NO310037B1 - Side well restoration tool - Google Patents

Description

The present invention generally relates to a device as stated in the preamble to independent claim 1.

Horizontal well drilling and production have in recent years become increasingly important for the oil industry. While horizontal wells have been known for many years, it is only relatively recently that it has been established that they are a cost-effective alternative (or at least equivalent) to conventional vertical well drilling. Although drilling a horizontal well costs significantly more than its vertical counterpart, a horizontal well often improves production by a factor of 5, 10 or even 20 in naturally fractured reservoirs. Typically, projected productivity from a horizontal well must triple that of a vertical hole for horizontal drilling to be economical. This increased production reduces the number of platforms, cuts investment and operating costs. Horizontal drilling makes reservoirs in urban areas, permafrost zones and at great depths offshore more accessible. Other applications for horizontal wells include peripheral wells, thin reservoirs that would require too many vertical wells, and reservoirs with constriction problems where a horizontal well could be optimally distanced from fluid contact.

Horizontal wells are generally classified into four categories depending on the turning radius: 1. An ultra-short turning radius is 1-2 feet; building angle is 45-60° per foot. 2. A short turning radius is 20-100 feet; building angle is 2-5° per foot. 3. An average turning radius is 300-1000 feet; building angle is 6-20° per 100 feet. 4. A long turning radius is 1000-3000 feet; building angle is 2-6° per 100 feet.

Certain horizontal wells also have additional wells that extend laterally from the main vertical wells. These additional lateral wells are sometimes referred to as tap holes and vertical wells containing more than one lateral well are referred to as multilateral wells. Multilateral wells are becoming increasingly important, both from the point of view of new drilling operations and from the increasingly significant point of view of further work on existing well drilling, including remedial work and stimulation work.

As a result of the above, increased reliance on and importance of horizontal wells, horizontal well completion and especially multilateral well completion have become important measures and have produced (and are beginning and continue to produce) a host of difficult problems to overcome. Lateral completion, especially at the transition between vertical and lateral well drilling, is very important to avoid collapse of the well in unconsolidated or weakly consolidated formations. Thus, open hole completions are limited to stable rock formations; and even then, open hole completion is insufficient as there is no control or ability to re-access (or re-enter the sidebore) or to isolate the production zones inside the well. Coupled with this need to complete lateral wells is the growing desire to maintain the wellbore dimension in the lateral well as close as possible to the dimension of the vertical main wellbore for easier drilling and completion.

Typically, horizontal wells have been completed using either slotted casing completion, external casing expansion packs (ECP) or cementing techniques. The main purpose of installing a slotted casing in a horizontal well is to protect against hole collapse or collapse. In addition, a liner provides an appropriate path for introducing various tools, such as coiled tubing, into a horizontal well. Three types of casing have been used, namely (1) perforated casing, where the holes are drilled in the casing, (2) slotted casing, where slots of different width and depth are milled along the length of the pipe, and

(3) prepackaged casings.

Slotted casings provide limited sand control through the choice of hole dimensions and the sizes of the width of the slots. However, these casings are prone to clogging. In unconsolidated formations, steel wire-encased, slotted casing pipes have been used to control sand production. Gravel packing can also be used for sand management in a horizontal well. The main disadvantage of a slotted casing is that effective well stimulation can be difficult due to the open annular space between the casing and the well. Likewise, selective production (eg zone isolation) is difficult.

Another choice is a casing with partial insulation. External Casing Expansion Packs (ECPs) have been installed on the outside of the slotted casing to divide a long horizontal wellbore into several small sections (Figure 1). This method provides limited zone isolation, which can be used for stimulation control or production control along the length of the well. However, ECP is also associated with certain disadvantages and shortcomings. E.g. ordinary horizontal wells are not absolutely horizontal along their entire length, instead they have many bends and curvatures. In a hole with several bends, it can be difficult to insert a casing with several external casing expansion packs.

Finally, it is possible to cement and perforate wells with a medium and long radius, such as e.g. shown in US patent 4,436,165.

While sealing the transition between a vertical and lateral well is important for both horizontal and multilateral wells, re-entry and zone isolation are of particular importance and present particularly difficult problems in multilateral well completions. Refitting of lateral wells is necessary to carry out the completion work, further drilling and/or remedial work and stimulation work. Isolation of a lateral well from other lateral branches is necessary to prevent fluid migration and to handle completion practices and regulations with regard to the separate production of different production zones. Zonal isolation may also be necessary if the borehole drifts in and out of the target reservoir due to insufficient geological knowledge or poor directional control; and due to pressure differences in vertically bypassed strata, which will be discussed below.

When horizontal boreholes are drilled in naturally fractured reservoirs, zonal isolation is considered desirable. The output pressure in naturally fractured formations can vary from one fracture to the next, as can hydrocarbon gravity and the probability of constriction. Allowing these to produce together allows cross-flow between the fractures and a single fracture with early water breakthrough, putting the entire well's production at risk.

As mentioned above, originally horizontal wells were completed with uncemented slotted casing unless the formation was sufficiently strong for an open hole completion. Both methods make it difficult to determine the production zones and, if problems develop, virtually impossible to selectively treat the right zone. Today, zone isolation is achieved by using either external casing expansion gaskets on slotted or perforated casing or by conventional cementing and perforation.

The problem of lateral wellbore completion (and especially multilateral wellbore) has been recognized for many years as reflected in the patent literature. E.g. US Patent 4,807,704 discloses a system for completing multiple side well bores using a double expansion pack and a deflecting guide element. US patent 2,797,893 shows a method for completing lateral wells using a flexible liner and deflection tool. US patent 2,397,070 likewise describes lateral wellbore completion using flexible casing together with a shut-in screen to shut off the lateral well. In US patent 2,858,107, a removable guide wedge unit provides a means for locating (eg re-entering) a lateral well after a completion thereof. US patent 3,330,349 shows a mandrel for guiding and completing multiple horizontal wells. US Patent No. 4,396,075; 4,415,205; 4,444,276 and 4,573,541 all generally relate to methods and devices for multilateral completions using a well frame or pipe-conducting head. Other patents of general interest in the area of horizontal well completion include US patent no. 2,452,920 and 4,402,551.

Regardless of the above-described attempts to achieve cost-effective lateral well completions that can be worked on, there is still a need for new and improved methods and devices to provide such completions, especially sealing between the transition of vertical and lateral wells, where the ability to re-enter side wells (especially in multilateral systems) and achieve zone isolation between respective side wells in a multilateral well system.

The above-mentioned and other disadvantages and shortcomings of the known technique are overcome or avoided with the many methods and devices according to the present invention for the completion of lateral wells and more specifically the completion of multilateral wells. In accordance with previous US patent application 07/926,451, filed on August 7, 1992 and assigned to the present applicant, all contents of which are hereby incorporated by reference, a number of methods and devices are shown for solving important and serious problems arising from lateral (and especially multilateral) completion including: 1. Methods and devices for sealing the transition between a vertical and lateral well. 2. Procedures and devices for re-entering the selected lateral well to carry out completion work, further drilling or remedial work and stimulating work in the . 3. Procedures and devices for isolating a lateral well from other lateral branches in a multilateral well in order to prevent the migration of fluids and to be in line with good completion practices and provisions with regard to separate production and different production zones.

The present invention is characterized by the features indicated in the characteristics of independent claim 1. Advantageous embodiments of the invention appear from the independent claims.

An improved method is presented regarding the preceding multilateral and related completion methods. More specifically, a method is presented for completing multilateral wells and maintaining optional re-entry into these multilateral wells. To do this, a primary well bore is drilled and lined. Next, a first lateral well is drilled out of the bottom of the wellbore and a driving tool guides a string of external furrow packings, which have sliding sleeves arranged between them and a packing bore receiver, in this (or in a preferred embodiment) a new side connection receiver that uses instead the gasket bore receiver). Then a guide wedge and an anchor are fitted to the packing bore receiver (or side coupling receiver) and when they are flush a second side well is drilled away from the first side well. After retrieving the guide wedge and the anchorage, a new diverter and trap head unit is then driven down with preferably the same anchoring flight as the guide wedge anchorage to correctly connect the diverter head with the other sidewell. At this point, a second string of external casing pipe gaskets which also have sliding sleeves can be driven down into the second side well. A selective reintroduction tool with a new parallel seal assembly below can then be run down a single production tubing string and tied back to the surface of a standard wellhead. In a preferred embodiment, the selective reentry tool includes a diverter flap that can be remotely operated to select either the first or second sidewell bore for reentry. The diverter flap does not prevent fluid flow from any of the side bores below.

In a preferred embodiment, the trap head includes a pair of parallel offset bores, one of which communicates with the main wellbore while the other communicates with the side wellbore. The bore leading to the side bore has been fitted with a new guide tube retraction sleeve. Both wells are then fitted with a new parallel seal unit and this parallel seal unit is then joined to either a selective re-entry tool or other production tubing.

It should be understood that the present method provides the possibility of entering any of the wellbore's completion strings for the purpose of directing an activity such as acid treatment, fracturing, washing, perforating and the like. The present invention enables an operator to select from the surface any side bore using a remote controlled string or wireline methods and thus guide the equipment into a selected side bore.

In addition to the foregoing novel methods, the present invention includes a number of important and novel tools and devices for use with the described methods as well as other complementary methods (multilateral or otherwise). In accordance with the present invention, e.g. a new lateral coupling receiver or LCR is provided which functions to (1) provide a means for driving down a lower completion into the well; (2) providing a means for orienting a retrievable guide wedge assembly and/or trap head/deflector assembly; and (3) provide means for attaching an upper complement

to a lower complement.

The LCR includes an upper section to accommodate a locking thread and smooth seal bore that respectively thread to and mate with the seals from an orientation anchor. A central portion of the LCR includes an orientation cam for mating with the orientation anchor and provides a fixed reference point for the retrievable guide wedge and/or catch head/deflector assembly; and a lower portion of the LCR includes an internal mating (eg, profiled) surface for attachment to a suitable insertion tool. Advantageously, the LCR includes three cylindrical, threadedly joined pipe fittings (which respectively include (1) the locking thread and the sealing bore; (2) the orientation anchor's alignment lug and (3) the insertion tool's profiled mating surfaces) and a fourth lower pipe fitting. LCR combines all the features mentioned above to provide a new tool that gives the ability to place an indefinite number of side wells on top of each other in a single well.

