This application is the U.S. national stage application of International Application PCT/NO2017/050075, filed Mar. 28, 2017, which international application was published on Oct. 5, 2017, as International Publication WO 2017/171556 in the English language. The International Application claims priority of Norwegian Patent Application No. 20160522, filed Apr. 1, 2016 and Norwegian Patent Application No. 20161363, filed Aug. 26, 2016. The international application and Norwegian applications are all incorporated herein by reference, in entirety.
The present invention relates to a device for directing a fluid flow in an annulus around a pipe string in a horizontal or deviated well. The invention also relates to a pipe string comprising such a device as well as to a method for operating such a device in a well.
In horizontal or deviated wells, a stationary bed of cuttings tends to form on the low-side of the borehole when drilling the well due to gravity. This so-called cuttings bed may cause problems such as high drag, difficult hole cleaning and a higher probability of getting the pipe stuck etc. The problems are more pronounced in higher inclination wells and even more so with lower flow velocities of various fluids. Because of the cuttings bed, fluids tend to preferentially flow on the high-side of the borehole, an effect known as “high-side channelling”. Another implication of the high-side channelling is that cement tends to flow on the high-side of the borehole when casing strings and liners are to be cemented in place in the well. The low flow on the low-side often causes poor cement bond quality behind the casing on the low-side of the borehole, further potentially leading to well integrity problems. “Bad cement jobs” may have far-reaching effects and high risk impact on well construction.
It is known to provide centralizers around pipe strings in order to increase the stand-off between the pipe string and the low-side of the borehole. However, centralizers typically do not provide a good level of stand-off in high inclination and horizontal wells, and high-side channelling remains a significant problem.
The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.
The object is achieved through features, which are specified in the description below and in the claims that follow.
The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.
In a first aspect the invention relates to a device for directing a fluid flow in an annulus around a pipe string in a horizontal or deviated well, the device comprising:
The theory of critical fluid velocities for avoiding cuttings beds was discussed in the paper “Estimating critical velocity to prevent bed development for Horizontal-Inclined Wellbores” presented at the Middle East Drilling Technology Conference and Exhibition, 2007 (SPE/IADC 108005). Reference is made to this paper for an in-depth description of the theory behind cutting beds and critical fluid velocities.
In one embodiment, the device may comprise an orientation member for orienting said fluid direction member in the borehole. It will normally be difficult to predict the orientation of the pipe string when it reaches the depth in the well were the fluid direction member is to be activated. Therefore it may be useful, if needed, to be able to orient the fluid direction member to the preferred orientation before activating it, so as to be able to predict its orientation in the well, and thereby also the direction of the fluid flow.
In most embodiments it will be useful if the fluid direction member is adapted to impede the fluid flow on the high-side of the borehole so as to increase the fluid flow on the low-side of the borehole. This will typically be the case when using the device when cementing a casing string or a liner in the well or when cleaning the annulus around the casing string prior to cementing or when cleaning an annulus around a drill string or a work string. The flow direction member will impede the flow of fluid on the high-side of the borehole while improving, i.e. increasing the velocity of, the fluid flow on the low-side. The theory behind this was discussed in the above-referenced SPE/IADC paper.
In an alternative embodiment, the fluid direction member may in addition or as an alternative be adapted to impede the fluid flow on the low-side of the borehole so as to increase the fluid flow on the high-side of the borehole. This may be useful in gravel packing operations while installing well completion assemblies. In this embodiment, the lower completion assembly most commonly includes sand screens. After installing the lower completion assembly to the required depth, an inner string may be run inside the lower completion assembly to the end of the wellbore and used to pump gravel out the end of the lower completion assembly. If one or more devices according to the first aspect of the invention are activated to partially block the low-side of the wellbore, this would help to divert the flow of gravel up onto the high side of the lower completion assembly and thereby help to achieve full wellbore coverage of gravel around the lower completion assembly. Rather than having a tendency for ‘high side channeling’, gravel tends to flow on the lower 50% of the wellbore and therefore achieving full coverage on the high-side is a problem.
In its simplest form, the orientation sensing member may be a weight member adapted to self-orient the fluid direction member by means of gravity. The weight member may be an integrated part of the fluid direction member or it may be attached to the fluid direction member. This simple embodiment of the device according to the invention may operate without any sophisticated orientation sensing means and the flow direction member means may as such be its own orientation member.
In an alternative embodiment, the orientation sensing member may be a buoyant member filled or partially filled with air or other buoyant fluids, gases or materials adapted to self-orient the fluid direction member by means of buoyancy. The buoyant member may be an integrated part of the fluid direction member or it may be attached to the fluid direction member. The buoyant member may be designed to run on a low friction surface such as a bearing in order to ensure that the buoyant force overcomes the frictional force required to orientate the member. This embodiment of the device according to the invention may operate without any sophisticated orientation sensing means and the flow direction member means may as such be its own orientation member.
