Embodiments of the present invention generally relate to wellbore completions, and more particularly, to a screen design for sand control.
Hydrocarbon wells are typically formed with a central wellbore that is supported by steel casing. The casing lines the borehole in the earth, and the annular area created between the casing and the borehole is filled with cement to further support and form the wellbore. While some wells are produced by simply perforating the casing of the central wellbore and collecting the hydrocarbons, wells routinely include portions left open or unlined with casing. Because they are left open, hydrocarbons in an adjacent formation migrate into these wellbores where they are affected along a perforated tubular or sand screen having apertures in its wall and some kind of filtering material to prevent sand and other particles from entering. The sand screen is attached to production tubing at an upper end and the hydrocarbons travel to the surface of the well via the tubing.
Since open wellbores lack support along their walls and the formations have a tendency to produce sand and particulate matter in quantities that hamper production along a sand screen, open wellbores are often treated by fracturing and packing. Fracturing a wellbore or formation means subjecting the walls of the wellbore and the formation to high pressure solids and/or fluids that are intended to penetrate the formation and stimulate its production by increasing and enlarging the fluid paths towards the wellbore. Packing a wellbore refers to a slurry of sand that is injected into an annular area between the sand screen and the walls of the wellbore to provide a gravel pack that supports the wellbore and provides additional filtering to the hydrocarbons. Apertures through the sand screen are sized to retain the gravel pack.
Since the sand screen's function includes filtering of particles, these particles can build up over time with smaller particles forming bridges at the sand screen that at least partially plug the sand screen. After producing through the sand screen for some time, the sand screen becomes plugged and prevents or slows the flow of fluids for production. This can occur regardless of whether the wellbore includes a gravel pack. A backflow of fluid by reverse pressurization supplied through the production tubing reopens the plugged sand screen in order to reestablish flow through the sand screen. Often, the fluid used in the backflow includes an acid that aids in dissolving and dislodging debris trapped by the sand screen. The backflow operation requires applying reverse pressures that can be approximately three thousand pounds per square inch.
During some wellbore completion or remediation procedures, it is necessary to stop the flow of production with a fluid loss mechanism. These mechanisms can include mechanical flappers; however, mechanical flappers often stick open or shut requiring costly and time consuming efforts to correct. Alternatively, a solution containing particles in liquid can provide a chemical seal that applies to the sand screen to plug the apertures through the sand screen. Application of a second solution at a predetermined time removes the chemical seal from the sand screen. If normal procedures for releasing the chemical seal from the sand screen fail, a reverse pressurization must be applied across the sand screen in order to stimulate the chemical seal such that the plugged sand screen reopens.
Originally, sand screens simply consisted of slotted tubing; however, this provides little control as to the size of particles actually screened. A second type of sand screen includes a perforated tubing with a wire wrapped screen positioned on its outside that is formed by wrapping wire around longitudinal rods such that the spacing between the wraps of wire is selected to be sufficiently small to filter particles. A variation on the wire wrapped screen includes providing a packing of sized particles between two wire wrapped screens. This packed screen increases pressure across the sand screen which decreases velocity in order to slow production as required in various completions. However, this packed screen is heavy, and it is difficult to provide and insure an even distribution of the sized particles therein. Another type of more recent and improved sand screen includes premium screens consisting of layers of metal fiber or metal powder between sheets of woven mesh that wrap around a perforated tubing. Therefore, the premium screens require a longitudinal weld in order to secure and seal the sheets of material that wrap around the perforated tubing. Thick premium screens become brittle at the longitudinal weld due to the heat affected zone at welds of the premium screen. Especially suited for thin premium screens, weak resistance welds provide one option for longitudinally welding. A shroud having apertures in its wall may be necessary to protect the premium screens.
Current sand screens lack the ability to withstand the reverse pressurization procedures. Under normal pressure conditions, the perforated tubing provides support for the premium screen since forces acting on the premium screen urge the premium screen against the outside surface of the perforated tubing. However, the reverse pressure urges the premium screen outward and places hoop stresses on the premium screen thereby causing the premium screen to fail at the longitudinal weld that holds it wrapped around the production tubing. Additionally, reverse pressurization using acid in excessive concentration dissolves a phenolic resin coating on the sized particles within packed screens. Thus, acid reverse pressurization can further plug the screen with the dissolved phenolic resin, damage other production tools and equipment with the dissolved phenolic resin, or destroy the functionality of the packed screen itself.
There exists a need for an improved sand screen for use in a wellbore that is seamless and adaptable for different particle size filtration and production tubing diameter.
The present invention generally relates to a sand screen for use in a well that employs a seamless tube shaped filter member covering perforations in a length of perforated tubular. The filter member includes a monofilament or multifilament wire that is precisely wound to control angle and spacing of the wire. Configuration of a wind pattern and the amount of wire wound controls aperture size for filtering particles, flow characteristics through the filter member, and overall strength of the filter member. Seals at each end of the filter member can secure and circumferentially seal the filter member on the perforated tubular.
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
In one embodiment, the mandrel 400 is a perforated tubular that the wire 200 winds around to form the filter member 108. As such, the wire 200 can wind directly around the perforated tubular 110 shown in
The filter member 108 may be wound to produce a tortuous path for fine filtration, a straight path for increased permeability, or anywhere in between. The tortuous path slows velocity flow and increases pressure to prevent formation erosion which is particularly useful in high production rate wells. In order to provide the straight path, the wire 200 winds such that overlapping portions are non-offset as schematically shown in
As shown in
Assembling the sand screen 106 includes winding a wire 200 into a substantially seamless tubular shape of the desired configuration, length, diameter, and thickness in order to provide a filter member 108. Sintering the filter member 108 diffusion bonds the wire contact points. Positioning the filter member 108 around an outer wall of a perforated tubular 110 covers at least some apertures 112 through the perforated tubular 110 with the filter member. Providing seals 114 at each end of the filter member circumferentially seals the filter member 108 at its end to the perforated tubular 110 to provide the sand screen 106.
Since the filter member 108 lacks weld joints, the filter member provides a uniform and effective filtration surface about its entire circumference. Additionally, the hoop strength of the filter member 108 is uniform in order to effectively distribute any hoop stresses applied to the filter member. The wall thickness of the filter member 108 can be increased to provide further strength to the filter member.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims benefit of U.S. provisional patent application Ser. No. 60/495,480, filed Aug. 15, 2003, which is herein incorporated by reference.
Number | Date | Country | |
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60495480 | Aug 2003 | US |