Another important tool unit that is used in methods for lateral completion according to the present invention is the aforementioned new trap head/deflector unit which is installed at the transition between the main wellbore and the side branch and which enables the production pipe of each of these to be oriented and anchored. This traphead/divert assembly further provides dual seal bores to connect back to surface either a dual packing completion or a single production tubing string completion utilizing a selective re-entry tool (SRT). The trap head/deflector comprises a trap head, a diverter pipe socket, two stays as connecting elements between the trap head and the diverter pipe socket and a production pipe joint that communicates between the trap head and the diverter pipe socket. The catch head has a large and a small bore. The large bore is a receiver for a pullback sleeve (described later) inserted on top of the lateral drill string, and the small bore is a seal bore to connect the main wellbore back to the surface. Under the trap head, a pipe section is screwed to the small bore. The pipe passes through an angled smooth bore in the diverter pipe stub which causes the pipe section to deflect from the lateral displacement in the small bore of the trap head back to the center line of the trap head, and thus the center line of the bore hole with which it is concentric. Taking the offset through the length of a pipe section (typically 30 ft) allows for a gradual bend that will not prevent the passage of a wireline or tool through the production pipe for remedial work and simulation work in the side well.

As mentioned, the catch head and the diverter pipe piece are connected with two struts which rigidly attach the catch head and the diverter pipe end both axially and rotationally. As the "window length" of the side bore entrance varies depending on the hole dimension and the build angle of the side track, the distance between the catch head and the diverter pipe stub is made adjustable by varying the length of the struts. This is important for the system to function correctly, as the trap head and diverter must overwrite the side track's exit window from the main wellbore.

In accordance with an important feature of the trap head, the profile on the top of the trap head is designed to direct the production pipe of the side well into the large bore of the trap head and also orients the parallel seal assembly (described later) when connecting back to the surface with a double packing completion or a single pipe completion. The orientation is carried out by combining an inclined profile with a slotted inclined surface around the wellbore and a compound angled surface above the slot. When the pipe for the side bore is inserted, if its nose first contacts the diverter it is inserted into the large bore, and if it first lands over the smaller bore; it is prevented from entering because the diameter of the nose is wider than the slot above the smaller bore. As the nose cannot pass the slot, it becomes down the compound angle which also leads it to a larger borehole. Likewise, when the parallel sealing unit is oriented, the side bore seals, which are longer than the main bore seals, first contact the catch head and are guided to the larger borehole in this in exactly the same way as described for the side bore pipe string. When the sidebore seals in the parallel seal assembly are guided in the correct borehole, the main well seals are limited in the amount of rotational misalignment they can have due to the fact that the parallel seal assembly can only pivot about the sidebore seal axis with the amount of diametrical clearance between the major diameter of the parallel seal unit and the inside diameter of the concentric main bore in which they are installed. The compound angle of the trap head is designed so that its surface will have this amount of rotational misalignment, applying a force against the primary wellbore seals to drive them into their seal bore.

The above-mentioned trap head/deflector unit functions to orient and anchor multiple pipe strings at the Y-junction in an oil or gas well with multiple lateral well bores. An important advantage of this arrangement is to provide communication to many reservoirs or tap different places within the same reservoir and be able to re-enter these well bores for remediation and stimulation. The larger bore in the trap head allows the secondary wellbore's production pipe (casing) to pass through until the top of the casing is in the trap head. In accordance with an important feature of this invention, a novel casing tie-back sleeve is used to thread on top of the casing and locate, lock and provide a seal receiver to isolate the secondary wellbore production fluids. The liner's tie-back sleeve also includes an insertion profile for a suitable insertion tool. The casing tieback sleeve comprises two cylindrical parts which, when assembled, provide an insertion tool profi 1 for inserting the casing into the wellbore. The sleeve has a locating shoulder on the outer surface to indicate when the sleeve is positioned in the catch head, and a locking slot for locking pawls from the catch head to snap into, to provide resistance when tensile stress is applied to the sleeve. Once the sleeve is in place and the insertion tool removed, an internal thread and seal bore is exposed for the parallel seal assembly (or other tool or production tubing) to plug in to isolate the secondary side bore. By providing the sealing point between the parallel sealing unit and the sleeve, the need to perform a seal in the trap head on the large bore side is eliminated.

To implement a seal inside the catch head, a new offset parallel seal unit with a centering device is used. This parallel seal assembly carries the pressure loads on the main wellbore side and has a cut-out mechanism on the secondary wellbore side. This sealing unit can also form the connection between the capture head and the selective re-entry tool (SRT). As described above, the SRT is the tool that connects the two separate tubing strings below it into a single production tubing string to the surface or the next lateral well. This parallel sealing unit has two sealing devices parallel to each other, where one sealing device has a larger diameter and is longer than the other. The larger seal assembly seals into the seal bore of the tieback sleeve that locks into the trap head, and is attached to the top of the secondary wellbore production tubing string. The smaller sealing unit seals in the smaller bore in the catch head. The smaller unit acted to isolate the main wellbore. The larger seal assembly is longer than the smaller seal assembly allowing the larger seal assembly to enter the correct bore in the catch head and align the entire assembly. The alignment is performed by capturing the larger sealing unit in its bore and capturing the centering device in the wellbore. This positively limits the rotational misalignment that can be found in the smaller sealing unit prior to entry into the trap head. The parallel seal unit automatically accommodates as much as 120° of rotational misalignment. The centering device advantageously comprises two cylinders with two offset countersunk bores which are screwed together. When screwed together, the couplings located in the countersunk bores connect the seal assemblies to their respective production pipe fittings and are captured in the countersunk bores. This limits the axial movement available to the centering device. An important feature of the centering device is that it raises the sealing units off the wellbore wall during run-in and entry; and facilitates the automatic alignment pull of the parallel seal unit and catch head as a system.

As mentioned, a selective reentry tool is run on the completion string to enable an operator to select the desired branch so that the desired branch can be entered with a coiled tubing work string (or similar) and perform the desired operation (eg stimulation, fracturing , purification, exchange, etc). In a preferred embodiment, the selective re-entry tool includes an outer stationary tube piece and an inner longitudinally movable mandrel or sleeve. Advantageously, this sleeve is connected to a rectangular box located at a distance from an outlet pipe piece which has a pair of outlet openings. A flap is pivotally connected at the interface to the exit opening. Laterally extending lugs on opposite sides of the flap are engaged in a restrictive pair of elongate, ramp-shaped guide slots formed on opposite side surfaces of the case. During manoeuvring, a known exchange tool will move the inner sleeve upwards or downwards, which causes the case to likewise move (in relation to the outer tube piece). Longitudinal movement of the case will cause the ears in the flap to move along the guide slots whereby the flap will swing between a first position which guides a coil tube through one of the outlet openings to a second position which guides the coil tube through the other outlet opening.

Advantageously, a double-ended collar is attached to a stationary piece of pipe and is carried on the inner sleeve. The collar includes a locking elevation that mates with (eg snaps into) one of the two corresponding slots on the inner sleeve. The grooves are positioned so that they correspond to the two desired positions of the flap. The collar will only be released from the inner sleeve when an appropriate release force is exerted with the exchange tool so that the collar normally maintains the flap in a fixed, locked position.

Advantageously, the trap head/deflector system is driven into the wellbore using a new trap head insertion tool. This insertion tool allows circulation through its internal bore, and has internal pressure integrity to test any seals under the insertion tool before releasing the capture head. This insertion tool includes a fastening head from which an insertion spigot and a housing extend (or coupling mandrel). The insertion spigot and the housing are mutually parallel and are dimensioned and designed to respectively be occupied in the large and small diameter bores of the catch head. The catch head insertion tool thus allows torque to be transmitted around the centerline of the catch head assembly despite being fixed in one of the offset bores. This torque transfer is carried out by connecting the coupling mandrel between the insertion tool and the catch head at the same offset as the large bore in the catch head. This torque transfer is important to reliably manipulate the catch head assembly with the insertion string.

The coupling mandrel in the insertion tool has an internal bypass sleeve that opens at a predetermined pressure which allows a trigger ball to be circulated down to its seat if the catch head is to be inserted and anchored in a closed system. This is necessary when you have to hydraulically manipulate other equipment (which requires a closed system) down the well before installing the trap head. Once the bypass sleeve is moved to allow circulation, circulation can only continue until the ball is in contact. At this point, the circulation ports are shut off from above and the resulting increasing production tubing pressure will release the insertion tool.

The above-described and other features and advantages of the present invention will be apparent and understood by the person skilled in the art from the following detailed description and the drawings.

Reference is now made to the drawings in which like elements are numbered alike in the several Figures: Figures 1-9 show sequential longitudinal sections illustrating a method of multilateral completion using a guide wedge/expansion packing assembly and a selective reinsertion tool; Figure 10 shows a side view in section of a selective reinsertion tool in accordance with the first embodiment of the present invention; Figure 11 shows a top view in section of the device according to Figure 10; Figure 12 shows a top view in section of an embodiment of a deflector flap in accordance with the present invention; Figure 12A shows a cross-sectional view along the line 12A-12A of Figure 12; Figures 13A and 13B show longitudinal sections of a well completion unit for completing multilateral wells in accordance with a preferred embodiment of the present invention; Figure 13C shows an enlarged cross-sectional view of a portion of the well completion assembly depicted in Figure 13A; Figure 14 shows a longitudinal section of a lateral coupling receiver or LCR in accordance with the present invention; Figures 15A, B and C are respective top, side and bottom views of a portion of the orienting anchor pipe piece; Figure 16 shows a side view of a trap head/deflector unit in accordance with the present invention; Figure 17 shows a left end view of the trap head/deflector unit according to Figure 16; Figures 18-20 are cross-sectional views taken along the lines 18-18, 19-19 and 20-20, respectively in Figure 16; Figures 18A and 18B are sectional views taken along the lines 18A-18A and 18B-18B respectively in Figure 18; Figure 21 shows a longitudinal section through a ferrule-pull sleeve in accordance with the present invention; Figure 22 shows a longitudinal section through the casing pull sleeve according to Figure 21 connected to an insertion tool; Figure 23 shows a longitudinal section of a parallel sealing unit in accordance with the present invention; Figure 24 shows a cross-section along the line 24-24 according to Figure 23; Figures 25 and 26 show longitudinal sections through a preferred embodiment of the selective reintroduction tool in accordance with the present invention shown with the flap valve placed in respective positions for the main well bore and the side bore; Figure 27 shows a side view, partially in section, depicting the flapper valve sub-assembly used in the selective reinsertion tool of Figures 25 and 26; Figure 28 shows a cross-sectional view along the line 28-28 according to Figure 27; Figures 29 and 29A show longitudinal sections through a trap head/deflector assembly insertion tool in accordance with the present invention; Figures 30, 31 and 32 show sections along lines 30-30, 31-31 and 32-32 respectively in figure 29; Figure 33 shows a schematic elevation depicting the catch head insertion tool of Figure 29 which inserts a completion unit in accordance with the present invention; and Figures 34A-J are sequential schematic depictions showing a preferred method for completing multilateral wellbores in accordance with the present invention.

