Embodiments described relate to multilateral completions assemblies. In particular, tools and techniques are described that allow for the undertaking of completions operations and hardware installation in a manner that substantially avoids interference from unintended fluid production. Thus, these tools and techniques may be particularly advantageous when employed in conjunction with wells having a variety of uncased, or at least temporarily open, lateral legs emerging from a main bore.
Exploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses, added emphasis has been placed on efficiencies associated with well completions and maintenance over the life of the well. Over the years, ever increasing well depths and sophisticated architecture have made reductions in time and effort spent in completions and maintenance operations of even greater focus.
In terms of architecture, a well often includes a variety of lateral legs emerging from a main bore. For example, the terminal end of a cased well often extends into an open-hole region branching out into multiple lateral legs providing reservoir access. Of course, such open-hole lateral legs are also often found extending from other regions of the main bore as well. This type of architecture may enhance access to the reservoir, for example, where the reservoir is substantially compartmentalized. Regardless, such open-hole lateral leg sections often present their own particular challenges when it comes to completions installation and maintenance.
In many circumstances, the mere creation of the multilateral architecture presents stability issues. That is, once the main bore is formed, and generally cased, the noted variety of lateral legs are sequentially drilled into the formation, emerging from the bore. This results in exposure of the main bore to an emerging open network of legs connected thereto without any fluid or pressure control. This may be of consequence where the nature of the well architecture is such that fluid access is more readily attained, for example, without the need for prior stimulation. That is to say, depending on the nature of the architecture relative the reservoir, the mere process of completing the well and installing hardware may result in fluid losses well in advance of intended production.
In order to avoid such fluid loss interference and allow completions operations to continue, comparatively heavy solid particle fluids may be pumped into the well. Unfortunately, this manner of killing fluid loss or production has significant drawbacks. That is, aside from the operational time lost to the kill application, once installation is completed, follow-on applications dedicated to regaining reservoir access must be undertaken. These applications require more time and resources devoted to the introduction of stimulation and recovery fluids, namely directed at removal of the heavier kill fluids. Overall, the time lost to killing and restoring the well for sake of multilateral completions may be in the neighborhood of days to weeks at a cost of several hundred thousand dollars.
Once more, complete revival of the well following the kill is unlikely. That is, even following well restoration or clean-out applications, the overall efficiency and productivity of the well will remain compromised to a degree as a result of having undertaking the kill application. This is due to the fact that complete removal of the kill fluid is impractical. Indeed, in the multilateral situation, it is quite likely that production from one or more of the multilateral legs will remain closed off even after well restoration. Nevertheless, in the case of multilateral completions prone to fluid losses during installation, operators are left with only the options of utilizing the noted kill techniques or limiting the overall sophistication of the multilateral in terms of depth and number of open legs.
A multilateral completions assembly is detailed which includes a main bore casing and at least one sidetrack sleeve. The sleeve is positioned at pre-determined locations of the casing and configured for selectively opening and closing. This selective opening may be utilized to create a lateral leg of the well therefrom following by sealing isolation of the leg upon the closing of the sleeve. Additionally, with the sleeve in place during production, selectively opening and closing thereof may be used to govern production at the location of the sleeve.
Embodiments are described with reference to certain multilateral completions assemblies. For example, embodiments herein are detailed with reference to a multilateral assembly having a main bore with at least three legs emerging at angled orientations therefrom and into a surrounding formation level. Additionally, these lateral legs of the well are open in nature. However, hardware and techniques detailed herein may be advantageously employed on a host of different well architecture types. For example, the legs may vary widely in number or be subsequently cased. Regardless, embodiments described herein include at least one shiftable isolation sleeve disposed in the main bore adjacent a pre-located window through which a leg into the formation may be formed. Further, the leg may be left controllably uncased or otherwise open relative the formation for at least some period of time without significant concern over fluid losses.
Referring now to
With added reference to
Continuing now with particular reference to
In the embodiment shown, even with multiple lateral legs 250, 255, 257 open to the lower formation level 195, the well 180 retains an isolated central borehole, largely unaffected by any potential fluids in these legs 250, 255, 257. So, for example, further multilateral leg creation into the upper formation level 295 may efficiently proceed without any undue concern over interference from fluids draining into the main bore from the depicted legs 250, 255, 257. Along these lines, formation of the depicted legs 250, 255, 257 themselves is likely achieved in a sequential manner, beginning with the lowermost leg 257 and working uphole. Thus, selectively opening and closing sleeves 202, then 201, then 101, to maintain isolation during leg creation may be utilized.
Continuing with reference to
Where coiled tubing 210 is utilized, a mobile coiled tubing truck 235 with reel 230 may be provided as shown. The truck 235 may also accommodate a control unit 237 for directing a sleeve shifting, water jetting or other downhole application as detailed further below. Additionally, in the embodiment shown, a mobile rig 240 is provided which supports a conventional gooseneck injector 245 and provides alignment over valve and pressure regulating equipment, often referred to as a ‘Christmas tree’ 247. Through such equipment 225, coiled tubing 210 may be utilized to transform a sleeve outfitted well 180 from a vertical borehole to the more sophisticated multilateral depicted without undue concern over leg fluid interference as noted above.
Referring now to
Continuing with reference to
The landing 330 is the lowermost portion of the whipstock tool 300 which is displaced from the head 310 by an extension 320. With added reference to
Referring now to schematic views of
With particular reference to
With the tool 300 and sleeve 101 fully coupled together, a running tool 400 of the coiled tubing 210 may be advanced further downhole to shift open the sleeve 101 as shown in
Referring now to the schematic of
Regardless of the particular application taking place across the open window 187, the sleeve 101 may subsequently be closed as shown in
Overall, the described manner of achieving such multilateral architecture may provide a more reliable and cost-effective well 180 in terms of both installation and production. Once more, the efficiency of production may be further enhanced due to the availability of pre-located sleeves 101, 201, 201 as depicted in
Referring now to
Once more, in addition to controllably isolating legs for completions, the finished assembly remains outfitted with the described sleeves. As a result, production may be initiated with all or most sleeves open as indicated at 675. Nevertheless, over the course of production, circumstances may dictate that one or more sleeves be selectively closed as noted at 685, for example as associated legs begin to produce water, gas or other undesirable contaminants. Thus, the efficiency of production may be enhanced, particularly over later years of the life of the well.
Embodiments described hereinabove include a completions assembly that enhances the efficiency and controllability of installation through use of isolation sleeves at pre-located casing windows. As such, fluid losses during installation, from recently formed legs of a multilateral well, are substantially avoided. This eliminates the need for introduction of solid particle well killing fluids. Thus, substantial time and expenses are saved in terms of killing and reviving the well for sake of hardware installation. Once more, avoiding the introduction of well killing fluids also avoids potentially compromising ultimate production from regions where debris from such fluids is less than fully removed. In total, embodiments of the completions assembly detailed allow for more sophisticated multilateral wells of greater depths without significant concern over fluid losses during installation or corresponding well killing techniques directed thereat.
The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Furthermore, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.
This patent Document claims priority under 35 U.S.C. §119 to U.S. Provisional App. Ser. No. 61/370,623, filed on Aug. 4, 2010, and entitled, “Through Completion Sidetrack System”, incorporated herein by reference in its entirety.
Number | Date | Country | |
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61370623 | Aug 2010 | US |