DOWNHOLE TOOLS TREATED BY PLASMA ELECTROLYTIC OXIDATION

Abstract

A downhole tool comprising a body made of aluminum material, dissolvable material or light alloy material having a coating formed by the plasma electrolytic oxidation process. The tool is a slip, a drag block, a button or any tool with wear blocks to get drag or keep the tool centered.

Claims

1. An downhole tool, comprising: a body; and a coating formed by a plasma electrolytic process on the body.

2. A downhole tool according to claim 1 wherein the tool is a slip.

3. A downhole tool according to claim 2 wherein the slip is a wicker slip.

4. A downhole tool according to claim 2 wherein the slip is a flat wedge slip.

5. A downhole tool according to claim 2 wherein the slip is a hydraulic hold down slip.

6. A downhole tool according to claim 1 wherein the tool is a drag block.

7. A downhole tool according to claim 1 wherein the tool is a button.

8. A downhole tool according to claim 1 wherein the body is constructed of aluminum.

9. A downhole tool according to claim 1 wherein the body is constructed of dissolvable material.

10. A downhole tool according to claim 1 wherein the body is constructed of a light alloy.

11. A downhole tool according to claim 4 further including a button attached to the flat wedge slip.

12. A downhole tool according to claim 1 wherein the coating is formed on a portion of the body.

13. A process for making a downhole tool, comprising the steps: making a body; and treating the body by a plasma electrolytic process.

14. A process according to claim 13 wherein the tool is a slip.

15. An apparatus prepared by a process comprising the steps of: making a downhole tool body; and treating the downhole tool body by a plasma electrolytic process.

16. An apparatus according to claim 15 wherein the downhole tool is a slip.

Description

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] According to the present invention downhole tools are disclosed comprised of light material such as aluminum, dissolvable material, and light alloys. The light material is treated by the plasma electrolytic oxidation process. The tools are lighter than tools made of heat treated steel and have extremely high hardness which is higher than that of heat treated steel. Furthermore, those tools have high strain tolerance, corrosion resistance and thermal and chemical stability suitable for withstanding the high adverse pressure, temperature and pH conditions encountered downhole. Moreover, the material is easily drill able to open the sealed passages.

[0018] The plasma electrolytic oxidation process is a well known process which has been described in various publications. Plasma electrolytic oxidation is a bath-based method of producing ceramic layers on the surface of light alloys. The coatings are characterized by their wear resistance, corrosion resistance and thermal and chemical stability. The method is suitable for treating alloys of high aluminum, magnesium and titanium composition, but can also be applied to other metals such as zirconium, tantalum, niobium, hafnium and cobalt. The process is utilized by various manufactures such as Keronite Inc., 2121 Southtech Drive, Suite 220, Greenwood Ind. 46143, USA. More information about the process can be found at www.keronite.com. The process has been used to manufacture equipment components in many industries including automotive, aerospace, oil and gas.

[0019] In a typical manufacturing process of the tool, the tool is manufactured from the light material and then the portion requiring treatment is immersed in a liquid bath to undergo the plasma electrolytic oxidation process. Preferably, only the portion of the tool that needs to withstand the anchoring and centering forces is treated to strengthen it, with the remaining portion remaining untreated so that it can be easily be drilled or dissolved following the termination of the operation. The downhole tools manufactured through the plasma electrolytic oxidation process in accordance with the present invention include but are not limited to slips, drag blocks and buttons. The tools so formed have a Rockwell Hardness of greater than 55 C and very high wear resistance. Aluminum material, dissolvable material or other light weight alloy material may be used to make the tools by treating them with the plasma electrolytic oxidation process. Examples of dissolvable material include but are not limited to magnesium. Examples of light weight alloys include but are not limited to aluminum. Other material treatable by the plasma electrolytic oxidation process may also be used to make the tools by treating them with the plasma electrolytic oxidation process.

[0020] Slips manufactured in accordance with the present invention with the use of the plasma electrolytic oxidation process include wicker slips, hydraulic hold down slips and flat wedge slips. Because the slip products manufactured by that process have the above referenced qualities which would allow for the use of the slips downhole, the use of steel and carbide and ceramic inserts is eliminated. The tool is lighter and performs better that the previous tools that were made of steel and used carbide or ceramic inserts. Further the slips are easily drill able to open the sealed passages.

[0021] Similarly, in the case of drag blocks, the manufacturing of drag blocks from light material by using the plasma electrolytic oxidation process eliminates the use of heavy steel and carbide and ceramic inserts. The drag blocks so manufactured are lighter and perform better that the previous drag blocks that were made of steel and used carbide or ceramic inserts.

[0022] As regards buttons, the buttons manufactured from light material such as aluminum, light alloys or dissolvable material and having the coating formed by the plasma electrolytic oxidation as disclosed herein, are hard enough to bite the casing without the use of ceramic, carbide or steel when used in connection with slips or the like. These treated buttons, however, may be used in other applications in a downhole tool, including but not limited to, using the buttons as pins to hold a tool together before setting.

[0023] It should be understood that any downhole tool that would have a pad to keep the tool centered and contains carbide or other wear type buttons could be made without the buttons or the inserts by treating the block or pad with the plasma electrolytic oxidation process to eliminate the use of steel or inserts. This is due to the high wear resistance that the subject treatment imparts into the substrate metal or substance. Because of the wear resistance and ability of the part to bite into casing, all tools that have wear blocks to get drag or keep the tool centered may be manufactured in accordance with the present invention by utilizing the plasma electrolytic oxidation process.

[0024] While the invention is described with respect to specific embodiments, modifications thereof can be made by one skilled in the art without departing from the spirit of the invention. The details of said embodiments are not to be construed as limitations except to the extent indicated in the following claims.