In accordance with the present invention, various designs and methods and devices for the completion of lateral, branched or horizontal wells that proceed from a single main well bore are described, and more specifically for the completion of multiple wells that proceed from a single mainly vertical well bore (multilateral bores ). It should be understood that although the terms main, vertical, derivative, horizontal, branching and lateral are used here for appropriate reasons, the person skilled in the art will understand that the devices and methods for the various embodiments of the present invention can be used with respect to wells that run in different directions from the mainly vertical or horizontal. E.g. the main wellbore can be vertical, inclined or even horizontal. Therefore, in general, the mainly vertical well will sometimes be referred to as the main well and the well bores that extend laterally or laterally or mainly laterally from the main well bore will be referred to as branch bores.

Reference is now made to Figure 1 where a vertical wellbore 10 has been drilled and a casing 12 has been introduced into this in a known manner using cement 14 to form a cemented well casing. As shown in Figures 2 and 2A, a first lateral well 16 (side well) is drilled and completed in a known manner using a casing or extension pipe 18 such as, for example. is attached to the casing 12 with a suitable extension pipe hanger (not shown).

A string 20 including one or more external casing expansion packs 22 is driven down into the lateral well 16 by means of an insertion tool (not shown). It should be understood that any number of external casing seals 22 may be used depending on the borehole parameters. The external guide pipe gaskets 22 are advantageously those manufactured and sold by the applicant for the present invention. The external conduit seals 22 are expandable and function to, among other things, block fluid and gas migration. Located on the string 20 and positioned between the outer casing packings 22, it will be understood that slide sleeves 24 are arranged to open and close for communication with one or more producing zones.

The string 20 also includes a packing drilling receiver 26 placed up in the hole from the external casing packings 22 which is driven inside the side well 16 to a place where it is desirable to drill a further well. The packing bore's receiver 26 is used, among other things, for the releasable attachment of a number of tools required for drilling further side wells. The packing bore receiver 26 is manufactured and sold with the benefit of the applicant of the present invention and includes a receiving portion 27 and a wedge gap 28. It should be understood that the wedge gap 28 functions as a receiver for orientation and alignment e.g. of a guide wedge to ensure correct directional drilling which will be discussed later. A preferred structurally modified packing bore receiver (also known as a side link receiver or LCR) is described in detail with reference to Figures 13, 14 and 15A-B. As will be described in detail later, the new side-coupling receiver acts as a mechanism for inserting the lower complement, orienting guide wedge assembly and capture head/off guide assembly and provides an interface between the lower and upper complements.

Then one wedge pipe piece 30 with a profile is driven into the side well 16 to ensure the orientation of the wedge gap 28. It should be understood that the wedge pipe piece 30 includes a device 32 with the possibility of measuring while it is being drilled, a circulation pipe piece 34 and guide wedge test anchorage 36. The guide wedge test anchorage 36 includes a male portion 38 sized to fit in the receiving portion 27 of the packing bore receiver 26, and an anchor wedge 40 sized to fit with the wedge slot 28. A preferred anchor 26 is depicted at 176 in Figure 13 and will be described in detail later. As shown in Figure 3, the male portion 38 is slid inside the receiving portion 27 and the anchor wedge 40 in the guide wedge test anchor 36 is inserted into the wedge slot 28. The wedge pipe piece 30 with profile uses the apparatus 32 for measurement while drilling to determine the radial direction of the wedge slot 28 (which best shown in Figure 2A) and which communicates that information to the surface.

Reference is now made to Figure 4 where, after the wedge gap 28 device profile has been determined with the MWD technique, a retrievable guide wedge unit 50 is driven into the sidewell 16 with an insertion tool 52. The guide wedge unit 50 advantageously includes a production injection packing unit 54, an anchor 56 (also known as inflatable anchor) and an angled outer surface 58. The production injection packing assembly 54, which is well known, can be inflated with a fluid to secure the guide wedge assembly 50 in the bore in the side well 16 when the anchor 56 is mated to the receiver 26. The insertion tool 52 includes an elongated nose portion 60 which can be releasably blown into a gap 62 provided through the outer surface 58 of the guide wedge assembly 50. The anchor 56 includes a male portion 64 and an anchor wedge 66 both of which are also sized to contact it receiving portion 27 and the wedge slot 28 in the receiver 26. The outer surface 58 of the guide wedge assembly 50 provides a surface angle to enable or facilitate drilling of a further side well which will be described in what follows. A preferred retrievable guide wedge assembly is shown in US patent, filed January 25, 1994, entitled "Retrievable Whipstock Packer Assembly" by inventor Daniel E. Dinhoble which is assigned to the applicant of the present invention and is hereby incorporated by reference.

As shown in Figure 5, after the insertion tool 52 has been released from the guide wedge unit 50, a window can be milled out (not shown) in the bore in the side well 16. Then a suitable and known drill 70 can be used to drill a second side well 72 which communicates with the first side well 16.

After the drilling of the second side well 72 is finished, the drill bit 70 is removed as shown in Figure 6 and a retrieval tool 80 is driven down the main well 10 and into the side well 16. The retrieval tool 80 includes a pair of centering devices 82, which are connected by a coupling 84, and an elongated nose part 86 which is dimensioned and designed similarly to the nose part 60 of the insertion tool 52. The nose part 86 is releasably locked to the slot 62 in the guide wedge unit 50 for extraction of the same. The centering devices 82 are arranged to center the nose portion 86 inside the wellbore 16 for engagement with the guide wedge assembly 50. The coupling 84 is located between the centering devices 82 at an oblique angle which compensates for the increased volume at the transition between the wellbore 16 and the wellbore 72 (see Figure 6A ). The pick-up tool 80 is then removed, taking with it the guide wedge unit 50. It should be understood that a preferred pick-up tool is shown in the aforementioned US application filed on January 25, 1994.

Reference is then made to figure 7 where a trap head insertion tool 88 is driven into the wellbore 16. Connected to the tool 88 is a pipe section 90 which in turn is fitted to a diverter 91 and the trap head unit 92 (see also figure 9A). The traphead assembly has an inlet port 94, a first outlet port 96 and a second outlet port 98. The pipe section 90 includes an anchor 99 having a male portion 100 and a wedge 101 which mates with the packing bore receiver 26 as previously described. The catch head unit 92 is oriented so that when the anchor 99 is inserted into the packing drilling unit 26, the second exit opening 98 is placed in communication with the second side well 72. After placing the catch head and diverter unit 92 in the correct position, the insertion tool 88 can then be picked up. A preferred trap head/deflector assembly is shown and described in detail hereinafter with respect to Figures 16-20. A preferred insertion tool 88 is also described in detail below with respect to Figures 29-32.

At this point, as shown in Figure 8, a second string 102, including at least one external casing seal 103, at least a pair of sliding sleeves 104 and a pointed end 106, can be driven into the second side well 72. This is carried out with the insertion tool 110 which moves the second string 102 through the main well bore 10 and then into the unit 92. It will be understood that the pointed end 106 is designed to contact and deflect from the deflector 91 in which the second string 110 will be forced into the second side well 72. Both the outer casing packing 103 and the sliding sleeves 104 are preferably those that have been described previously. When the second string 110 is in place inside the second side bore 72, the expansion gaskets 103 are expanded and, as previously described, the insertion tool 110 is then removed.

In accordance with an important feature of the present invention and referring to Figures 9 and 9B, a selective reintroduction unit 120 is fitted to the diverter and capture unit 92 and a single production tubing string 122 extends from the latter and is connected back to the surface of e.g. a standard wellhead (not shown) production tubing string 122 includes an expansion packer 124, the function of which is known. The selective reinsertion assembly 120 includes a locating wedge 126 for orientation with the catch head assembly 92. The reinsertion assembly 120 functions to either maintain surface access to the first side bore

16 or to provide access to the other side well 72.

Reference is now made to Figures 10 and 11 where a new selective reintroduction unit 120 is arranged and includes an input housing 150 which is connected to an output housing 152. The output housing 152 includes a male portion 154 which has threads 156 and a seal 158 for assembly to the input housing 150. pairs of laterally spaced parallel bores 160 and 161 are arranged axially through the output housing 152. The bores 160 and 161 communicate with the first output port 96 and the second output port 98 of the diverter and trap head assembly 92.

The inlet housing 150 includes an inlet bore 159 which is connected to the individual production pipe string 122 with e.g. threads (not shown) and has a collar 163 which forms a substantially stepped shape. Arranged in the collar 163 is a sliding pipe section 165 which comprises an up-in-the-hole pipe-slider 166, a coupling 168 and a downward-in-the-hole pipe-slider 170. The up-in-the-hole pipe-slider 166 can be formed of any suitable substance such as steel alloy and includes an alignment slot 172 , a pair of engagement grooves 174 and a central bore 176. The alignment slot 172 is shaped to receive a projection 178 extending from the inner surface 173 of the collar 163. It should be understood that the engagement grooves 174 function to receive wedges (not shown) on an actuator (not shown) such as the HB-2 shift tool, made by the present applicant, which can be mounted to the wellbore end of a coiled tubing string, a standard threaded tubing section, or similar.

The coupling 168 is preferably threaded between the slider 166 at the top of the hole and the slider 170 at the bottom of the hole and is also advantageously made of steel.

The slider 170 down the hole includes a central bore 180, a positioning collar 182 and a diverter flap 184. The central bore 180 is of a substantially larger inner diameter than the inner diameter of the central bore 176 in the slider 166 up in the hole to ensure communication between the inlet bore 159 and each of the bores 160 or 161 in the output housing 152. The positioning collar 182 is used to enable a two-position snap-locking arrangement of the pipe section 165. A first position to provide communication between the input bore 159 in the input housing 150 and the bore 161 in the output housing 152 and a second position for communication with the bore 160. In order to achieve this feature with two positions, the positioning collar 182 is preferably mainly of thin cross-section and formed of an elastic material, e.g. a steel alloy. The positioning collar 182 is also cylindrical in shape and includes an annular projection 190 which contacts each of a pair of ring grooves 192 and 194 provided on an interior surface 196 of the collar 164. The annular projection 190 includes chamfered edges (not numbered) which function to provide snap-lock movement from one annular groove to another during movement of the tube section 165. Flow slots 196 are advantageously also used on the positioning collar 182.

