RU2731010C1 - Processing system for sea cluster drilling - Google Patents

Abstract

FIELD: soil or rock drilling.

SUBSTANCE: invention relates to deep-sea drilling from sea-going vessels and can be used in cluster prospecting, exploration and production drilling. Technological complex for sea cluster drilling is arranged on ship, made in the form of pontoon module, containing at least two cases, connected by inter-housing rigid structure, which is base for arrangement of drilling equipment. On each of transverse frames there installed is drilling frame arranged on compensators of oscillations. Drilling pits are provided in pontoon housings. In transverse and drilling frames there are wellhead holes above drilling shafts. Well is drilled in two stages – preparatory stage and borehole putting-down stage. At least on one of the drilling frames above the wellhead holes there are drilling units – installation for the preparatory stage of drilling with a drill pipe from pipes with detachable connections and installation for putting-down of borehole with a drill string of flexible continuous pipes. When drilling several wells each of the units can be transferred to another drilling frame arranged on the other transverse frame. At least one of transverse frames accommodates equipment common for all drilling rigs – flushing unit and unit for operation of equipment and tool.

EFFECT: increasing useful time of complex use and providing possibility of deep-sea drilling with improvement of environmental safety.

1 cl, 3 dwg

Description

It belongs to the field of deep-water drilling from offshore vessels and can be used for cluster prospecting, exploration and production drilling.

In deep-sea drilling of wells, a riser is used - a riser, designed to connect the ship's drilling equipment with a block of subsea wellhead blowout equipment installed on the surface of the well. A drill string is placed inside the riser.

It is envisaged to install a derrick with a drilling rig on the ship and use a drill string composed of split pipes. At the bottom wellhead, a blowout preventer is placed, controlled from the vessel. The specificity of offshore drilling is that the position of the derrick and the drilling rig changes along with the vibrations of the vessel. At the same time, the load on the rock cutting tool changes, which worsens the working conditions, reducing the resource. Vibrations of the vessel adversely affect the technical condition of the riser. To ensure optimal operating conditions for the riser and drilling equipment and tools, it is required to equip the vessel with compensators for longitudinal and lateral movements.

Known installation for deep-water drilling with a riser and the technology used in this (Gamsakhurdia G.R., Vaynerman M.I., Basovich D.V., Bachurin A.A. "Technology of exploratory drilling for oil and gas from a drilling research vessel "Technical sciences: theory and practice: materials of the II international scientific conference (Chita, January 2014). - Chita: publishing house" Young scientist ", 2014. - pp. 65-74; http: //moluch.ru/conf/tech/archive/88/4697/). For tripping operations, a drilling rig with a crown block and a traveling block with an upper power drive moved along vertical rails, a candle receiver, a hook on which a swivel-stuffing box is suspended, connected by a sleeve with a riser of a flushing pump, and a rolling table are used. On the drilling deck there is a control panel, drawworks, rotor, wrenches for making up drill pipes, as well as a winch for the core receiver and geophysical equipment. The use of drawworks with the mode of active compensation of vertical movements of the vessel during rolling is provided. In the bow of the vessel, on the 2nd deck, there is a hold for riser sections, and in the stern there are stocks of casing and drill pipes. In the bow, on the main deck, there are research laboratories, below them in the hold there is a core storage. In the aft part, behind the drilling rig, in the hold there are technological complexes for the preparation of drilling and cement slurries. Between the drilling and main decks, under the tower, there is a room for placing large-sized equipment: a drill pipe funnel, underwater wellhead equipment. In the center of the vessel in the hold there is a drilling shaft designed to accommodate the upper part of the riser, and its lower part is connected to a block of downhole bottom wellhead equipment.

The drilling technology in this article assumes that at the preparatory stage of work on split drill pipes with threaded connections (TPC), a direction (guiding articulated self-aligning centering device) is lowered and buried into the sea bottom, assembled with a funnel for re-entering the drill string into the well, drilling is carried out until target depth, then the drill pipes are raised. The wellhead is cased and cemented, creating a conductor. A blowout preventer unit and a control system are connected to the conductor.

