GB2496954A - Whipstock with lockable cutting tool - Google Patents

Abstract

A whipstock or deflecting wedge 1 comprises a whipstock fixing unit 3 and a cutting or milling tool 5 run-in the wellbore attached to the whipstock by means of a shear element 6. The fixing unit comprises a hydraulic cylinder that interacts with a lower portion of the whipstock via a piston rod, the upper part of which has a segment removed to that it can interact with a wedge bevel plane. The milling tool also comprises a cylinder in which is located a spring-biased piston. The piston below the spring is equipped with a wedge shaped nose that corresponds with the form of a transverse slot formed in the upper part of the shear element. The cutting tool is also provided with a locking element that is able to fix the piston in its top position.

Description

WtDQE DEFLECHN G DEVICE FOR SIDETRACKiNG The present invention relates to drilling and performing workover operations on oil and gas wells, in particular, for sidetracking from earlier drilled cased and open-hole boreholes.

From the prior art a setting tool for wedge deflecting device is known (SIJ 1564319 Al), including the kllowing elements: a housing with an axial cylindrical channcl for circulation of drilling fluid; in-channel positioned piston, spring-biased against the housing a fixing unit, connected to the piston and comprising a sleeve with a ial hole, coaxially installed in below-the-piston cavity of the housing's cylindrical channel and rigidly connected to it; a rod, located inside the sleeve and rigidly connected to the piston, and a pin, inserted into the sleeve radial hole; besides, the rod from the pin's side has a longitudinal groove inclined to the piston, and the pin is positioned in the groove.

The known prior art device allows Lo mu the deflecting device in the bole and.

disconnect a drilling string from it under action of the drilling fluid pressure.

However, it has several disadvantages: In case the deflecting device is run up to plug back total depth, to fix it reliably inthe borehole, an axial load of at least 50 kN is to becreatcd. At such a load, the pin will be distorted and jammed in the sleeve hole, which will make impossible to disconnect the device from the deflecting device, and cause an emergency situation; -a solid, stable, faceted plug back is required to install and fix the deflecting deviec in the borehole, which Leads to increase of terms and costs of the well construction; -narrow field of application, connected with impossibility of bringing to the end of the design axial load, required to extend an anchor slip and firmly fix the wedge deflecting device in horizontal sections of directional wells with bending proffles, or in wells with complex profiles; -necessity of additional round-trip operation to run-in a mill assembly, which results in a well construction time increase.

Another prior art device lbr sidetracking from a cased borehole is described in RU 2263196 Cl. It comprises a deflecting wcdgc with a fixing mechanism in form of a corrugated pipe with plugged-up one end between which a sub is located; a movable joint, connecting the sub to the wedge; a cutting tool.; a channel for fluid delivery into the corrugated pipe, arranged as a hydraulic line, localed in the deflecting wedge and eornrnunicatmg the corrugated pipe cavity with a drillpipe internal space and the cavity of the cutting tool, attached. to flue upper portion of the wedge by means of a shear bolt.

The device has the following disadvantages: the complexity of creating secure shear bolt joint of the hydraulic line with the wedge body due to insufficient thickness of the upper portion of the wedge, which can reduce the reliability of the device and lead to a breakdown. increasing well consfruetion.

costs; -low reliability of operation of a unit, deflecting the wedge head to the welihore wall, and lixing it in the position, in particular, in horizontal section.s of directional/multilateral wells because oi' small application arm of' the dellecting force at the lower portion of the wedge and, as a consequence, small wedge-to-wall deviating Ibrcc, impossibility of lixing the wedge in the position during the entire lateral drilling cycle, tha.t limits the range of original-hole azimuth orientation for the wedge within ± 45° from its low wall. [his, in turn, leads to complication of a latei-al hole profile, increasing its length, and creates problems with running a well liner to the bottom because of its higher rigidity compared to the drilling sthng rigidity and, consequently, results in a lateral drilling costs increase.