The diverter flap 184 is advantageously made of a suitable strong material, such as steel and is centrally mounted in the bore 180. The diverter flap 184 includes a plate 200 which extends radially from a pin 202. Each of the outer ends 204 and 204' of the pin 202 extends through a pair of slots 206 and 206' in it downwards in the hole tube slides 170 and is rotatably mounted in the collar 164. The pin 202 is arranged at a sufficient distance from the bore 160, 161 in the output housing 152. A pair of gears 208 and 208' are arranged on the pin 202 and is engaged with teeth 210 and 210' placed within slots 206 and 206'. Flow slits 212 are arranged through plate 200. In operation, the pipe section 165 is slid inside the input housing 150 as previously mentioned which causes the gears 208 and 208' to turn, which in turn causes the plate 200 to move from e.g. a position 220 to a position 222 which thus provides communication from the bore 159 to each bore 160 or 161.

Figures 12 and 12A show a preferred embodiment of the deflector flap 184 in accordance with the present invention. In this embodiment, the diverter flap 184 includes a plate 230 extending from a pin 232. The pin 232 is pivotally mounted on the output housing 152. A pair of lugs 234 extend outwardly from opposite side edges of the plate 230 through a pair of slots 236 positioned on opposite sides of it downwardly in the hole tube slides 170. Each of the slots 236 includes an angled portion 238 and two flat portions 240 and 242. Upon movement of the sliding tube section 165, the lugs 234 slide through the slots 236 to rotate the plate 230 to provide selective communication with either the bore 160 or 161 (figure 10).

It will be understood that an even more preferred embodiment of the selective reinsertion tool is described in detail hereinafter with reference to Figures 25-28.

Advantageously, the above method when completing multilateral wells uses a selection of tools that have preferred constructions which will now be discussed in detail. In some cases these preferred constructions are somewhat different from the constructions in analogous tools in the preceding method described above and in this respect the methodology of the preceding method is somewhat changed to use the preferred tool constructions. More specifically, a detailed description will now be given of preferred designs or constructions of a side coupling receiver, a catch head assembly, an extension tube pulling tool, a parallel seal assembly, a catch head insertion tool and a selective reinsertion tool. In some cases, the following detailed description will make reference to Figures 13A-C which are sectional views showing preferred constructions of each tool in an assembled unit down the wellbore.

Reference is now made to Figures 13-15A-C where a preferred structure of a side-switch receiver (shown generally at 250 in Figure 14) will now be described. It will be understood that the LCR 250 is functionally similar to the packing bore receiver 26; however, as will be discussed, the LCR 250 has several significant differences and beneficial improvements. The LCR 250 has at least three main functions including

(1) provide a device for driving the lower completion into the well; (2) providing a means for orientation of the retrievable guide wedge and catch head assemblies; and (3) provide a means for attaching the upper complement to the lower complement.

A secondary function with the LCR 250 includes the ability to maintain the orientation between respective side completions in the event that such side completions are placed on top of each other inside the wellbore in a well.

Reference is now made in particular to Figure 14 where the LCR 250 includes three main structural features (which can be arranged in any order). A first feature includes a profile for engagement of an insertion tool, a second feature includes an orientation cam to orient either the guide wedge assembly or the catch head deflector assembly and a third design feature includes a locked thread and sealing bore for anchoring and sealing respectively. A combination of these features in a single tool makes it possible for the LCR 250 to provide a new service and it gives the opportunity to place an unlimited number of side wells on top of each other in a single well. With each lateral well completed, the LCR 250 diverter equipment coupling device (eg trap head/diverter assembly) becomes at the Y transition to the lateral well as discussed in the aforementioned method and which will be discussed in more detail below. While the LCR 250 may comprise a single or one-piece tool housing, from a manufacturing standpoint, the LCR 250 advantageously comprises three graduated (eg, decreasing outer diameters) cylinders 252, 254 and 256 bolted together with premium couplings. In a preferred embodiment, the inside diameters of cylinders 252 and 254 are substantially equal (eg, 121 mm) while the inside diameter of cylinder 256 is smaller (eg, 93 mm). The upper cylinder 252 has an internally threaded entry 258 to receive an armature lock which will be discussed later. Downstream from the threaded section 258 is a smooth sealing surface 260 for receiving seals on the armature lock. The upper cylinder 252 also has an integral guide ring 272 to facilitate insertion into the seal bore during entry, and a thickened outer diameter to keep the LCR 250 centered in the wellbore.

Bolted to the upper cylinder 252 is the orientation tube piece 254. The tube piece 254 has an orientation cam 262 which extends outward and radially into the inner diameter of the orientation tube piece 254. The orientation cam 262 is approximately rectangular in cross section and, as will be discussed later, fits with a gap in the anchor lock. The cam 262 is mounted in a milled slot 270 set in a countersunk bore in the premium end thread. This allows for a non-pressure-retaining weld for the cam that does not conflict with the action of the premium coupling. Down the wellbore from the orientation pipe piece 254 and threaded thereto is the coupling pipe piece 256. The coupling pipe piece 256 includes a pair of spaced apart profiles 264 and 266 which are sized and positioned to mate with a suitable insertion tool which is preferably the HR extension pipe insertion tool manufactured and sold by Baker Oil Tools and shown generally at 372 in Figure 22. Advantageously, the lower tube piece 268 is threadedly attached to the lower end of the coupling tube piece 256. The lower tube piece 268 includes internal threads 269 for coupling the LCR 250 to the lower completion (as shown with 22 and 24 in Figure 2). The lower pipe section has a smaller total inner and outer diameter than the previous pipe sections, where the inner diameter is advantageously 76 mm. As is clear from the above, the many cylinders 252, 254 and 256 are advantageously oriented so that the insertion tool profile 264, 266 is at the bottom of the tool while the orientation cam is in the middle and the locking thread and sealing bore are at the top of the tool.

Referring now to Figures 13B and 15A-C, the LCR 250 is shown attached to an orienting anchor 276. It should be understood that the orienting anchor 276 is the preferred construction for the test guide wedge anchor 36 shown in Figures 2 and 3. In Figure 13B seals 278 from the anchor 276 are shown in sealing contact with the seal bore 260 in the LCR 250. The orienting anchor 276 includes a centering anchor device 279 from which an outer housing 280 extends. The outer housing 280 carries the seals 278 and houses the knurled mandrel 281 as shown in Figures 15A-C. The grooved mandrel has a V-shaped section which progressively diverges towards a tip from which a longitudinal slit or slot 284 extends.

The orienting anchor 276 is attached either to the retrievable guide wedge assembly or to the catch head/deflector assembly as mentioned above and corresponds to the LCR 250. In Figure 13B the catch head/deflector assembly is shown with the orienting anchor 276 attached thereto and being joined to the LCR 250. It is to be understood that when the orienting anchor 276 is entered into the borehole, the V-shaped surface 282 of the grooved mandrel 281 will eventually contact the orienting cam 262 and will ride along the progressively diverging V-shaped walls until it engages and enters the slot 284. When the orienting lug 262 reaches the end of the slot 284, it is clear at the surface that either the retrievable guide wedge assembly or the catch head/deflector assembly has been correctly positioned oriented in the borehole. The LCR 250 thus acts as a fixed reference point for use with both the guide wedge and the catch head systems and acts to orient and accurately locate the entire completion system and in particular a second lateral bore completed above the first lateral bore. It should be understood that in a single open hole secondary lateral completion, there would be a requirement for two LCRs. A first LCR would be run on top of the primary wellbore completion for the trap head and diverter assembly to orient and plug in while the second LCR would be run over the selective reentry tool to plug in with the final production pipe to the surface. In a lined hole completion, only one LCR is required, as the guide wedge packing assembly would provide the orientation of the guide wedge and trap head/distractor assembly .

Reference is now made to Figures 16-20 where a preferred embodiment of the trap head/deflector unit is shown which will now be described. The trap head/diverter assembly is shown generally at 290 and includes a trap head 292, a diverter tube piece 294, a pair of connecting rods 296 and 297 connecting the trap head 292 to the diverter tube piece 294 and a length of production pipe 298 communicating between the trap head 292 and the diverter tube piece 294. The trap head 292 advantageously constitutes a single piece of machined metal (steel) having spaced longitudinal bores 300, 302 of different diameters. The larger bore 302 is a receiver for an extension pipe pull sleeve 350, or return sleeve 350, shown in Figures 13A-B and ultimately communicates with the top of the lateral well drill string. The smaller bore 300 is a sealing bore to connect the main wellbore back to the surface. Below the catch head 292, a tube section 298 is screwed to the smaller bore 300 preferably with a premium coupling 301. The tube 198 passes through the angled smooth bore 304 in the diverter tube piece 294 which causes the tube section 298 to deflect from the offset of the small bore in the catch head 292 back to the center line of the catch head; and thus the centerline of the borehole with which it is concentric. It will be appreciated that taking the offset through the length of a pipe section 298 (typically 30 ft) allows for a gradual bend that will not impede the passage of a wireline or tool being passed through the production pipe for later remedial and stimulation work.

The diverter tube piece 294 also advantageously constitutes a single piece of machined metal (steel) and together with the axial bore 304 includes an angled diverter surface 306 to divert the lateral drill string into the lateral drill hole as will be described later. As mentioned, the trap head 292 and the deflector pipe piece 294 are connected with a pair of parallel, spaced struts 296, 297 which are screwed with screws 208 to the trap head 292 and the deflector pipe piece 294 in order to rigidly attach the trap head and the deflector pipe piece both axially and rotationally. By not requiring the diverter tube piece 294 to be a pressure retaining element or a tie in the production tubing string, premium connections can be maintained from the trap head 292 down to the anchor point for the trap head and diverter tube piece assembly. As the window length (a window is shown with 310 in figure 13) to the side bore's entrance varies depending on the hole dimension and the construction angle of the side well, the distance between the trap head 292 and the diverter pipe piece 294 can be made adjustable by varying the length of the rods 296, 297. This is an important feature of the present invention since, for correct functioning, the trap head 292 and the diverter 292 must be above the lateral exit window from the main well.

