[NANOTUBE ELECTRON EMISSION THERMAL ENERGY TRANSFER DEVICES]
In some embodiments, the invention relates to a sidewall coring tool that includes a tool body, a hollow coring shaft extendable from the tool body, and a formation cutter disposed at a distal end of the hollow coring shaft. The coring tool includes a retention member segmented into a plurality of petals and disposed proximate a distal end of the internal shaft. An internal sleeve may be disposed inside the hollow coring shaft.
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Wells are generally drilled into the ground to recover natural deposits of oil and gas, as well as other desirable materials, that are trapped in geological formations in the Earth's crust. A well is drilled into the ground and directed to the targeted geological location from a drilling rig at the Earth's surface.
Once a formation of interest is reached, drillers often investigate the formation and its contents by taking samples of the formation rock and analyzing the rock samples. Typically, a sample is cored from the formation using a hollow coring bit, and the sample obtained using this method is generally referred to as a “core sample.” Once the core sample has been transported to the surface, it may be analyzed to assess, among other things, the reservoir storage capacity (porosity) and the flow potential (permeability) of the material that makes up the formation; the chemical and mineral composition of the fluids and mineral deposits contained in the pores of the formation; and the irreducible water content of the formation material. The information obtained from analysis of a sample is used to design and implement well completion and production facilities.
“Conventional coring,” or axial coring, involves taking a core sample from the bottom of the well. Typically, this is done after the drill string has been removed, or “tripped,” from the wellbore, and a rotary coring bit with a hollow interior for receiving the core sample is lowered into the well on the end of a drill string. Some drill bits include a coring bit near the center of the drill bit, and a core sample may be taken without having to trip the drill string. A core sample obtained in conventional coring is taken along the path of the wellbore; that is, the core is taken along the axis of the borehole from the rock below the drill bit.
A typical axial core is 4-6 inches (˜10-15 cm) in diameter and can be over 100 feet (˜30 m) long. The rotary motion is typically generated at the surface, and the coring bit is driven into the formation by the weight of the drill string that extends back to the surface. The core sample is broken away from the formation by simply pulling upward on the coring bit that contains the sample.
By contrast, in “sidewall coring,” a core sample is taken from the side wall of a drilled borehole. Sidewall coring is typically performed after the drill string has been removed from the borehole. A wireline coring tool that includes a coring bit is lowered into the borehole, and a small core sample is taken from the sidewall of the borehole.
In sidewall coring, the drill string cannot be used to rotate the coring bit, nor can it provide the weight required to drive the bit into the formation. Instead, the coring tool must generate both the rotary motion of the coring bit and the axial force necessary to drive the coring bit into the formation.
In sidewall coring, the available space is limited by the diameter of the borehole. There must be enough space to withdraw and store a sample. Because of this, a typical sidewall core sample is about 1 inch (˜2.5 cm) in diameter and less than about 2 inches long (˜5 cm). The small size of the sample does not permit enough frictional forces between the coring bit and the core sample for the core sample to be removed by simply withdrawing the coring bit. Instead, the coring bit is typically tilted to cause the core sample to fracture and break away from the formation.
An additional problem that may be encountered is that because of the short length of a side wall core sample, it may be difficult to retain the core sample in the coring bit. Thus, a coring bit may also include mechanisms to retain a core sample in the coring bit even after the sample has been fractured or broken from the formation.
Sidewall coring is beneficial in wells where the exact depth of the target zone is not well known. Well logging tools, including coring tools, can be lowered into the borehole to evaluate the formations through which the borehole passes. Multiple core samples may be taken at different depths in the borehole so that information may be gained about formations at different depths.
Rotary coring tools typically use a hollow cylindrical coring bit with a formation cutter at a distal end of the coring bit. The coring bit is rotated and forced against the wall of the bore hole. As the coring bit penetrates the formation, the hollow interior of the bit receives the core sample. A rotary coring bit is extended from the tool using a shaft of mechanical linkage. The shaft is typically connected to a motor that imparts rotary motion to the coring bit and forces the bit against the formation wall. Rotary coring tools are generally braced against the opposite wall of the bore hole by a support arm. The cutting edge of the rotary coring bit is usually embedded with tungsten carbide, diamonds, or other hard materials for cutting into the formation.
While existing coring tools are useful, there is still a need for a coring tool that will more effectively ensure a good core sample can be retrieved for analysis.
