RU2405917C1 - Bore-well system of oil and gas production from offshore fields and method of system application - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: system comprises underground tunnel, marine riser part sealed under ground and connected to tunnel, pipeline for transportation of products from well to shore, additional pipelines, also for provision of independent functioning of system. Tunnel is laid from shore under sea bottom towards the field. Wellhead is installed and equipped in tunnel with the possibility of further access and service at the tunnel side. With the help of tunneling equipment or by other method, underground tunnel is erected under sea bottom. Tunnel is connected to marine riser installed into sea bottom, inside of which the well is drilled. Lower part of string is removed in tunnel interval, underground wellhead is piped and connected to underground pipeline. Upper part of marine riser is removed for complete underground isolation of the system.

EFFECT: improved environmental safety of oil and gas production from marine fields.

15 cl, 10 dwg

Description

The invention relates to the field of development of oil and gas deposits lying under the seabed.

A known method of using the system for offshore oil and gas production, including drilling and completion of the first well in the first section of the wellhead, drilling, installing casing pipes in the second section of the wellhead, lowering the operating module with the product pipeline and connecting to the second section of the wellhead, followed by drilling and completion of the second well, production of the product from the first well through the manifold and the operating module in the second section of the wellhead while continuing to drill the second wells / RU 2191888 C2, IPC 7 Е21В 43/013, ЕВВ 33/05, В63Н 25/00, Е21В 7/128, publ. 10/27/2002 /.

There is a method of underwater development of oil and gas fields, including drilling a well from a floating drilling platform, installing a sealed chamber, inside which there are fountain fittings, connecting it to shore facilities using a tunnel laid along the bottom of the sea / K. Yablokov. and other searches, exploration and exploitation of mineral deposits of the seabed. - M .: "Nedra", 1975. - S.171-172).

Known methods for developing offshore oil or gas production for deposits in shallow water areas have disadvantages due to unstable bottom soils, currents and difficult ice conditions (ice drift), for example, such as the Gulf of Ob and the Taz Bay of the Kara Sea. Traditional solutions for the construction of stationary platforms and bulk bases include ice protection, strengthening rock fillings, etc. Underwater production systems with placement of wellhead harnesses and collection systems at the bottom of the sea are also not quite applicable due to the frequent passage of ice hummocks scraping the bottom during the ice drift.

Known offshore drilling rig, including the wellhead and oilfield equipment installed in the tunnel under the bottom of the sea / RU 2001135365 A, IPC EV 21/128, publ. 10/27/2002 /. The wellhead is located in a monolithic vertical trunk, protruding above the surface of the sea to a height equal to the height of the maximum storm wave. The floating platform is mounted on the protruding part of the trunk. At the level of the wellhead in the wellbore there is an exit to the tunnel, in which equipment and a pipeline are installed to divert the extracted oil to the surface.

A disadvantage of the known offshore drilling rig is a monolithic vertical trunk protruding above the surface of the sea, and its inapplicability as a stationary installation for production in conditions of currents with the passage of massive ice hummocks.

The construction and subsequent operation of known methods causes irreparable damage to the environment, especially in freshwater natural complexes.

The task to which the claimed technical solution is directed is to develop a method and system for oil and gas production on the seabed, providing for the safe conduct of work and further operation.

When carrying out the invention, the task is solved by achieving a technical result, which consists in improving the environmental safety of oil and gas production from offshore fields.

The specified technical result for the facility - the device is achieved by the fact that the mine-borehole system for oil and gas production from offshore fields or sections of fields lying under the sea bottom contains an underground tunnel (or a network of tunnels) laid from the coast under the sea bottom in the direction of the field , a well (or a system of wells), the mouth of which is located and equipped in the tunnel with the possibility of subsequent access and maintenance from the side of the tunnel, a part of the riser column sealed under the bottom, connected with a tunnel through which the indicated well was drilled, while in the tunnel there is a pipeline (or a network of pipelines) designed to transport products from the well to the shore.