In an alternative embodiment, the orientation sensing member may comprise a gyroscope, and the orientation member may comprise a downhole, electric motor for orienting said fluid direction member in the borehole. A device according to this more sophisticated embodiment, may prove to be more reliable in some applications. In other alternative embodiments, the orientation sensing member may comprise simple gravity-based devices, such as a mercury switch or an electrical switch including conductive fluid.
The fluid direction member may typically comprise one or more segments/parts adapted to protrude, when in the activated position, from the circumference of the pipe string. In one embodiment, the fluid direction member may be an expandable packer or sleeve having a non-uniform radius, or it may be several packer or sleeve segments distributed around the circumference of the pipe string. In the widest sense, the fluid direction member may be any object adapted to be orientated or activated so as to extend from the outer surface of the pipe string and into the annulus around. The fluid direction member may also be a sheath, activatable by means of a cone, axially movable relative to the sheath, the sheath covering a segment of the annulus, such as in the order of 90-180°.
A variety of different activation members may be used to activate the fluid direction member once the pipe string has reached a desired depth/location in the well. In some embodiments the activation member may be operateable by means of one of the following sources:
The activation member itself may be a valve or an actuator or the like adapted to be operated by one or more of the sources mentioned above.
All of the above-referenced sources of activation may be useful if no de-activation of the fluid direction member is required, i.e. when the fluid direction member may be left in the activated/expanded position in the well after operation. This may be useful when running the fluid direction member into the well as part of a casing string with the aim of improving the distribution of cement in the borehole. The activated fluid direction member may then be left in the well, integrated in the cement. Some of the above-referenced sources, in particular the downhole electric motor, may also be useful in case de-activation of the fluid direction member is desirable. This may typically be the case if the fluid direction member is run into the well on a drill string or work string with the aim of improving cleaning of the annulus around the pipe/work string. For subsequent retrieval of the string from the well, it would likely be advantageous if it is possible to de-activate the fluid direction member into a non-expanded or retracted position. Re-settable packers are known in the art.
As already mentioned above, the pipe string may be a drill string or a work string or it may be a casing string or liner. In a drill string, a device according to the first aspect of the invention may typically be integrated between joints or stands of the string. It may comprise one or more segments, as described above, the one or more segments being attached to a bearing, the bearing allowing the fluid direction member to be kept at a substantially fixed orientation while continuing to rotate drill string. It should also be noted that a plurality of devices according to the first aspect of the invention may be integrated in a pipe string with axial, and optionally circumferential, distance therebetween. In a casing string, a device according to the first aspect of the invention may typically be integrated between joints of casing or ‘slipped-on’ to a casing joint using a bearing system. When cementing the casing, the device according to the first aspect of the invention may only be activated once the casing string is installed at the correct depth. After activation, cementing operations may be performed. The cementing operation would typically include circulating fluid as ‘pre-flush’, then spacer fluid, then cement. The flow device according to the first aspect of the invention may remain activated and therefore be cemented into the wellbore. The device according to the invention may also be deployed on a coiled tubing string, then as part of the bottom hole assembly (BHA).
For gravel packing operations, a device according to the first aspect of the invention may typically be integrated between joints of casing or sand screens as a ‘sub assembly’ as part of the lower completion assembly or alternatively attached externally to a joint of casing or sand screens on the lower completion assembly. The device according to the first aspect of the invention then serves to divert the flow of ‘gravel’ in the annular space between the lower completion assembly and the wellbore as described above.
In a second aspect, the invention relates to a method for directing a fluid flow in a horizontal or deviated well by means of a device according to the first aspect of the invention, wherein the method comprises the steps of:
The activation, and optional de-activation, of the fluid directing member as such may be controllable via signal transmission from the surface of the well. The signals may be transferred wirelessly from the surface. In an alternative embodiment, the activation may be automatic in the sense that no signals need to be transferred from the surface for the activation to commence. The activation may be automatically initiated after a certain time, or a downhole indicator/trigger may be embedded in a well construction element, such as in a casing or in a liner, that will be able to communicate locally with a device according to the first aspect of the invention once in the proximity of the trigger. The trigger/indicator may be a RFID tag adapted to communicate with a RFID tag on a device according to the first aspect of the invention. If RFID technology is used, a tag may also be dropped into the casing and pumped down with fluid. When the RFID tag passes the device according to the first aspect of the invention, it may ‘tell’ the fluid direction member to activate. Alternatively, the device could be designed to recognize a series of pressure pulses either inside the casing or drill pipe or in the annulus. Finally, a series of ‘repeaters’ could be installed on the outside of the casing to allow an electrical telematics signal to be transmitted from the rig all the way down to the tool.
In one embodiment the device may be run into the well on a drill string or on a work string, and the method may further comprise the step of:
In another embodiment the device may be run into the well on a casing string or liner, where the method may further comprise the step of:
It should also be noted that it may also be useful to clean the annulus around the casing with the aid of a device according the invention prior to cementing. This will ensure a better homogeneity of the subsequent cement or any other fluidised plugging material.