The riser is assembled and installed and its upper part is connected to the ship drilling rig, and the lower part to the blowout preventer of the conductor. The main stage of drilling - hole deepening (bottomhole movement under the action of a rock cutting tool on rocks) - is performed using a drill string located inside the riser. The string at both stages of drilling is composed of high-strength TRS and is connected to downhole mechanisms with rock cutting tools.

The specified technical solution does not address the issue of vessel stability and riser performance. The solution is not intended for single hole drilling. When drilling the next well, the ship moves to a new point.

The design of the vessel used for drilling is determined by the requirements for stability and the required carrying capacity, which depends on the depth of the sea and the depth of the wells. Drilling technology places increased demands on the positioning of the vessel at the drilling point. Therefore, the use of the vessel for drilling is reduced due to the limitations of the meteorological conditions.

Catamaran-type vessels appear to be a promising type of vessels for deep-water drilling (https://studwood.ru/1285847/geografiya/morskie_burovye_ustanovki_burovye_suda). Compared to single-hull ships of the same displacement, they have a number of advantages: higher stability (the amplitude of the side roll of the catamaran is 2-3 times less than that of single-hull ships), which makes it possible to work in strong sea waves (the working time coefficient of double-hull ships is greater than single-hull, at least 25%); a significantly larger (by 50%) usable deck area (since the interhull space is used), which makes it possible to place the required amount of heavy large-sized drilling equipment on the deck with a shallow draft and high maneuverability, and place the equipment more balanced.

Known floating platform for drilling wells according to French patent No. 2244665 (IPC В63В 35/44, Е21В 17/01, Е21В 7/128, prior. 09/21/1973, publ. 04/18/1975), consisting of two hulls connected by a platform above them and the platform has a shaft opening in which the swivel fitting is supported by a gimbal and, in turn, supports a freely suspended drill string, which serves to connect the vessel to the wellhead equipment of the deep water well.

Also known is a semi-submersible drilling platform of the catamaran type according to RF patent No. 2529098 (IPC В63В 35/44, В63В 35/34, Е21В 43/01, prior. 10.12.2012, publ. 27.09.2014). Surface deck superstructures of the platform are made in the form of drilling, technological, power modules and functional blocks.

Known modular complex for engineering and geological research according to claim 5 of the patent of the Russian Federation No. 32291 (IPC G01V 1/38, В63В 35/00, prior. 05/07/2003, publ. 07/05/2003), which is a floating craft made in the form of a self-propelled or a non-self-propelled multi-hull pontoon module containing at least two hulls connected by inter-hull bridges, and a working platform for placing technological equipment. The equipment of the drilling complex includes a drilling rig, racks for casing and drill pipes, a crane.

The listed drilling systems are designed for drilling single wells and can only be used at shallow sea depths.

The closest to the proposed complex is a multi-crane platform for drilling and production of natural gas and oil at sea under French patent No. 2298474 (IPC В63В 35/44; Е02В 17/02; Е21В 15/04, prior 27.01.1975, publ. 20.08. 1976), which is intended for cluster drilling. On the catamaran-type floating craft, a superstructure is provided that connects two parallel hulls, on which crane installations are located symmetrically to the left and right sides, serving one, two, three or four wells. Reducing the time required to drill several wells occurs due to the simultaneous operation of several similar crane installations. Crane installations have large dimensions and lifting capacity, since they act as drilling rigs during round-trip operations. The platform is installed on the seabed on 4-8 supports, which in the transport position are raised and fixed on the floating craft. During drilling, the drill strings are placed inside the supports. The supports are not rigidly connected to the bottom equipment, are not isolated from the aquatic environment and are not equipped with blowout preventers. Drilling from the platform can only be carried out at shallow depths. Traditional drilling technology is used, i.e. the drill string is made up of TRS. The used drill pipes have connections, the outer diameter of which exceeds the diameter of the pipe body. Therefore, the drill string assembled from such pipes is not smooth-bore and is not balanced in weight. During operation, the column rotates at a high frequency inside the supports.

Technological complexes for deepwater cluster drilling are unknown.

