WO2018004040A1

WO2018004040A1 - Robot and method for installing seafloor pressure control system

Info

Publication number: WO2018004040A1
Application number: PCT/KR2016/007091
Authority: WO
Inventors: Hyungoo KIM
Original assignee: Latticetechnology Co., Ltd.
Priority date: 2016-07-01
Filing date: 2016-07-01
Publication date: 2018-01-04

Abstract

Provided are a robot and a method for installing a seafloor pressure control system that allow the seafloor pressure control system included in a flowline of gas and crude oil to control pressure of fluid within the flowline to be installed. Particularly, provided are a robot and a method for installing a seafloor pressure control system that allow the seafloor pressure control system to be efficiently and easily installed additionally to any existing deep seafloor oil and gas production system.

Description

ROBOT AND METHOD FOR INSTALLING SEAFLOOR PRESSURE CONTROL SYSTEM

The present invention relates to a robot and a method for installing a seafloor pressure control system, and more particularly, to a robot and a method for installing a seafloor pressure control system that allow the seafloor pressure control system included in a flowline of gas and crude oil to control pressure of fluid within the flowline to be efficiently and easily installed, in an ocean industry of developing, mining, and transferring gas and crude oil of a deep seafloor.

Fossil fuels such as oil, gas, and the like are currently used as the most important energy resource in all technology fields. Because of problems such as destruction of the environment and exhaustion of fossil fuel, and the like due to the use of the fossil fuel, a great effort has also been made in the development of alternative energy, but since efficiency of an apparatus using fossil fuel has been excellent until now, it is difficult to provide an apparatus using alternative energy that is equally efficient as the efficiency of the apparatus using the fossil fuel, such that it is expected that the fossil fuels will be actively used for a long time now and forever. Accordingly, the development and exploration of fossil fuel resources have been expanded to a seafloor area as well as a land area. In particular, it is a current trend that an interest in a resource production in a deep seafloor is increased as the resources are exhausted. However, since extracting crude oil or gas deeply present in the deep seafloor has various difficulties as compared to the land or an existing seafloor which is relatively less deep, it requires highly sophisticated technology, which is yet in a research process or is very restrictively realized up to now.

FIG. 1 illustrates a basic configuration of a deep seafloor oil and gas production system. As illustrated in FIG. 1, the deep seafloor oil and gas production system is configured to basically include an offshore platform, a riser, manifolds, flowlines, x-trees and wellheads, and production tubings. The x-tree and wellhead is installed on a seabed, and is connected to the production tubing extended to an oil and gas reservoir to extract crude oil, or the like from the oil and gas reservoir to the seabed. The x-tree and wellhead may be installed on each of the oil reservoirs, and accordingly, a plurality of x-tree and wellhead may be installed. The manifold is each connected to the plurality of x-tree and wellheads by the flowline, and collects crude oil, or the like from the plurality of extracting units. The crude oil, or the like collected in the manifold is raised to the offshore platform through the riser, which results in a production of the crude oil, or the like. An example of the deep seafloor oil and gas production system is suggested in various documents such as Korean Patent Laid-Open Publication No. 2015-0123975 (entitled "METHOD FOR DRILLING A PLURALITY OF SUBSEA WELLS FROM A STATIONARY FLOATING VESSEL, AN OFFSHORE DRILLING VESSEL, A DRILLING RISER TRANSPORT SYSTEM, AND AN OFFSHORE VESSEL" published on November 4, 2015), and the like as various illuminations.

Meanwhile, it is well known that an output of crude oil is limited due to a technical limit up to now in extracting the crude oil, or the like reserved in a seafloor oil reservoir. This limit occurs because of a pressure difference due to a height difference between various equipments extracting the crude oil, or the like, or a height difference between the equipments and the oil reservoir, and also, this limit is further increased as pressure in the oil reservoir is reduced by extracting the crude oil, or the like from the oil reservoir which is saturated. In order to overcome this limit a little, a method for directly increasing the pressure in the oil reservoir by forcedly injecting fluid such as carbon dioxide or water into the oil reservoir was used, but even though the above-mentioned technology is used, the output is raised only up to about 40 to 50% of an amount of oil deposits.

