GB2399110A - Driving device for a wireline conveyed tool - Google Patents

Abstract

A driving device for assisting the movement of a wireline tool is adapted for mounting on a toolstring (3) in such a way as to allow relative longitudinal movement between the device and the toolstring (3). The device includes a spring portion (2) and a gripping portion (1) and in use upward force applied via the wireline causes the gripping portion (1) to grip the wall of a casing. When the upward force is released, the energy released by the spring (2) drives the toolstring (3) downwards which in turn "picks up" the gripper portion (1) and spring portion (2); the process can be repeated.

Description

239911 0 Extended Reach Borehole Tool The present invention relates to a

running tool for use especially, though not exclusively, by the oil, gas, water and geothermal industries in a pipe, pipeline, wellbore or other tubular member.

In oil and gas wells and other boreholes, it becomes necessary from time to thee to install or change various devices in the well and to perform investigative and other surveys.

Most of these operations rely on the use of a wireline which may be one of two types, namely slickline or electric line. A variety of tools or devices may be attached to the wirelinc and lowered to the bottom of the wellbore aided by gravity. Electric line has a 0 conductor and insulator such that downhole tool responses may be electrically controlled or measured from surface as they happen. Slickline is a single strand of wire which can only be manipulated up or down to influence the tool or instrument operation in the wellbore.

Many wells are deviated in order that they may be drilled from a central point but may drain a large area. Deviated wells where the angle of deviation is 70 degrees or more present a problem for wireline operations as the gravity effect is overcome by the friction of the wire and the rolling resistance of the tools or devices. Traditionally, the remedy for this problem has been to increase the weight at the end of the wireline by adding heavy weight bars and to reduce the rolling resistance of the tools and weight bars by adding wheels and centralizers. Other wells have horizontal or near horizontal sections often thousands of feet long situated at the bottom of a vertical shaft. These horizontal sections or laterals have been designed to improve drainage or to access distant pockets of hydrocarbons.

Devices exist for use on both electric line and slickline called "tractors" for pulling the wireline along highly deviated or horizontal sections. The e-line tractors convert a high voltage electrical supply which is passed down the insulated core of the electric wireline through a motor to a hydraulic pump which is then used to power a number of hydraulic motors. The motors arc linked to wheels which are disposed around the body of the tractor and drive it along the wellbore. Electric line tractors can have a variety of tools and devices attached for the purposes as described previously. They are selectively positioned in the wellborc by powering the tractor until their required location is reached. The tool is retrieved by simply pulling on the cable after powering down the tractor.

The nature of electric wireline is such that an amount of special equipment for pressure control is required. Because the wireline is braided, the mechanism required for the prevention of well pressure escape is bulky and maintenance intensive. The wire required to carry the high voltages associated with electric line tractors is not the type which would typically be on site already and the presence of the high voltages in the presence and proximity of hydrocarbons raises several safety questions during the operation ol'this equipment. Specialist personnel, in addition to the normal e- line crew are required to operate the tractor equipment. Electric line operations are, in general, expensive.

lo Slickline wirelinc units on the other hand are almost universally present at production sites and have simpler more manageable pressure control equipment. The crew size is smaller and the standard wire is sul'i'icient for operation of the invention. Slickline operations are relatively inexpensive. A slickline tractor exists as disclosed in US patent No. 6,345,669 B I. This device features two gripper assemblies which both engage the i s tubing or casing wall. Both grippers allow travel in the downwards direction only and are linked by an extending mechanism. Around the extending mechanism is located a large spring which is compressed when the extending mechanism is functioned to the fully out position. The extension and charging of the spring is accomplished by pulling on the wire from surface. This will push the forwards or lower section of the tool outwards allowing so the lower gripper to engage and grip the tubing wall. Slacking off wire tension will allow the spring to discharge, the extending mechanism to close and the upper part of the tool and wire / toolstrhg to advance into the well. The device may be described as a self advancing mechanism. This device has many advantages over the electric line variant but due to its mode of operation, it is not particularly well suited to operation on an electric line.

Electric line winches are insensitive and unresponsive when compared to slickline units. The pressure control equipment which is necessary for braided line (electric line) is cumbersome and neither the equipment or the winch lend themselves to the multiple reciprocations which are required lor the slickline tractor mechanism. Due to this, the slickline tractor is not best suited to operations on electric line although its operation is acceptable in certain circumstances.

Globally, there are a large number of wells which are deviated 70 or more degrees in order to reach their target. The maximum deviation may only be present for a short section of the well and may be in the middle reaches of that well. If wireline tools are unable to pass this short section, the remainder of the well becomes inaccessible liar s wireline operations. The normal procedure to overcome this situation is to tit a heavy toolstring to the bottom of the wire and to run into the deviated section at maximum permissible speed in order that the maximum kinetic energy is stored within the toolstring.

The hope is that if sul't'icient energy is present, the tools will run through the difficult deviated section and into an easier less deviated section. There are many types of roller in 0 the market which may be fitted to successfully reduce the friction between the tools and the casing. Similarly, there are chemicals which may be pumped down the well in order to lubricate the well and reduce the friction between the wire and the casing. Both these measures enjoy limited success.

As a toolstring is run into a well (both slickline and e-line), it is lowered down Is with gravity assisting its descent. Whilst running wire and tools into a vertical well, a safe running speed must be observed. The faster the tools are allowed to drop and the greater the weight -> I'the tools, the more kinetic energy is contained in the tools. A sudden event at surface which requires the application of the brake to the wireline unit may damage or break the wire if the kinetic energy is sufficient. This possible scenario limits maximum running speeds. Similarly, when trying to enter the deviated section of a well, it is advantageous to carry as much kinetic energy as possible but within limits. As the tools pass along the deviated section, the friction on the wire and tools will gradually diminish the speed (kinetic energy) of the tools until they come to a halt. At this point there is no choice but to pull the tools back up the well to an area where the tools will run freely in Is order to have another attempt at the deviated section.