A riser must be used for deep water drilling. During rotation of an unbalanced drill string and tripping operations inside the riser due to torsional shocks and vibration loads, the string mechanically affects the riser, leading to a decrease in its reliability and, accordingly, to a decrease in the environmental safety of drilling operations (danger of water pollution), and on borehole walls, which reduces their stability. In addition, due to the rigidity of the drill string, the vibrations of the vessel during rough seas are transmitted to the rock cutting tool. This excludes the fulfillment of the main technological condition - maintaining the constancy of the axial load on the rock cutting tool, which reduces its resource and leads to more frequent tripping operations. To reduce fluctuations, ship compensation systems are used, which are structurally complex and expensive. Due to the strong influence of vessel vibrations during rough seas, there are restrictions on the hydrometeorological conditions of use (wind and waves of the water surface), which significantly reduces the time of using the vessel directly for drilling operations. This reduces the economic efficiency of offshore drilling operations. And, finally, in offshore drilling, the traditional method uses the same structurally complex large-sized heavy energy-intensive equipment as onshore. This leads to an increase in windage and a decrease in the stability of the vessel. Maintenance of equipment requires a lot of labor, time and material costs.

The technical problem is to increase the time of use of the drilling complex for cluster drilling and to ensure the possibility of deep-water drilling while ensuring environmental safety.

The technical objective of the invention is to develop a technological complex for deep-water cluster drilling, having high stability, equipped with drilling equipment, which makes it possible to rationally organize work simultaneously on several wells, thereby increasing the useful life, reducing the mechanical effect of the drill string on the riser and ensuring the constant load on the bottomhole ...

A technological complex for cluster drilling is proposed, in which a vessel is used as a drilling vessel, made in the form of a self-propelled pontoon module containing at least two hulls connected by an inter-hull rigid structure, on which drilling equipment of two types is located - for traditional drilling with a drill string made of TRS and for drilling with drill string made of continuous coiled tubing (CT). To reduce the influence of meteorological conditions and increase stability, it is advisable to make the ship semi-submersible.

The use of two different types of drilling rigs on one ship - an umbilical (with a flexible reinforced hose of great length) with a turbodrill and a rotary one - is known (A.V. Lukoshkov "Technique for the study of the seabed." ). But in this solution, installations of different types are used independently of each other, each for drilling a well using the same technology from start to finish. The umbilical is for continuous face drilling, and the rotary one is for core drilling with the help of light-alloy split pipes with removable core receivers.

The offered complex allows drilling wells in two stages.

Traditional equipment with a drill string made of TRS is used only at the preparatory stage (surface drilling and cementing, wellhead construction and installation of a riser and blowout preventer).

The stage of the deepening of a deep-water well is produced by a drilling device using a drill string made of gas turbine, i.e. it is proposed to use coiled tubing technology at the deepening stage. GNT is smooth-bore and does not rotate while drilling. In addition, the HNT drill string is lighter than the TPC drill string. This minimizes the mechanical impact of the string on the riser and on the wellbore walls.

The need to use traditional technology at the preparatory stage is caused by a large number of trips with heavy riser sections, casing pipes and bottom equipment. The use of coiled tubing technology in such works would significantly reduce the resource and reliability of the gas pipeline string.

While one of the wells has completed the preparatory stage, the preparatory stage (PC) is released and can be used to drill the next well. At the same time, the first well is being deepened using a coiled tubing unit with gas turbine pumping. This makes it possible to rationally use the equipment of two types for work simultaneously on several wells. Therefore, the entire volume of drilling operations takes less time.

The rigid structure connecting the hulls of the ship consists of at least two transverse frames fixed to the pontoon hulls, connected by a longitudinal frame. An additional pontoon can be placed under the longitudinal frame to increase strength and stability.

On the transverse frames there are the ship's heave compensators. The drilling rigs are located above the pontoon bodies on drilling frames mounted on expansion joints. There are drilling shafts in the pontoon bodies. In the transverse frames and in the drilling frames installed on them, wellhead holes are provided above the shafts. The riser is connected to the vessel through blowout preventers and an emergency disconnect unit from the vessel. When deepening the well, the drill string from the gas pipeline is located inside the riser.

