a short radius curve without buckling. As noted above, conventional wire-wound high-pressure hoses are not configured to exhibit transverse moduli sufficient to prevent such buckling from occurring during the drilling of a long lateral extension. The sleeved hose assembly disclosed herein includes both a wire-wound high-pressure hose having a transverse stiffness insufficient to prevent such buckling from occurring, and a sleeve having a transverse stiffness that is sufficient to prevent such buckling from occurring. The wire-wound high-pressure hose is inserted into the sleeve to achieve a sleeved hose assembly having a transverse stiffness sufficient to prevent buckling. As disclosed in greater detail below, a critical buckling load can be determined for a particular drilling application. Based on the critical buckling load that is thus determined, an adequate sleeve material can be selected. In a particularly preferred embodiment, the sleeve material exhibits a transverse modulus of at least about 10 GPa. It should be recognized however, that such a figure is intended to be exemplary, rather than limiting. Carbon fiber reinforced epoxy composites can be used to provide the sleeve, although other types of reinforcing fibers, such as fiberglass or aramid fiber, may be employed. The use of composite sleeve materials also reduces the weight and sliding friction resistance of the sleeved hose assembly, which allows drilling of longer laterals before buckling occurs. Because the composite material retains its elasticity, it will straighten upon exiting the curve, allowing straight drilling of lateral holes.
Also disclosed herein is a method for drilling a short radius curve using such a sleeved hose assembly and a method for drilling a lateral borehole using such a sleeved hose assembly.
Another aspect of this novel approach is directed to a method for drilling an ultra-short radius curve using a rotating jetting tool with a bent housing. The method includes the steps of selecting a wire-wound high-pressure hose capable of withstanding a fluid pressure required to operate the rotating jetting tool that will be used to drill the ultra-short radius curve. A sleeve is selected that is capable of jacketing the wire-wound high-pressure hose. The wire-wound high-pressure hose is then inserted into the sleeve to achieve a sleeved hose assembly. A drill string including the sleeved hose assembly and the rotating jetting tool is assembled, and the drill string is inserted into a borehole. The jetting tool incorporates a bent housing to facilitate drilling of the curved hole. A pressurized fluid is introduced into the sleeved hose assembly to energize the rotating jetting tool. The rotating jetting tool is then used to drill the short radius curve.
The method for drilling the lateral borehole includes the steps of selecting a wire-wound high-pressure hose capable of withstanding a fluid pressure required to operate a drilling tool to be used to drill the lateral drainage borehole, wherein a transverse stiffness of the wire-wound high-pressure hose is insufficient to prevent buckling of the wire-wound high-pressure hose during lateral drilling. A sleeve is selected that is capable of jacketing or encompassing the wire-wound high-pressure hose, and having a transverse stiffness sufficient to prevent buckling of the wire-wound high-pressure hose when jacketed/encompassed by the sleeve during lateral drilling. The wire-wound high-pressure hose is then inserted into the sleeve to achieve a sleeved hose assembly. A drill string is assembled that includes the sleeved hose assembly and a straight drilling tool, and the drill string is inserted into a borehole. A pressurized fluid is introduced into the sleeved hose assembly to energize the drilling tool, and the drilling tool is used to drill the lateral drainage borehole, without danger of the wire-wound high-pressure hose buckling during the lateral drilling.
Alternatively, a mechanism may be incorporated into the bent housing, which causes it to straighten when subjected to a change in pressure or axial load. For example, the housing could incorporate a knuckle joint that bends at high load, enabling the tool to drill a curve, but then straighten at a lower load, enabling straight hole drilling. Exemplary (but not limiting) high load (or high pressure) conditions can range from about 1000 psi to about 10,000 psi, while exemplary (but not limiting) low load (or low pressure) conditions can range from about 0 psi to about 500 psi. Those of ordinary skill in the art will readily recognize that such a pressure/load actuated bendable housing can be configured to predictably respond to various pressure/load conditions.
Because such ultra-short radius curves are particularly useful for drilling lateral extensions in relatively thin producing zones, additional desirable steps include selecting a sleeve having a transverse stiffness sufficient to prevent the wire-wound high-pressure hose from buckling during the short radius curve drilling, and drilling lateral extensions beyond the short radius curve.
This Summary has been provided to introduce a few concepts in a simplified form that are further described in detail below in the Description. However, this Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Various aspects and attendant advantages of one or more exemplary embodiments and modifications thereto will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
Figures and Disclosed Embodiments Are Not Limiting
Exemplary embodiments are illustrated in referenced Figures of the drawings. It is intended that the embodiments and Figures disclosed herein are to be considered illustrative rather than restrictive.
Those of ordinary skill in the art will readily recognize that
An exemplary deployment sequence for the sleeved hose assembly is schematically and sequentially illustrated in
At this point, high-pressure pump 24 is stopped, so that the pressure in high pressure tubing 26, sleeved hose assembly 22, and jet drill 34 decreases. The tubing (high pressure tubing 26, sleeved hose assembly 22, spring-biased housing 37, and jet drill 34) is then un-weighted and pulled up slightly, to allow the bend in spring-biased housing 37 to straighten. Once the bend in spring-biased housing 37 is removed, the now straight housing enables: a lateral well extension 32 to be drilled, as is schematically illustrated in
Exemplary Properties of the Sleeved Hose Assembly
The critical buckling load for a tube in a horizontal well (expressed in Newtons (N)) is defined as:
where E is the transverse stiffness of the tube material in Pascals (Pa), I is the beam section moment of inertia in m4, w is the weight of the tube per unit length (expressed in N/m), and r is the radial clearance between the tube and the borehole (expressed in meters).
Steel wire-wound hose (i.e., wire-wound high-pressure hose 10) is used to provide mass, w, which helps to stabilize sleeved hose assembly 22 against buckling. In an exemplary preferred embodiment, sleeve 20 is formed of a carbon fiber reinforced epoxy composite material. The composite sleeve provides a substantially higher transverse stiffness obtained from the product of modulus, E, and moment of inertia, I, than is available from wire-wound high-pressure hose 10 alone. The composite sleeve (i.e., sleeve 20) also reduces the clearance, r, between the sleeve assembly and the borehole. In one particularly preferred exemplary embodiment, sleeved hose assembly 22 exhibits the following properties:
It should be recognized that the above identified properties are intended to be exemplary, rather than limiting. A rotary jet drill of this size may require 200 N of axial thrust for effective drilling. The additional thrust is used to overcome the frictional resistance due to the submerged weight of the sleeved hose in the borehole. Assuming a sliding friction coefficient of 0.5, this assembly could be used to drill an 800 m lateral without buckling.
Although the present invention has been described in connection with the preferred form of practicing it and modifications thereto, those of ordinary skill in the art will understand that many other modifications can be made to the present invention within the scope of the claims that follow. Accordingly, it is not intended that the scope of the invention in any way be limited by the above description, but instead be determined entirely by reference to the claims that follow.
This application is based on a prior provisional application Ser. No. 60/649,374, filed on Feb. 1, 2005, the benefit of the filing date of which is hereby claimed under 35 U.S.C. § 119(e).
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Number | Date | Country |
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Number | Date | Country | |
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Number | Date | Country | |
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60649374 | Feb 2005 | US |