This application is a 35 U.S.C. § 371 national stage application of PCT/NO2018/050160 filed Jun. 15, 2018 and entitled “Drilling System for Rock Drilling”, which claims priority to European Patent Application No. 17178322.8 filed Jun. 28, 2017, each of which is incorporated herein by reference in their entirety for all purposes.
Not Applicable.
This disclosure relates to a drilling system for rock drilling.
A usual solution for creating a hole in the earth's sub-surface is a drilling system for rock drilling. It can be used, for instance, when drilling water wells, oil wells, or natural gas extraction wells. A typical task performed during a drilling operation is pulling the drill string out of a wellbore and then running it back in. This task is commonly referred to as “tripping” or making a “round trip.” There are multiple reasons for performing such a task, for example to perform a casing operation or a cementing operation after a certain depth has been reached. Other reasons may be to replace a worn-out drill bit, a downhole tool that might have broken down or a damaged drill pipe.
The task of performing a round trip is known to be time consuming. The entire drill string needs to be removed from the wellbore and its drill pipes need to be disconnected and stored, usually in a rack, until they are connected together again to form the drill string to be run back in. A way to improve the efficiency of a round trip is disconnecting the drill string only in some of the joints when the drill string is pulled out of the wellbore, so as to form at least one segment with a length of at least two drill pipes. These segments, usually referred to as “stands,” may be then stored until they are reconnected together for being run back in. As a consequence, a lower number of joints are disconnected, when the drill string is being pulled, and also a lower number of respective joints are connected, when the drill string is being run back in. Only the joints between the segments of a drill string need to be disconnected and connected, which reduces the time needed for disconnecting and connecting drill pipes.
The ability to store a longer segment of a drill string when performing a round trip allows improving the efficiency of a round trip, which can, for example, represent a significant reduction in operation costs. However, it may be challenging to store longer segments of a drill string in a drilling system, in a cost efficient and stable manner.
Nowadays, a drilling system adapted to store segments of the drill string, for the purpose of reducing the round trip duration, usually includes a hoisting structure such as a derrick. The segments are normally held in a vertical rack next to the hoisting structure. A well-known approach for storing longer segments in these drilling systems involves increasing the height of the hoisting structure in order to provide room for longer segments. For example, a drilling system with a 64-meter derrick is usually capable of holding segments with 40 meters in length, typically up to four drill pipes in length. However, several difficulties are observed due to the increased height. Since the segments of the drill string are longer and heavier, stronger equipment may be needed. Moreover, since the equipment supported by the hoisting structure is further elevated, security risks also increase and it also becomes more difficult to provide maintenance for the equipment due to the increased difficulty in reaching it. Also, a higher hoisting structure and the machinery required for handling longer segments becomes significantly heavier. For example, a usual derrick capable of holding segments of a drill string with three drill pipes in length can weight, approximately, 30 metric tons, whereas a usual derrick capable of holding segments of a drill string with four drill pipes in length can weight, approximately, 100 metric tons. The difficulties resulting from the increased weight supported by the hoisting structure or its higher centre of mass, are normally solved by appropriately reinforcing the hoisting structure and altering it to have the required robustness. However, this change has a cost which may be significant.
In particular, in the case of a maritime vessel comprising a drilling system with a hoisting structure, for example a drillship, it is possible that the maritime vessel itself is prone to suffer disturbances due to the motion produced by the waves or due to the wind, such as disturbances in the roll axis of the maritime vessel, thus creating additional difficulties in the stability of the maritime vessel. Moreover, the increased height may also forbid the maritime vessel from entering certain important maritime passages such as the Panama canal, in which the maximum height allowed is 57 meters (190 feet), and the Turkish straits, in which the maximum height is 64 meters (210 feet).
Thus, although the well-known approach of reducing the usual duration of a round trip in a drilling system by increasing the height of a hoisting structure has proven to be an effective solution in the past, nowadays several technical and economical drawbacks are observed due to the increased height. And these drawbacks may make it unfeasible to keep on following this approach, which constraints the achievable reduction for the duration of a round trip.
Alternatively, instead of increasing the length of the segments of a drill string held temporarily while performing a round trip, the approach may be to provide the drilling system with equipment which would allow to manoeuvre the segments faster. This approach would not reduce the number of joints between drill pipes that have be disconnected and connected during a round trip. Also, this may add a significant cost, not only for the new equipment but also for any reinforcement required to withstand the additional forces in place, and the reduction in the duration of a round trip may be insufficient to compensate for this investment.
Apparatus, systems, and methods described herein go against the conventional approach of increasing the height of a hoisting system comprised in a drilling system in order to reduce the duration of a round trip.
Disclosed is a drilling system for rock drilling with a drill string, wherein the drill string comprises at least one bendable drill pipe, the drilling system comprising:
In some embodiments, the at least one conveyor device may be two conveyor devices for guiding the drill string in a curved path between the first direction and the second direction.
In some embodiments, a conveyor device may comprise at least two rollers for guiding the drill string.
In some embodiments, a conveyor device may comprise a groove for the drill string to run on.
In some embodiments, the second direction may be arranged vertically.
In some embodiments, the first direction may be arranged horizontally.
In some embodiments, the first direction may be arranged with an inclination relative to a horizontal plane.
In some embodiments, the drilling system may comprise a top drive for exerting a torque around the first direction on the end of the drill string.