The terminating end 312 of the production pipe 298 is connected to the orienting anchor 276 for orientation, positioning and attachment to the LCR 250 as shown in Figure 13B. As will be discussed below with respect to Figures 29-33, a new trap head/divert assembly insertion tool 510 is used to insert the assembly 290 into the LCR 250. It will be understood that the production tubing 298 is maintained in rigid contact with the diverter tubing 294 via a pair of screws 314 as best shown in figure 20.

As will be discussed below with respect to the extension tube feedback sleeve 350 of Figure 21, such an extension tube feedback sleeve is locked within the larger diameter bore 302 via a pair of mating spring actuated pawls 303 within the catch head 292 and which is best shown in FIG. 18. The locking mechanism for the feedback sleeve comprises the pair of circumferentially spaced actuation pawls 303 which are generally pressed into the bore 302 with a spring 318 mounted to a cover plate 320 via a pair of screws 322. Each pawl 303 is mounted in an opening 324 extending radially from the bore 302 The aperture 324 includes three consecutive countersunk bores of different and increasing diameters. The pawl 303 includes an outer ring 326 which is carried by the shoulder in the first smaller diameter countersunk bore and the plate 320 is carried on the shoulder 328 at the intersection of the second and third countersunk bores. In addition to the spring actuated pawls 303, the bore 302 in the larger diameter catch head 292 includes a locating shoulder 330 to mate with a complementary surface on the extension tube feedback of Figure 21. The interaction between both the spring actuated pawls 303 and the shoulder 330 inside the extension tube feedback sleeve 350 of figure 21 will be discussed in what follows.

The profiled surface 332 at the top (or end) of the scoop head 292 constitutes an important feature of the present invention as it is designed to guide the side bore production pipe into the larger bore 302 and also orients the parallel seal unit 380 (which will be discussed hereinafter with respect to Figures 23 and 24) when tied back to the surface with a double packing completion or a single production tubing completion. In a single production pipe completion utilizing a selective re-entry tool, it is necessary to orient the parallel sealing unit so that the operator knows which wellbore is being entered at the position of the selective re-entry tool. This orientation is accomplished by combining a surface 334 that slopes downward toward and surrounds the larger bore 302 with (1) a slotted bevel surface 336 extending from the large bore 302 and surrounding the small bore 300 and (2) a compound angled surface 338 , 340 which slopes down from

each side of the slotted surface 336.

When the side well pipe is driven in as will be described below with regard to the parallel sealing unit, if the nose of the side well pipe first contacts the inclined surface 332, it is led into the larger bore 302. If the nose of the pipe first lands above the small bore hole 300, it is prevented however, due to the fact that the diameter of the pipe nose is wider than the slotted surface 336 above the small borehole 300. As the production pipe nose cannot pass the slot 336, it slides down the compound angle which also leads it to the larger borehole 302. Likewise , when the parallel seal assembly is oriented, the side well seals which are longer than the main well seals first contact the catch head surface 332 and are then guided towards the larger bore hole in the catch head in exactly the same manner as described for the side well pipe. When the side well seals are inserted into the correct borehole, the main well seals are limited in the amount of rotational misalignment they can have because the parallel seal unit can only swing about the side well seal axis an amount corresponding to the diametrical clearance between the main diameter of the parallel seal unit and the inside diameter of the main concentric well in which they are installed. The composite angled surfaces 338, 340 are designed so that these surfaces will have this amount of rotational misalignment, and apply a force against the main well seals to guide them into their respective seal bore. The final positioning of the parallel sealing unit in the catch head 292 will be discussed with respect to Figure 13 after a detailed description of the parallel sealing unit as appears from what follows.

The inside diameter of the smaller seal bore 300 includes a suitably profiled countersunk surface 343 to mate with the catch head insertion tool 510 discussed with respect to Figures 29-33 hereinafter. In addition, it should be understood that adjacent raised profile 342 includes a forward or upward in-hole shoulder 344 which acts as a locating stop for the completion tube or parallel seal unit (as shown in Figure 13).

As discussed, the trap head 290 acts to orient and anchor multiple production tubing strings at the Y-junction in an oil or gas well with multiple or lateral well bores. An advantage of the trap head and associated units is to provide communication in several reservoirs or tap different locations within the same reservoir and enable reintroduction into these well bores for improvements and stimulation. The large bore 302 in the trap head 290 functions to be able to pass a second wellbore production pipe or extension pipe through it until the top of the extension pipe is in the trap head as was shown in Figure 8 in connection with the extension pipe 202 placed in the side bore shown there. Reference is made to Figures 13 and 21 where an extension tubing return sleeve is shown at 350 which functions to screw onto the top of the extension tubing 202 and then locate, lock and provide a seal receiver to isolate the secondary wellbore production fluids. In addition, the extension tube's feedback sleeve 350 also includes a drive-in profile for attachment to a suitable insertion tool which will be discussed in connection with figure 22.

The sleeve 350 is a cylindrical tool, and for ease of manufacture it consists of two cylindrical parts including an upper cylindrical tool part 352 and a lower cylindrical tool part 354. The parts 352 and 354 are threadedly connected with the threads 356. The parts are further connected via a series of set screws 358. The lower cylindrical portion 354 terminates in a threaded opening 360 which is intended for threaded attachment to the lateral completion extension tube 202. The remaining longitudinal and internal length of the lower portion 354 includes a smooth directional surface 362 for connection either to production tools or to the parallel sealing unit 380 which will be discussed later. It should be understood that in Figures 13A and C, the parallel seal assembly 380 is shown in sealing relationship with the seal bore 362 in the sleeve 350. In addition, the upper portion of the lower part 354 includes internal threads 370 (preferably left-hand conical, square locking threads) for attachment to a suitable corresponding surface on the parallel seal bore assembly which will be discussed hereinafter.

The upper cylindrical portion 352 of the sleeve 350 includes a downwardly sloping shoulder 364 located on the outside of the portion 352 about midway along the length of the portion 352. The shoulder 364 acts as a local serration member on the outer surface of the sleeve 350 to stop and position the sleeve 350 along an annular complementary groove 330 in the catch head 290 as best shown in Figure 13A. Adjacent to and upstream of the locating shoulder 364, a locking groove 366 for internal locking with the spring-activated locking pawls 302 is connected to the catch head 292. The locating shoulder 364 on the outer surface of the portion 352 indicates when the sleeve is in the catching head 292 and the locking groove 366 snaps with the locking pawls from the catching head to provide resistance when there is a tensile load against the sleeve 350. This resistance must be greater than the necessary cutout force for the parallel seal unit. The interior of the upper portion 352 includes spaced, preselected profiles 368 and 369 for attachment to a suitable insertion tool.

Reference is now made to Figure 22 where a portion of the extension tube feedback sleeve 350 is shown attached to a suitable insertion tool. In this case, the insertion tool is an HR insertion tool 372 which is a commercially available insertion tool manufactured by Baker Oil Tools, Houston, Texas. HR insertion tool 372 operates in a known manner where the insertion tool engages and/or disengages the inside of the extension tube 350 at the respective profiles 368 and 369 via a pair of releasable gripping devices 374, 378. It will be understood that in use a secondary or side bore- production pipe, as shown at 202 in Figure 8, threaded to the thread 360 of the casing 350. Then, the insertion tool 372 attached to the profiles 368, 369 and the casing 350 sidebore production pipe 202 assembly is entered below so that the production pipe and the return casings are placed in the larger bore 302 until the shoulder 364 of the sleeve 350 comes into contact with the annular shoulder 330 and the pawls 303 from the catch head 290 are locked to the locking groove 366. When the sleeve 350 is in place and the insertion tool 372 is removed, the locking thread 370 and the sealing bore 362 are exposed to the parallel sealing unit for plugging in to isolate the secondary side bore. It will be appreciated that by providing the seal location between the parallel seal unit and sleeve 350, there is an elimination of the need to perform a seal in the catch head on the larger bore side. Instead of a parallel sealing unit being locked in the sleeve 350, in an alternative mode of use another production pipe or other tool can likewise be locked into the sleeve 350 in a manner similar to the parallel sealing unit as shown in Figure 13A.

Referring now to Figures 23 and 24 (as well as Figure 13A), a parallel direction assembly shown generally at 380 will now be described. It should be understood that the parallel seal assembly may function to seal the inside (bores 300 and 302) of the trap head 292. The parallel seal assembly 380 includes a pair of parallel, staggered or laterally offset tube seals 382 and 384 each connected to a centering device 386. As the will be described later, the parallel seal unit 380 carries pressure loads on the main wellbore side and has a cut-out mechanism on the secondary wellbore side. An important feature of the parallel seal assembly is that it acts as the connection between the trap head 292 and each production pipe, or more advantageously a selective reinsertion tool of the type shown at 220 in Figure 9 or at 460 in Figures 13 and 25-26.

The centering device 386 comprises two axially aligned cylinders 388, 390 which are screwed together by a pair of screws 392. The two cylinders 388, 390 each include two offset countersunk bores which respectively mate with each other to form a pair of parallel cylindrical bores or openings 394, 396. .Each parallel cylindrical bore 394, 396 includes a socket coupling shown respectively at 398 and 400. Opposite ends of each socket coupling 398, 400 are threaded as shown at 402a-b, 304a-b respectively. The upper thread 402a, 444a is threaded to the tube sections 406, 408 which in turn are connected either to a double gasket or to a selective reinsertion tool 460 (as shown in Figure 13A). The lower thread 402b, 404b is threaded to the parallel pipe/seal units 382, 384 respectively. When the split housing 386 is screwed together, the couplings 398 and 400 connecting the seal assemblies 382, 384 to their respective production tubing pieces 406, 408 are captured in the countersunk bores in the centering housing 386. This limits the axial movement available to the centering device 386. Advantageously, a further space 410a-d at each end of the couplings 398, 400 inside the countersunk bore so as to accommodate slightly different pipe lengths 406, 408. The purpose of the centering device 386 is to raise the sealing units 382, 384 off the wall of the wellbore during insertion and to facilitate the automatic alignment feature of the parallel seal unit and catch head system which will be discussed later.

The sealing unit 382 has a longer length than the sealing unit 384 and is in a mutually parallel relationship with the sealing unit 384. The shorter sealing unit 384 comprises a length of pipe which terminates in a seal which is advantageously a known adhesive seal shown at 412. Such adhesive seals include elastomer tied or stapled to metal rings for durability. In a preferred embodiment, a lower pipe piece 414 is also threaded to the final end of the pipe 384 and is locked in this using a number of set screws 416.