A shaft-well system for producing oil and gas from offshore fields may have the following additional features.

The riser may additionally have helical guides on the outer wall of the column for efficient and accurate screwing into the bottom of the sea.

An underground tunnel (a system of tunnels or mines) can be filled with air and have equipment that allows people to be safely in the tunnel.

An underground tunnel (a system of tunnels or mines) may have underground galleries of an increased size (relative to the diameter of the tunnel) in places of concentration of downhole and other equipment.

A well (or a system of wells), the mouth of which is located and equipped in the tunnel with the possibility of subsequent access and maintenance from the side of the tunnel, may have an increased diameter, a multi-column structure and several faces in the interval of the reservoir.

Wells, the mouths of which are located in the tunnel (galleries), can be grouped into bushes from several wells with acceptable technological gaps between the underground mouths.

A pipeline (or network of pipelines) located in a tunnel may include several pipelines, including collection and injection lines, high and low pressure lines, separate phase transport lines, etc.

An underground tunnel (a system of tunnels or mines) can be used to arrange communications such as electrical cables, ventilation systems, communication lines, etc., as well as communications designed for autonomous functioning.

The specified technical result for the facility method is achieved by the fact that the method of using the mine-well system for oil and gas from offshore fields or sections of deposits lying under the bottom includes the construction of an underground tunnel (or network of tunnels) under the bottom, the installation of a riser with a deepening in the bottom having the upper - water separating and lower - underground parts, the connection of the tunnel with the underground part of the water separating column, drilling a well through the water separating column, removal after completion of the storm borehole of the lower - underground part of the riser in the tunnel interval to gain access to the underground wellhead and its strapping, development of the well, removal of the upper - water separator of the riser for complete underground isolation of the system, connect the well to the pipeline laid in the tunnel, and transfer the product from the well through the pipeline to the shore.

The method of using the mine-well system for oil and gas production from offshore fields may have the following additional features.

The riser is installed in a rotational shock or other way into the bottom from a floating platform, which may have precise positioning and orientation means to ensure through passage of the riser through a previously constructed tunnel.

Tunneling is carried out using accurate positioning and orientation means to ensure its docking with a riser previously installed in the bottom from a floating platform and additionally performed the function of studying a geological section.

The emptying of the in-annular space of the well is carried out by lowering the level of the filling fluid in the well below the level of the tunnel by increasing the density of the filling fluid without providing back pressure on the reservoir.

Well development (inflow call) is carried out using a vertical flare line installed on the underground wellhead piping and ending on a floating platform.

The underground part of the riser remaining after drilling the well, located above the wellhead, is used as a beaker for subsequent round-trip operations when servicing the well, for which it is expanded to a larger diameter.

The method provides for the possibility of simultaneous operation of previously drilled wells and the drilling of subsequent wells.

Between the claimed technical result and the essential features of the invention there is the following causal relationship. All elements of a mine-well system for extracting oil and gas from offshore fields, when used, are completely isolated from natural complexes of the water area and the bottom and are located at a sufficient depth below the ground (bottom), namely an underground tunnel (or a network of tunnels) laid from the coast under bottom of the sea in the direction of the field; a well (or a system of wells), the mouth of which is located and equipped in the tunnel with the possibility of subsequent access and maintenance from the side of the tunnel; a pipeline (or a network of pipelines) located in the tunnel for transporting products from the well to the shore; communications and equipment located in the tunnel, including to ensure the autonomous functioning of the system. A water separating column connects the floating platform and the tunnel, which ensures complete environmental safety of standard technological operations for drilling a well. In this case, when applying (forming) a system of mine-borehole oil and gas production, a tunnel is built under the sea bottom without causing environmental damage to the environment. Technological operations to remove the bottom part of the riser column after completing drilling of the well in the interval of the tunnel to gain access to the underground wellhead, to tie it and connect the well to the underground pipeline, to remove the upper - water separating part of the riser column, ensure complete underground isolation of the system and its subsequent environmentally friendly operation.