In yet another embodiment, the device may be run into the well as part of a bottom hole assembly, and the method may further comprise the step of:
There is also described herein an embodiment of device for diverting a fluid flow in an annulus around a pipe string similar to the device according to the first aspect of the invention, but where the flow diverter device is not provided with an orientation sensing member. The idea is then that a plurality of such, simplified flow diverters may be axially and circumferentially distributed along a pipe string and activated when the pipe string has reached a desired depth in the well so as to create a spiralling fluid flow along the pipe string. Each of the devices will impede the fluid flow in part of the annulus, but instead of orienting the devices to certain orientation in the borehole, the circumferential and axial distribution of the devices ensures an even improvement of the fluid flow around the full circumference of the pipe string. There is also described a pipe string, such as a drill string, work string, coil tubing or casing or liner string comprising a plurality of such flow diverters distributed axially and circumferentially around the pipe string so as to create a spiralling fluid flow along the axial direction of the pipe string. Activation and optional de-activation of the alternative flow diverter devices may be initiated in a similar way as described above for the devices with the orientation sensing member. The methods described herein for directing a fluid flow in a horizontal of deviated well also apply for a pipe string provided with a plurality of these simplified flow diverter devices.
In the following are described examples of preferred embodiments illustrated in the accompanying drawings, wherein:
In the following, the reference numeral 1 will be used to indicate a device according to the first aspect of the invention, whereas the reference numeral 10 will be used to indicate a pipe string comprising a device 1 according to the first aspect of the invention. Identical reference numerals refer to identical or similar features in the drawings. It should also be noted that the drawings are shown schematically and simplified and that the various features in the drawings are not necessarily drawn to scale. In the following the device 1 according to the invention will be referred to as a flow diverter.
a, b and c show a first embodiment of a flow diverter 1 in a perspective view and in longitudinal and axial cross-sections, respectively. The flow diverter 1 is shown provided on a pipe string 10, wherein only a short portion of the pipe string 10 is shown in the figures for simplicity. The flow diverter 1 is attached to a not shown bearing in order to enable independent rotation of the pipe string 10 relative to the flow diverter 1. The flow diverter 1 is shown comprising a steel base 2 encircling the pipe string 10, and a fluid direction member 4 in the form of a swellable elastomer packer. The swellable elastomer packer 4 covers about half, i.e. a sector of 180°, of the circumference of the pipe string 10 extending radially into a not shown annulus. The steel base 2 is further formed with a weight member 6, in the form of a radial protrusion, ensuring that the flow diverter 1 will self-orient itself due to gravity. The radial protrusion 6 will tend to end up at the low-side of the not shown borehole, further implying that the swellable packer 4, in its activated/extended/swelled position, will impeded the flow of fluids on the high-side of the borehole so as to improve the flow on the low-side, in the area between the elastomer packer 4 and the weight member protrusion 6, of the borehole in order to avoid or significantly reduce the problem of cuttings beds described herein. The steel base 2 with the protrusion 6 thus acts both as an orientation sensing member and as an orientation member. In a more sophisticated embodiment, the orientation sensing member may be a gyroscope, a mercury switch or similar, while the orientation member may be a downhole electrical motor. This first embodiment constitutes a simple and low-cost implementation of the invention. It may be particularly useful in use when there is no need to de-activate the fluid direction member 4, such as for cleaning and/or cementing an annulus outside a casing string or liner. A person skilled in the art will understand that the swellable elastomer packer 4 acts as its own activation member, in that it is activated in contact with a certain fluid, typically water or oil.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.
The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.
Number | Date | Country | Kind |
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20160522 | Apr 2016 | NO | national |
20161363 | Aug 2016 | NO | national |
Filing Document | Filing Date | Country | Kind |
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PCT/NO2017/050075 | 3/28/2017 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/171556 | 10/5/2017 | WO | A |
Number | Name | Date | Kind |
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5086842 | Cholet | Feb 1992 | A |
10001007 | Pelletier | Jun 2018 | B2 |
20040040749 | Terry et al. | Mar 2004 | A1 |
20060021797 | Krueger | Feb 2006 | A1 |
20100175923 | Allan | Jul 2010 | A1 |
20140262266 | Ingold | Sep 2014 | A1 |
Number | Date | Country |
---|---|---|
2383430 | Nov 2011 | EP |
2015094163 | Jun 2015 | WO |
Entry |
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“Estimating critical velocity to prevent bed development for Horizontal-Inclined Wellbores” presented at the Middle East Drilling Technology Conference and Exhibition, 2007 (SPE/IADC 108005). |
International Search Report, PCT/NO2017/050075, dated Jun. 13, 2017. |
Written Opinion, PCT/NO2017/050075, dated Jun. 13, 2017. |
Norwegian Search Report, Norwegian Patent Application No. 20161363, dated Mar. 24, 2017. |
Norwegian Search Report, Norwegian Patent Application No. 20160522, dated Oct. 27, 2016. |
Number | Date | Country | |
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20190048673 A1 | Feb 2019 | US |