Since these facilities of subsea well require resources such as significant time, costs, manpower, and the like in installing the facilities once, it is advantageous to allow more crude oil, or the like to be produced from an oil reservoir which is already developed, rather than finding a new oil reservoir and constructing new facilities. Here, since the most reason that the output of crude oil, or the like is only up to about 40 to 50% of the amount of oil deposits within the oil reservoir is the pressure difference as described above, a research and an effort trying to increase the output of crude oil, or the like by further applying transfer pressure to deep seafloor equipments have been continuously made. As this example, there is also a method for increasing an amount of crude oil, or the like which is ultimately extracted into the manifold through the production tubing by installing a large pump on the flowline to further apply the pressure to fluid transferred from the x-tree and wellhead to the manifold. Alternatively, there is also a method for directly installing the above-mentioned pump on the production tubing.

However, several methods as described above have limits, of which the most limit is a compatibility problem with the existing facilities. In the case of the existing methods as described above, it was necessary to previously design at a point of time of initially constructing the deep seafloor oil and gas production system so that an additional equipment may be added later in order to additionally install the large pump, or the like. That is, the additional facilities of the additional equipment were possible only in the case in which a connection structure capable of connecting the additional equipment onto the flowline or the production tubing was previously formed at the time of the initial construction. In other words, in the case of a production system made without considering the additional facilities later, there is a problem that it is very difficult or impossible to apply the additional equipment.

[Related Art Document]

[Patent Document]

Korean Patent Laid-Open Publication No. 2015-0123975 (entitled "METHOD FOR DRILLING A PLURALITY OF SUBSEA WELLS FROM A STATIONARY FLOATING VESSEL, AN OFFSHORE DRILLING VESSEL, A DRILLING RISER TRANSPORT SYSTEM, AND AN OFFSHORE VESSEL" published on November 4, 2015)

An object of the present invention is to provide a robot and a method for installing a seafloor pressure control system that allow the seafloor pressure control system included in a flowline of gas and crude oil to control pressure of fluid within the flowline to be installed. Further, an object of the present invention is to provide a robot and a method for installing a seafloor pressure control system that allow the seafloor pressure control system to be efficiently and easily installed additionally to any existing deep seafloor oil and gas production system.

In one general aspect, a robot for installing a seafloor pressure control system includes: a body 151; a connection module 152 removably connecting a pressure control system 100 receiving power from the outside to the body 151; a propulsion module 153 receiving the power from the pressure control system 100 and pushing the robot to be movable to a flowline 515 included in a deep seafloor oil and gas production system; and an installation module 154 receiving the power from the pressure control system 100 and installing the pressure control system 100 on the flowline 515.

The installation module 154 may install the pressure control system 100 on the flowline 515 in a state in which a flow of fluid within the flowline 515 is maintained, using a hot tapping manner.

The pressure control system 100 receives the power from an offshore platform 500 included in the deep seafloor oil and gas production system, or receives the power from a subsea distributing unit 540 included in the deep seafloor oil and gas production system and receiving the power from the offshore platform 500.

A method for installing a seafloor pressure control system in which the pressure control system 100 is installed in a deep seafloor oil and gas production system including an offshore platform 500, a subsea distributing unit 540 receiving power from the offshore platform 500, and a flowline 515 transferring fluid including crude oil or gas extracted from an oil reservoir includes: an operation of mounting a pressure control system connecting the pressure control system 100 receiving the power from the offshore platform 500 through a first power line 101 to a body 151 of an installation robot 150 by a connection module 152 of the installation robot 150; a first movement operation in which a propulsion module 153 of the installation robot 150 receives the power from the pressure control system 100 to push the installation robot 150, and moves the installation robot 150 to the subsea distributing unit 540; an operation of connecting a second power line in which the pressure control system 100 is docked with the subsea distributing unit 540 by the movement of the installation robot 150, and the pressure control system 100 is connected to the subsea distributing unit 540 by the second power line 102 to receive the power; an operation of recovering a first power line in which the connection between the first power line 101 and the pressure control system 100 is disconnected, and the first power line 101 is recovered to the offshore platform 500; a second movement operation in which the propulsion module 153 receives the power from the pressure control system 100 to push the installation robot 150, and moves the installation robot 150 to the flowline 515; and an operation of installing a pressure control system in which an installation module 154 of the installation robot 150 receives the power from the pressure control system 100 and installs the pressure control system 100 on the flowline 515.

The method may further include: after the operation of installing the pressure control system, an operation of removing a pressure control system in which the connection module 152 disconnects the connection between the installation robot 150 and the pressure control system 100; and an operation of recovering an installation robot in which the installation robot 150 floats on a surface of water and is recovered to the offshore platform 500.