At least one of the transverse frames is equipped with a UE and an installation for a deepening (UU). Each of the installations is made with the ability to place it in a working position above the shaft to accommodate the wellhead of the riser, and after completing the task, move it within one frame or to another frame to perform the next task. After the completion of the preparatory stage with the help of the UE, the CU can be moved to a position above the shaft, to which a riser is connected, installed above the drilled well and connected to its conductor. The number of transverse frames and installations of each type is determined by the drilling tasks. Since it takes more time to deepen the wells than to complete the preparatory stage, to perform the necessary drilling operations on a given cluster of wells, more CUs may be needed than CUs.

Rigs for each of the stages of drilling contain drilling equipment, a drill string and rock cutting tools.

At least one of the transverse frames contains equipment that is common to the UP and CU. The main units of the common equipment are: a flushing unit containing a pumping group and a system for collecting and cleaning drilling mud, connecting all wells, and a unit for working with equipment and tools that are used for installation and auxiliary work. The unit includes a winch, telpher, racks for drill and casing pipes, riser sections, downhole mechanisms and rock cutting tools.

UE contains a drill string made of TRS, a downhole mechanism with a rock cutting tool and a ship's part, including an oil derrick with a crown block, a traveling block with a hook, a drawworks winch, a drill string rotator (for example, a rotor or top drive) and a swivel with a leading pipe. In non-working position, the tower can be folded to increase stability. In arctic conditions, it is also important to reduce the volume of heated equipment.

UU contains a drill string from GNT. The column is connected to the downhole mechanism. The downhole mechanism includes a hydraulic downhole motor of a rotary type, a hydraulic hammer and a rock cutting tool. The marine part of the installation contains a wellhead block and a winch for GNT with lowering and lifting brakes, a GNT stacker-cleaner, a continuously variable drive and a flushing seal. The wellhead block includes a gander (bent guide for gas pipelines), a drill string centralizer with a straightening device and a flaw detector, a pipe hanger for gas pipelines (injector) and a blowout preventer. The flaw detector must have a connection with the winch control system to fix the emergency section of the gas pipeline.

All UE and UU are connected with a flushing unit containing a pumping group and a system for preparation, collection and cleaning of drilling mud, which is used when drilling in the traditional way with a well-controlled well.

The GNT column must be in anticorrosive wear-resistant design. The column is composed of flexible pipes with different wall thicknesses with decreasing thickness towards the bottom of the column.

A turbodrill or downhole drilling motor (PDM) can be used as a rotary hydraulic downhole motor. When drilling vertical wells, it is preferable to use a turbodrill, and when drilling directional and horizontal wells, a PDM.

The technical result of the proposed solution is to increase the useful time of the complex and ensure the possibility of deep-water offshore cluster drilling while ensuring environmental safety. This is achieved through the rational placement, movement and use of two types of installations - with TRS and with GTP - and use at the stage of deepening of coiled tubing. The complex allows you to combine different stages of work in time. While preparatory work is being carried out at one of the wells, a deepening is being carried out at the other. Since the traditional method of drilling from the wellhead is used only at the preparatory stage (when driving a smaller part of the well depth), drilling requires equipment (derrick, drawworks, etc.) with a lower carrying capacity and, accordingly, smaller dimensions and energy consumption than would be required when drilling on the entire depth of the well only from the HRS. Accordingly, the stability of the vessel is increased by reducing the height of the drilling equipment and its weight. Due to the use of coiled tubing while deepening the well, the mechanical effect of the drill string on the riser and on the wellbore walls is reduced. As a result of increasing the stability of the vessel and reducing the mechanical impact on the riser, the environmental safety of deep-water drilling increases. The dynamic positioning system is simplified. The design requirements for the vessel are reduced. The rational placement and simultaneous use of the two types of rigs also reduces the total number of rigs and shortens the total operating time. In general, the economic efficiency of cluster deepwater drilling is increasing.

Additional advantages of using a hydraulic hammer are to reduce the value of the required axial load on the rock cutting tool, to ensure a given direction of the well, and to improve bottomhole cleaning from cuttings when drilling horizontal sections of the well. The hydraulic hammer, due to the rotation and flow of the drilling fluid, creates a shock-rotary effect on the bottom of the well at low values of the load on the rock cutting tool, much less than when using only a rotary type motor, increasing the axial load. The resource of rock-cutting tools is increased, due to which the number of round-trip operations is reduced and, accordingly, the resource of the gas pipeline string and the efficiency of the installation as a whole increase.

