The field of the invention is production techniques for equalizing flow from formations and more particularly from formations that produce more viscous hydrocarbons in the preferred range of about 20-1000 centipoise.
Some completions involve long runs of screens in the producing zone. To get more balanced production along a lengthy section of screen that in some cases could be thousands of feet long devices have been used to offer different resistance at different locations along the screen sections. The screen sections closest to the surface that constitute a potential path of least resistance would need more restriction that screen sections further down. What has been tried in the past is illustrated in U.S. Pat. No. 6,622,794. In this patent screen sections had an annular space between a base pipe and the screen and inserted in the annular space before the flow could get to openings in the base pipe were helical paths that offered different degrees of resistance to a given flow rate. Using this design would require expensive machining raising the cost of each stand of screen. Additionally, an inventory of different screens opening sizes had to be kept and for each screen opening size the spiral paths that created different levels of resistance to a given flow also had to be kept in inventory for a variety of different completion situations. Beyond that, the screen sections needed to be carefully marked so that they would be assembled at the well in the correct order so as to provide more flow resistance closer to the wellhead and tapering down to less of no resistance at locations most remote from the wellhead.
Apart from this design sliding sleeves have been run with screens and some examples of those designs are U.S. Pat. Nos. 5,896,928; 6,371,210; 7,096,945; 7,055,598; 6,994,170; 6,481,494; 6,978,840; 6,568,472 and US Publication No. 2006/0237197.
The present invention provides an economical design for balancing screen flow particularly well suited for applications where highly viscous hydrocarbons about 10 to 10,000 centipoise with a preferred range of 20-1000 centipoise are being produced. In these situations the screen design incorporated an annular flow path to the base pipe openings that can be high enough to pass solids that might clear a screen and yet provide enough flow resistance at high viscosities to achieve the desired screen flow balancing. The design is considerably cheaper to produce than the prior spiral path designs. These and other benefits of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the claims are the full measure of the invention.
A flow balancing system for long screen sections particularly useful in high viscosity hydrocarbon production features an annular flow path whose height and length can be varied to provide a predetermined resistance to a given flow rate of a material of a given viscosity. In assembling a long length of screen sections, greater resistance configurations are placed closer to the wellhead end of the screen section with the more remote sections having progressively less restriction until the furthest section of the screen string where low or no resistance to flow internally to the screen section is offered.
Referring now to
It should be noted that the openings 12 are preferably not flow restrictive when compared to passage 28. Additionally, the assembly from end ring 18 to end 22 is simple to fabricate in a variety of lengths and heights. Screen sections need not be finished until ordered for a specific job and then quickly welded to the base pipe 10 after the openings 12 are properly located.
It is preferred that the illustrated sleeve over a tubular design be used for fluids having preferred viscosities of at least about 20 centipoise so that the height 26 can be greater than the size of particles that may get through the screen 14 during normal filtration activities.
Those skilled in the art will appreciate that the preferred embodiment illustrates a cost effective design that reduces inventory cost and can be fabricated to suit when a specific job is ordered or even at a local stocking warehouse just prior to shipment to a job. The use of an annular flow path also reduces risk of clogging from solids that get through the screen 14. It is far simpler than spiral designs that wrap around many times before coming to the base pipe openings. Optionally, some baffles can be used for structural support or for reduction of turbulence in passage 28. If the well is short enough, the same flow resistance in passages 28 for the various screen sections may be used along the entire length. Or, if the goal is to react to the formation permeability heterogeneity, the same flow resistance may be used in conjunction with annular isolation packers.
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.
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Number | Date | Country | |
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