In the operation of installing the pressure control system, the installation module 154 may install the pressure control system 100 on the flowline 515 in a state in which a flow of fluid within the flowline 515 is maintained, using a hot tapping manner.

The method is performed for one flowline 515 one or more times, such that one or more pressure control systems may be installed on the flowline 515.

According to the present invention, transfer pressures at the respective units of the deep seafloor oil and gas production system are appropriately adjusted, thereby making it possible to ultimately much increase an output of crude oil and gas as compared to an existing output. More specifically, according to the present invention, the pressure control system controlling the transfer pressure is installed on the flowline transferring crude oil, gas, or the like in the deep seafloor oil and gas production system, thereby making it possible to perform various pressure controls such as increasing the transfer pressure to increase an output, decreasing the transfer pressure under the necessity such as preventing hardening of fluid, pipe erosion, or the like. Conventionally, the output is increased by simply additionally installing a pump. However, according to the present invention, there is a great effect that the pressure control system capable of pressurizing or depressurizing the transfer pressure is installed, thereby making it possible to improve the output and to improve overall system efficiency and lifespan at the same time.

Further, according to the present invention, there is a drastic effect that the above-mentioned additional facilities may also be applied to an existing production system which is made without previously considering the additional installation of the pressure control system, the pump, or the like during any amount of time. Conventionally, there was a problem that it is very difficult to add the facilities later in the case in which a design for the additional facilities is not previously made at the time of initially constructing the production system. However, by the method for installing a seafloor pressure control system according to the present invention, since there is no restriction or configuration required in advance in installing the pressure control system, it is possible to easily apply the method for installing a seafloor pressure control system to any existing production system, which results in drastically excellent compatibility as compared to existing pump added facilities.

FIG. 1 illustrates a basic configuration of a deep seafloor oil and gas production system.

FIGS. 2A to 2C illustrate exemplary embodiments of a robot for installing a seafloor pressure control system according to the present invention.

FIG. 3 illustrates an exemplary embodiment of a method for installing a seafloor pressure control system according to the present invention.

FIGS. 4 to 9 illustrate states of the respective operations of the method for installing a seafloor pressure control system according to the present invention.

FIGS. 10A and 10B illustrate work comparison graphs when one and a plurality of pressure control systems are used.

Hereinafter, a robot and a method for installing a seafloor pressure control system according to the present invention having the above-mentioned configuration will be described in detail with reference to the accompanying drawings.

Deep Seafloor Oil and Gas Production System

In order to clarify a position, an object, and the like that an installation robot according to the present invention installs a seafloor pressure control system, a configuration of a deep seafloor oil and gas production system will be first described in more detail. FIGS. 4 to 9 illustrate states of the respective operations of a method for installing a seafloor pressure control system according to the present invention, and the deep seafloor oil and gas production system is a configuration which is commonly illustrated in FIGS. 4 to 9.

The seafloor oil and gas production system is configured to include an offshore platform 500, an riser 505, an manifold 510, a flowline 515, an x-tree and wellhead 520, and a production tubing 525, as described in FIG. 1. The x-tree and wellhead 520 is installed on a seabed, and is connected to the production tubing 525 extended to an oil reservoir R to extract crude oil, or the like from the oil reservoir R to the seabed. The x-tree and wellhead 520 may be installed on each of the oil reservoirs R, and accordingly, a plurality of x-tree and wellheads 520 may be installed. The manifold 510 is connected to each of the plurality of x-tree and wellheads 520 by the flowline 515, and collects crude oil, or the like from the plurality of x-tree and wellheads 520. The crude oil, or the like collected in the manifold 510 is raised to the offshore platform 500 through the riser 505, which results in a production of the crude oil, or the like.

Meanwhile, several deep seafloor apparatuses such as the manifold 510, the x-tree and wellhead 520, and the like need to be supplied with power in order to perform a working of extracting or transferring fluid. More specifically, it is required to supply power for operating the above-mentioned apparatuses, and it is also required to supply hydraulic pressure in order to satisfy a pressure condition as required. Meanwhile, a mixture in which crude oil, gas, sand, water, and the like are mixed flows in the flowline 515, and in this case, there is a risk that the mixture is hardened because of a low temperature of a deep seafloor, which causes a pipe clogging. In order to avoid the above-mentioned risk, chemicals such as methanol, mono-ethylene glycol, and the like for preventing the hardening and facilitating a flow of fluid need to be further injected into the flowline 515.