FIG. 1 shows a layout of drilling equipment on a ship for a variant when a rigid structure contains three transverse frames.

FIG. 2 shows the rig for the preliminary stage of drilling (UP).

FIG. 3 shows the installation for deepening the well (UU).

The pontoon bodies 1 are connected by transverse ship frames 2. The transverse frames 2 for rigidity are interconnected by the longitudinal frame 3. In the frames 2 at the locations of the drilling rigs there are holes for the drill string. Cross frames 2 can be combined into a common working platform.

In the initial position, UU 4 is located, for example, in position 1-1 on the first transverse frame, and UU 5 is in position 1-2 on the same frame. On one of the transverse frames 2, there is a flushing unit 6 containing a pumping group and a system for collecting and cleaning drilling mud (not shown in the drawing) and a unit 7 for working with equipment and tools (includes a winch, telpher, racks, etc.). Pump group 6 must contain variable speed drive pumps, at least one of which must be a spare.

It is possible to place a general technological unit on one of the transverse frames, including a control panel, a power unit, a geophysical unit, racks for storing pipes and drilling tools and an assembly site, a warehouse for chemicals, oils and working fluids, a center for preparation and cleaning of drilling mud, mud settling tanks and sludge containers, laboratory unit and core storage, mechanical repair section. These blocks can also be placed on different parts of the boat.

UE 4 contains an oil derrick 8 with crown block 9, traveling block 10, hook 11, swivel-stuffing box 12, riser 13 with a hose 14 connecting the UE hydraulic line with pumping group 6, drawworks 15 with a gearbox, drill string rotator 16, lead pipe 17 and the drill string 18 from TRS. A downhole mechanism 19 is connected to the drill string 18, to which the rock cutting tool 20 is connected. To raise and lower the tool and equipment, a winch 21 is used, included in block 7. During the preliminary stage of drilling, the drilled wellhead section of the well cased and cemented, forming a conductor 22. A riser 24 is connected to the conductor through a bottom set of equipment 23 (includes a wellhead with a preventer and a control system for it, a flexible assembly with a riser and a sealing device; not shown in the drawing).

UU 5 contains a column of GNT 25, wound on a winch for GNT 26 with a flushing gland 27 connected to the pumping group 6, a wellhead block connected to the column of GNT 25, and a downhole mechanism. To raise and lower the tool and equipment, a winch 21 is used, which is included in block 7. The winch for GNT 26 should be equipped with lowering and lifting brakes, an orderly reeling and reeling system with a continuously adjustable reversible drive and a hollow shaft for connection with a flushing gland 27. Oil seal 27 it is advisable to complete it with a flushing fluid flow meter. An installation for coiling-coiling should be provided to replace the worn out or damaged part of the GTP string. The wellhead unit includes a blowout preventer 28, a tubing-feeder GNT 29 with a guide funnel (not shown), a gander 30 and a centralizer 31 GNT with a straightening device (not shown). The wellhead unit can also include a GNT cleaner from dirt, cuttings, collecting it in a container and moving it away from the wellhead. The downhole mechanism contains a hydraulic downhole motor 32 of a rotary type and a hydraulic hammer 33 and a rock cutting tool 34. It is advisable to provide in the composition of the UU 5 video cameras located in the wellhead block and in the bottom wellhead equipment.

Above the hydraulic downhole motor 32, a hydraulic or mechanical loader can be placed, which creates an axial load on the rock cutting tool and a shock absorber of axial and torsional vibrations, which reduces the effect of torsional loads on the tubing string.

On the outer surfaces of the rotary-type engine and the hydraulic hammer, 2-3 expander-centralizers are placed. To the upper part of the engine 32, a string of GNT 25 is attached, which is unwound from the winch 26, and is passed through the gander 30, the feed pipe holder 31, the centralizer 29 and the blowout preventer 28.