-high risk of emergency situations due to the uncontrollable disconnecting force due to the fact tim shear bolt is positioned not pcrçcndieular to the wedge deflecting surface (since it is perpendicular to the axis of the device), which leads to bending of the bolt instead ol'its shearing; -narrow field of application, associated with impossibility of use of the disconnecting device of the design in corn plex profile wells due to the fact that when straining of a drillstring takes place, it tcnds to take a straightline position and sticks in bending well section because of thickness increase in pipe joints, not allowing to control axial load, applied to the shear bolt, which makes impossible to disconnect the cutting tool from the wedge.

The closest to the present invention by its technical essence is a sidetracking device, disclosed in RU 2366793 Cl, comprising a dellecting wedge with a fixing mechanism in Form of a corrugated pipe with pluggcthup one end, between which an a sub is located; a movable joint, connecting the the sub to the wedge; a fixing unit of The deflecting wedge installed in the sub, made as a fixing element and a piston with a rod, located in a hydraulic cylinder, communicating with the corrugated pipe; further, the upper part of the rod is arranged so that it can interact with the lower portion of the wedge from the side of its deflecting surthce; a cutting tool, connected to the upper portion of the wedge by means of shear holt; a fluid delivery channel, communicating the drilipipe intnal space and the cutting tool caviL with the corrugated pipe cavity. Besides, the fluid delivery channel is made in form of a supply tube, and the lower portion of the wedge from its deflecLing surface side is arranged as a downward wedge nose with a bevel plane directed oppositely to the wedge deflecting surface; herewith, the upper part of the rod is made in form of a side cut, which can interact with a wedge bevel plane, between which the fixing element is positioned.

The disadvantage of the device lies in its narrow field of application, associated with impossibility of use of the disconnecting device of' the design in horizontal sections of directional wells with bending profiles, or in complex profile wells clue to the fact that when straining of a drillstring takes place, it tcnds to take a stra.ightline position and sticks in bending sections because of thiclmess increase in pipe joints, not allowing to control the axial load, applied to the shear bolt, which makes impossible to disconnect the cutting tool from the whipstoek. Eniergency situations arising thereof can lea.d even to loss of the main wellbure, since it is practically impossible to pull out the mill assembly staying in the hole, or mill it up, which].eads to well construction time and costs increase.

The technical objects of the present invention are: -field of application expansion due to opportunity of using it in the complex profile wells; -increasing reliability of the device in horizontal scctions of directional/multilateral wells with bending profiles by way of disconnection of the wedge by the fluid pressure increase; reducing risk of emergency situations by applying redundant methods of dsconnection of the cutting tool due to installation of the shear element perpendicularly Lo the top deflecting st.nthce of the wedge, and fitting-up th.e shear element with an external circular groove, located below the wedge deflecting surface, which, as a whole, will provide reduction of terms and costs of construction of the complex geometry/horizontal wcll.s with a complex prolilc.

The said technical object is achieved by means of the suggested wedge deflecting device for sidetracking, including: a deflecting wedge with a hydraulic fixing mechanism.

with an sub located therebetween; a movable joint, connecting the sub and the wedge; a deflecting wedge fixing unit, installed in the sub and comprising a fixing element and a piston-rod assembly, located in the hydraulic cylinder, communicating with the fixing unit cavity; besides. the upper part of thc rod is arranged so that it can interact with the lower portion of the wedge from the side oil Is deflecting surface; a cutting tool, run-in on the drillstring and connected to the upper portion of the wedge by means of the shear clcmcnt; a fluid supply lube, communicating tile drilistring internal space and the ei.iI.ling tool cavity with the fixing unit cavity; furthermore, the lower portion of the wedge from its deflecting surface sidc is arranged as a downward wedgc nosc with a bevel plane directed oppositely to the wedge deflecting surface; herewith, the upper part of the rod is made in form of a side cut, interacting with a wedge bevel plane, with the fixing element positioned inbetween.