Therefore, the deep seafloor oil and gas production system includes an incorporated supplying unit 530 for supplying the power, the hydraulic pressure, the chemicals, and the like as described above, and the incorporated supplying unit 530 is supplied with the power, the hydraulic pressure, the chemicals, and the like from the offshore platform 500 through an incorporated supplying line 535 (for reference, generally in a practical field, the incorporated supplying line 535 is also referred to as a umbilical cable, and the incorporated supplying unit 530 is also referred to as umbilical termination assembly (UTA)). The power, the hydraulic pressure, the chemicals, and the like supplied to the incorporated supplying unit 530 are distributed by a subsea distributing unit 540 according to a kind thereof, the subsea distributing unit 540 is connected to those requiring the power, the hydraulic pressure, the chemicals, and the like through the respective supplying lines 545 to supply the power, the hydraulic pressure, the chemicals, and the like (also for reference, generally in a practical field, the subsea distributing unit 540 is also referred to as a subsea distribution unit (SDU), and the supplying line 545 is also referred to as a flying lead (F/L)). That is, a specific form of the supplying line 545 may be varied depending on a resource to be supplied, for example, the supplying line 545 may also be a power cable, a hose supplying the hydraulic pressure, a line supplying the chemicals, and so forth.

Robot for Installing Seafloor Pressure Control System

FIGS. 2A to 2C illustrate exemplary embodiments of a robot for installing a seafloor pressure control system according to the present invention. A robot 150 for installing a seafloor pressure control system according to the present invention is an apparatus installing a pressure control system 100 on the flowline 515, and as illustrated in FIG. 2A, a remoted operated vehicle (ROV) used in a system such as an ocean exploration, an offshore drilling, and the like may be generally utilized. The ROV is an apparatus connected to a ship serving as a center plant through a wire to receive power and to be operated, and may include various tools and receive a control signal to perform various works. The tools included in the ROV may be variously and appropriately changed depending on a required work. For example, in the case in which the ROV is used for the work extending a cable to a desired position, the ROV may include a reel around which the cable is wound, and in the case in which the ROV is used for work such as cutting, welding, drilling, or the like, the ROV may include a tool such as a cutting machine, a welding machine, a drilling machine, or the like.

In an ocean industry field, as an apparatus similar to the ROV, an AUV which is wirelessly operated and receives a control signal to perform several types of work is also used, but since the AUV is operated using a battery as a power source, it has a significant limit in usable power, which may cause the AUV to perform only a light level of work. However, since the ROV is connected to the plant ship through the wire to receive the power, it may also perform work having a significant large load during any amount of time, that is, have higher availability. The installation robot 150 according to the present invention may be configured based on the above-mentioned ROV.

A configuration of the installation robot 150 according to the present invention will be described in more detail with reference to FIG. 2B. The installation robot 150 according to the present invention is configured to include a connection module 152, a propulsion module 153, and an installation module 154 in a body 151.

The connection module 152 serves to removably connect the pressure control system 100 to the body 151. The installation robot 150 is used to install the pressure control system 100 by moving the pressure control system 100 from the offshore platform 500 to the flowline 515. Therefore, after the pressure control system 100 is installed on the flowline 515, there is no necessity for the installation robot 150 to be continuously connected to the pressure control system 100. Rather, it is much preferable that the installation robot 150 is recovered to be repetitively used to install other pressure control systems 100. Accordingly, the installation robot 150 is removably connected to the pressure control system 100 by the connection module 152.

The propulsion module 153 serves to push the installation robot 150 so as to be movable to the flowline 515, and the installation module 154 serves to install the pressure control system 100 on the flowline 515. Since the propulsion module 153 has an original propulsion function which is already variously conducted in an existing ROV described above as various configurations, an existing configuration is properly selected. Further, the installation module 154 may include the cutting machine, the welding machine, the drilling machine, and the like required to do hot-tapping manner for the installation, and as described above, since the existing ROV also includes various tools to perform various types of work and is configured to be operated by receiving the control signal, an existing configuration may be properly selected.

One problem considered importantly in the installation robot 150 according to the present invention is a problem of how to supply the power to the pressure control system 100 after the pressure control system 100 is installed on the flowline 515. In an existing manner in which a pump was additionally installed on the flowline or a production tubing, as described above, since a design is performed by considering at a point of time of an initial system design that an additional installation is performed later, a consideration for a supply of power was also made. However, according to the present invention, since it is intended to provide the robot and the method for installing a seafloor pressure control system which may also be applied to a system without considering that the additional installation is performed later at the time of the initial design, in designing the installation robot 150 according to the present invention, only an installation function of the pressure control system is not simply considered, but it needs to be considered how the pressure control system receives the power and is able to be continuously operated after the installation of the installation robot 150.