The design of the upper part of the gander 30 and the clamping devices of the pipe-feeder 31 should exclude mechanical damage to the GNT when it comes off the winch drum 26 and winding on it. To determine the load on the rock cutting tip on the gander, it is advisable to install an indicator of the weight and length of the launched GTP. It is necessary to keep records of the number of GNT trips to control and predict the service life of the GNT string.

To prevent the ingress of foreign bodies into the downhole motor, a filter should be used in the GNT string. For the same purpose, filters can be installed in the flushing gland 27 and in the rotary type hydraulic downhole motor 32. A check valve can be installed in the hammer 33 for the same purpose.

A turbodrill or downhole drilling motor (PDM) can be used as a rotary hydraulic downhole motor.

The engine 32 is connected to the GNT string 25 by an emergency disconnecting adapter (not shown), and to the hydraulic hammer 33 through a swivel adapter with an emergency disconnecting unit (not shown). A damper (not shown) is placed between the hydraulic downhole motor 32 of the rotary type and the hydraulic hammer 33. Before deepening the well, UU 5 is connected to the riser 24 through the ship's set of equipment 35 (the set includes a hinge that excludes friction of the gas pipeline string and associated parts of the ship, a vessel vibration compensator, a sealing device with a guide bell, a flexible coupling, a riser tension system, an emergency disconnect assembly from the riser; not shown in the drawing).

UE 4 and UU 5 are installed on the drilling frames 36, placed on each of the ship frames 2, above the corresponding holes in it for the drill string. Drilling frames 36 are mounted on vibration compensators 37, in turn mounted on each of the frames 2.

In the process of deepening, UU 5 is placed above the upper part of the riser 24 installed at the preparatory stage. UU 5 is connected to the riser 24 through the sealing device of the ship equipment 35 of the riser 24. The riser 24 is connected to the conductor 22 through the bottom equipment set.

The technological complex works as follows.

In the transport position, both types of drilling rigs are located at opposite ends of the drilling frame 36 mounted on the first transverse frame 2. The HTP string is in a mothballed state on the winch drum 26 (for example, it can be filled with inert gas and closed with plugs). Before starting work, the GTP column will be de-mothballed.

1. After positioning the vessel at a given point of work, a preparatory stage of drilling the first well is carried out with the help of UE 4. UE 4 is connected to the pumping group 6. Drilling is performed in bottom rocks to the design depth. To do this, a direction assembled with a funnel for re-entering the drill string into the borehole is lowered and buried in the bottom of the sea. After that, the wellhead is cased and cemented, forming a conductor 22. A bottom set of equipment 23 with a preventer and a control system for it is lowered to the TPC and attached to the conductor 22. The riser 24 is lowered and assembled section by section and connected to the bottom set of equipment 23 and the ship's set equipment 35. Raise the drill pipes.

2. After the completion of the preparatory stage at the first well, the UP 4 is moved with the help of the winch 21 to the drilling point of the next well. At the same time, the UE is disconnected from the pumping group 6 and, after moving, is reconnected to the pumping group 6. A preparatory stage is performed at the next well.

3. After completing the preparatory stage at the second point, the UE 4 can be moved using the winch 21 drilling in a similar way to the third well.

4. UU 5, located on the first drilling frame 36, located on the transverse frame 2, with the help of a winch 21 is moved to the operating position above the riser 24 installed on the first well and connected to the riser through the ship's equipment set 35. Connect UU 5 to the pumping group 6 and the well is deepened. To do this, a downhole tool (consisting of a rotary hydraulic downhole motor 32 and a hydraulic hammer 33 and a rock cutting tool 34) is assembled with the help of a winch 21 and fixed in a pipe holder 29. The type of hammer and rock cutting tool is selected depending on geological conditions.

5. After the end of the deepening of the first well, the freed UU 5 is moved with the help of a winch 21 to the point of drilling of the next well at which the preparatory stage is performed, connected to the pumping group 6 and the deepening of this well is made.

6. In the same way, the third well is deepened using UP 4 and UU 5.

This order can be repeated, if necessary, with moving the units to the next frames. At all stages of work, it is necessary to ensure the balance of the load on the vessel to maintain its stability, for which, while drilling, the drilling rigs must be on opposite sides of the catamaran. Since the time for deepening the well with the help of the CU exceeds the time of using the CU, the latter during the operation of the CU can perform the preparatory stage of drilling in several planned wells. In the idle position, the holes in the drill frames are closed.