The novelty lies in the fact that the shear element is provided with an external.

circular groove, located bclow the wedge deflecting surface, and with a transverse slot in its upper part, and the cuffing tool is provided with a longitudinal cylinder and a downwards spring-biased piston with upper and lower sea elements, inserted into the eylindcr; the piston above the lower seal elements and below the spring is equipped with a lateral longitudinal wedge nose, form of which corresponds to the form of the transverse slot of the shear element; besides, below-the-piston space of ti-ic longitudinal cylinder communicates with the drilistring and the supply tube, and above-rhe-pisLon space communicates with th.e borehole interior; flirtherniore, the cuffing tool is provided with a radial locking element spring biased inward, arranged in such a way it is able to fix the piston in its top position, in which the piston is located above the shear element.

Fig. 1 demonstrates the general cross-sectional view of the wedge deflecting device, Fig. 2 shows a cutting tool to wedge connection unit and a. disconnecting device in its run-in position, Fig. 3 shows the deflecting wedge uixing unit.

The device comprises a deflecting wedge 1 (Fig. 1), a sub 2, a hydraulic fixing mechanism 3, made, for instance, in form of a profile pipe, hydraulic anchor or a packer (see rnJ 2166058, RU 2164282, US 5113938, US 5816324), a movable hinge joint between the wedge 1 and sub 2 with an axis 4. There are the following ejenients installed above the wedge 1: a cutting tool 5 in form of null assembly, a bypass valve, a tube screen, attached to the drillstring (riot shown at Fig. 1), mechanically connected to the wedge 1 by means of the disconnecting device in form of the shear element 6. lime supply tu.be 7 is intended for delivery of drilling fluid from the drillstring through the cutting tool S and the sub 2 into internal space of the hydraulic fixing mechanism 3. Guide slot of the wedge 1 comprises two defi ecting surfaces: the upper one 8 and the basic one 9 (Figs. I and 2). The sub 2 (Fig. 1) includes a wedge I fixing unit, comprising a fixing element 10 (Fig. 3) and a piston 11 with a rod 12, installed in the hydraulic cylinder 13, communicating with the fixing unit 3 (Fig. 1); besides, the top part of the rod 12 Thg. 3) k installed so that it can interact with the lower portion of the wedge 1 from its deflecting surface 9; therewith, the lower portion of the wedge 1 from its deflecting surIace 9 is made in fonn of a downward wedge nose 14 with a bevel plane 1 5, directed oppositely to the wedge 1 deflecting surface 9; further, the top part of the piston rod 12 is made in form of a side cut, interacting with the bevel plane 15 of the wedge I, with the fixing element 1 0 in form of the notches positioned inhetween (the other types of the notches are possible in accordance with RU 2366793). The shear element 6 (Fig. 2) is provided with an external circular groove 17, located below the deflecting surface 8 of the wedge 1, and wi C a transverse slot 18 in its upper portion, and the cutting tool S is provided with a longitudinal cylinder 19 and a downwards spring-biased piston 20 with upper and lower seal elements 21, inserted into the cylinder 19; the piston 20 above the lower seal 1:. elements 21 and below the spring 22 is equipped. with a lateral longitudinal wedge nose 23, form of which corresponds to the form of the transverse slot 18 of the shear element 6; besides, below-the-piston space of the longitudinal cylinder 19 communicates with the drillstring and the st.ipply tube 7, and above-the-piston space communicates with borehole interior through the opening 24 in the body of the cutting tool 5; furthermore, the cutting tool 5 is provided with a radial inward spring-biased locking element 25, arranged in such a way it is able to fix the piston 20 in its top position, in which the piston 20 is located above the shear element 6.

Tn. order to simplify the attached drawings, any technological connecting and sealing elements are not shown or shown schematically.

The device operates in the following way.