According to the present invention, the pressure control system does not receive the power by directly connecting a power line to the installation robot 150, but it receives the power by connecting the power line to the pressure control system 100, and the installation robot 150 is configured to receive the power from the pressure control system 100, thereby solving the above-mentioned problem, that is, a continuous operation problem of the pressure control system after the installation thereof. Although a detailed description will be provided in the method for installing a seafloor pressure control system later, a simplified description will be provided herein. The pressure control system 100 is connected to the power line to receive the power from the outside, and the installation robot 150 is connected to the pressure control system 100 to receive the power from the pressure control system 100 to perform various types of work such as the propulsion, the installation, and the like. After the installation of the pressure control system 100 is completed, the connection between the installation robot 150 and the pressure control system 100 is disconnected. In this case, since the power line is still connected to the pressure control system 100, there is no problem in a continuous operation of the pressure control system 100 after the pressure control system 100 is installed.

That is, in summary, according to the related art, it was difficult for 'the system in which the additional installation is not considered later at the time of the initial design' to perform an additional installation and to solve a problem of how to supply the power to an additionally installed equipment. However, according to the present invention, since the pressure control system 100 is installed in a state in which the power line is connected to the pressure control system 100, there is no need for an additional process of drawing the power after completing the installation of the pressure control system 100, the operation of the pressure control system 100 may start immediately from a point of time at which the installation is completed, and the pressure control system 100 may also be continuously operated during any amount of time.

Meanwhile, in the case in which the connection between the installation robot 150 and the pressure control system 100 is disconnected, since the installation robot 150 is not supplied with the power, the operation of the installation robot 150 is stopped. The stopping of the operation of the installation robot 150 merely means that the installation robot 150 does not swim or drive in water, and the installation robot 150 may float onto a surface of water without a separate motion. As such, in the case in which the installation robot 150 floats onto the surface of water, the installation robot 150 may be easily recovered, and may be repetitively reused to install another pressure control system during any amount of time.

Another problem considered importantly in the installation robot 150 according to the present invention is a problem of how to an installation process itself such that it does not have a negative influence on a flow of fluid flowing within the flowline 515. In the case of 'the system in which the additional installation is performed later at the time of the initial design' according to the related art as described above, a proper area on the flowline is removably formed in advance, and valves are installed at both ends of the proper area. When it is intended to perform the additional installation, the flow of fluid within the flowline is stopped by closing the valves, a pipe of an area between the valves is removed, an equipment to be additionally installed is inserted between the valves, the valves are re-connected to each other, and the valves are then again opened, thereby making the fluid flow. As such, according to the related art, the fluid within the flowline needs to be stopped while not flowing during the additional installation process. In the case in which the fluid within the flowline, which is a mixture in which crude oil, gas, sand, water, and the like are complicatedly mixed, is left for a long time at a low temperature of the deep seafloor, the risk that the fluid is hardened is very high. In particular, when the fluid does not flow and is stopped, the risk of the above-mentioned hardening occurrence is further increased, which becomes a large problem causing the pipe clogging. That is, according to the related art, since the flow of fluid is stopped during the additional installation, the problem that a large bad influence such as the pipe clogging occurs was inevitably caused.

According to the present invention, in order to solve the above-mentioned problem, the installation module 154 installs the pressure control system 100 on the flowline 515 in a state in which the flow of fluid within the flowline 515 is maintained, using a hot tapping manner. The hot tapping manner, which collectively terms a tapping or a plugging for work such as a branching, a replacement, a repair, and the like without blocking the supply of gas, oil, steam, hot water, and the like within the pipe as described above, is a manner which is currently already widely used for the work such as the branching, the replacement, the repair, and the like of various pipes such as a gas pipe, a steam pipe, and the like of the ground. A detailed description of the hot tapping manner is well disclosed in 'HOT TAPPING & PLUGGING' page (link: http://www.kogas-tech.co.kr/kor/page.do?menuIdx=93) within an official website by the Korea Gas Technology Corporation. That is, the installation module 154 is configured to include tools such as a drilling machine, a welding machine, a blocking equipment, a finishing equipment, and the like used for the hot tapping.

