The present invention relates generally to a multi-operational system for use in petroleum exploration and development. More particularly, the present invention relates to an offshore drilling system comprising a well operation system for lifting well equipment and/or performing well operations.

Offshore production of oil and gas requires the use of offshore drilling, completion and work-over rigs. These drilling, completion and work-over rigs are used in different phases of operation for the exploration and production of oil and gas. Offshore rig operations require a vast amount of manpower and the cost of operating these rigs is substantial. The rigs comprise systems for, among other operations, lifting and handling of loads, rotating of tubulars, power generation, circulation of fluids, monitoring of downhole activity, and maintenance of well control and safety.

Conventional systems comprise drilling equipment used in offshore activity for lifting and moving loads, rotating and handling of tubulars (e.g. drill pipe, drill collars, logging tools casing etc.), and assembling of tubulars (e.g. connecting multiple pieces of pipe in an end-to-end manner, etc., prior to lowering the multi- piece unit into the well bore), assembling pipe(s) and equipment, disassembling pipe(s) and equipment, lowering pipe(s) and equipment to the sea floor, and inserting components into the wellbore, and are also used in recovery operations. The systems are also used in drilling, completion and work-over operations.

When drilling operations are conducted in deep water, greater costs and logistical challenges can be confronted relative to operations in shallower waters. A major cost associated with drilling and producing a well is the cost of leasing the platform and associated equipment. Each day of rig time can cost hundreds of thousands of dollars. Accordingly, it is desirable to plan and design drilling operations to operate as efficiently as possible. The increased costs are compounded, for example, by the additional time needed to deal with the challenges of operating in deep waters, and the make-up and break-out of tubulars during a conventional drilling operation, for example.

Traditionally, offshore wellbores are formed (e.g. drilled, completed) using a single load path (e.g. derrick, rig, drilling assembly), thus requiring all wellbore tasks (e.g. drilling, completion, simulations, workovers etc.) to be performed from a single assembly. Recently, efforts have been made to decrease the time required to drill wells offshore by performing some tasks simultaneously. For example, US

6.085.851 and US 6.056.071 , disclose a multi-activity apparatus and method for conducting drilling operations. In general, the patents disclose a drilling platform having dual drilling assemblies (e.g. separate load paths and/or derricks). In the method disclosed in the patents, some activities during a top hole drilling phase and the post drilling phase are performed substantially simultaneously by a main derrick and an auxiliary derrick. However, according to these patents, drilling operations are performed from a single load path during the bottom hole drilling phase (i.e. after the BOP has been installed). Another solution proposed to improve the efficiency of offshore drilling operations is disclosed in US 5.762.279, where a single derrick structure is provided for two drilling rigs. The crown block platform receives the crown blocks for both drilling operations such that both crown blocks are slidable along the crown block platform. The hoisting lines are reaved in a conventional manner, except for the deadlines. The deadlines from the two crown blocks are connected together by means of a sheave assembly which is locked in position during normal independent operation of the crown blocks and their respective travelling blocks. The sheave assembly connecting the two deadlines is unlocked to allow relative movement between the deadlines during simultaneous use of the drawworks for both travelling blocks. This allows the deadlines' loads to be equalized even though the separate drawworks do not rotate at precisely the same speed.

It is therefore an object of the present invention to provide a multi-operational system for well operations, where the multi-operational system reduces the time required to perform different well operations. It is a further object of the present invention to provide a multi-operational system for well operations that can more fully utilize a platform rig assembly with multi- activity exploration and/or production capabilities, as well as completion, testing, work-over and maintenance capabilities.

It is a further object of the present invention to provide a multi-operational system for well operations for eliminating the use of some physical equipment traditionally required to conduct offshore drilling operations.

It is also an object of the present invention to provide a drilling system that is more efficient, thus decreasing the costs associated with leasing capital drilling equipment. It is also an object of the present invention to provide a multi-operational system for well operation, where the multi-operational system can be used for different operational modes for the well operations and where the multi-operational system also provides a redundancy.