The longer sealing device 382 also includes a sealing mechanism along the outer length shown at 418 and advantageously again comprises a known staple seal. In a preferred embodiment, a lower tube piece 420 is threadedly attached to the terminating end of the tube 382 and is further locked to this using a number of set screws 422. It should be understood that the seal 418 on the larger sealing unit 382 is arranged for sealing engagement against the internal sealing bore 362 in the feedback sleeve 350 (after the feedback sleeve 350 has been locked in the catch head 292). Thus, the tubing 382 sealingly contacts and communicates with the secondary (lateral) wellbore production tubing string. Naturally, the seal 412 on the smaller tubing unit 384 seals into the smaller diameter bore 300 in the trap head 292 and thus provides a sealing engagement against any production tubing string or other completion pipe down the hole from the trap head 292. The smaller seal unit 384 thus acts to isolate the main well from the secondary well or the side well.

The longer seal assembly 382 includes as an important feature a locking and shearing mechanism for attachment to the locking thread 370 of the feedback sleeve 350. This locking mechanism includes a locating ring 424 pivotally connected to the production pipe 382 with a number of pins 426. Downstream of the locating ring 424 is a collar lock 428 which rests on a raised support 430 which extends upwards from the tube 382 so that the terminating end 436 of the collar clasp 428 is spaced from the tube 382 as shown at 437. In addition, the raised support 430 also provides a space 432 between the bottom 444 of the collar clasp 428 which lies against the locating ring 424. The end part 436 of the collar lock 428 forms a number of cantilever beams which have a knurled edge 438. Advantageously, the knurled edge has a back angle of about 5° and a front angle of about 45°. The cantilever beam 436 will bend inward when the sealing assembly 382 is inserted inside the feedback sleeve 350 and the knurled edges 438 will interlock in a ratchet-like manner to lock the thread 370 as best shown in the enlarged view of Figure 13C. Further downstream from the collar lock 428 and at a distance from this is a shear block 440 which captures a shear 442. The shear block 440 and the shear ring 442 are attached to the outside of the sealing device 382 using a shear block holder 444 and a number of set screws 446. The shear block 440 extends outwards from a shoulder 448 of the tube 382 so as to form a space 450 between the shear block 440 and the collar lock 428. The length of the space 450 should be less than the length of the space 432 of the collar lock 428 for loading on the shoulder of the shear ring 442 during the insertion of the sealing unit 382 and

4

the interlocking attachment between the locking surface 438 and the locking thread 370 of the extension tube return sleeve. Lock ring 424

provides resistance during insertion or entry so as to maintain the respective distance 432 and 450. As best shown in Figures 13A and C, when fully inserted, the cantilever 436 will be forced downward into abutment contact with the shear block 440 so that the longer parallel seal 382 will be in locking engagement with the extension pipe sleeve 350. Then, when it is desired to pick up the parallel sealing unit 380 from down in the well, tension is applied to the centering device 386 which will eventually cut off the ring 442 at a predetermined shear value. When cut, the shear block 448 will be released and will move axially downward over the outer surface of the tube 382. This will cause the cantilever 436 to be allowed to freely bend inwardly and ratcheted out of its interlocking contact with the locking thread 370. As a result, the parallel seal assembly will 380 is removed from the extension tube sleeve 350 as well as the catch head 292.

The distance D between the end of the sealing unit 382 and the end of the seal 384 can be functionally important as it enables the larger sealing unit 382 to enter the desired larger bore 302 in the catch head 292 and thus align the unit. In a preferred embodiment, the distance D is approximately 1 meter. This alignment is accomplished by capturing the larger sealing unit 382 in the bore 302 and capturing the centering device 386 in the wellbore. This positively limits the rotational misalignment available to the smaller seal unit 384 prior to entry into the catch head 292. The parallel seal unit thus automatically aligns with as much as 120° of rotational misalignment. It should be understood that the countersunk bores in the split housing 388 of the centering device are preferably offset (eg, not symmetrical) to match the offset bore arrangement in the catch head 292. Additionally, as the selective reinsertion tool will have a different laterally offset centerline than the catch head, the centering device 386 and associated pipe assembly are designed to provide sufficient deflection in the pipe pieces to conform the selective reinsertion tool to the catch head.

While the selective reinsertion tool depicted in Figures 10-12 is well suited for its intended purposes, in a preferred embodiment a functionally equivalent, yet structurally improved selective reinsertion tool is used. This improved tool is shown generally at 460 in Figures 13, 25 and 26 and consists of a flap 462, a pair of rails 464 on each side of the flap 462, a rectangular box 466, a fixed cylinder 468, an outlet tube piece 470, a double-ended collar 472 . A first set of lugs 478 is pivotally attached to the alignment pipe piece 476 and is held in position via the retaining sleeve 474. The lugs 478 are located at the lower or down-hole end of the flap 464. At about midway along the longitudinal extent of the flap 464, the second set of lugs 480 The lugs 480 are manipulation lugs that allow movement of the selective reinsertion tool along the slot 488 provided in the rectangular case 466. The rectangular case 466 is mounted on an inner mandrel 482 which is attached to the case but has the ability to move longitudinally. inside the tool 460 relative to the output tube piece 470. The inner mandrel 482 is moved inside the collar 472. The upstream end of the inner mandrel 482 is connected to profiled sections 486, 487 for engagement with a known exchange tool.

The rectangular box 466 has at least two functions. First, the box 466 guides the coiled tubing string (or similar device) through a small cross-section so that it does not get stuck or tend to rewind. The case 466 also includes the aforementioned pair of symmetrical, laterally arranged guide slits 488 which are used to manipulate the flap from one side of the tool to the other side. Each guide slot 488 includes an upper groove and a lower groove which are joined by an inclined groove to form an elongated ramp. As mentioned, the flap 462 has two rails 464 which are mounted perpendicular to the flap. These rails also serve two functions. First, the rails help guide the coil tube out of the case and into the alignment tube piece 474. Another important function of the rails is that they take some of the shock load on the coil tube by carrying the flap in its proper positions. The box 466 is connected to the outlet pipe 470. The outlet pipe 470 allows the coiled pipe to exit a smaller bore 490 or 492 (as well as return therefrom) without becoming stuck. As best shown in Figures 27 and 28, the case 466 is assembled using the mandrel 482 to the cylindrical pipe fitting 468. The ear fitting 468 includes longitudinal bypass slots 496 as shown in Figure 28.

A choke tube working string (or other similar device) can be placed directly over one of the bores in the trap head (or any other device located downward in the hole of the selective reinsertion tool) by deflecting the flap 462 oriented to each opening 490 or 492 depending on the position of the inner sleeve or mandrel 482 located in the upper portion of the selective reinsertion tool. The flap 462 is driven by angled slots 488 located in the case 466. When the case 466 must be in an upward position in the hole, as shown in Figure 25, the flap 462 lies against one side of the selective reinsertion tool which thus guides the coiled tubing to enter the hole 492 on the opposite page. By moving the inner mandrel or sleeve downwards in the hole, the flap 462 is caused to slip to the other side of the tool which thus allows the coil tube to be fed to the second hole 490. The case 466 is moved up or down by using a standard hydraulically actuated changeover tool such as the HB-2 available from Baker Oil Tool into the changeover sleeve profile 486, 387 located in the upper portion of the tool. An upward stroke or downward stroke is then applied depending on the flap's desired position. To go from the "up" flap position shown in Figure 25 to the "down" flap position shown in Figure 26, a downward stroke is made on the changeover tool which causes the inner mandrel 482 to move downwardly through the tool with respect to the output tube piece 470, which in turn causes the box 466 to move downwards. As the case 466 moves downwardly, ears 480 will be pressed and driven upward along the inclined ramp of the guide grooves 488 from the position shown in Figure 25 to the upper position shown in Figure 26. When the ears 480 are driven in this manner, the flap 462 will swing along the pivot point formed by the ears 470 into the position shown in figure 26.

In accordance with an important feature of the invention, a double-ended collar 472 is provided which optionally contacts either a groove 496 (as shown in Figure 25) or a groove 498 (as shown in Figure 26) on the inner mandrel 482. The double-ended collar 472 is threadedly connected to the stationary tube piece 468 by the threads 500. The collar 472 remains stationary with respect to the movement of the inner mandrel 482. However, it should be understood that in order for the inner mandrel 482 to move in any direction, a collar snapping force must is overcome to push the interlocking rib or ridge 502 from the collar out of the slot 496 or 498. Then it is this collar-snapping force that must be overcome to allow the case to shift positions. It should be understood that the collar can be easily made interchangeable for different snap-out forces by simply removing the collar 472 and screw-wise replacing it with another collar. Thus, when moving from the positions according to figure 25 to figure 26, the interlocking rib 502 has snapped out and away from the slot 496 which enables the inner mandrel to move downwards whereupon the rib 502 from the collar 472 contacts the receiving slot 498 which thus locks the mandrel in the position shown in Figure 26.

The selective reinsertion tool 460 is thus operated in the following manner:

(1) the hydraulic changer is driven to a depth on a coiled tubing work string that has a suitable changer thereon; (2) the exchange tool hydraulically grips the profiles 486, 487 at the top of the selective reinsertion tool; (3) an alternating load is then applied with the alternating tool sufficient to overcome the snapping force of the collar and the inner movable sleeve or mandrel 482 is then moved in the desired direction (either up or down); (4) the exchange tool is then detached from the selective reinsertion tool; and (5) a coiled pipe or similar work string is run through the selective reintroduction tool whereby the flap 462 guides the pipe string into a selected opening 490 and/or 492 which naturally fits a selected well pipe or other work tool such as the trap head 292 discussed above.

Reference is now made to Figures 29-32 where a novel insertion tool for use with the catch head/deflector assembly is shown generally at 510. The insertion tool 510 includes an assembly 512 attached to an insertion plug 514 and a housing 516. It is to be understood that the insertion plug and housing 516 are parallel to each other and are dimensioned and designed so that they can be accommodated in the offset bores 300, 302 in the catch head 292. The mounting head 512 includes an axially elongated neck 518 which has an internal socket thread 520. The neck 518 diverges outwards along a skirt portion 522 to a lower head section 524 with a larger diameter relative to the neck 518, the diameter of which approximately matches the diameter of the catch head 292. The inside of the mounting head 512 includes an axial opening 526 in the neck 518 which then slopes downward to form an angled bore 528 which emanates from the lower plug 524 to form axial offset exit bore 530. The lower plug 524 also includes a longitudinal flow opening 532 which per from the shoulder 522 to an exit opening 534. It will be understood that the exit opening 530 has a smaller diameter than the exit opening 534 with the exit opening 530 dimensionally designed to receive the housing 516 and the exit opening 534 dimensionally designed to receive the insertion plug 514 with a larger diameter.