SUMMARY OF INVENTIONIn one or more embodiments, the invention relates to a sidewall coring tool that includes a tool body, a hollow coring shaft extendable from the tool body, a formation cutter disposed at a distal end of the hollow coring shaft, and a retention member segmented into a plurality of petals and disposed in the hollow coring shaft. In some embodiments, the plurality of petals comprises three petals.
In some embodiments, the invention relates to a method for taking a core sample that includes extending a coring bit into a formation, receiving the core sample in an internal sleeve having a retention member segmented into a plurality of petals proximate a distal end of the internal sleeve, and withdrawing the coring bit from the formation.
In some other embodiments, the invention related to a sidewall coring tool that includes a tool body, a hollow coring shaft extendable from the tool body, a formation cutter disposed at a distal end of the hollow coring shaft, an internal sleeve disposed inside the hollow coring shaft, and at least one retention mechanism selected the group consisting of a piston and a check valve, wherein the piston is disposed in the internal sleeve and moveable with respect to the internal sleeve, and the check valve is disposed in the internal sleeve.
In some embodiments, the intention relates to a method for taking a core sample that includes extending a coring bit into a formation, receiving the core sample in an internal sleeve having a piston disposed therein such that the piston is moveable with respect to the internal sleeve, and withdrawing the coring bit from the formation.
In some embodiments, the invention relates to a sidewall coring tool that includes a tool body, a hollow coring shaft extendable from the tool body, a formation cutter disposed at a distal end of the hollow coring shaft, and an internal sleeve disposed inside the hollow coring shaft. The internal sleeve may include a bladder configured to apply radial pressure to a core sample when the bladder is selectively filled with a fluid.
In some embodiments, the invention relates to a sidewall coring tool that includes a tool body, a hollow coring shaft extendable from the tool body, a formation cutter disposed at a distal end of the hollow coring shaft, and an elastic retention member disposed proximate a distal end of coring tool and having an aperture at its center.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
In some embodiments, the invention relates to a coring bit with a retention member that retains a core sample in a coring bit. In other embodiments, the invention includes a piston or cushion that enables a core sample to be received and retained in a coring tool. In other embodiments, the invention relates to methods for retaining a core sample in a coring tool. The invention will now be described with reference to the attached drawings.
The coring bit 401 in
As shown in
A retention member 411 is disposed at the distal end of the internal sleeve 407. The retention member 411, as will be seen, enables a core sample to enter the coring bit 401 and the internal sleeve 407, and it also retains the core sample 410 in the internal sleeve 407 once the core sample 410 has been received in the coring bit 401.
In soft rock, the petals 411a, 411b may completely close and trap the core sample 410 in the coring bit 401. This may be advantageous because of the tendency of unconsolidated or soft formations to fall out of the coring bit. Instead of losing ¾ inch (˜1.9 cm) to 1 inch (˜2.5 cm) of the core sample of an unconsolidated formation, the petals 411a, 411b may close to retain the core sample 410 in the coring bit 401. The only core sample 410 that is lost is that part of the core sample that extends past the petals 511a, 511b. In some embodiments, the petals are about ¼ inch (˜0.6 cm) in length, and about ¼ inch of the core sample is lost in the closing of the petals. This assists in capturing and retaining core samples of a soft formation that can simply fall out of the coring bit when the sample is taken using a conventional coring bit.
The retention member 411 shown in
In some embodiments, a retention member may not be attached at a distal end of an internal sleeve. For example,
It is noted that a coring bit in accordance with the invention may have various combinations of the described features. For example, may include a retention member located as shown in
The petals 602a, 602b, 602c shown in
In some embodiments, a retention member 601 includes cuts or perforations 607. The cuts 607 provide additional flexibility for the petals 602a, 602b, 602c when the retention member 601 is constructed of a stiff material or when there are only a small number of petals making each petal stiff.
In fact, it is noted that the many of the above disclosed embodiments of a retention member may use radial perforations to segment the retention member into petals. This would enable the retention member to serve as a cover that will prevent contaminants from entering the coring bit before a sample is taken and the perforations are broken.
It is noted that radial perforations are distinguished from circumferential perforations that may be used to increase the flexibility of the retention member.