The well-borehole system for extracting oil and gas from offshore fields and the method of its use (formation) are illustrated by the drawings, in which Fig. 1 schematically shows a well-borehole system for extracting oil and gas from offshore fields, figure 2-10 describes in detail use (formation) of a mine-well system for oil and gas production from offshore fields.

Figure 1 shows a hydrocarbon field 1 under the sea floor (h ₁ - sea depth 3-15 m); underground tunnel (mine) 2 (or a network of tunnels) located at a considerable distance from the coast, laid at a depth of h ₂ - 50-80 m below the sea bottom in the direction of the field (the depth of the underground tunnel is determined by the stability and geological structure of the rocks of the upper part of the sedimentary cover , the estimated laying depth is shown); floating platform 3; a riser column (riser) 4, substantially (more than 50-80 m) buried in the bottom and passing through tunnel 2; a guiding column through which the well 5 is drilled through the internal cavity of the riser 4 installed at a distance L ₁ from the shore; a well 6 completed by drilling, having an underground mouth 7 and a piping connected to a pipeline 8 laid in a tunnel 2 for transporting products 9 from a well 6 to the shore; underground part 15 of the riser (riser) 4.

Figure 2 shows the construction process of the underground tunnel 2 under the sea floor. During its construction, standard methods are used, including a mining technique 10, which may have means of precise positioning and orientation. The depth of the tunnel 2 is determined by the stability and geological structure of the rocks of the upper part of the sedimentary cover, the estimated depth of the laying of 50-80 m under the sea bottom. In the process of laying the tunnel 2, its walls are sealed and strengthened (including concrete) also by standard methods, it is possible to construct a drainage system. The diameter of tunnel 2 depends on the technological capabilities of the equipment and on the estimated throughput of tunnel 2 (diameters and number of pipelines, communications, etc.). The standard diameter of the tunnel is 5 m. The length of tunnel 2 will be determined by technical and economic criteria, the deviation of L _{2 from the} bottom of the well from the vertical. The estimated technologically possible length of tunnel 2 is several tens of kilometers.

Figure 3 shows the installation process of the riser 4 (riser) 4, which is a hollow pipe made of high strength steel with a standard diameter of 1-1.5 m. The riser 4 (riser) 4 is installed from a floating platform 3, which may have means for accurate positioning and orientation. A feature of the method is the deepening of the water separating column (riser) 4 into the bottom of the sea and its connection with the tunnel 2. This forms the upper - water separating and lower - underground parts of the water separating column (riser) 4. The length of the lower - underground part of the water separating column (riser) 4 can be greater than the length of the upper - water separating part. Through passage of the water separating column (riser) 4 through the tunnel 2 can provide a positioning system. The process of installing the water separating column (riser) 4 can be carried out by shock-rotational or other means, for which the water separating column (riser) 4 can additionally have spiral guides on the outer wall of the column for its efficient and accurate screwing into the bottom of the sea. When approaching the lower point of the riser 4 (riser) 4 to the tunnel 2, the final positioning and preparation of the process windows for the through passage of the riser 4 (riser) 4 through the tunnel 2 is performed. The riser 4 can also act as a pile foundation for subsequent fixing of the floating platform 3.

Figure 4 shows a process similar to that shown in figure 3. At the same time, the lower - the underground part of the water separating column (riser) 4 passes through the gallery 13 of tunnel 2.

Figure 5 shows the construction process of the "tunnel-water separation column" system, in which the tunnel 2 is laid using accurate positioning and orientation means to ensure its connection with the water separation column (riser) 4, previously installed from the floating platform 3. This method eliminates possible collapse of the tunnel 2 when performing the operations shown in figure 3-4. At the same time, the water separating column (riser) 4 can be installed in advance and preserved by disconnecting the upper - water separating part of the water separating column (riser) 4 and sealing the lower - underground part of the water separating column (riser) 4 with a cover. In the process of installing the water separating column (riser) 4 in advance, the tasks of geological exploration of the section in the area of the future tunnel 2 can be additionally solved, for which the lower part of the water separating column (riser) 4 must be equipped with the necessary devices (not shown).