As such, according to the present invention, since the installation module 154 performs the installation work while continuously maintaining the flow of fluid without stopping the flow of fluid, it is possible to obtain a large advantage that occurrence possibility of the pipe clogging due to the stop of the flow of fluid during the installation process is basically excluded, as described above. As well, since the hot tapping manner may be applied to any pipe, it may be applied to even 'the system in which the additional installation is performed later at the time of the initial design' without any problem. That is, since the installation module 154 installs the pressure control system 100 using the hot tapping manner, the additional installation of the pressure control system 100 may be easily performed for any existing system.

Method for Installing Seafloor Pressure Control System

FIG. 3 illustrates an exemplary embodiment of a method for installing a seafloor pressure control system according to the present invention, and FIGS. 4 to 9 illustrate states of the respective operations of the method for installing a seafloor pressure control system according to the present invention. The method for installing a seafloor pressure control system according to the present invention will be described in more detail for each operation with reference to FIGS. 3 to 9.

First, in an operation of mounting a pressure control system, the pressure control system 100 is connected to the body 151 of the installation robot 150 by the connection module 152 of the installation robot 150. In this case, as described above, the power line is connected to the pressure control system 100, and the installation robot 150 is configured to receive power from the pressure control system 100. More specifically, in this operation, the pressure control system 100 is configured to receive the power through a first power line 101 from the offshore platform 500.

Next, in a first movement operation, the propulsion module 153 of the installation robot 150 receives the power from the pressure control system 100 to push the installation robot 150, and moves the installation robot 150 to the subsea distributing unit 540. In this case, since the installation robot 150 receives the power from the pressure control system 100, and the pressure control system 100 is connected to the offshore platform 500 by the first power line 101 to receive the power from the offshore platform 500, a power source that operates the installation robot 150 may be the offshore platform 500.

Next, in an operation of connecting a second power line, as illustrated in FIG. 5, the pressure control system 100 is docked with the subsea distributing unit 540 by the movement of the installation robot 150. Accordingly, as illustrated in FIG. 6, the pressure control system 100 is connected to the subsea distributing unit 540 by a second power line 102. As a result, the pressure control system 100 may receive the power from the subsea distributing unit 540.

Next, in an operation of recovering a first power line, also as illustrated in FIG. 6, the connection between the first power line 101 and the pressure control system 100 is disconnected, and the first power line 101 is recovered to the offshore platform 500. In this case, even in a case in which the first power line 101 is recovered, since the second power line 102 is still connected to the pressure control system 100, the power is still stably supplied to the pressure control system 100.

Next, in a second movement operation, as illustrated in FIG. 7, the propulsion module 153 receives the power from the pressure control system 100 to push the installation robot 150, and moves the installation robot 150 to the flowline 515. In this case, since the installation robot 150 receives the power from the pressure control system 100, and the pressure control system 100 is connected to the subsea distributing unit 540 by the second power line 102 to receive the power from the subsea distributing unit 540, a power source that operates the installation robot 150 may be the subsea distributing unit 540.

Next, in an operation of installing a pressure control system, as illustrated in FIG. 8, the installation module 154 of the installation robot 150 receives the power from the pressure control system 100 and installs the pressure control system 100 on the flowline 515. In this case, the installation module 154 installs the pressure control system 100 on the flowline 515 in a state in which the flow of fluid within the flowline 515 is maintained, using a hot tapping manner, as described above.

At a point of time at which the installation of the pressure control system 100 is completed using the above-mentioned operations, as illustrated in FIG. 8, since the pressure control system 100 is connected to the subsea distributing unit 540 by the second power line 102, the pressure control system 100 is in a state in which it already stably receives the power. Unlike the related art in which after an additional equipment is installed, an additional process of separately drawing and connecting a power line is required, according to the present invention, since the method for installing a seafloor pressure control system was designed by considering the connection of the power line in advance, the pressure control system 100 may be smoothly operated immediately after the installation of the pressure control system 100 is completed while not requiring a separate additional process at all. Of course, since the pressure control system 100 is configured to receive the power from the subsea distributing unit 540 (which is an apparatus that originally supplies the power, or the like to various equipments of a seafloor system), stable power is continuously supplied to the pressure control system 100 even after the pressure control system 100 is installed, thereby making it possible to smoothly operate the pressure control system 100.

Meanwhile, since the installation robot 150 does not play any role any more after the installation of the pressure control system 100 is completed, it is preferable to recover the installation robot 150 in order to install another pressure control system. Accordingly, after the operation of installing a pressure control system, the following operations may be further performed.