These objects are achieved according to the present invention with a multi- operational system for well operations as described in the independent claim.

Further embodiments of the invention are defined in the dependent claims. The present invention relates to a multi-operational system for performing well operations offshore, where the multi-operational system comprises a first and second set of lifting systems arranged in a derrick, where each of the first and second set of lifting systems comprises a drawwork, a crown block, a travelling block, a top drive and a deadline anchor, where the hoisting lines for each of the first and second set of lifting systems are reaved in a conventional manner.

Furthermore, the multi-operational system for performing well operations according to the present invention is provided to have three operational modes, including a first mode, where one of the first or second sets of lifting systems is active while the other set of lifting systems is passive, a second mode, where one set of the lifting systems performs preparation work while the other set of lifting systems performs a well operation, and a third mode, where the first and second set of lifting systems are connected to a common yoke, thereby performing a single well operation simultaneously, wherein in all three modes, the first and second set of lifting systems functions independently of each other on the same well center.

Thus, through the multi-operational system for well operations according to the present invention it is provided a system that can be used according to the need for lifting capacity, as the multi-operational system renders it possible to use only one set of lifting systems, this being one extremity, i.e. when the load to be lifted or lowered is relatively small or light and/or when a well operation is to be carried out, or both sets of lifting systems, this being the opposite extremity, when the load to be lifted or lowered is large or heavy. Furthermore, the system for well operations also provides the possibility to use both sets of lifting systems, this being an intermediate mode, where one set of lifting systems performs a well operation, while the other set of lifting systems is prepared for a well operation, thereby decreasing the tripping time (i.e. the time required between two well operations).

Furthermore, the multi-operational system for well operations according to the present invention is a more cost effective system, as it is cheaper to provide two independent sets of lifting systems with smaller/lower lifting capacities than only one set of lifting systems with larger/higher lifting capacity, this also seen in view of that the lifting capacity in the vast majority of cases can be satisfied by only one set of lifting systems (a set of lifting systems with lower lifting capacity will be able to lift a lower load but with higher speed, and opposite a set of lifting systems with higher lifting capacity will be able to lift a higher load but with lower speed), but where the system according to the present invention also provides a possibility to lift with double capacity when needed, the system for well operation according to the present invention also providing a redundant system, as the system for well operations according to the present invention can still be used if one set of the lifting systems is damaged and/or has to be maintained. A well operation which the multi-operational system for well operations according to the present invention is to perform should be understood to be drilling, completion, workovers etc., this also including pipe handling, such as make-up and break-out of tubulars, lifting and lowering of tubulars, drilling risers, BOPs etc. In an aspect of the invention each of the first and second sets of lifting systems may be connected to a dolly, where each dolly comprises at least a rail adapted to cooperate with a corresponding guiding rail provided in the derrick, thereby allowing the dolly to be moved in the longitudinal direction of the derrick.

Furthermore, the dolly may also comprise at least one arm, the arm in one form, for instance, being a hydraulic cylinder. The at least one arm and the at least one rail are connected to each other through an end of the arm and a pivot connection, thereby allowing the at least one arm to move relative to the guiding rail in the derrick.

It should be understood that the at least one arm may also be a beam, a rod or the like, where the at least one arm then may be supported by a hydraulic cylinder.

Each dolly is also connected to each of the first and second sets of lifting systems, this being done through a second end of the arm, in a pivotal way.

Each dolly is also, through appropriate means, connected to a common control unit, such that the at least one arm can be moved between an extended and a retracted position relative to the guiding rail in the derrick.

The rail of the dolly is provided with a plurality of rollers, wheels or the like, such that the dolly can be moved substantially without friction with respect to the guiding rails in the derrick.

The arrangement of the dolly with the rail and hydraulic means will provide a dolly that is movable between an active or extended position and a passive or retracted position. Furthermore, as the dollies are connected to the first and second set of lifting systems, the first and second set of lifting systems can be moved from an extended to a retracted position, an extended position indicating a position where the set of lifting systems performs a well operation and a retracted position indicating a position where the set of lifting systems is not in use.