A device which will allow the tools to be recharged with kinetic energy at this stalling point would obviously greatly extend the range of operations. The ability to repeatedly recharge the device would allow the tools to be deployed in very highly deviated wells and to great reaches.

The present invention has therefore been developed primarily, though not exclusively, with a view to provide a simplified means of extending the useful range of electric (and slickline) operations in terms of maximum deviation where this service may be deployed.

According to the invention there is provided a driving device for assisting the movement of a wirelinc-conveyed tool along the length of a tubular member, said device s being intended to be mounted on a portion of a toolstring so as to allow relative longitudinal movement therebetween, and the device comprising: a gripping means which is outwardly expandable to engage and to lock with the inner wall of said tubular member; and, an energy storage means arranged to be chargeable with stored energy upon 0 application of a pulling ir-'rce to the wireline upstream of the driving device, said storage meals applying a biassing force to the gripping means: in which the toolstring is moveable downstream of the tubular member, upon release of the pulling force and application of stored energy to the movement of the toolstring, so as to disengage the gripping means from the wall of the tubular member and allow enhanced downstream movement of the toolstring.

The energy storage means preferably takes the form oJ a powerful compression spring.

In a preferred embodiment of the invention, the driving device comprises two main components.

These are a gripping means which engages and locks with the tubing or casing wall and is selectively released when required and also a spring arrangement which may be charged with energy by pulling on the wire from surface. The gripping means functions in the manner of a ratchet, allowing progress only in the downwards direction but locking with the casing when subjected to an upwards load. The gripping means (and the spring arrangement) may be arranged around the exterior of tile toolstring in such a way that the toolstring is free to move up and down inside the device. I'he gripping means is urged to an upwards position by the spring when in normal use. When pull is applied from above and the gripper locks with the casing, the spring may be charged up with potential energy by pulling on the wirelinc from surl:ace. Once fully compressed and fully charged, the wire may be spooled back out allowing the toolstring to accelerate downwards having being charged up with kinetic energy. As the toolstring speeds downwards and past the gripper and spring, both are "picked up" and carried downwards with the tools. When the inertia has again leaked oM end the tools come to a halt, the above process may be repeated.

The gripping means may feature various types of release mechanism. Among these are a shear pin type or an hydraulic type. Shear pins may locate a cone which provides an adjustable land for wheels to run upon. The wheels allow the device to run freely or upon application of line pull, to lock the device to the casing with a wedging action. The wheels may be retained by two or more pivoting arms. Load applied from surface will transmit through the toolstring, through the compressed spring (and spring stop), through the retaining mechanism be it hydraulic or shear pin, through the cone, lo wheels and on to tl.e casing. Shear pins will be released by firing a jar or slide hammer mechanism above the tool releasing the tool. Hydraulic release will be accomplished by maintaining the line pull for a period of time and allowing hydraulic oil to meter from one chamber to another and subsequently releasing the cone.

In Figure 1 of the accompanying drawings, there is shown in longitudinal section a Is driving device according to the invention in the form of an extended reach borehole tool, which is intended to be mounted on a toolstring, and to assist the downstream movement of a wireline-conveyed tool along a tubular member, such as a wellbore of an oil and / or gas well.

In the drawing, the gripping means is designated by reference 1, the energy storage means (e.g. compression spring) by reference 2, and the reciprocating toolstring by reference 3.

Claims (10)

1. I. A driving device for assisting the movement of a wreline-conveyed tool along the length of a tubular member, said device being intended to be mounted on a portion of a toolstring so as to allow relative longitudinal movement therebetween, and the device comprising: a gripping means which is outwardly expandable to engage and to lock with the inner wall of said tubular member; and, an energy storage means arranged to be chargeable with stored energy upon application of a pulling force to the wireline upstream of the driving device, said storage lo means applying a biassing force to the gripping means: in which the toolstring is moveable downstream of the tubular member, upon release of the pulling force and application of stored energy to the movement of the toolstring, so as to disengage the gripping means from the wall of the tubular member and allow enhanced downstream movement of the toolstring.
2. 2. A driving device according to claim 1, in which the energy storage means comprises a compression spring.
3. 3. A driving device according to claim 1 or 2, and comprising two main components.
4. 4. A driving device according to claim 3, in which the two main components comprise; a. a gripping means which is engageable with and locks with the tubing or casing wall and is selectively realisable when required; and b. a spring arrangement which can be charged with energy by pulling on the wire from surface.
5. 5. A driving device according to claim 4, in which the gripping means functions in 2s the manner of a ratchet, allowing progress only in a downwards direction, but locking with the casing when subjected to an upwards load.
6. 6. A driving device according to any one of claims 3 to 5, in which the gripping means, and the spring arrangement, are arranged around the exterior of the toolstring in such a way that the tool string is free to move up and down inside the device.
7. 7. A driving device according to any one of claims 3 to 6, in which the gripping means comprises a release mechanism.
8. 8. A driving device according to claim 7, in which the release mechanism is of the shear pin type or hydraulic type.
9. 9. A driving device according to claim 8, in which shear pins locate a cone which provides an adjustable land for wheels to run upon.

   lo
10. 10. A driving device according to claim 9, in which the wheels are retained by two or more pivoting arms.