First, in an operation of removing a pressure control system, the connection module 152 disconnects the connection between the installation robot 150 and the pressure control system 100. In this case, a connection that the installation robot 150 mechanically holds the pressure control system 100 is not only disconnected, but also a power connection between the installation robot 150 and the pressure control system 100 is disconnected. Therefore, after the operation of removing the pressure control system, the power is no longer supplied to the installation robot 150, and the operation of the installation robot 150 is completely stopped.

Finally, in an operation of recovering an installation robot, as illustrated in FIG. 9, the installation robot 150 floats on a surface of water and is recovered to the offshore platform 500. Even though the operation of the installation robot 150 is stopped as described above, the installation robot 150 includes a floating system using buoyancy, thereby making it possible to allow the installation robot 150 to float without the power. As such, when the installation robot 150 floats on the surface of water, the offshore platform 500 may easily recover the installation robot 150 using search and recover equipment, and the recovered installation robot 150 may be repetitively reused for installation work of another pressure control system for any amount of time.

The pressure control system 100 is installed on the flowline 515 by the operations as described above, wherein the operations are performed once for one flowline 515, such that one pressure control system 100 may be installed on the flowline 515, and alternatively, the operations as described above are performed many times for one flowline 515, such that a plurality of pressure control systems 100 may also be installed on the flowline 515.

First, as transfer pressure is increased, a recovery rate of crude oil is increased. As such, in the case in which a plurality of pressure control systems 100 are installed in series on one flowline 515, system efficiency may be significantly improved. FIGS. 10A and 10B illustrate work comparison graphs when one and a plurality of pressure control systems are used, where a vertical axis denotes pressure, and a horizontal axis denotes volume. In this case, a graph area is a work value consumed in increasing the pressure to target pressure. FIG. 10A illustrates a case in which the pressure is increased to the target pressure at once using one pressure control system, and FIG. 10B illustrates a case in which the pressure is finally increased to the target pressure by gradually increasing the pressure little by little in each of the pressure control systems using the plurality of pressure control systems. As instinctively seen from FIGS. 10A and 10B, the pressure is gradually increased using the plurality of pressure control systems, thereby making it possible to significantly reduce an amount of the work until the pressure reaches the target pressure. Actually, intercooling should be done between each pump for reducing the amount of the work. In the present invention, the pressure control systems 100 are installed at intervals on the flowline 515. Therefore intercooling is naturally done in fluid passing through the pipe and reducing the amount of the work is realized. That is, this means that the power to be supplied to the system is much saved, and particularly, a large energy saving effect may be obtained in a long-range view, thereby making it possible to ultimately obtain an effect improving the system efficiency.

Meanwhile, a function of the pressure control system 100 and an effect thereby will be described below in more detail. The pressure control system 100 has a pressurization function of simply increasing the transfer pressure, as well as a depressurization function. While it has been described above that the transfer pressure is increased to increase the recovery rate of crude oil, depressurization of the transfer pressure is required, as needed. In particular, as described above, since the plurality of pressure control systems 100 may be installed on one flowline 515, a pressurization operation or a depressurization operation is properly performed depending on a point at which the pressure control system is installed, thereby making it possible to further improve the system efficiency.

Pressurization Effect 1: At the most basic, the pressure control system 100 may obtain an effect of increasing the recovery rate of crude oil using a fluid boosting by pressurizing the transfer pressure.

Pressurization Effect 2: As described above, the gas, the sand, the water, and the like are mixed in the crude oil extracted from the oil reservoir. Among these, the sand, which is a solid, has relatively much high density as compared to other materials, and as a result, in a case in which speed of flow is not a predetermined degree or more, the sand sinks and is accumulated in the pipe, which may in turn disturb the flow. Therefore, the pressure control system 100 installs a position at which the sand accumulation frequently occurs to strongly pressurize the position and to sweep off the sand, thereby making it possible to obtain an effect of preventing the sand accumulation and a negative influence corresponding to the sand accumulation.

Pressurization/ Depressurization Effect: As described above, the fluid flowing within the flowline is in a mixture state in which liquid and gas such as the crude oil, the gas, and the like are mixed. As such, the mixture in which the liquid and the gas are mixed often causes a slug flow. The slug flow has a problem that causes life-shortening of the pipe by a fatigue by causing vibration to be generated in the pipe. The pressure control system 100 is installed at a position at which the slug flow frequently occurs to properly perform the pressurization or the depressurization and to prevent the occurrence of the slug flow, thereby making it possible to consequentially increase the lifespan of the pipe.

