Cement as anchor for expandable tubing

Inactive Publication Date: 2012-03-15
ENVENTURE GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]In some embodiments, the hardened cement material is designed to have with specific mechanical properties such that it can withstand sufficient forces to allow the tubular to be radially expanded to a larger diameter. Some embodiments of the invention include a two-slurry approach in which a rapid-hardening cement slurry is placed in the annulus around the lower portion of the tubular to be expanded, thereby providing an anchor, and a second, slower-setting slurry is placed around a second portion of the tubular and does not harden until after the expansion process is complete, so that formation isolation is achieved.
[0011]In other embodiments, one or both cement slurries are designed to have mechanical properties such that the slurry placed around the bottom of the tubular provides the means to anchor the tubular during initiation of expansion, but without resulting in mechanical failure of one or both cement sheaths. In further embodiments, either cement slurry may contain elastomeric materials that swell if contacted by wellbore or subterranean fluids such as water, hydrocarbon, gas, and / or drilling fluids, etc., and re-establish annular hydraulic isolation, even if the presence of mechanical damage to the hardened cement.

Problems solved by technology

After cement has hardened in a wellbore, it is well known that the hardened cement can be subjected to mechanical damage—stress fractures and / or separation from the casing wall (debonding)—such that hydraulic isolation may be jeopardized Likewise, during the process of expanding tubulars that are surrounded by hardened cement, the cement is often mechanically failed and therefore isolation is lost.
Therefore, it may not be practical to use top-anchoring techniques and it may be desirable to anchor the lower end of the tubing instead.
The reliability of the mechanical jack systems is not well-established, however, and they are uneconomical for certain applications.
However, this method also has reliability and cost issues.

Method used

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  • Cement as anchor for expandable tubing
  • Cement as anchor for expandable tubing

Examples

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Effect test

example 1

[0031]A 9 ⅝-inch, 43.5 lb / ft casing section 24-inches long was placed inside an outer jacket of 13 ⅜-inch casing. Before installation, the outside of the 9 ⅝-inch pipe was blasted with medium grit aluminum oxide to increase the roughness of the pipe, thus improved shear bond between the pipe and the cement. The annular gap was filled with a cement slurry composed of API Class H Portland cement +73% fresh water +0.6% Hydroxyethyl cellulose (viscosifier) +0.2% fluid loss agent, mixed at 13.8 lb / gal. The cement was cured at 170° F. and atmospheric pressure for approximately 8 hrs, at which time samples indicated a compressive strength of 579 psi. At this time a force was applied to the 9 ⅝-inch casing while holding the outer jacket and cement stationary. The force required to break the shear bond between the cement sheath and the 9 ⅝-inch casing was recorded as 38,200 lbs, which equates to 68.2 psi. This information is then used to determine the length of cemented casing required to ac...

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PUM

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Abstract

A method for expanding an expandable tubular in a borehole, comprising the steps of: a) positioning the expandable tubular at a desired position in the borehole; b) anchoring the tubular at the desired position solely by means of a first cement portion in the annulus between the tubular and the borehole wall; c) expanding the tubular by moving an expansion device through the tubular. The cement may be cured or not cured when step c) is carried out and may or may not fracture during step c). The method may include providing an exit path for water expelled from the cement during expansion, providing a second cement portion having a longer cure time than the first cement portion, or calculating the length of cement that is required to anchor, based on the properties of the cement and the expected expansion force.

Description

RELATED CASES[0001]This application claims benefit of U.S. application Ser. No. 61 / 165128, filed on Mar. 31, 2009, which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The invention relates to the use of cementitious materials as a means for anchoring tubular goods in a wellbore during expansion of the tubular goods and for providing zonal isolation after expansion.BACKGROUND OF THE INVENTION[0003]In the context of oil and gas drilling, cementitious materials, including but not limited to Portland cements, resins, blast-furnace slag, and blends of those materials, are typically placed in the annulus between the casing and the wellbore so as to isolate and protect the casing during drilling, completion, and operation of the well. Once pumped in place and allowed to harden, these materials provide isolation between the various formations and between the formations and surface such that the hydrocarbons can be safely produced, or alternatively the wellbore can be used ...

Claims

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Application Information

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IPC IPC(8): E21B33/14E21B29/10
CPCE21B43/103E21B33/14
InventorALGU, DEVENDRA R.HEATHMAN, JAMES FRANK
OwnerENVENTURE GLOBAL TECH LLC