Thus, cluster drilling of several wells is realized with one vessel localization. The number of holes that can be drilled depends on the number of transverse frames.

Let's consider the operation of the proposed drilling complex for a specific option, when the pontoons are connected by two transverse frames.

In the transport position, UP 4 is fixed in position 1-1 (Fig. 1), and UU 5 above the hole in the drilling frame 36 in position 1-2.

At the beginning of drilling the first well in position 1-1 with the help of UE 4 located on the first of the transverse frames 2, a drill string from TRS 18, downhole mechanism 19, pumping group 6 and other equipment are prepared for operation.

The preparatory stage of drilling is carried out in the traditional way. The direction is connected with a guide funnel, which ensures the alignment of the well and the running string 18, and it is lowered onto the TRS until it reaches the seabed. The direction is deepened using a drill string rotator 16. Then, using a rotator 16, drilling is performed in hard rocks to the casing depth of the wellhead. The casing depth is selected to ensure trouble-free operation of the blowout preventer. With the help of TPC, a string of casing pipes is lowered and cemented, forming a conductor 22.

The lower bottom sealing device 23 with a blowout preventer and a control device is lowered onto the TPC and attached to the conductor 22. The riser 24 is assembled and lowered section by section and connected to the blowout preventer assembly of the bottom sealing device 23. The riser 24 is connected through the upper sealing device of the set 35 with the vessel to provide communication with the wellhead of the offshore well.

Upon completion of the assembly of the riser 24, the TPC plugs raised on the ship are disassembled and placed on racks. During assembly, the riser 24 is equipped with a tension system and vibration compensators.

Disconnect the riser 13 from the hydraulic line 14 of the pump group 6.

UE 4 is unfastened and with the help of a winch 21 is moved diagonally from position 1-1 to the opposite end of the second transverse frame 2 to position 2-2 above the hole in the drilling frame 36 and secured.

UU 5 using a winch 21 is moved from position 1-2 to position 1-1.

Let us consider the operation of UU 5 for the variant with a turbodrill.

UU 5 is positioned and fixed in the operating position 1-1 above the riser 24. The flushing gland 27 is connected with the pumping group of the unit 6. The drilling fluid is cleaned or replaced in the drilled well and in the riser 24. Hydraulic hammer 33 with the rock cutting tool 34 attached to it is winches 21 for working with the tool are passed through the pipe-feeder 31 and fix it inside the pipe-feeder. The turbodrill 32 is grabbed from the rack using a winch 21 and connected to the hydraulic hammer 33. In this case, the shaft of the turbodrill 32 is connected to the shaft of the hydraulic hammer 33 through a hinge adapter with a damper and an emergency disconnect unit. Turbodrill 32 is connected to a column of GNT 25, wound on a winch drum 26.

The pumping group of block 6 is started and after the establishment of continuous circulation of the flow of drilling fluid in the well, the pipe-feeder 31 is loosened and the downhole mechanism is lowered until the bottom of the well is reached. Start deepening the borehole, while adjusting the speed of winding the string GST 25 from the winch drum 26 and the flow rate and pressure drop of the drilling fluid. To maintain a constant load on the rock cutting tip, including during vertical vibrations of the vessel, the retraction speed must be synchronized with the vertical movement of the gas pipeline passing through the feed pipe hanger 31. Since the rotation of the drill string is excluded when using the technology of drilling with gas turbine, the control of the drilling process is simplified. This allows the use of an automated computerized system, which reduces the likelihood of accidents, increases work safety and reduces the risks of technology disruption.