The lead-in plug 514 comprises a cylindrical tube which is received by the exit bore 534 and is removably screwed to the lower mounting head 524 with a screw 536 engaged in a transversely oriented threaded passage 538 as best shown in Figure 30. The lead-in plug 514 also includes an opening 540 for the purpose of fluid passage by circulation during insertion. It will be understood that the flow opening 532 communicates with the inside of the exit bore 534 and thus with the inside of the introduction plug 514 so that fluid can pass from the shoulder 522 through the flow opening 532 and thus through the introduction plug 514 into the bore 302 in the larger diameter trap head 292.

The housing 516 includes an inner mandrel 542 which is movable relative to the housing (or coupling mandrel) 516 and which is sealed against the coupling mandrel 516 with a number of O-ring seals 544. The coupling mandrel 516 also includes O-ring seals 546 around its outer periphery for sealing engagement with the bore 300 in the catch head 292 with a smaller diameter. The coupling mandrel 516 further includes at its lower end a pair of openings 548, each of which receives a pawl 550, 552. As will be discussed below, each pawl 550, 552 is captured either between a raised surface 554 on the inner mandrel 542 or a recessed surface 556 also on the mandrel 542 and close to the raised surface 554. Directly upstream of the recessed surface 556 between the inner mandrel 542 and the connecting mandrel 516 is a shear ring 558 which, unless subjected to a preselected shear force, excludes movement between the respective inner and connecting mandrels. The inner mandrel 542 also includes a number of spaced ports 560 to eliminate any fluid lock problem during operation of the insertion tool. The upstream portion of the inner mandrel 542 includes a bypass sleeve 562 or one that can be pumped to an open position that is attached to the inner mandrel 542 with a number of shear screws 564. As best shown in Figures 1 and 32, the bypass sleeve 562 is sealed against the inner mandrel 542 with a pair of spaced 0-ring units, each of which includes an 0-ring 566 and an additional 0-ring 568. Sandwiched between sleeve 562 and outer mandrel 516 is a bypass port 570 through the inner mandrel 542. At a distance from the bypass port 542 downstream thereof is another bypass port 572 which communicates with a shallow recess 574 on the inner surface of the outer mandrel 516. The sleeve 562 also includes a fluid port 576 for transferring fluid to the space between the sleeve 562 and the inner mandrel 542. The lower part of the sleeve 562 ends in a cylinder 578 which can ride along a bearing surface 580 on the inner mandrel 542 until either 578 abuts the shoulder 582.

The catch head/deflector unit insertion tool 510 is operated as follows: First, the tool 510 is attached to the catch head 292 in a manner shown in figure 29 whereby the pawl 550, 552 are locked into corresponding recesses 343 and the smaller diameter bore 300 in the catch head 292. This is done by first to place pawls 550, 552 into the windows 548 in the housing 516 and then introduce the inner mandrel 542 into the housing 516 until the raised surfaces 554 contact the pawls 550, 552 and press the pawls into corresponding recesses 543. At the same time, the insertion plug 514 is positioned in the bore 302 with larger diameter in the trap head 292 and the insertion plug is screwed to the assembly head 512. It should be understood that the trap head 292 will be connected to the diverter as well as to the lower production pipe 298 and the orientation anchor 276. Fluid is circulated while the insertion tool is driven down the well (see figure 33) . When lowered, the seals 278 on the orientation anchor (which has been positioned in eg the LCR 250) are tested by continuing to circulate and test the pressure. Once the orientation anchor has been entered, the system is now "closed". At this point the pressure continues to build up whereupon, at a proportional pressure build-up, the increasing pressure cuts off the shear screws 564 which causes the bypass sleeve 566 to be pressed downwards along the recess 582 until the ends 578 of the bypass sleeve 562 are held by the shoulder 582 which thus opens the bypass -valve (see figure 33). When the bypass sleeve 562 opens, fluid will again be able to flow (ie, the system returns to an "open system") whereby fluid inside the inner mandrel 542 is allowed to flow through the port 576 to the space between the bypass sleeve 562 and the inner mandrel 542 and then through port 570 through recess 574 and finally out through port 572.

Once it has been confirmed that the assembly is correctly seated and oriented in the casing, i.e. that the orienting anchor is correctly oriented and sealed in the LCR 250, the insertion tool is removed from the catch head 292. This is done by circulating a ball 589 through the axial opening 520 and the opening 528 until the ball abuts an angled ball seat 586 on the bypass sleeve 562. The bypass sleeve 562 will then apply a force (caused by circulating fluid exerting a force against the ball in abutment) against the shoulder 582 which presses the entire inner mandrel 542 downwards whereby the cutting ring 558 will be cut off so that the recess 556 on the inner mandrel 542 will be placed across the pawls 550, 552. At this point the pawls will retract into the recess 556 and out from the recess 343 in the catch head 292 which thus makes that the insertion tool 510 can be lifted from the catch head and pulled out from the hole (see Figure 33).

The catch head insertion tool according to the present invention has many important features and advantages. For example the insertion tool 510 allows torque to be transmitted along the centerline of the catch head assembly despite being attached to one of the offset bores. This torque transfer is accomplished by connecting the housing 516 between the insertion tool and the catch head in the same lateral displacement as the large bore in the catch head. This torque transfer is important in order to reliably manipulate the catch head unit together with the run-in current. Another important feature of the insertion tool according to the present invention is that if the locking pawls 550, 552 (which carry the load during insertion) are not correctly engaged in the catch head profile, the insertion tool cannot be completely assembled. This is because the inner mandrel 542 will not move under the locking pawls unless they are aligned with their grooves 343 and unless the inner mandrel is under the locking pawls, as the assembly head of the insertion tool will not thread or screw onto the housing 516.

The aforementioned preferred embodiments of the many multilateral completion tools, components and units shown in figures 13A-C are used in a well method for borehole completion which is quite similar to the method described with reference to figures 1-9. As there are some minor modifications to the entire method (most of which is discussed above), however, the following discussion with reference to figures 34A-J provides a clear and concise description of the preferred method for multilateral complementation in accordance with the present invention. Reference is first made to Figure 34A, where a lined borehole is shown at 550 terminating in an open hole 552. A drill pipe 554 has been entered down the lined borehole 550 into the open hole 552. The drill pipe 554 terminates in a known insertion tool such as the aforementioned HR insertion tool 556. Attached to the insertion tool 556 in a manner described in detail above is a side coupling receiver (LCR) 250 and threaded to the LCR 250 on the downstream side thereof is a completion string consisting of known elements, including a work string stop tube stub 558, a number of slide sleeves 560, spaced ECPs 562, an overhaul string centering pin 564 and a snap-in/out indicating collar with seals 566. In Figure 34B, the insertion tool 556 has been removed from the LCR 250 and the lower completion has been inserted on known manner.

Then, according to Figure 34C, the HR drive-in tool and attached drill pipe 554 have been removed and a new drill pipe 568 has been inserted through the pilot bore 550 into the open hole 552. The drill pipe 568 includes an MWD pipe piece 570 which is attached to the orienting guide wedge change 276. The orienting guide wedge anchor 276 is then inserted into the LCR 250 so that the slot 284 of the anchor 176 engages the cam 270 as described in detail above which causes the orienting guide wedge anchor 276 and the LCR 250 are combined for intervention. At this point, the MWD pipe determines the radial orientation of the orienting wedge anchor 276 and this information is sent to the surface in a known manner. This final intervention is shown in Figure 34D which is shown in circulation tubing 572 which is used to circulate fluid through the drill pipe and thus provide a flow path for pulse signals sent from a mud pulsator into the MWD tubing which contained the encoded information with respect to orientation ( which has been taken up by MWD pipe piece ).

Next, the drill pipe 568, MWD pipe piece 570 and circulation pipe piece 572 are detached from the LCR 250 by tension in the shear release orientation anchor 276 and removed from the borehole. A retrievable guide wedge system is then inserted into the lined borehole 550 and joined with the orienting guide wedge anchor (which has been snap-locked into engagement with the LCR 250). Figure 34E shows a preferred open hole retrievable guide wedge assembly of the type described in the aforementioned US patent application filed January 25, 1994. Such a retrievable guide wedge assembly includes an insertion tool 574 with a protective housing or shield 576 contacting a guide wedge 578. The guide wedge 578 includes an expandable anchor 580 for anchoring to the walls of the open hole 552. The anchor 580 is attached to the anchor 276 using a grooved expansion joint or joint 582. Next, the insertion tool 574 and housing 576 are removed and, as shown in Figure 34F, a side drilling or branching 584 in a known manner by using the drill 586 which is deflected with the guide wedge 578 in the desired orientation and direction. As shown in Figure 34G, the drill 586 is removed followed by removal of the guide wedge 578 using a guide wedge removal tool 588.

At this point, the assembly according to Figure 33 including the trap head insertion tool 510, the trap head 292, the pipe section 298, the diverter pipe piece 294 and the orienting anchor 276 is inserted down the borehole to be joined with the LCR 250 as shown in Figure 34H. Advantageously, an MWD pipe socket 570 is used to maintain a correct orientation for easy joining of the anchor 276 into the LCR 250. As shown in Figure 341, a suitable insertion tool, such as the HR insertion tool 556, is then used to drive in the extension pipe - the feedback sleeve 350 in a manner described in detail above. Naturally, sleeve 350 would be bolted into the lateral completion string shown in Figure 341 which is composed of any desired and known completion components, including slide sleeves 556 and ECP 560. Finally, as shown in Figure 34J, the parallel seal assembly is assembled 380 on the selective reintroduction tool 460 and driven into the downhole so that the parallel seal assembly contacts and seals against the bore receiver in the small bore in the catch head 292 in the bore receiver in the extension pipe feedback sleeve 350. It is to be understood that the multilateral completion components shown in the multilateral completion according to 34J is also shown in more detail in Figures 13A-C discussed above. As can be seen in Figure 34J, the coiled pipe or the like can now be easily inserted and using the selective reinsertion tool 460 the coiled pipe can enter either the main borehole 554 or the lateral borehole 584. Naturally, the selective reinsertion tool 460 can be removed and replaced with a single pipe completion or a double-pack completion as desired. It will further be understood that the multilateral completion shown in Figure 34J can be repeated any number of times as desired along other portions of the wellbore 550. Thus, the many multilateral completion components described herein, including the lateral coupling receiver, trap head/divert assembly, extension pipe feedback sleeve, , the parallel sealing unit and the selective reintroduction tool, all be used as modular components in wellbore completions having any desired number of lateral or branched wellbore completions.

