RU2726742C1 - Method for elimination of flowing wells at offshore wells with underwater location of wellheads thereof - Google Patents

Abstract

FIELD: oil, gas and coke-chemical industries.SUBSTANCE: invention relates to oil and gas production and geological exploration. Aim of the invention is the operation to guide the underwater shut-off wellhead assembly (hereinafter referred to as the USWA) at the mouth of the gushing well with its underwater location by a set of executive technological equipment located according to the operational plan for emergency rescue operations at safe distances from the mouth of the flowing well in marine conditions, providing buoyancy of sea vessels, as well as improving the efficiency of guidance technology. Set goal is achieved by a method of eliminating open fountains on offshore wells with underwater location of their mouth using sea vessels, having equipment of rope tools and located at the required safe distance from the mouth of the flowing well, as well as using a wave roll compensator. At that, guidance of underwater shut-off wellhead assembly (USWA) is carried out remotely, by placing at some distance, afts from each other, two sea crane vessels. USWA is placed in metal frame with hydraulic station installed in it, which actuates remotely controlled hydroelectrical winches, which is docked with set of sealed pontoons, which provide change in weight of induced USWA depending on degree of sparseness of water thickness above well due to filling, or displacement, with water used as ballast. At final stage of guidance process, produced by synchronized actions of rope systems of sea crane vessels, guided USWA is engaged with blow out preventer equipment of flowing well using a remote unmanned underwater vehicle (RUUV) by executing instructions sent from a board of a floating crane.EFFECT: invention is intended for elimination of open fountains of oil-and-gas wells at underwater location of their wellhead.1 cl, 2 dwg

Description

The invention relates to oil and gas production and geological exploration industries and is intended to eliminate open oil and gas fountains at offshore facilities.

There is a known method of guiding blowout equipment at the mouth of a gushing well, located on an offshore stationary platform and having the necessary horizontal areas for the installation of cable equipment, in which a crane vessel serves blowout equipment into the stream of a gushing well and lowers it to the mouth (1).

In the known method, spontaneous vertical movements of the blowout preventer equipment together with the vessel under the action of waves are compensated by the use of a free hanging load as a traction mechanism. In this case, the sequence of work is as follows:

- the directed blowout preventer is lifted and moved away from the gushing stream with the help of the main crane vessel;

- the free hanging cargo is lifted by an auxiliary vessel;

- carry out strapping of the elements of the circuit with rope equipment;

- the free hanging cargo is lowered by the auxiliary vessel;

by the main crane vessel blowout preventive equipment is fed into the stream of flowing wells and lowered at the wellhead.

However, the known method of directing blowout equipment at the wellhead of a flowing well has a number of disadvantages:

- the method is designed to guide the blowout preventer equipment to the surface wellhead from fixed offshore platforms;

- the scheme for guidance of blowout preventers is not intended for guidance at offshore facilities with subsea wellhead location;

- in the event of a fire of the ejected borehole fluid during the guidance of blowout equipment, there is no possibility of the crane vessel moving away from the mouth of the gushing well to a safe distance;

- in the event of griffin formation around the mouth of a gushing well, there is a danger of a decrease in the density of water due to its rarefaction in the area of the location of ships and, as a result, their losses (may sink) when aiming blowout equipment at the mouth of a gushing well;

- the likelihood of a high concentration of explosive gases and their subsequent ignition in the area of the crane vessel.

There is a known method of guiding blowout equipment during the elimination of open fountains at offshore facilities, including strapping the layout and hanging it above the mouth using a floating crane (2).

However, the known guidance method has the following disadvantages:

- the method is designed to guide the blowout preventer equipment to the surface wellhead from fixed offshore platforms;

- there is a risk of sparks and subsequent ignition of a gas-polluted well near the wellhead zone with crane vessels located in this zone;

- the scheme for guidance of blowout preventers is not intended for guidance at offshore facilities with subsea wellhead location;

The purpose of the invention is to carry out an operation to guide an underwater shut-off wellhead assembly (hereinafter referred to as PZUS) at the mouth of a gushing well with its underwater location by a complex of executive technological equipment, located according to the operational plan for performing emergency rescue operations at safe distances from the mouth of a gushing well in sea conditions, ensuring maintaining the buoyancy of sea vessels, as well as increasing the efficiency of the guidance process technology.

This goal is achieved by the method of eliminating open gushers in offshore wells with an underwater location of their mouths using sea vessels equipped with cable rigging and located at the required safe distance from the mouth of a flowing well, as well as using a wave compensator, characterized in that guidance underwater shut-off wellhead assembly (PZUS) is carried out remotely, by placing at a certain distance, stern from each other, two sea crane vessels, due to the lack of the possibility of their placement directly above the axis of the emergency mouth, in order to ensure vertical access to the wellhead, due to arising during the gushing of a well, high rarefaction of seawater from the incoming gas fluid, which causes a dangerous risk of loss of buoyancy of ships and possible flooding, while the PSS is placed in a metal frame with a hydraulic station installed in it, which is remotely actuated controlled hydraulic winches, docked with a set of sealed pontoons, which provide a change in the weight of the induced PZUS depending on the degree of rarefaction of the water column above the well due to their filling, or displacement, with water used as ballast, and at the final stage of the guidance process, produced by synchronized actions of cable systems of marine crane vessels, the guided PZUS is coupled with the blowout prevention equipment of a gushing well using a remotely controlled unmanned underwater vehicle (ROV) by executing commands sent from the board of the floating crane.