As each dolly is connected to each of the set of lifting systems, it will follow the movement of the set of lifting systems. Through the connection to the guiding rails in the derrick, the dolly will be able to maintain the set of lifting systems in a substantially vertical position. If the first set of lifting systems, for instance, is to be used to perform a well operation, an operator will bring the dolly connected to the first set of lifting systems to an extended position, whereby the first set of lifting systems will be brought to a longitudinal axis extending through a well center in the derrick.

Similarly, if the second set of lifting systems is to be used while the first set of lifting systems performs a well operation, then the operator will bring the dolly to a position where the second set of lifting systems can be clarified or made ready for a well operation after the first set of lifting systems has finished its operation. This position may, for instance, be a position where the second set of lifting systems is located nearer the longitudinal axis extending through the well center than to the retracted position of the dolly. If both sets of lifting systems are to be used simultaneously, then the operator will bring each of the dollies to a position where the first and second set of lifting systems are located nearby the longitudinal axis extending through the well center, each set of lifting systems being located on opposite sides of the longitudinal axis and at the same distance from the

longitudinal axis.

The system for well operations according to the present invention is also provided with each crown block being guidable or slidable in a horizontal direction, over at least a part of the derrick's width direction. The crown blocks may then be mounted on or in a crown block support, for instance in form of a beam or a bar provided with a longitudinal slot extending in the beam's or bar's axial direction.

Furthermore, either the crown block or the crown block support may be provided with rollers, wheels or pads, to ease the movement of the crown blocks in the beam's or bar's axial direction. The movement of the crown blocks may be provided, for instance, with an actuator, typically a hydraulic cylinder.

Each of the crown blocks will then be moved to be positioned substantially over the associated set of lifting systems. Other advantages and special features of the invention will become apparent from the following detailed description, the attached drawings and the following claims, in which

Figure 1 illustrates a multi-operational system for well operations in a first mode according to the present invention, Figure 2 illustrates the multi-operational system for well operations in a third mode according to the present invention, and

Figure 3 shows the multi-operational system according to figure 1 from above.

Figure 1 show a multi-operational system for well operations mounted in a derrick D, where it can be seen that a first and second set of lifting systems 1 , 2 are arranged in the derrick D. Each set of lifting systems 1 , 2 comprises a drawwork 6, a crown block 3, a travelling block 4, a top drive 5 and a deadline anchor (not shown). Each of the hoisting lines 20 are reaved in a conventional manner, i.e. the hoisting lines 20 are run from draw works 6, which are rigidly mounted on a derrick floor or supports, around fairleads or sheaves 21 , through the crown blocks 3 and around pulleys on travelling blocks 4 and further to the deadline anchor comprising a drill line drum. The derrick D is formed from a drill floor, legs 22 and a crown block support 13 which is positioned at the appropriate location on an offshore structure. The derrick floor is provided with a well center (drill slot) 8 to accommodate the drill string and drilling riser. The legs 22 are rigidly attached to each corner of the drill floor and extend upwardly therefrom. On the top of the derrick D, for instance, is provided a crown block support 13, where the crown block support 13 is provided with a longitudinal slot (not shown) extending in the crown block support's 13 axial direction. The crown blocks 3 are then mounted on or in the crown block support 13 in a guidable or slidable way. Either the crown blocks 3 or the crown block support 13 is then provided with rollers, wheels or pads (not shown), in order to ease the movement of the crown blocks 3 in the crown block support's 13 longitudinal direction, where the crown blocks 3 can be moved between a retracted position and an extended position, the extended position being located on the longitudinal axis A extending through the well center (8). The movement of the crown blocks 3 between the retracted and extended position is provided through hydraulic means (not shown), for instance an actuator, typically being a hydraulic cylinder. A person skilled in the art will known how this can be done and this is therefore not described further herein.

