Patent Application
20060272814
The field of the invention is flow equalizing devices to control inflow from a formation into production tubing in a manner so as to draw more evenly from diverse sections of the producing formation.
Annulus flow, particularly in long horizontal runs in a formation creates an undesirable uneven flow into production tubing and encourages production of sand and along with it erosion that adversely affects downhole equipment such as screens. To combat this tendency of uneven inflow caused by annular flow around the outside of screen sections, what has been tried in the past is the addition of a flow control mechanism to individual screen sections to redirect much of the flow that used to come in closer to the uphole or heel end of the screen assembly because that would represent the path of least resistance. In essence, the solution to this problem involved the reconfiguration of the screen sections so that in each screen section the flow could go through the screen material and then in an annular space defined between the screen and the base pipe, which would be non-perforated in the screen section. After passing through that zone the flow would be put through a tortuous path before arriving at a hole in the base pipe. Each section of screen could have a form of this built in resistance so that an assembly of screens in the aggregate would equalize the flow from the formation over the length of the producing zone. To illustrate this approach, reference is made to the Equalizer™ screen sold by Baker Hughes Incorporated of Houston, Tex. and described at length in SPE Paper 78293 entitled An Investigation of the Economic Benefit of Inflow Control Devices on Horizontal Well Completions Using a Reservoir-Wellbore Coupled Model by Jody Augustine. U.S. Pat. Nos. 3,450,207; 5,435,393 and 6,112,815 are also relevant to this concept. In using these devices the annular space was traditionally gravel packed to control annular flow characteristics and limit production of undesirable sand.
More recently, the concept of expansion of pipe downhole has taken hold and screens have been expanded to reduce the size of the surrounding annulus with an eye toward eliminating the need to gravel pack. In long horizontal runs, in particular, there were concerns about the distribution of gravel and the ideal of screen expansion took hold as a way to ease those concerns by reducing the size of the annular space around a screen in open hole of a slotted liner.
However, despite the incorporation of expansion technology the issues relating to annular flow and uneven flow from the formation into the production tubing remained through screens remained. The unique construction of the known flow equalizing devices did not make an assembly that was amenable to expansion. Accordingly, the present invention is directed to an assembly that is amenable to expansion while still providing the capability to distribute flow from a formation evenly into a production string. These and other features of the present invention will be more readily appreciated by those skilled in the art by a review of the detailed description of the preferred embodiment, the drawings and the claims that appear below.
The invention involves the use of a base pipe perforated only in a specific section under each screen section. Inflow comes through an outer shroud that is optional and goes through the screen material and into an annular space between the screen material and the unperforated base pipe. After traveling longitudinally in that annular space, the flow must go through a restriction that preferably comprises a porous media in a passage defined outside the still unperforated base pipe. After passing through the porous media in a particular screen section, the flow can pass through openings in the base pipe. A surrounding ring preferably protects the porous media during run in and expansion and can also optionally create additional resistance to flow to work in tandem with the porous media. Other flow restricting techniques in place of the porous media are contemplated.
Referring to
Arrow 30 in
As shown in
The external structure 16 can take many forms. One of its purposes is to create a flow channel to the openings 12. Another use for it would be to contain or protect the porous media 24 during run in or expansion. Advantageously the porous media 24 should be resistant to being crushed in the expansion process.
The present invention can be used to balance the flow of oil gas or water produced from a zone whether the zone is vertical horizontal or anything in between. By assuring more uniform production and further by having a configuration that is amenable to expansion the invention further reduces annular channeling and can in some cases do away with the need for gravel packing while at the same time provide a way to better produce the zone so as to extract the most hydrocarbons from it. The even flow that can be achieved also will reduce erosion and production of other solids or liquids from the zone that can displace the desired fluids from the zone.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below.