The embodiment of an internal sleeve 757 that is shown in
A retention member in accordance with any of the embodiments of the invention may be designed specifically for a single use, or it may be designed to capture and retain multiple cores. For example, some coring bits are designed so that the core samples are stored in the internal sleeve. That is, the internal sleeve is moved from inside the coring bit into a storage area. In other embodiments, only the core sample is moved into a storage device, and the internal sleeve is used to capture another sample.
As will be understood by those having ordinary skill in the art,
In the embodiment shown, the internal sleeve 807 has a diameter that is substantially the same as the inner diameter of the formation cutter 805. In order to fit with the internal sleeve 807, the piston 802 has a diameter that is substantially the same as the inner diameter of the internal sleeve 807 so that the piston seals 812 are able to form a seal between the internal sleeve 807 and the piston 802.
Additionally, when the coring bit 800 is withdrawn from the formation 810, the piston 802 helps to hold the core sample in the internal sleeve 807. In some embodiments, the chamber 815 behind the piston 802 includes a check valve or other means (not shown) to allow air or fluid to be pushed out of the chamber 815, but that will not allow the return flow. Thus, a vacuum behind the piston 802 will prevent the piston 802 from moving on the outward direction.
In some embodiments, the chamber 815 behind the piston is completely vented. Nonetheless, the core sample 801 may not be able to move out of the internal sleeve 807 without also moving the piston 802. This may be caused by a vacuum created between the piston 802 and the core sample 801. The friction between the piston 802 and the internal sleeve 807 will create additional resistance to the movement of the core sample 801, which will help retain the core sample 801 in the coring bit 800.
Further, in addition to a simple piston 802, the internal sleeve 807 may also include a ratchet device or a locking device. Such a device would prevent the piston from moving in the outward direction.
The cavity (shown at 918) in the internal sleeve 917 behind the core sample 901 is filled with a fluid, such as water. The proximal end of the internal sleeve 917 includes a valve 921 for selectively permitting fluid to pass between the sleeve 917 and the rest of the tool. The valve 921 may be, for example, a check valve that enables the fluid to exit the cavity 918 as a core sample 901 moves into the internal sleeve 917. When the coring bit 900 is withdrawn from the formation, the valve 921 may be used to prevent the reverse flow of fluid into the cavity 918, and a vacuum is created behind the core sample 901 that retains the core sample 901 in the coring bit 900.
In at least one embodiment, the check valve 921 in
When the bladder 1007 is filled, it will compress inwardly and exert a radial pressure on a core sample (not shown). The pressure will apply an overburden to the core sample that will both stabilize and retain the core sample.
Embodiments of the invention may present one or more of the following advantages. A coring bit with a retention member or other retention device in accordance with the invention will retain the core sample in the coring bit while the coring bit is being withdrawn from the formation. This will prevent the core sample from being damaged or lost during this process.
Advantageously, a coring bit may include a retention member that will close completely when capturing a sample in soft or unconsolidated formation. When the retention member closes, the core sample will be completely enclosed in the coring bit and protected against further damage and loss.
Advantageously, a coring bit that includes a non-rotating internal sleeve will not degrade the core sample through friction between the core sample and the internal sleeve and the retention member. The internal sleeve and the retention member will not rotate with respect to the formation and the core sample as it is being captured.
Advantageously, embodiments of the invention that include a piston in the internal sleeve provide additional guidance for a core sample as it is being received. The piston is displaced by the core sample, and once the sample is fully received, the piston creates a vacuum or void behind the core sample that retains the core sample in the internal sleeve as the coring bit is withdrawn from the formation.
Advantageously, embodiments of the invention that include a cushion provide steady guidance for the core sample as it enters the coring bit. Once received in the coring bit, the core sample is retained by a vacuum or void behind the core sample.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims
1. A sidewall coring tool, comprising:
- a tool body;
- a hollow coring shaft extendable from the tool body;
- a formation cutter disposed at a distal end of the hollow coring shaft; and
- a retention member defining one of a plurality of petals, an aperture and combinations thereof, the retention member disposed in the hollow coring shaft.
2. The sidewall coring tool of claim 1, further comprising an internal sleeve disposed inside the hollow coring shaft, and wherein the retention member is connected to the internal sleeve.
3. The sidewall coring tool of claim 2, wherein the retention member is disposed proximate a distal end of the internal sleeve.
4. The sidewall coring tool of claim 2, wherein the internal sleeve comprises a non-rotating sleeve.
5. The sidewall coring tool of claim 2, wherein the internal sleeve comprises a radial notch such that the petals of the retention member can be positioned radially outward into the notch.
