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Ultra-low friction coatings for drill stem assemblies

A technology of ultra-low friction and drill pipe components, applied in the direction of drill pipe, drill pipe, coating, etc., can solve the problems of worn casing, serious friction problem, excessive wear of casing, etc.

Active Publication Date: 2011-09-14
EXXON RES & ENG CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Hardsurfacing protects the drill pipe assembly, but tends to cause excessive wear of the casing
This problem is especially acute in directional drilling because the drill stem assembly tends to rest against the casing, continuously wearing down the casing as the drill string rotates
In addition, some hardfacing alloys, such as tungsten carbide, can also cause more friction problems

Method used

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  • Ultra-low friction coatings for drill stem assemblies
  • Ultra-low friction coatings for drill stem assemblies
  • Ultra-low friction coatings for drill stem assemblies

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0107] The DLC coating was applied to the 4142 steel substrate using vapor deposition techniques. The thickness of the DLC coating ranges from 1.5 to 25 microns. Hardness measurements range from 1,300 to 7,500 Vickers. Laboratory tests based on disk-ball geometry were performed to illustrate the friction and wear properties of the cladding. Quartz balls and low-carbon steel balls are used as mating materials to simulate the states of open wells and cased wells, respectively. In an ambient temperature test, uncoated 4142 steel, DLC clad and a commercially available state of the art hardbanded welded cladding were tested under "dry" or ambient air conditions under the following conditions: Quartz is matched with face material, 300g normal load and 0.6m / s sliding speed to simulate open hole conditions. like Figure 7 It has been shown that DLC cladding can provide up to a 10-fold improvement in friction characteristics (reduction in coefficient of friction) over uncoated 4142...

Embodiment 2

[0113] In an indoor wear / friction test, the velocity dependence (weakening or strengthening) of the coefficient of friction of DLC-coated and uncoated 4142 steel was measured over a sliding velocity range of 0.3 by examining the shear stress required to slide m / sec-1.8m / sec. In the dry sliding wear test, quartz balls were used as the mating end face material. exist Figure 11 The velocity attenuation characteristics of DLC coatings relative to uncoated steel are described in . Uncoated 4142 steel shows a decreasing coefficient of friction with sliding velocity (i.e., significant velocity weakening), while, at the same time, DLC cladding shows no velocity weakening and, in fact, appears to have a slight COF velocity enhancement (i.e., A slight increase in COF) with increasing sliding velocity is very beneficial for mitigating torsional instability, a precursor to stick-slip vibration.

Embodiment 3

[0115] Multiple layers of DLC coatings are manufactured in order to maximize the thickness of the DLC coatings to enhance their durability in drill stem assemblies used in drilling operations. In one embodiment, the total thickness of the multilayer DLC coating is from 6 microns to 25 microns. Figure 12 SEM images of both single-layer and multi-layer DLC coatings for drill stem assemblies produced by PECVD are depicted. The bonding layer(s) used with the DLC overlay are silicon buffer layers.

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Abstract

Provided are drill stem assemblies with ultra-low friction coatings for subterraneous drilling operations. In one form, the coated drill stem assemblies for subterraneous rotary drilling operations include a body assembly with an exposed outer surface including a drill string coupled to a bottom hole assembly or a coiled tubing coupled to a bottom hole assembly and an ultra-low friction coating on at least a portion of the exposed outer surface of the body assembly, wherein the coefficient of friction of the ultra-low friction coating is less than or equal to 0.15. The coated drill stem assemblies disclosed herein provide for reduced friction, vibration (stick-slip and torsional), abrasion and wear during straight hole or directional drilling to allow for improved rates of penetration and enable ultra-extended reach drilling with existing top drives.

Description

technical field [0001] The invention relates to the field of rotary drilling. More particularly, it relates to ultra-low friction coatings and the application of such coatings on drill stem assemblies to reduce friction and wear in subterranean rotary drilling operations. Background technique [0002] In rotary drilling operations, the drill bit is attached to the end of a bottom hole assembly, which is attached to a drill string, including drill pipe and tool joints, via a rotary table or top drive Rotate on the surface. The weight of the drill string and bottom hole assembly causes the rotating drill bit to drill a hole in the earth's crust. As the operation progresses, new sections of drill pipe are added to the drill string to increase its overall length. During drilling operations, periodically, the open hole is casingd to stabilize its walls and drilling operations resume. As a result, drill strings are typically run both in open hole boreholes and in casings alrea...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B17/10
CPCE21B7/046E21B17/1085C23C14/0605C23C16/26C23C30/005
Inventor N·V·班加鲁A·奥赛克森H·W·金E·A·O·比迪格尔J·R·贝利V·古普塔M·D·埃尔塔斯W·C·艾尔克斯
Owner EXXON RES & ENG CO