TECHNICAL FIELD OF THE INVENTION
This application claims the benefit of Ser. No. 60/532,934, entitled “Expandable Sand Screen Utilizing Multiple Expansion System,” filed provisionally on Dec. 29, 2003.
- BACKGROUND OF THE INVENTION
This invention relates generally to the field of wellbore completion and, more particularly, to a multiple expansion sand screen system and method.
Sand control is important during completion and subsequent production of a wellbore that is in hydraulic communication with Earth formations susceptible to production of solid materials from the formation. Such formations are known in the art as “unconsolidated” and, if not protected with suitable wellbore equipment, may produce solid materials of a character and quantity so as to damage the wellbore, or at least reduce its capacity to produce oil and gas from the formation. Devices known in the art as “sand screens” are typically used to protect such unconsolidated formations. Sand screens include a structural member, called a “base pipe”, having apertures therein to maintain the mechanical integrity of the sand screen (meaning to provide mechanical support for the screen. A “filter layer” is typically disposed outside the base pipe. Many different types of filter layer are used, including, for example, wound wire and mesh screen.
More recently, radially plastically deformable sand screens, called “expandable sand screens” have been used in some wellbores to increase productivity of wellbores completed in unconsolidated Earth formations. A principal reason for the use of expandable sand screens is to mechanically support the unconsolidated formation prior to initiating fluid production. By supporting the formation prior to initiating production, it is possible to reduce loss of formation permeability due to movement of solid materials against the screen during fluid production. A conventional (non-expandable) sand screen must necessarily have an external diameter smaller than the drilled out diameter of the wellbore (“open hole”) prior to insertion of the sand screen, in order for the screen to fit in the wellbore. The smaller screen diameter results in an annular space between the outer surface of the screen and the wall of the wellbore, which may become filled with formation solids moved from the formation during fluid production. Expandable sand screens are intended to provide a way to close the annular space prior to beginning fluid production, and thus prevent movement of formation solids. Expandable sand screens are run into the wellbore in an unexpanded state, wherein the external diameter of the screen is less than the drilled out diameter of the wellbore. After insertion, the screen is expanded using one or more types of expansion tools, preferably to cause the screen to be placed into firm contact with the wellbore wall.
During the expansion of expandable sand screens, it is advantageous to push the sand screen outward to an extent so that it “conforms” to, and applies pressure to, the wellbore wall in order to hold the sand in place and increase oil and/or gas flow into the wellbore. Many wellbores may include sections where the actual diameter of the wellbore exceeds the drilled out diameter (drill bit diameter) due to washout or other cause. In such sections, it maybe necessary to expand a screen to 35 or 40 percent greater than its unexpended diameter in order to place the screen in form contact with the wall of the wellbore.
- SUMMARY OF THE INVENTION
One problem with expandable screens known in the art is that they are difficult to expand more than about 30 to 35 percent because the base pipes made out of carbon steel or stainless steel begin to fail. As a result, these screens may often not be expanded enough to apply the high contact pressures needed to hold the sand in place in enlarged wellbores, thus resulting in failure of the sand screen or inadequate production. Conversely, if expanded to the degree necessary to provide a suitable amount of contact pressure, the base pipe may be weakened to an extent so as to have very little resistance to crushing under external pressure, thus leaving the wellbore susceptible to failure.
It is desirable to have an expandable sand screen that can be made to conform to the wall of a wellbore, even if it is necessary to expand the screen to 35 percent or more beyond the unexpanded diameter of the screen, while maintaining sufficient mechanical integrity to resist failure of the screen and consequent loss of the wellbore.
In one embodiment, a wellbore completion method includes disposing an expandable screen assembly into a wellbore, in which the expandable screen assembly includes a base pipe, an intermediate expansion system, and a screen element. The method further includes radially expanding the base pipe and radially expanding the intermediate expansion system after radially expanding the base pipe.
Embodiments of the invention may provide a number of technical advantages. In one embodiment, an expandable screen possesses high collapse strength (e.g., 1000 to 3000 psi) due to the strong base pipe. Such a screen may also be quickly and reliably expanded with fixed or compliant cone expanders without limited expansion like prior fixed-cone expansion screens.
BRIEF DESCRIPTION OF THE DRAWINGS
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.
FIGS. 1 and 2 are cross-sectional elevation views illustrating a wellbore completion method in accordance with one embodiment of the present invention.
FIGS. 1 and 2 are cross-sectional elevation views illustrating a wellbore completion method in accordance with one embodiment of the present invention. Referring first to FIG. 1, a wellbore completion system 100 is utilized in completing a wellbore 101 drilled within a formation 102. Wellbore 101 may be drilled using any suitable drilling techniques and may have any suitable diameter, length, and direction. Formation 102 may be any suitable geological formation; however, the present invention is particularly suitable for unconsolidated formations, such as sandstone.
Holding the sand or other particles from formation 102 in place during the completion process is important for effective oil and/or gas flow into wellbore 101. Thus, expandable sand screens are sometimes utilized to hold the sand in place. A major problem with prior expandable sand screens is that they are difficult to expand more than about 30-35% before the base pipes from which they are made begin to fail. Thus, these prior screens may often not be expanded enough to apply high contact pressures to hold the sand in place.