Figures 6 and 6a show the operating state of the riser 4 (riser) 4 for installing and drilling the well, with the upper riser 14 of the riser 4 and the lower underground portion 15 of the riser 4 connected to each other friend. Both parts of the riser 4 (riser) 4 have flanges that are connected using bolts 16 and have o-rings 17.

Fig.6b-6g shows the process of separation after completion of the well drilling of the upper - water separating part 14 of the water separating column (riser) 4 and sealing the lower - underground part 15 with the cover 19. To do this, unscrew the bolts 16 and tighten the cap screws 18, then install the cover 19 and bolted by bolts 16, after which the upper - water separating part 15 of the water separating column (riser) 4 can be removed. The process can be performed in the reverse order, in the case of reconnecting the upper - water separating 14 and lower - underground 15 parts of the water separating column (riser) 4.

7 schematically shows the process of drilling a well 5. To perform technological operations for drilling a well 5, a guide column 20 is installed inside the riser 4 (riser) 4. Then, in the process of building the well 5, standard methods and materials are used, the necessary technological equipment located, for example , on a floating platform 3.

On Fig shows the state of the system after drilling and obtaining safe access to the underground mouth 7 of the well 5. To do this, it is necessary to empty the in-pipe space of the well 5 by lowering the level of the filling fluid 21 in the well 5 below the level of the tunnel 2, for example, by increasing the density of the filling fluid 21 without backpressure on the reservoir. After that, part 22 of the lower - underground part 15 of the riser column (riser) 4 in the interval of the tunnel 2 is removed, the upper part of the guide column 20 is cut off and raised to the surface.

Figure 9 shows the process of developing well 5 (inflow call) using a vertical flare line 23 installed on the underground wellhead piping of well 5 and ending on a floating platform 3. The inflow and development of well 5 are called by standard methods. In case of additional intensification of the inflow or repair of the well 5, work can be carried out from the floating platform 3.

Figure 10 shows the process of final preparation of the well 5 after successful development. On the underground mouth 7 install the rest of the equipment, which can be standard. In accordance with the operations previously shown in Fig.6b-6d, the process of separating the upper - water separating part 14 in the interval of the tunnel 2 is carried out to gain access to the underground mouth 7 of the well 5 and sealing the lower - underground part 15 with the cover 19. The cover 19 may be located at a depth of 3-5 m below the bottom of the sea. For complete underground isolation of the system and its subsequent environmentally friendly operation, the upper part 14 of the riser column - riser 4 is removed. If necessary, the riser part 14 can be installed again. The lower - the underground part 15, remaining after drilling the well 5 and located above the wellhead 7, can be further expanded and used as a beaker for subsequent tripping and lifting operations when servicing the well.

Upon completion of work through pipeline 8, which may have several production lines (collection and injection lines, high and low pressure lines, separate phase transport lines, etc.), products from well 6 are fed ashore for further transportation. In this case, it is possible to simultaneously carry out the drilling of the next well in the described manner, moreover, the well (or system of wells) may have an increased diameter, a multi-column structure and several faces in the interval of the reservoir. Wells can be grouped into clusters from several wells with admissible technological gaps between underground mouths. In places of concentration of downhole and other equipment, underground tunnel 2 (or a network of tunnels) can have underground galleries 13 of an increased size relative to the diameter of tunnel 2. For people to be safely in the underground tunnel (or network of tunnels), it can be filled with air. In an underground tunnel (or tunnel network), electrical cables, ventilation systems, communication lines, etc., as well as communications intended for autonomous functioning, can be located.

Thus, the claimed mine-borehole oil and gas production system and the proposed method for its use provides environmental safety for the environment, are relevant and promising for offshore fields, as well as deposits located offshore in water areas and river deltas, in severe climatic conditions.