6. The sidewall coring tool of claim 5, wherein the retention member has a petal circumference that is substantially the same as an inner diameter of the internal sleeve.
7. The sidewall coring tool of claim 2, further comprising a piston disposed inside the internal sleeve and axially moveable with respect to the internal sleeve.
8. The sidewall coring tool of claim 2, further comprising a check valve disposed in the internal sleeve.
9. The sidewall coring tool of claim 8, wherein the check valve is disposed in a proximal end of the internal sleeve.
10. The sidewall coring tool of claim 9, wherein the check valve enables a fluid to flow out of the internal sleeve.
11. The sidewall coring tool of claim 1, wherein an inner diameter of the internal sleeve is substantially the same as an inner diameter of the formation cutter.
12. The sidewall coring tool of claim 1, wherein an inner diameter of the internal sleeve is larger than an inner diameter of the formation cutter.
13. The sidewall coring tool of claim 1, wherein the internal sleeve comprises a bladder configured to apply radial pressure to a core sample when the bladder is selectively filled with a fluid.
14. The sidewall coring tool of claim 1, wherein the plurality of petals comprises 3 petals.
15. The sidewall coring tool of claim 1, wherein the plurality of petals overlap.
16. The sidewall coring tool of claim 1, wherein the plurality of petals are separated by gaps.
17. The sidewall coring tool of claim 1, wherein the retention member comprises perforations.
18. The sidewall coring tool of claim 17, wherein the perforations are circumferential perforations disposed outside a petal circumference.
19. The sidewall coring tool of claim 17, wherein the perforations are radial perforations disposed at least partially inside a petal circumference.
20. The sidewall coring tool of claim 1, wherein the plurality of petals are adjacent.
21. The sidewall coring tool of claim 1, wherein the retention member is constructed of rubber.
22. The sidewall coring tool of claim 1, wherein the retention member is rounded and extrudes towards a distal end of hollow coring shaft.
23. The sidewall coring tool of claim 1, wherein the retention member is rounded and extrudes towards a proximal end of the hollow coring shaft.
24. A method for taking a core sample, comprising:
- extending a coring bit into a formation, the coring bit having a retention member segmented into a plurality of petals;
- receiving the core sample in the coring bit; and
- retaining the core sample in the coring bit with the retention member while withdrawing the coring bit from the formation.
25. The method of claim 24, further comprising selectively filling a bladder with a fluid to apply a radial pressure to the core sample.
26. The method of claim 24, wherein the retention member is connected to an internal sleeve disposed in the coring bit and the core sample is received in the internal sleeve.
27. A sidewall coring tool, comprising:
- a tool body;
- a hollow coring shaft extendable from the tool body;
- a formation cutter disposed at a distal end of the hollow coring shaft;
- an internal sleeve disposed inside the hollow coring shaft; and
- at least one retention mechanism selected from the group consisting of a piston and a check valve, wherein the piston is disposed in the internal sleeve and moveable with respect to the internal sleeve, and the check valve is disposed in the internal sleeve.
28. The sidewall coring tool of claim 27, wherein the at least one retention mechanism is the piston.
29. The sidewall coring tool of claim 28, further comprising a seal disposed between the piston and the internal sleeve.
30. The sidewall coring tool of claim 28, wherein an inner diameter of the internal sleeve is substantially the same as an inner diameter of the formation cutter.
31. The sidewall coring tool of claim 28, further comprising a check valve operatively connected to the internal sleeve.
32. The sidewall coring tool of claim 27, further comprising a retention member segmented into petals disposed proximate an opening at a distal end of the internal sleeve.
33. A method for taking a core sample, comprising:
- extending a coring bit into a formation;
- receiving the core sample in an internal sleeve having a piston disposed therein such that the piston is moveable with respect to the internal sleeve; and
- withdrawing the coring bit from the formation.
34. The method of claim 33, further comprising selectively filling a bladder with a fluid to apply a radial pressure to the core sample.
Type: Application
Filed: Dec 23, 2003
Publication Date: Jun 23, 2005
Applicant: SCHLUMBERGER TECHNOLOGY CORPORATION (Sugar Land, TX)
Inventor: Anthony Veneruso (Missouri City, TX)
Application Number: 10/707,596