At the plant the piston 20 (Fig. 2) of the disconnecting device oF the cutting tool 5 (window cutting mill) is brought iii the operating position by means of a flange (not shown in Fig. 2), positioned on face of its union joint 26, and an adjuster bolt (not shown in Fig. 2), inserted into the flange and screwed into thread 27, provided on the upper part of the piston 20, whereby the spring 22 is compressed, diverting the piston 20 with the wedge nose 23 to open passage area of the opening 28 for the shear element 6. Ihe shear element 6 is attached to the wedge 1 by way of inserting it perpendicular to the upper deflecting surface 8 into the opening 29 in the upper portion 15 of the wedge, and secured (for instance, by soldering, welding, calki.ng, mechanical attachment, etc., not shown in Fig. 2) such that ftansverse slot 18 was located perpendicular to the axis of the device and directed to the headpiece of the wedge I (i.e., uivard). The cutting tool 5 is attached to the wedge 1 by way ol inserting the shear element 6 into the opening 28 of the cLLtting tool 5. After screwing back the adjustment. bolt, [he cutting tool 5 is flxed on the wedge 1 :1 by means of the transverse slot 18 of the shear clement 6 and the wedge nose 23 of the piston 20 and the spring 22. Spring 22 force and the wedge-shaped form of the nose 23 make it possible to press the cutting tool S against the wedge 1. and fix it securely in the position for the period of transportation, R.TJ-T. orientation and setting. Alter that, they remove die adjustment bolt with a flange, attach the supply tube 7 to the cutting tool 5, and blank off the union joint 26 (not shown in Fig. 2). The wedge I is connecLed to the sub 2 with the axis 4 (Fig. I). The bottom end of the sub 2 is blanked off (not shown in Fig. 1). In such form, the wedge 1 with the sub is ready for storage and transportaLi.ou.

Betbre RIH, the wedge deflecting device is assembled on a walkway in thc following sequence: protective plugs are removed from the union joint 26 of thc cutting H [aol S arid the sub 2 (Fig. I), the wedge 1 with the sub 2 is connected to the hydraulic fixing mechanism 3, for instance, with a thread (not shown. in Fig. 1) or countersunk bolts 30, and run in the hole at the elevator (not shown on Fig. I.).

A drillpipe with a. tube screen above is connected to the cutting tool 5 (Fig. 2) through the union join.t 26, and above them a bypass valve is installed (not shown in Figs. 1 and 2). The assembly is run down the hole 011 a drillstring to the depth selected, and the wedge deflecting device is oriented, for example, by means of an inclinometer or a gyroscope (not shown in Fig. 1) in the required direction in azimuth. While running down the hole, operating fluid available downhole comes through the bypass valve and fills-up the cavities of the cutting tool (Fig. 1), drillpipes, and hydraulic fixing mechanism 3, preVenting their collapse under action of the fluid head pressure. The tube screen retains large sludge particles getting in the drilistring cavity through bypass valve, preventing plt.tgging of the supply tube 7. During running of the device into (lie well, due to cyclic character of the operation and stop of the dri.l.lstring at rotary shp»=4 for drillpipe connection, there are hydraulic impacts taking place in the drilistring cavity, which transfer to the longitudinal cylinder 19 (Fig. 2) of the cutting tool 5, and affect the piston 20. Compression force of the spring 22 exceeds the hydraulic impacts force, buffers them, and thus, excludes inadvertent disconnection of the cutting tool S from the wedge I. When the wedge deflecting fevice reaches the setting interval, a pinup from the wellh.ead creates an operating fluid pressure within the drilistring, which, through the cutting tool 5 (Fig. 1) by tile supply tube 7 and the sub 2, is transferred to the hydraulic fixing mechanism 3, bringing it to operating position and anchoring it securely in the borehole, At the same time, the operating fluid pressure displaces the piston 11 (Fig. 3) with the rod 12, which, acting with its side cut 16 on the bevel plane 5 of the wedge nose 14, turns the wedge 1 (Fig. 1) around the axis 4 and presses its headpiece (i.e., the upper portion of die wedge 1) against the borehole wall (not shown in Fig. 1). Arranging of the wedge nose 14 (Fig. 3), directed downwards, with the bevel plane 15, oi-iented inversely relative to the wedge 1. deflecting surface 9 and interacting with the upper part of the rod 12, allows us to increase the ann of forceS.pplicatin to the upper part of the wedge in any required ratio, regardless of well diameter or internal diameter of the casing (not shown in Figs. 1 and 3), which ensures pressing of the wedge I upper portion (Fig. 1) to the hoi-ehole wall with higher force and its secure fixing in the position during all the tUne of sicletraclcing, drilling and casing operations. In its top position, the piston 11 (Fig. 3) and the rod 12 are blocked between the hydraulic cylinder 13 wall and the lower wedge 1 nose 14 by means of the notches 10. Construction of the rod 12 with the piston 11 as a single integrated cylinder, combined with the fixing element 10. allows to simplify desi of the hearing assembly, increase its strength, reliability, and reduce dimensions. In case the device is used in large-diameter boreholes, for example, in surface casing, the rod 12 with.

