Oriented Perforating Non-Perpendicular to Gun Axis and Well Bore
Publication Date: 2011-Oct-25
The IP.com Prior Art Database
The present disclosure relates to perforating, and more specifically to perforating in deviated oil wells.
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Title: Oriented Perforating Non-Perpendicular to Gun Axis and Well Bore
The present application relates to perforating, and more specifically to perforating in deviated oil wells.
The following description concerns a number of embodiments and is meant to provide an understanding of the embodiments. The description is not in any way meant to limit the scope of any present or subsequent related claims.
As used here, the terms "above" and "below"; "up" and "down"; "upper" and "lower"; "upwardly" and "downwardly"; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. However, when applied to equipment and methods for use in wells that are deviated or horizontal, such terms may refer to a left to right, right to left, or diagonal relationship as appropriate.
This article describes a shaped charge oriented perforating gun systems for perforating highly deviated wells. A highly deviated well can be, for example, a 70 degree well from the vertical. Deviations from that would be considered a highly deviated well also, for example, 60 degrees or 50 degrees or 80 degrees. This perforating gun system tilts the charges backwards, e.g., 20 degrees inside the gun loading tube so that the charges are no longer shooting perpendicular to the gun axis but still shoot vertically.
Shooting a perforating gun system in a horizontal well (i.e., shooting perpendicular or 90 degrees from the horizontal and gun axis) provides charges that perforate vertically. In contrast, this articles relates to shooting a perforating gun with the charges tilted backwards to compensate for the deviation.
This article also describes a shaped charge perforating gun system for perforating highly deviated wells. As noted, a well that is 70 degrees from the vertical is generally considered a highly deviated well. By design, this gun system tilts the charges backwards inside the gun loading tube so that the charges are no longer shooting 90 degrees from the
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gun axis but shoot vertically, or close thereto, into the formation instead. An advantage of shooting a tilt back gun system like this is to maximize perforating tunnel stability and reduce the risk of sand production.
Sand production from a perforated completion can be highly dependent on the strength of the rock, the stress field and the direction of the perforation tunnel.
Reservoir rocks are subjected to horizontal and vertical stresses. These stresses are usually not equal, with the vertical stress dominant and a maximum and minimum horizontal stress. Perforation tunnels are also subjected to these unequal forces and may collapse if the stresses are great enough and the rock weak enough. Geo-mechanical data and software can be use to determine the direction of maximum perforation stability. In many cases this is in a vertical direction. So ideally it is d...