Anchored wavy conduit in coiled tubing

Abstract: A conduit (2) is disclosed for installation internally of a coiled tube (1), said conduit (2) lying on the inside wall (3) of the tubing. A plurality of anchors (20) is located along the length of the conduit, the anchors (20) being activatable between an "active" state when the anchors (20) engage the inside wall (3) and a "neutral" state when the anchors (20) are disengaged from the inside wall (3). The invention also extends to an anchor for use in the conduit and a method of installing the conduit (2) in the coiled tube (1).

Description: This invention relates to a conduit which is installed internally of a tube and more particularly to an anchored wavey conduit in coiled tubing. Coiled or continuous reel tubing has been used in the oil industry for the last 20-30 years. The fact that it is a continuous single tube provides several advantages when entering a live oil or gas well which could have anything up to 7,000 psi well head pressure. This means the well does not have to be killed, (i.e. a heavy fluid does not have to be pumped down the production tubing to control the oil or gas producing zone by the effect of its greater hydrostatic pressure). Continuous tubing has the advantage of also being able to pass through the tubing through which the oil and/or gas is being produced, not disturbing the tubing in place. Since its introduction, the uses and applications for coiled tubing have grown immensely, and now, rather than just being used to circulate various fluids in a wellbore, it is not uncommon for coiled tubing to be used for conveying various hydraulically powered tools and more recently electrically powered tools on its end into the well. This has resulted in conventional electrical wireline logging cables or small hydraulic conduits being inserted into the inside of the reel of tubing so that these more sophisticated tools and services can be performed. A disadvantage which has resulted from this practice is the capstan effect of the smaller diameter wireline or hydraulic tube tending to be pulled very tightly to the inner surface of the continuous reel of tubing. when considering the effect this has on the geometry, it will be appreciated that the wireline or small hydraulic conductor will have a slightly smaller pitch circle diameter to that of the larger reeled tubing. The consequence of this is that for each complete 360 degrees the wireline or hydraulic tube will be slightly shorter in length than the larger reeled tubing, so if this is added up over its total length of 12,000 ft (3657 m) or usually longer the difference in lengths could be as much as 200 ft (61 m). This problem has been recognised due to the operational problems encountered. Either one end of the wireline or hydraulic tube has been pulled out of its connection, or else the reeled tubing itself has started to form a low frequency waveform caused by the tension in the conduit inside the reeled tubing, which prevents the reeled tubing being lowered any deeper into the well without the risk of damaging it. Another disadvantage with using traditional wireline inside reeled tubing is that it is not compatible with many of the fluids pumped through the reeled tubing, the more common ones being corrosive stimulation fluids, and cement slurries used generally for zonal isolation. The reason for this, is the wireline has two outer reinforcing layers of braided wire beneath which is an insulation layer protecting the conductors, which typically number up to eight. The normal insulation material is not compatible with the acid systems, although some expensive materials are available, but the total price becomes prohibitively expensive. Alternatively, when pumping cement slurries, the gaps between the braided wire of the cable form natural traps which collect some deposits of the cement slurry, which, when set, either make it difficult for the wireline to bend or, more commonly, the particles of set cement break off leaving residue inside the reel. According to the present invention, there is provided a method of installing a conduit in a tube, said conduit and tube each comprising first and second ends, the method comprising the following steps: (a) locating a first end of the conduit in the first end of the tube; (b) enclosing the first end of the tube in a high pressure chamber; (c) providing a seal between the conduit and the high pressure chamber; (d) pressurising the chamber by pumping in an appropriate fluid; (e) pulling the conduit through the seal by means of pulling means within the high pressure chamber. The following is a more detailed description of some embodiments of the invention by way of example, reference being made to the accompanying drawings, in which: Fig. 1 shows a side view of a coiled tubing reel showing a conduit lying inside it on its inner surface; Fig. 2 shows a side view of a section of braided wireline with formers making it into a wavey shape; Fig. 3 shows a side view of a tube being rolled into a wavey shape; Fig. 4 shows a side view of a wavey conductor inside a conduit for installation inside a coiled tubing reel; Fig. 10 shows a side sectional view of a coiled tubing tube for hanging in an oil well with a wavey conduit inside being suspended by an apparatus anchoring it to the coiled tubing inner wall; Fig. 17 shows a cross-sectional view of coiled tubing with a wavey conduit bonded to the lower inner surface of the coiled tubing tube; Fig. 22 shows an apparatus for installing a conduit in a tube; and Fig. 23 shows the conduit being installed in the tube whilst the tube is coiled on a drum. Referring first to Fig. 1, there is shown a side cross-sectional view of one wrap of coiled tubing 1, with a conduit 2, lying on the inside wall 3 of the coiled tubing. A dotted line 4 shows the diameter centre line of the coiled tubing 1 while a second dotted line 5 shows the diameter centre line of the conduit 2. It will be appreciated that because they have different centre line diameters, their lengths per wrap will be slightly different with the coiled tubing being slightly longer. Multiplying this difference in length by the total number of wraps enables the difference in overall length to be determined, which can be in excess of 100 ft (30 m). It is this problem which this invention overcomes. Referring now to Figs. 2 and 3, there is shown a method and apparatus