the piston II construction can be implemented as a split-type one to simplify the technique and reduce manufacturing costs. T,arge diameter and length of the piston II allow it to work steadily, leaving deflecting/wedging function for the rod 12. Design of the rod 12 in form of a wedge increases deflecting force and the wedge headpiece-to-wall pressing fOrce, and makes i.t possible to reliably fix the wedge in the position, since th.e wedging force of the rod 12 is many l:imes higher than the axial force, created by the operating fluid pressure on the piston 11, Furthermore, the deflection forces, induced in the wedge during operation process, affect the wedge not in axial direction, but perpendicular to the side cut 16 surthee of the rod 12, not shifting the piston 11 to the initial position, but increasing its fixation force (other types of the fixing elenient.s are also possible in accordance with RU 2366793).

Reliability of the wedge setting in the well is checked by rated-force drilistring straining. Then, creating a pressure, exceeding the hydraulic fixing mechanism 3 activation pressure (Fig. 1), the spring 22 is compressed by the piston 20 (Fig. 2) with upper and lower seal clcmcnts 21, bringing the wedge nose 23 out of the transverse slot 18 of the shear element 6, disconnecting the cutting tool S tiom the wedge 1; at the same time, the fluid is removed through the opening 24 from the above-the-piston cavity to the borehole. The piston 20, continuing its movement under thc fluid pressure effect, rests with the slot lower swface 31 against the shear element 6, and by its slope surface pushes the cuLLing tool 5 away from the wedge 1 to the opposite side of the borehole. Thereat, bending of the shear element 6 in the transverse slot 18 location area takes place, increasing its angle of tilt to the axis 6 oF the device and, thus, increasing by that the force, pushing the cutting tool 5 away from the wedge 1. The piston 20, having passed the shear clement 6 zone, is fixed in its top position with the locking element 25. Fluid pressure, acting on the shear element 6 with the fluid jet reaction force, will complete disconnection of the cutting tool 5 from the wedge 1, and open the opening 28. Fluid pressure drop in Che drillstring means disconnection of cutting tool 5 from the wedge I took place.

Dctachment of the supply tube 7 from the cutting tool 5 is accomplished by straining the drlllstring. Opening oIthcsc ports communicates internal cavity of the drilling pipes with the borehole. While milling a window and drilling a lateral, the total area of the openings imikcs it possible to pump sufficient flush fluid volume and maintaining required speed of the upward flow, carrying out the grit and cement/rock particles from the window

II

milling/sidetracking area, which is not available in the prior ait devices. Also, in the process of milling-out the remaining part of the shear element 6, after disconnecting the cutting tool 5 from the wedge 1, the circular groove 17 lhcilitates its fast destruction, preserving cutting elements of the cutting tool 6, and accelerating the process of cutting out the window and sidetracking.

In case of any complications in the well (for example, plugging of the drillstring internal cavity with scale or some dropped metal parts) and impossibility of disconnecting thccuttingtools(Fig.1)fromthewedgclwiththemethoddescribed,requitcd detachment is performed by breaking the shear clement 6 by the external circular groove 17 (Fig.2) by way of straining the drillstring with a rated force not exceeding load capacity of the derrick (not shown in Fig. 1). After that, the drillstring is rotated, flush fluid circulation out of the weilbore restarted, and a window in the well casing is milled by way of moving the cutting tool 5 (Fig. 1) across the deflecting surface 8, and later, acrossthesurfaee9ofthewedgc 1.

