Patent Application
20080196879
In many downhole fluid production wells, particulate matter production is to be avoided. In view hereof, “sand screens” are often used to exclude particulate matter from fluidic components entering the production apparatus. Sand screens sometimes include a holed base pipe, a filtration medium and a shroud. The filtration medium and shroud are often preassembled as a jacket before installation thereof on the holed base pipe. In order to enhance life of service of the production-well and particularly as the wells get deeper, it is common to use higher alloy steels in the base pipe. While this material does indeed present excellent resistance to abrasive degradation, it also promotes an ancillary problem. The problem is related to the method commonly used for attachment of the jacket to the base pipe. Generally, the favored attachment means is by welding. Welding high alloy materials, while being effective from an affixation standpoint, also may cause the high alloy material to corrode more readily. Since wellbore environments are naturally highly corrosive, the drawback associated with welding as noted is particularly detractive.
In view of the foregoing, the art would welcome screen jacket coupling methods and apparatus that avoid welding thereby avoiding the foregoing effects and additionally avoiding, generally necessary, heat treating operations after welding to stress relieve and temper the final product.
A particulate exculder tool includes a basepipe having one or more retention features; a screen jacket disposed radially outwardly of the basepipe; one or more end housings at the screen jacket; and a deformable element disposed between a portion of the one or more end housings and one or of the one or more retention features and method.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
Referring to
The tool 10 includes a base pipe 12 having at least one undercut, and illustrated with retention features such as undercuts 14 and 16 (undercut 14 illustrated in enlarged form in
Disposed about the base pipe 12 is a screen jacket 22, (a sand exclusion device) which screen is configured to exclude particulate matter having dimensions greater than a predetermined set of dimensions. Such screen jacket is in one embodiment configured as noted above to have a filter medium 24 and a shroud 26. The jacket 22 is substantially the same as screen jackets on commercially available sand screens from Baker Oil Tools, Lafayette, La. and therefore requires limited discussion here.
The screen jacket disclosed herein includes end housings 28 and 30 that are configured with a first inside dimension at numeral 32 and 34, respectively, and a second inside dimension at 36 and 38, again respectively. In each case, the first inside dimension is selected to closely clear an outside dimension of the base pipe 12 while the second inside dimension is selected to be spaced from the outside dimension of the base pipe 12 by an amount sufficient to accept a deformable element (which may in some configurations be both a mechanical attachment and a seal and in other configurations represent less than 360 degrees of contact with the base pipe such that the deformable element acts only as a mechanical attachment) 40 in clearance relationship therewith where the element 40 is in an unactuated condition and in an interference relationship when the element is in an actuated condition. For purposes of clarity of disclosure, the space defined by the second inside dimension of the end housings and the base pipe will be referred to herein as pockets 42 and 44. Pockets 42 and 44 are to be aligned axially with undercuts 14 and 16, respectively so that seals 40 disposed within pockets 42/44, when activated, contact each undercut. Further, each end housing 28 and 30 includes a box thread 46 and 48, respectively, which is to threadably receive a collar 50 and 52, respectively. Collars 50 and 52 thread into their respective end housings 28 and 30 to reduce the axial dimension of pockets 42 and 44. By reducing this axial dimension, with the element 40 installed therein, the element is caused to deform both radially inwardly and radially outwardly into contact with undercuts 14 and 16 and, respectively, the second inside dimension of each end housing 28 and 30. By so deforming the element, the screen jacket 22 is mechanically locked in place without the need for welding to the basepipe. Further the post heat treatment generally required after such a welding operation is avoided saving both cost and time.
In one embodiment, the element 40 is a metal element and may be a mini z seal commercially available from Zeroth Technology Limited.
As is visible in
While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.
