Apparatus and method for gravel packing an interval of a wellbore

Abstract

An apparatus and method for gravel packing an interval of a wellbore. The apparatus comprises a packing shroud having a small number of packing ports and a large number of production ports. The production ports are initially plugged with a removable material. A medial annulus between the shroud and a sand screen is used as a conduit for delivering slurry to a borehole interval to form a sand pack. The packing ports are distributed along the shroud to allow uniform formation of a sand pack, while limiting loss of carrier fluid to high permeability zones. After the sand pack is formed, the material plugging the production ports is removed, e.g. dissolved by ambient fluids, to provide flow paths for produced fluids.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] None TECHNICAL FIELD OF THE INVENTION [0002] This invention relates in general to preventing the production of particulate materials through a wellbore traversing an unconsolidated or loosely consolidated subterranean formation and, in particular to, an apparatus and method for obtaining a substantially complete gravel pack within an interval of the wellbore. BACKGROUND OF THE INVENTION [0003] Without limiting the scope of the present invention, its background is described with reference to the production of hydrocarbons through a wellbore traversing an unconsolidated or loosely consolidated formation, as an example. [0004] It is well known in the subterranean well drilling and completion art that particulate materials such as sand may be produced during the production of hydrocarbons from a well traversing an unconsolidated or loosely consolidated subterranean formation. Numerous problems may occur as a result of the production ...

AI Technical Summary

Benefits of technology

[0012] The apparatus for gravel packing an interval of a wellbore of the present invention comprises a shroud adapted to be placed in a borehole around a sand control screen to facilitate formation of a sand pack between the screen and a borehole wall and adapted to remain in place during production of fluids from the well. The shroud defines a medial annulus between the screen and the shroud and an outer annulus between the shroud and the borehole. The shroud includes a relatively small number of packing ports and a relatively large number of production ports. The production ports are sized and positioned to provide a relatively unrestricted flow of produced fluids. However, the production ports are substantially closed or plugged with a removable material during formation of a sand pack to at least substantially prevent flow of fluids from the medial annulus to the outer annulus through the production ports. The packing ports are sized, shaped and positioned to facilitate distribution of slurry throughout the producing interval despite possible formation of sand bridges and to limit fluid loss from the slurry to high permeability zones.

Problems solved by technology

Numerous problems may occur as a result of the production of such particulate.

For example, the particulate causes abrasive wear to components within the well, such as tubing, pumps and valves.

In addition, the particulate may partially or fully clog the well creating the need for an expensive workover.

It has been found, however, that a complete gravel pack of the desired production interval is difficult to achieve, particularly in long or inclined / horizontal production intervals.

These incomplete packs are commonly a result of the liquid carrier entering a permeable portion of the production interval causing the gravel to form a sand bridge in the annulus.

It has been found, however, that shunt tubes installed on the exterior of sand control screens are susceptible to damage during installation and may fail during a gravel pack operation.

In addition, it has been found that it is difficult, time consuming, and expensive to make all of the necessary fluid connections between the numerous joints of shunt tubes required for typical production intervals.

The high permeability of the shroud desired for production has been found to cause problems during the sand packing operation.

Slurry pumped past the leak off zone therefore has a higher concentration of particulates, requiring higher pumping pressure which increases the chance of formation of another sand bridge and increasing the leak off rate.

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