As a whole, it allows to expand application field of the suggested device due to possibility of using it in the complex profile wells and increase reliability of its operation in horizontal sections of directional/multilateral wells by way of disconnection of the cutting tool from the whipsiock by destructing the shear bolt with fluid pressure increase; to reduce risk of emergency situations by installation of the shear element perpendicularly to the top defleoting surface of the wedge and applying redi.indant methods of disconnection of the cutting tool from the wedge, which, in total, will provide reduction of construction tennis and costs of the complex geomey wells and complex profile horizontal wells.

Claims (1)

1. <claim-text>CLAIMThe wedge deflecting device, comprising: a deflecting wedge with a hydraulic fixing mechanism, with a sub located therchetween; a movable joint, connecting Lhe SLth and the wedge; a deflecting wedge fixing unit, installed in the sub and comprising a fixing element and a piston-rod assembly, located in the hydraulic cylinder, communicating with the fixing unit cavity, besides, Qic upper part of the rod is arranged so that it can interact with the lower portion of the wedge from the side of its dcflceting surface; a cutting tool, run-in on the drj.listrmg and connected to the upper pori,icn of the wedge by means of the shear element; a fluid supply tube, communicating the drillstting internal space and the cutting tool cavity with the fixing unit cavity, furthermore, the lower portion of the wedge from its deflecting surface side is arranged as a downward wedge nose with a bevel plane, directed oppositely to the wedge deflecting surface; herewith, the upper part of the rod is made in form of a side cut, interacting with a wedge bevel plane, with the fixing element positioned inbetween; wherein the shear element is provided with an external circular groove, located below the wedge deflecting surface, and with a transverse slot in its upper part, the cutting tool is providcd with a longitudinal cylinder and a downward spring-biased piston with upper and lower seal elements, inserted into the cylinder; the piston above the lower seal clemens and below th.e spring is equipped with a lateral longitudinal wedge nose, fom of which corresponds to the form of the transverse slot of the shear element; bekiw-the-piston space of the longitudinal cylinder conimuiñeatcs with the drillsUing and the supply tube; above-thepiston space communicates with the borehole interior; furthermore, the cutting tool is provided with a. radial inward spring-biased locking element, arranged in such a way it is able to fix the piston in its top position, in which the piston is located above the shear elernenLAMENDMENT TO CLAIMS HAVE BEEN FILED AS FOLLOWS :iiCLAIM1. The wedge deflecting device, comprising: a deflecting wedge with a hydraulic fixing mechanism, with a sub located therebetween; a movable joint, connecting the sub and the wedge; a deflecting wedge fixing unit, installed in the sub and comprising a fixing element and a piston-rod assembly, located in the hydraulic cylinder, communicating with the fixing unit cavity, besides, the upper part of the rod is arranged so that it can interact with the lower portion of the wedge from the side of its deflecting surface; a cutting tool, mn-in on the drillstring and connected to the upper portion of the wedge by means of the shear element; a fluid supply tube, communicating the drillstring internal space and the cutting tool cavity with the fixing unit cavity, furthermore, the lower portion of the wedge from its deflecting surface side is arranged as a downward wedge nose with a bevel plane, directed oppositely to the wedge deflecting surface; herewith, the upper part of the rod is made in a form having a segment removed and defining a side cut, interacting with a wedge bevel plane, with the fixing element * *. .** * positioned inbetween; wherein the shear element is provided with an external circular groove, located below the wedge deflecting surface, and with a transverse slot in its upper part, :: : the cuffing tool is provided with a longitudinal cylinder and a downward spring-biased piston with upper and lower seal elements, inserted into the cylinder; the piston above the lower seal elements and below the spring is equipped with a lateral longitudinal wedge nose, form of which corresponds to the form of the transverse slot of the shear element; below-the-piston space of the longitudinal cylinder communicates with the drillstring and the supply tube; above-the-piston space communicates with the borehole interior; furthermore, the cutting tool is provided with a radial inward spring-biased locking element, arranged in such a way it is able to fix the piston in its top position, in which the piston is located above the shear element.</claim-text>