Robust sand screen for oil and gas wells

Abstract

According to a first preferred aspect of the invention, there is provided a downhole sand screen device for use in well completions that comprises a plurality of isolated individual sand screens. Further, in the preferred arrangement the instant invention consists of two screens, one concentrically nested inside of the other, and further wherein the screen sections are not continuous but rather are periodically interrupted by sections of blank pipe. Further, the screen sections are arranged so that a screen section on the outer pipe will be matched by a corresponding, but staggered, blank pipe section on the inner pipe. As a consequence, if a hole develops in one of the outer screen sections the movement of sand will be blocked from entering the wellbore by a second / inner screen.

Description

RELATED CASE [0001] This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 738,197 filed on Nov. 18, 2005, and incorporates said provisional application by reference into this disclosure as if fully set out at this point.FIELD OF THE INVENTION [0002] This invention pertains generally to the field of oil and gas production and, more particularly, to production of oil and gas in formations containing unconsolidated sands. BACKGROUND OF THE INVENTION [0003] Those of ordinary skill in the well completion and well production arts will recognize that the presence of sand grains or other small items of particulate matter that can be found within oil or gas that is taken from a subsurface formation can be a major operational problem that could lead to premature equipment failure, among other things. By way of explanation, if the producing formation is not sufficiently well consolidated it can yield small fragments of detritus in the vicinity of the wellbore a...

AI Technical Summary

Benefits of technology

[0012] According to another preferred aspect of the instant invention, the inner screen will preferably be made coarser (e.g., have a larger mesh opening size) than the outer screen. Thus, during normal operations, i.e., when both the inner and outer screens are undamaged, the inner screen will not accumulate sand particles that have been passed through the outer screen and become plugged or otherwise blocked. This will result in less erosion because, among other reasons, the velocity is lower within the inner screen.

Problems solved by technology

Of course, one consequence of this planned blockage is that the well will thereafter be marginally less productive but that is a small price to pay when the alternative may be to shut down the well and repair the screen.

By way of comparison, screen sections in the prior art are on the order of 30 or 40 feet in length and, thus, a failure at any point along their length will eventually cause the entire screen to fail and result in a need for replacement

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