In FIG. 1 shows a diagram of the location and completeness of technological equipment for the safe conduct of the operation of targeting the PZUS at the mouth of a gushing well; in fig. 2 - PZUS, assembled complete with pontoons and equipped with hooks for gripping for the assembly of the air defense of the flowing well

The layout of the machinery and equipment includes TNLA 1, two floating crane vessels 2, equipped with their own tackle system, including a carriage 3 with a chain hoist system 4, hydraulically controlled winches 5 for moving the carriage and a surge compensator 6 for locking wellhead assembly 7. The chain hoist system 4 includes three traveling blocks 8, two of which are fixed on the carriage, tied with a steel cable 9 through the wave heaving compensator block 6. The shut-off wellhead assembly 7 is fixed in a metal frame 10 (Fig. 2), equipped with four vertically arranged pontoons 11 for moving seawater into as ballast when submerging and pumping out in the case of lifting the guided arrangement, a hydraulically controlled winch 12 with two suspended free-hanging hooks 13 for centering and guiding the shut-off wellhead assembly onto the gripper 14 of the gushing mouth, as well as a hydraulic station 15 with the ability to control the shut-off bodies both from the ship and and from TNLA.

Work on the elimination of the fountain, due to the need to guide the shut-off wellhead assembly using crane vessels, is carried out in the following order.

On the leeward side, two floating crane vessels 2 aft relative to each other are located at a safe distance from the explosion and gas safe zone arising from the gushing wellhead. On the mounted carriage 3 of displacement with installed traveling blocks 8 through the pulley system 4, steel cables 9 with hydraulically controlled winches 5 are strapped.Using a crane mechanism (not shown in the diagram), the PZUS 7 is lowered onto the water surface, connected to the wave compensator 6 and suspended on the block of the pulley system 4 carriages of movement 3. All traveling blocks 8 are equipped with safety devices (not shown in the diagram) against possible spontaneous falling of the steel cable 9 from the groove of the block.

Floating crane vessels 2 diverge to a safe distance L from the zone of influence of the gas jet, the layout of the PZUS 7 is lowered by unwinding the steel cable 9 from the hydraulically operated winch 5 through the chain hoist system 4 to a certain depth L2, necessary to ensure its stability and compensate for wave heaving. Floating crane vessels are displaced relative to the gushing axis, positioning the CCD relative to the mouth at a distance L1. The ROV 1 is activated and, executing commands from the board of the floating vessel, turns on the control station 15, the hydraulically controlled winch 12, hooks the suspended free-hanging hooks 13 to the air defense body, after which the pulling winches drag the PZUS onto the gripper of the wellhead with its subsequent closure. Then, the ROV, with the help of a hydraulic station, opens the side outlets of the PZUS and closes the well, after which it alternately closes the side outlets, stopping the free outflow of the well fluid from its wellhead.

The proposed method for eliminating open fountains at offshore facilities with an underwater wellhead was modeled and successfully tested in conditions as close as possible to real ones at the Training Range in Astrakhan.

Sources of information

1. Patent for invention No. 2161691 "Method for aiming blowout equipment and device for its implementation", Moscow, 10.01.2001

2. Patent for invention No. 2149978 "Method for guiding blowout equipment in sea conditions", Moscow, 27.05.2000.

Claims (1)

A method for eliminating open fountains in offshore wells with an underwater location of their mouth using sea vessels equipped with cable rigging and located at the required safe distance from the mouth of a gushing well, as well as using a wave heaving compensator, characterized in that the guidance of an underwater shut-off wellhead assembly (PZUS) is carried out remotely, by placing at a certain distance, aft from each other, two sea crane vessels, due to the lack of the possibility of their placement directly above the axis of the emergency mouth, in order to provide vertical access to the wellhead, due to the reason arising when gushing of a well, high rarefaction of seawater from the incoming gas fluid, which causes a dangerous risk of loss of buoyancy of ships and possible flooding, while the ESP is placed in a metal frame with a hydraulic station installed in it, which drives remotely controlled hydraulic winches, butt bathroom with a set of hermetically sealed pontoons, providing a change in the weight of the guided PZUS depending on the degree of rarefaction of the water column above the well due to their filling, or displacement, with water used as ballast, and at the final stage of the guidance process, produced by synchronized actions of cable systems of marine crane vessels , carry out the coupling of the guided PZUS with the blowout preventer equipment of the gushing well using a remotely controlled unmanned underwater vehicle (ROV) by executing commands sent from the board of the floating crane.

Images