Claims (15)

1. A well-borehole system for extracting oil and gas from offshore fields or sections of fields lying under the sea floor, containing an underground tunnel (or network of tunnels) laid from the coast under the sea bottom in the direction of the field, a well (or system of wells), the mouth which is located and equipped in the tunnel with the possibility of subsequent access and maintenance from the side of the tunnel, the underground part of the riser connected to the tunnel through which the indicated well is drilled, while being in tone the pipeline (or network of pipelines) is not located, designed to transport products from the well to the shore. 2. The well-borehole system for oil and gas production according to claim 1, characterized in that the water separating column additionally has helical guides on the outer wall of the column for its efficient and accurate screwing into the bottom of the sea. 3. The mine-well system for oil and gas according to claim 1, characterized in that the underground tunnel (a system of tunnels or mines) is filled with air and has equipment that enables people to be safely in the tunnel. 4. The well-borehole system for oil and gas production according to claim 1, characterized in that the underground tunnel (a system of tunnels or mines) has underground galleries of increased size relative to the diameter of the tunnel at the concentration of the borehole and other equipment. 5. The well-borehole system for oil and gas production according to claim 1, characterized in that the well (or well system), the mouth of which is located and equipped in the tunnel with the possibility of subsequent access and maintenance from the side of the tunnel, can have an increased diameter, multi-column design and several faces in the interval of the reservoir. 6. The mine-well system for oil and gas according to claim 1, characterized in that the wells, the mouth of which is located in the tunnel, are grouped in clusters of several wells with permissible technological gaps between the underground mouths. 7. The mine-well system for oil and gas production according to claim 1, characterized in that the pipeline (or network of pipelines) located in the tunnel includes several pipelines, for example, collection and injection lines, high and low pressure lines, lines separate transport phases. 8. The mine-well system for oil and gas according to claim 1, characterized in that the underground tunnel (a system of tunnels or mines) is used to arrange such communications as, for example, electric cables, ventilation systems, communication lines, as well as communications, designed for autonomous system operation. 9. The method of using the mine-borehole system for oil and gas production from offshore fields or sections of deposits lying under the bottom, including the construction of an underground tunnel (or network of tunnels) under the bottom, the installation of a riser with a hole in the bottom, with an upper - water separating and lower - the underground part, the connection of the tunnel with the underground part of the riser, drilling a well through the riser, removing after completion of drilling the bottom - underground part of the riser in shaft tunnel to access subsurface wellhead and its piping, well completion, removal of the upper - side riser riser for complete subterranean insulation system, the connection to the well conduit, laid in the tunnel, and transferring the product from the well through a pipeline to shore. 10. The method of using the mine-borehole system according to claim 9, characterized in that the riser is installed in a rotary shock or other way into the bottom of a floating platform that has precise positioning and orientation means to ensure through passage of the riser through a previously constructed tunnel. 11. The method of using the mine-borehole system according to claim 9, characterized in that the tunnel is laid using precise positioning and orientation means to ensure it is docked with the riser previously installed in the bottom from the floating platform and additionally performed the function of studying the geological section. 12. The method of using the mine-borehole system according to claim 9, characterized in that the devastation of the in-pipe space of the well is carried out by lowering the level of the filling fluid in the well below the level of the tunnel by increasing the density of the filling fluid without providing backpressure to the reservoir. 13. The method of using the mine-borehole system according to claim 9, characterized in that the development of the well is carried out using a vertical flare line installed on the underground wellhead piping of the well and ending on a floating platform. 14. The method of using the mine-borehole system according to claim 9, characterized in that the lower - underground portion of the riser remaining after drilling the well, located above the wellhead, is expanded to a larger diameter and used as a beaker for subsequent tripping operations when well maintenance. 15. The method of using the mine-borehole system according to claim 9, characterized in that it provides for the possibility of simultaneous operation of previously drilled wells and the drilling of subsequent wells.

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