In some embodiments, the drilling system may comprise at least one rack for holding at least one segment of the drill string while performing a round trip, the rack being arranged parallel to the first direction.
Also disclosed is a maritime vessel comprising at least one drilling system as described above.
In some embodiments, the first direction of the at least one drilling system on the maritime vessel may be arranged longitudinally in relation to the maritime vessel.
In some embodiments, the maritime vessel may comprise at least two drilling systems arranged vertically on top of each other. In some embodiments, the at least two drilling systems may have a common second direction.
In some embodiments, the maritime vessel may be a drillship and in other embodiments, the maritime vessel may be an oil and gas platform.
The apparatus, systems, and methods described herein may be advantageous in various ways as will be apparent from the description throughout. Particularly, that which is disclosed herein may reduce the duration of a round trip by allowing the manipulation of longer segments of a drill string, in a feasible manner, which in turn may represent a significant reducing in project costs. For example, drilling system which is capable of handling a segment of the drill string with at least 5 bendable drill pipes can be achieved without imposing a significant increase in cost, as it would occur for a drilling system with a hoisting structure such as a derrick.
The drill string 21 is shown in its state during operation, being bent between a first direction 211 and a second direction 212. For the purposes of providing a simple example, the first direction 211 and the second direction 212 are arranged with an inclination of 90 degrees. The first direction 211, horizontal, may be imagined as corresponding to the deck of a drill ship 11 and the second direction 212, vertical, may be imagined as corresponding to the direction on which a wellbore is to be drilled.
An end of the drill string 21 is driven along the first direction 211. There are several ways of accomplishing this actuation. One way is to use two block and tackle systems 23 for driving the drill string 21 back and forth in the first direction 211, in which one of the systems exerts tension on the drill string 21 so as to pull it from the wellbore and another exerts tension on the drill string 21 so as to push it. In
The drill string 21 is guided and bent between the first direction 211 and the second direction 212 by two conveyor systems 22 which guide the drill string 21 in a curved path. As a result, a motion of the drill string 21 is converted between the first direction 211 and the second direction 212.
In order to carry out the first embodiment when starting from a drilling system 2 without any drill string 21, the following approach may be followed. A first bendable drill pipe 213 is firstly pushed along the first direction 211 into the space between the two conveyor devices 22. During this motion, the first bendable drill pipe 213 should be guided and bent towards the second direction 212. Secondly, after the first bendable drill pipe 213 reaches a position which allows for a subsequent bendable drill pipe 213 to be added in the first direction 211, the first bendable drill pipe 213 is fastened in order to prevent its movement relative to the two conveyor devices 22, for example by using slips to hold the first bendable drill pipe 213 or any other known method for that effect. Then, an end of the subsequent bendable drill pipe 213 is joined with the end of the first bendable drill pipe 213 in the first direction 211, as to form a drill string 21 which is now pushed into the two conveyor devices 22 until it is again possible for a second subsequent bendable drill pipe 213 to be added to the drill string. This cycle is repeated to further extend the drill string. Furthermore, this way of carrying out the first embodiment may start from a segment of a drill string 21 with more than one bendable drill pipe 213 in length, instead of starting with an individual bendable drill pipe 213.
With the drill string 21 in place, the extending and retracting the drill string 21 may be achieved in the following ways. On the one hand, the steps of pushing the drill string 21 through the two conveyor devices 22 and adding a subsequent bendable drill pipe 213 when possible, may be repeated for extending the drill string 21 until an intended depth is reached. On the other hand, the loop for extending the drill string 21 may be performed in reverse and each of the disconnected bendable drill pipes 21 or each of the disconnected segments of the drill string, can be stored one by one.
The rack 24 can be used, for example, in the same manner a setback is used in a drilling system 2 with a derrick, by storing segments of a drill string 21 temporally while making a round trip. In order to move the bendable drill pipes 213 or the segments of a drill string 21 to and from the rack 24, other external means may be used, such a crane or at least one robotic arm.
A drilling operation may be performed by applying a torque to the drill string 21. In this second embodiment, the torque is exerted on the drill string 211 around the first direction 211, which then transmits the torque, through the drill string 21, to the second direction 212. In order to apply this torque around the first direction 211, a top drive 25 is provided at an end of the drill string 21 in the first direction 211.
Each of the conveyor devices 22 include three rollers 221 supported by a curved frame. Each roller 221 is of the “bow tie” type, which provides a better contact with the drill string 21. Particularly, these rollers 221 allow to bend the drill string 21 between the first direction 211 and the second direction 212 while it moves back and forth, or even if it turns, for example while drilling.
Three examples of an arrangement of the drilling system 2 on a drill ship 11 are shown in
In order to improve the efficiency of a round trip by increasing the length of the stored segments of a drill string 21, a drill ship 11 may be occupied in a longitudinal manner. In this regard, a segment of a drill string 21 can have, for example, up to 500 feet, i.e. approximately 152.4 meters. As can be seen on, for example,
The embodiment shown in
A further simplification can be achieved by providing a shared rack 24 when there is more than one drilling system 2 proximal to each other. For example, in
It should be noted that the above-mentioned ways of carrying out the invention defined by the claims that are set out below illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.
Number | Date | Country | Kind |
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17178322 | Jun 2017 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/NO2018/050160 | 6/15/2018 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2019/004836 | 1/3/2019 | WO | A |
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Number | Date | Country | |
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20200131868 A1 | Apr 2020 | US |