In the process of drilling, the drilling fluid passes through the stators of the turbodrill 32, the fluid flow swirls and its speed increases. In the rotors of the turbodrill 32, the kinetic energy of the flow is converted into the energy of rotation of the shaft connected to the hydraulic hammer 33. When the hydraulic hammer 33 rotates due to the valve periodically shutting off the fluid flow, a short-term hydraulic impulse arises, which is transmitted to the rotating rock cutting tool 34, which ensures the effective operation of the rock cutting tool when lower axial loads. The formation of a "slurry cushion" at the bottom is excluded. At the same time, drilling (expansion) of the wellbore takes place by the value of the difference between the diameters of the turbodrill 32 and the hydraulic hammer 33 with the simultaneous calibration of the well in diameter. The pulses arising in the hammer 33 are damped in the damper and are not transmitted to the turbodrill 32, which ensures the reliability of the turbodrill. The hammer can provide both coring and full-hole drilling.

The work of the control device occurs in a similar way when using the PDM.

While the UU is deepening the well 1-1, the UU is conducting the preparatory stage of drilling the well in position 2-2.

At the end of the preparatory stage, the released UE 4 from position 2-2 is transferred to position 1-2 and the preparatory stage of drilling is carried out.

After the end of the stage of the deepening in position 1-1, the UU is transferred to position 2-2 and the well is deepened 2-2.

Upon completion of the work of UE 4 in positions 1-2, it is transferred to position 2-1 and the preparatory stage of drilling is carried out at this point, after which it is transferred to one of the free positions (1-1 or 2-2). After completing the groove in position 2-2, UU 5 is transferred to position 1-2 and the groove is carried out.

After deepening wells 1-2, the CU is moved to position 2-1 and the well is deepened.

In the process of deepening, it is advisable to periodically assess the condition of the inner surface of the riser using a video camera lowered on the GTP string.

The combination of design parameters of downhole motors (rotary hydraulic motor and hydraulic hammer), flexible pipes, and a flushing gland should provide a well flushing mode with a minimum hydrostatic pressure of the drilling fluid with the condition of complete cleaning of the bottomhole from cuttings and maintaining the stability of the well walls and its straightness.

In case of cluster drilling with an increase in the number of risers connecting the vessel with simultaneously drilled wells, the rigidity of this connection increases, which can lead to an accident in case of sea waves. To avoid this situation, the possibility of emergency disconnection of the vessel from each riser must be provided. The connection between the riser and the vessel must be articulated. When drilling exploratory wells after the completion of work, the risers and the bottom set of equipment are dismantled with the help of UE, returned to the place of the UU, which completed the deepening.

Drilling equipment extending beyond the level of the upper deck can be sheltered from the adverse effects of the external environment by protective cages installed on the upper deck with a heating system for their internal volume.

The proposed drilling complex allows you to combine various stages of exploration and production operations, to speed up and simplify emergency operations and to ensure environmental safety.

One of the advantages of the coiled tubing technology used in the complex is the ability to continuously flush the well during tripping operations, including during geophysical surveys.

When drilling with coring, tripping operations with the help of a drill string made of gas turbine are carried out faster than with the help of a drill string made of tubing.

Claims (1)

A technological complex for offshore cluster drilling, located on a ship, made in the form of a self-propelled pontoon module containing at least two hulls connected by an inter-hull rigid structure, which is the basis for placing drilling equipment, characterized in that the inter-hull rigid structure contains at least two transverse frames connected by a longitudinal frame, at least one of the transverse frames contains a flushing unit containing a pumping group and a system for preparation, collection and cleaning of drilling mud, and a unit for working with equipment and tools, including a winch, telpher and racks, in housings pontoons, drilling shafts are provided, on each of the transverse frames a drilling frame is installed, placed on vibration compensators, at least one drilling frame is equipped with a device for the preparatory stage of drilling and a device for deepening the well, installed with the ability to move, a device for preparing stage of drilling contains an oil rig with a crown block, a traveling block with a hook, a drawworks, a swivel with a leading pipe, a drill string rotator, a drill string, a downhole mechanism with a rock breaking tool, and the drill string is made up of pipes with detachable joints, the installation for deepening the well contains gander, wellhead block, including a drill string centralizer with a straightening device and a flaw detector, a feed pipe hanger and blowout preventers, a drill string made of continuous flexible pipes, a winch for continuous flexible pipes with launch and ascent brakes, with a continuously variable drive, a stacker cleaner pipes and a flushing gland and a downhole mechanism, including a rotary-type hydraulic downhole motor, a hydraulic hammer and rock cutting tool.

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