Therefore, according to the teachings of one embodiment of the invention, an expandable screen assembly 104 is utilized that includes, in the illustrated embodiment, a base pipe 106, an intermediate expansion system 108, and a screen element 110. Among other things, expandable screen assembly 104 possesses high collapse strength due to the strength of base pipe 106 in addition to facilitating quick and reliable expansion without limited expansion.
Base pipe 106 may be any suitable pipe of any suitable size and configuration and may be formed from any suitable material, including without limitation, carbon steel and stainless steel. Base pipe 106 includes any suitable size and number of apertures formed therein to enable flow of fluid from formation 102 into the wellbore 101. Base pipe 106 may also have any suitable length and may be formed from one or more sections. Base pipe 106 may be disposed in wellbore 101 by any suitable method, such as the utilization of a suitable work string 112. As described in further detail below, any suitable method may be utilized to expand base pipe 106, such as a cone expander 114 or other suitable expander element. The expansion of base pipe 106 also expands intermediate expansion system 108 and screen element 110.
Intermediate expansion system 108 is disposed around the outside of base pipe 106 and may or may not couple directly to base pipe 106. Intermediate expansion system 108 is formed from one or more components that are operable to radially expand via an actuation system 116. Radial expansion of intermediate expansion system 108 causes radial expansion of screen element 110. Intermediate expansion system 108 may be any suitable material formed from one or more components that expand in response to actuation of actuation system 116.
Actuation system 116 may be any suitable actuation system that functions to radially expand intermediate expansion system 108. For example, actuation system 116 may be a chemical expansion system, a thermal expansion system, an electrical expansion system, a mechanical expansion system, or any other suitable actuation system.
In a chemical expansion system embodiment, spheres of any suitable material that swell when immersed in a suitable chemical may be utilized. The chemical may be pumped down base pipe 106 and through the apertures formed in base pipe 106 in any suitable manner in order to contact the swellable spheres. For example, a suitable rubber or elastomer that swells in the presence of a liquid such as crude oil may be utilized. As another example, compressible elastic spheres that are coated with a suitable material that holds them in compression until a chemical is utilized to dissolve or degrade this particular coating may be utilized. In this embodiment, the spheres elastically expand outward when the confining pressure produced by the coating is removed. Other suitable chemical expansion systems are contemplated by the present invention.
In a thermal expansion system embodiment, any suitable materials that expand or swell when they are heated may be utilized. For example, elastic spring-like materials, bimetallic springs that bend when they are heated, or shape memory alloys that transform into a different shape when heated may be utilized. Other suitable thermal expansion systems are contemplated by the present invention.
In an electrical actuation system embodiment, suitable materials that change dimensions when subjected to electric current, such as piezoelectric materials, may be utilized. Other suitable electrical expansion systems are contemplated by the present invention.
In a mechanical expansion system embodiment, a plurality of spheres or other particles that push radially outward and expand screen element 110 when subjected to axial compression from a piston or other suitable element may be utilized. Other suitable mechanical expansion systems are contemplated by the present invention.
Screen element 110 may be any suitable screen of any suitable size and configuration and may be formed from any suitable material. For example, screen element 110 may be formed from a suitable carbon steel and include a fine screen or coarse screen (or both) inside of a suitable sleeve (sometimes referred to as a “shroud”) having suitable apertures formed therein. Screen element 110 may also have any suitable length and may be formed from one or more sections. Screen element 110 is disposed around the outside of intermediate expansion system 108 and may or may not directly couple to intermediate expansion system 108. As described in greater detail below, after expansion of base pipe 106 and intermediate expansion system 108, screen element 110 engages and applies a force to the wall of wellbore 101.
System 100 may also include a pump 118 operable to dispose a completion fluid 120 into an annular space 122 between the wall of wellbore 101 and screen element 110. Any suitable pump is contemplated by the present invention. Completion fluid 120 may be any suitable completion fluid.
In operation of one embodiment of the invention, and with reference to FIGS. 1 and 2, wellbore 101 is first drilled by any suitable method within formation 102 and the upper portion thereof may be cased with a casing (not explicitly illustrated). A suitable liner hanger (not explicitly illustrated) is utilized to position expandable screen assembly 104 within wellbore 101. Work string 112 with expander 114 coupled thereto is then run-in-hole and completion fluid 120 is circulated down into wellbore 101. Completion fluid 120 fills annular space 122.
Work string 112 is then utilized to apply weight to expander 114, which translates downward and starts radially expanding base pipe 106. Expander 114 plastically deforms base pipe 106. As base pipe 106 is radially expanded outwards towards the wall of wellbore 101, intermediate expansion system 108 and screen element 110 may also be expanded radially.
After base pipe 106 has been expanded as desired, then intermediate expansion system 108 is expanded via actuation system 116. Intermediate expansion system 108 expands screen element 110 further towards the wall of wellbore 101 so that it applies a force to the wall of wellbore 101. In other embodiments, intermediate expansion system 108 may be radially expanded by actuation system 116 before base pipe 106 is expanded. Any suitable amount of expansion of base pipe 106, intermediate expansion system 108, and screen element is contemplated by the present invention.
Thus, system 100 includes expandable screen assembly 104 that increases the overall expansion of screen element 110 to ensure that screen element 110 contacts the wall of wellbore 101 and exert adequate force thereto for sand control and efficient production from wellbore 101.
Although embodiments of the invention and their advantages are described in detail, a person of ordinary skill in the art could make various alterations, additions, and omissions without departing from the spirit and scope of the present invention as defined by the appended claims.