In addition to the aforementioned features and advantages of the method and devices according to the present invention, another important feature of the present invention still involves the use of a retrievable guide wedge as an integrated component used in actual completion of two or more individual well bores. Guide wedges have historically been used as a means of drilling additional laterals inside a main wellbore. In some cases, several sidings have been drilled and produced through an open hole. It is not believed, however, that prior to the present invention (as well as the related inventions shown in the parent application with serial no. 07/926,451, that a method has been shown which enables a guide wedge to be driven into the hole and inserted over a completion unit, the guide wedge is then used to drill a lateral side track and the guide wedge is then brought up so that the lower completion can be connected to the upper lateral completion.

In contrast, an important feature of this invention is the use of a "retrievable" guide wedge. The fact that the retrievable guide wedge is used in this method is important in that it: (1) Combines the completion and drilling operations to make them highly interdependent for success. Common practice in the oil fields today separates the drilling phase from the completion phase. Using the retrievable guide wedge to drill a lateral well above a previously installed completion, then retrieve the guide wedge to continue the completion process is an important and beneficial feature; and is considered to be unknown until now. (2) The retrievable guide wedge serves as the lateral position to ensure that the lateral well is set in the desired angular direction. This is done by joining the guide wedge with the lower completion unit using an orienting anchor to achieve the desired lateral direction/position. Once the lateral branch is drilled, the guide wedge is then retrieved and the rest of the completion installed with the certainty that the side branch can be easily found for reinsertion due to the known orientation of the guide wedge side. The upper lateral completion equipment can now be installed using the same distance and angular settings as from the guide wedge. (3) Conventional guide wedge applications do not allow for coupling the lateral completion above the guide wedge to the completion below the guide wedge once it has been removed. (4) The guide wedge and completion system according to the invention can be in the situation either with a threaded hole or an open hole; and the tools shown here can be used in both applications. However, it should be understood that the basic completion technique is the same for each condition (eg, open or lined hole).

Another important feature of the invention is the use of known devices with measurement while drilling (MWD) and tools for well completion (including multilateral well completion). While the MWD techniques have been known for over 15 years and in that time have gained wide acceptance, the use of MWD has been limited only to drilling boreholes, especially directional or deviation drilling. It is not believed that there have been any proposals for the use of MWD techniques in wellbore completions despite the fact that MWD techniques are well known and widely used in the drilling of boreholes. (It should be understood that the parent application with serial no. 07/926,451 shows in Figure 14D the use of more time-consuming and therefore more expensive wireline-orienting sensing devices.) It has now been discovered that MWD can be advantageously used for well drilling completions and especially multilateral completions.

It should be understood that any commercial MWD system has the capability to work in conjunction with this new application. A preferred MWD system comprises a "positive pulse" type

(ie mud pulse countermetry) which requires circulation down the production pipe through the unit at the bottom of the borehole. The required circulation can be achieved using the trap head insertion tool and the trap head/distributor system. When the fluid is circulated, a pressure pulse is generated and conducted through the fluid medium back to the surface. This information is decoded and the angular orientation of the unit down the wellbore is determined. Rotation adjustments are then made on the surface. A commercial example of a suitable slurry pulse countermetry system would be the DMWD system in commercial use by Baker Hughes INTEQ, Houston, Texas. Another example of a suitable sludge pulse counting system is described in US patent 3,958,217 where all the contents thereof are incorporated by reference.

Examples of successful applications of MWD in completions have been described here with respect to lateral wellbores that can be installed to depths of 10,000 ft or more and that range from the vertical to the horizontal. When the catch head/deflector unit 290 is inserted, and also when the parallel seal unit 380 is inserted, it is desirable to align the tools at the approximate position at which they will engage the mating equipment. E.g. when the catch head/deflector assembly 290 is installed, the use of the MWD will allow the operator to orient the deflector surface 306 with the previously drilled sidewell before lowering the anchor 276 to minimize the torque that would be induced in the work string if the tool had to self-align. In a horizontal application, the work string may be the drill pipe and may be very stiff, thus preventing self-alignment of the anchor. The use of MWD as a means of pre-aligning the system prior to installation provides increased reliability during completion. While the parallel seal assembly 380 has been tested and has successfully self-aligned with the catch head 292 in the horizontal position when as much as 120° out of phase, it is also not desirable to rely entirely on the parallel seal assembly for to rotate the entire work string during this self-aligning process, and therefore the MWD technology for this phase of the completion is recommended and thus preferred.

Claims (24)

1. Device for selective re-entry in multilateral wells, where the device is remotely controlled with an actuator from an operator on the surface, characterized in that it comprises: a housing (150, 152) including a central bore (136), which central bore (136) includes a entrance bore and a number of exit bores (160, 161); sliding devices arranged in the central bore (176) in the housing (150, 152), which sliding device is longitudinally movable in relation to the housing (150, 152); selector means for selectively providing mechanical communication between the input bore (159) and one of the plurality of output bores (160, 161) in response to longitudinal movement of the sliding means; and engaging means for engaging the selector means where the sliding means is remotely controlled by the operator on the surface. 2. Device according to claim 1, characterized in that the housing (150, 152) is mainly tubular and that the sliding devices include a sliding tube sleeve (24, 104). 3. Device according to claim 2, characterized in that the sliding pipe sleeve (24, 104) includes: an upward in the hole pipe slide (166) having an end that communicates with the entrance bore (159) of the housing (150, 152); a down-hole conduit (170) having an end communicating with the number of exit bores (160, 161) in the housing (150, 152); and coupling devices to connect the upward in the hole pipe slide (166) with the downward in the hole pipe slide (170). 4. Device according to claim 3, characterized in that the housing (150, 152) includes a mainly stepped shape and that: the pipe slide (166) upwards in the hole includes an inner diameter with a first dimension; and the downwardly guided pipe (170) includes an inner diameter having a second dimension, which second dimension is greater than the first dimension. 5. Device according to claim 1, characterized in that the number of positions includes a pair of the positions (220, 222) and said number of output bores (160, 161) includes a pair of output bores (160, 161). 6. Device according to claim 1, characterized in that it includes snap-locking devices for snap-locking the sliding device in a number of the positions and that said housing (150, 152) includes a pair of grooves (192, 194), and the snap-locking devices include an elastic positioning collar (182 ) with an annular projection (190) sized to fit with each of the slots (192, 194) in the housing (150, 152). in 7. Device according to claim 6, characterized in that the positioning collar (182) includes a number of stiffening ribs (196). 8. Device according to claim 5, characterized in that the sliding device includes a pair of slots (206, 206') which have teeth (210, 210') arranged around the circumference of each slot (206, 206'), and the selector devices include a diverter flap with a pin, where each end is rotatably arranged in the housing (150, 152), where the deflector flap (184) also includes a pair of gears (208, 208') arranged on the pin (202, 232) and in contact with the teeth (210, 210') in the slot (206, 206') in the sliding device, where the deflector flap (124) also includes a plate (200, 230) extending radially from the pin (202, 232). 9. Device according to claim 8, characterized in that the plate (200, 230) includes a number of stiffening ribs (212). 10. Device according to claim 4, characterized in that the pipe slide (166) upwards in the hole includes an inner surface and that the engagement devices include a pair of engagement grooves (174) arranged on this inner surface (173) of the tube section (165). 11. Device according to claim 4, characterized in that the pipe slide (166) upwards in the hole includes an alignment gap (172); and that the housing (150, 152) includes a projection (178) which extends radially inwards from this. 12. Device according to claim 5, characterized in that the sliding device is rectangular in shape and that the sliding device includes a pair of slots (206, 206', 236); and that the selector devices include a diverter flap (184) which has a pair of lugs (234) which are engageable with the slot (206, 206', 236), where the diverter flap (184) includes a pin (232) rotatably arranged in the housing (150, 152 ) and the diverter flap (184) includes a plate (230) extending from the pin (232). 13. Device according to claim 12, characterized in that the slots (206, 206', 236) each include an angled part (230) and a pair of mainly horizontal parts (240, 242). 14. Device according to claim 12, characterized in that the pin (232) is centrally located in the housing (150, 152 ). 15 . Device according to claim 1, characterized in that the sliding device comprises an inner sleeve (482) and a rectangular box (466) attached to the inner sleeve (482). 16. Device according to claim 15, characterized in that the case (466) includes a pair of oppositely arranged, ramp-shaped guide slits (488) and that the selector device includes a flap (462) with a pair of laterally arranged ears (478, 480), where each of the ears (478 , 485 ) fit with each of the guide slots (488) where the ears (478, 480) are movable along the guide slots (488) in response to longitudinal movement of the inner sleeve (482) and case (466). 17. Device according to claim 16, characterized in that the outlet bore (160, 161) is located in an outlet pipe piece (470) and that the flap (462) terminates and is pivotable in an intersection between the outlet bores (160, 161) where the flap (462) moves radially about the junction in response to the ears (478, 480) moving along the guide grooves (488) and the flap (462) blocking one of the exit bores (160, 161) so that the object passing through the sleeve (482) and the case (466) ) is directed by the flap (462) into only one of the exit bores (160, 161). 18. Device according to claim 15, characterized in that the engagement devices comprise profiled surfaces (486, 487) on the inner surfaces of the inner sleeve (482) for receiving a complementary surface on a changing tool. 19. Device according to claim 16, characterized in that it includes guide rails (464) on the flap (462). 20. Device according to claim 15, characterized in that it includes locking devices for locking the sliding devices in a number of positions (220, 222) which correspond to a desired position of the selector devices. 21. Device according to claim 20, characterized in that the locking device includes a collar (472) attached to the housing (150, 152), where the collar (472) includes joining devices to fit with a selected one of a number of suitable surfaces on the inner sleeve ( 482). 22. Device according to claim 21, characterized in that the matching devices snap together with the matching surfaces. 23. Device according to claim 22, characterized in that the matching devices comprise an elevation (502) which protrudes from the collar (472), and the matching surfaces constitute a number of spaced grooves (496, 498) in an outer surface of the inner sleeve (482 ). 24 . Device according to claim 1, characterized in that the selector devices comprise a flap (462) pivotable between a number of positions (220, 222) to provide said communication.