Depressurization Effect 1: A chock valve for adjusting a flow rate is installed on the flowline. As the flow rate is adjusted by the chock valve, the pressure may be locally and sharply decreased. However, in the case in which the pressure in the fluid is sharply decreased, the temperature is sharply decreased(this phenomenon is called 'Joule-Tompson cooling'). This hardens the fluid and generates gas hydrate called a so-called 'burning ice', which causes the pipe clogging. The pipe clogging problem due to the generation of the gas hydrate may occur in the vicinity of the chock valve as well as a section in which the pressure is sharply increased by a shape of the pipe, or the like. The pressure control system 100 is installed at the section in which the pressure is sharply increased to perform the depressurization, thereby making it possible to reduce the generation of the gas hydrate as described above and to ultimately prevent the pipe clogging problem.

Depressurization Effect 2: It is natural that the flowline is formed by mixing a plurality of straight line sections and curved sections. However, while the fluid flowing within the flowline passes through the curved sections, the sand mixed in the fluid strongly collides with inner walls of the curved sections, thereby causing a problem that fast erosion of the flowline is caused. The pressure control system 100 is installed at a position at which the erosion is caused to properly perform the depressurization and to reduce a phenomenon in which the sand collides with the inner walls of the pipe and the pipe is eroded, thereby making it possible to consequentially increase the lifespan of the pipe.

The present invention is not limited to the above-mentioned exemplary embodiments but may be variously applied, and may be variously modified by those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims.

[Detailed Description of Main Elements]

100: pressure control system

101: first power line 102: second power line

150: installation robot

151: body 152: connection module

153: propulsion module 154: installation module

500: offshore platform 505: riser

510: manifold 515: flowline

520: x-tree and wellhead 525: production tubing

530: incorporated supplying unit 535: incorporated supplying line

540: subsea distributing unit 545: supplying line

R: oil reservoir

Claims

A robot for installing a seafloor pressure control system, the robot comprising:

a body;

a connection module removably connecting a pressure control system receiving power from the outside to the body;

a propulsion module receiving the power from the pressure control system and pushing the robot to be movable to a flowline included in a deep seafloor oil and gas production system; and

an installation module receiving the power from the pressure control system and installing the pressure control system on the flowline.
The robot of claim 1, wherein the installation module installs the pressure control system on the flowline in a state in which a flow of fluid within the flowline is maintained, using a hot tapping manner.
The robot of claim 1, wherein the pressure control system receives the power from an offshore platform included in the deep seafloor oil and gas production system, or receives the power from a subsea distributing unit included in the deep seafloor oil and gas production system and receiving the power from the offshore platform.
A method for installing a seafloor pressure control system in which the pressure control system is installed in a deep seafloor oil and gas production system including an offshore platform, a subsea distributing unit receiving power from the offshore platform, and a flowline transferring fluid including crude oil or gas extracted from an oil reservoir, the method comprising:

an operation of mounting a pressure control system connecting the pressure control system receiving the power from the offshore platform through a first power line to a body of an installation robot by a connection module of the installation robot;

a first movement operation in which a propulsion module of the installation robot receives the power from the pressure control system to push the installation robot, and moves the installation robot to the subsea distributing unit;

an operation of connecting a second power line in which the pressure control system is docked with the subsea distributing unit by the movement of the installation robot, and the pressure control system is connected to the subsea distributing unit by the second power line to receive the power;

an operation of recovering a first power line in which the connection between the first power line and the pressure control system is disconnected, and the first power line is recovered to the offshore platform;

a second movement operation in which the propulsion module receives the power from the pressure control system to push the installation robot, and moves the installation robot to the flowline; and

an operation of installing a pressure control system in which an installation module of the installation robot receives the power from the pressure control system and installs the pressure control system on the flowline.
The method of claim 4, further comprising: after the operation of installing the pressure control system,

an operation of removing a pressure control system in which the connection module disconnects the connection between the installation robot and the pressure control system; and

an operation of recovering an installation robot in which the installation robot floats on a surface of water and is recovered to the offshore platform.
The method of claim 4, wherein in the operation of installing the pressure control system, the installation module installs the pressure control system on the flowline in a state in which a flow of fluid within the flowline is maintained, using a hot tapping manner.
The method of claim 4, wherein the method is performed for one flowline one or more times, such that one or more pressure control systems are installed on the flowline.