to make the conduit 2 wavey, for a straight line length, so that, when it is installed inside the coiled tubing 1, its length produces a longer length of conduit which will be equal to or of a greater length than the coiled tubing. Two methods of achieving this wavey profile are shown. The first is a curved sleeve 6 which fits over a conventional braided wire-line 7 and forces the braided wire-line to make the wavey shape shown. The distance these sleeves are positioned along the braided wire-line determines whether a wavey or a not so wavey braided wire-line is produced. In the case of Fig. 3, the conduit could be a hydraulic tube 8 which has been mechanically shaped into the wavey form by rollers 9 and 10. Again the severity of the wave can be chosen to take away any desired frequency. With reference to Fig. 10, there is shown an anchoring apparatus 20 which is firmly attached to the conduit 21 inside the coiled tubing 22. The apparatus 20 has a plurality of arms 23 which are in an extended disposition and contact the inner surface 24 of the coiled tubing 22, anchoring the conduit 21 to the coiled tubing. This makes use of the coiled tubing 22 to carry the weight of the conduit 21 until the next anchoring apparatus 20, some distance further along the coiled tubing. It will be appreciated that because the conduit 21 does not have to support its entire length when hung vertically in an oil well, its dimensions and weight may be significantly reduced. It will also be appreciated that because the conduit 21 is anchored to the coiled tubing 22, no movement of the conduit is possible and the conduit remains in the same position regardless of pump rate and gravity effect. This prevents any "bird nesting" or bunching at the extreme end of the coiled tube string which is common with existing wireline installation and which causes cables to be pulled away from an electrical socket at the surface, which may cause the cable to crimp, resulting in a short circuit and disable the cable. In addition fibre optics may also be exploited, as the conduit is anchored to the coiled tubing, and it has a built-in slack due to its wavey form, both in the fibre optic cable inside its conduit, and in addition to the conduit itself having a wavey form, so that the fibre optic cable is not subjected to any stretching whatsoever. With reference to Fig. 17, there is shown a wavey conduit 21 laying on the lower inner surface 50 of the coiled tubing 22 and bonded at 44 to the coiled tubing along virtually its entire length. This is achieved either at the time of manufacture of the coiled tubing 22, exploiting the heating treating process necessary to stress relief the coil tubing weld line 45 to also cure the bonding agent 44 or alternatively, the bonding agent 44 could be a layer on the outer surface of the conduit and once all the conduit has been pumped into the coiled tubing cured by either exposing the adhesive layer to either a ketone solvent or by exposing the coiled tubing to a controlled heat source in excess of 120°C. An industrial adhesive available which could perform this function is a 3M product called Scotchgrip 847, which in addition retains some elastomeric properties while never being reactive again. Referring now to Figs. 22 and 23, a novel method is shown for installing a conduit 201 according to the invention in a tube 202. As shown in Fig. 23 the tube 202 is typically a coiled tube which is conveniently coiled on a drum 203 from which the tube 202 can be readily deployed down a well. The installing apparatus 210 is fitted to the end of the tube 202. The installing apparatus comprises a pressure chamber 211 in which a pulling mechanism 212 is located. The conduit 201 is threaded into the installing apparatus 210 through a seal 213 by the pulling apparatus 212 and finally into the tube 202. Any suitable pulling mechanism can be used comprising conically arranged grippers. Such pulling of the conduit 201 is much more effective and less damaging to the conduit than compression of the conduit to install it inside the tube. The pulling mechanism 212 also preferably comprises cammed pulleys acting on the conduit which serve to induce a wavey profile in the conduit which creates the greater length of the conduit than the tube 202 as discussed previously. Pressurised fluid is then introduced into the pressure chamber by means of an inlet valve 214. The pressurised fluid is preferably water including a friction reducing agent such as long chain polymers such as polyacrylamides. The pulling mechanism 212 pulls the conduit through the seal 213. A high sealing force is required to achieve the seal 213 and this has to be overcome as more conduit is introduced into the pressure chamber 211. Once the conduit is in the pressure chamber the flow of fluid acts on the conduit dragging it into the tube 202. The combination of the pulling tool and the flow rate of the fluid acts to force the conduit 201 down the tube 202. Effective installation is achieved by pulsing the pressure and the pulling on the conduit at the same time. Very short installation times have been achieved with this method.

Claims: A method of installing a conduit 21, 201 in a continuous coiled tube 22, 202, said tube 22, 202 being arranged on a reel 203 and having at least one complete 360 degree turn, said conduit 21, 201 and tube 22, 202 each comprising first and second ends, comprising the following steps: a) locating a first end of the conduit 21, 201 in the first end of the tube 22, 202, b) enclosing the first end of the tube 22, 202 in a high pressure chamber 211, c) providing a seal 213 between the conduit 21, 201 and the high pressure chamber 211, d) pressurising the chamber 211 by pumping in an appropriate fluid, e) pulling the conduit 21, 201, through the seal 213 by means of pulling means within the high pressure chamber 211, A method of installing a conduit in a tube according to claim 1, characterised in that the length of conduit 21, 201 installed in longer than the length of the tube 22, 202. A method of installing a conduit in a tube according to claim 1, characterised in that the pulling means comprises a cammed pulling means 212 to produce a wavy profile in the conduit.

Inventors: HEAD PHILIP FREDERICK, HEAD, PHILIP FREDERICK
Applicants: HEAD PHILIP F, HEAD, PHILIP FREDERICK
Application year: 1993
Main classification: E21B17
IPC codes: E21B17, F16L7, H02G1