A dolly 9 is associated to each of the first and second sets of lifting systems 1 , 2, where each dolly 9 is arranged to be moved in the axial direction of the derrick D. Each dolly 9 comprises a rail 10 and two arms 1 1. The rail 10 is then adapted to cooperate with a guiding rail 23 in the derrick D, thereby allowing the dolly 9 to be moved in the axial direction of the derrick D. However, it should be understood that the dolly 9 also can comprise a double set of rails 10 and arms 1 1 , whereby each set of rails 10 and arms 1 1 then is adapted to cooperate with an associated guiding rail 23 in the derrick D, for instance as shown in figure 3.

The rail 10 of the dolly 9 is provided with a plurality of rollers, wheels or the like 24, such that the dolly 9 can be moved substantially without friction with respect to the guiding rails 23 in the derrick D.

One end of the arms 1 1 is pivotally connected to the rail 10, while an opposite end of the arms 1 1 is pivotally connected to the top drive 5 of the sets of lifting systems 1 , 2. One or both of the arms 1 1 is/are connected to a hydraulic means 12, where the hydraulic means 12 is connected to a control unit (not shown) through appropriate conduits (not shown). As the dolly 9 is connected to each of the set of lifting systems 1 , 2, it will follow the movement of the set of lifting systems 1 , 2. Through the connection to the guiding rails 23 in the derrick D, the dolly 9 will be able to maintain the set of lifting systems 1 , 2 in a substantially vertical position. Through the arrangement of hydraulic means 12 and control unit, an operator can bring the dolly 9 to an active or extended position (as shown for the second set of lifting systems 2), or to a passive or retracted position (as shown for the first set of lifting systems 1). This refers to a first operational mode of the system for well operations according to the present invention, i.e. a mode where the second lifting system 2 is active and performs a well operation, while the first set of lifting systems 1 is passive and not in use.

A second operational mode of the system for well operations according to the present invention corresponds to a mode where one of the first or second sets of lifting systems 1 , 2 performs a well operation, while the other set of lifting systems 2, 1 performs preparation work (i.e. the set of lifting systems is prepared to perform a well operation, but is not performing the well operation yet). In such a mode, for the first set of lifting systems 1 (see figure 1), an operator will bring the dolly 9 to a position where the first set of lifting systems 1 can be clarified or made ready for a well operation after the second set of lifting systems 2 has finished its operation. This position may for instance be a position where the first set of lifting systems 1 is located nearer the longitudinal axis extending through the well center 8 than to the retracted position of the dolly 9.

Figure 2 shows a third operation mode of the system for well operations according to the present invention, for instance before heavy lifting is to be performed, where it can be seen that the operator has brought each of the two dollies 9 to a position where the first and second sets of lifting systems 1 , 2 are located nearby a longitudinal axis A extending through the well center 8, the first set of lifting systems 1 being located on one side of the longitudinal axis A, and the second set of lifting systems 2 being located on the opposite side of the longitudinal axis A. The first and second sets of lifting systems 1 , 2 are then connected to a common yoke 7, whereby the first and second sets of lifting systems 1 , 2 can perform the lifting simultaneously, this resulting in the lifting capacity being doubled.

Figure 3 shows the system for well operations according to figure 1 from above, where the first set of lifting systems 1 is arranged in a retracted position, while the second set of lifting systems 2 is arranged in an extended position, the extended position being aligned with the longitudinal axis A extending through the well center 8.

In this embodiment the dolly 9 comprises two rails 10 which are provided with a plurality of rollers or wheels 24, where the rollers or wheels 24 are arranged in the guiding rails 23 in the derrick D. Furthermore, each rail 10 comprises two arms 1 1 (only the upper arms 1 1 can be seen), where the arms 1 1 , through their opposite ends, are pivotally connected to the rails 10 and top drives 5. Through hydraulic means 12 the arms 1 1 can be moved relative the rails 1 1 , whereby the dollies 9 are used to move the first and second sets of lifting systems 1 , 2 between an extended and retracted position, as more clearly shown in figures 1 and 2.

The invention has now been explained by means of several non-limiting

embodiments. A person skilled in the art will appreciate that a number of variations and modifications may be carried out for the system for well operations as described within the scope of the invention as it is defined in the attached claims.