SU1792482A3 - Method of gas-hydrate underwater production - Google Patents

Description

The invention relates to methods for up to 1 liter of liquid or gaseous fluids at level wells.

A known method of producing gas hydrate from the sea by drilling with a hollow pipe, in the bottom of which the gas hydrate together with bottom sediments is raised to the surface in the form of cylinders of a single, non-indigenous core sample 1. Such>: is inefficient and suitable for producing experimental samples in egg quantity, since it is related to the convergence of raising and lowering again the pipe for lifting core samples, moreover, gas hydrate is not amenable to usual transportation to the place of combustion, because on the surface at atmospheric pressure I and a temperature close to 15 ° rapidly decomposes into gases and water.

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Scientific research institute It should be explained that gas hydrate is a frozen ice-like mass of combustible gases and fresh water located in huge quantities at the bottom of the seas and oceans under a pressure of about 30 atm. and above and a temperature of about 0 ° C. In view of the foregoing, the storage of gas hydrate on the surface in a ship is complicated and unsafe due to the possible accumulation and ignition of gas.

The purpose of the invention is to increase the efficiency and safety of production and transportation of gas hydrate.

This goal is achieved by the fact that the method of underwater production of gas hydrate includes drilling and lifting along the pipe string of products to the surface, after grinding the gas hydrate, underwater three-stage heating is performed to obtain the final decomposition products; gas and water; in this case, primary heating is carried out while the annular space is overlapped by a dome-shaped element that opens under the influence of gas pressure obtained as a result of the primary decomposition of gas hydrate; the third heating stage is carried out in a separator located on the shelf.

The method is illustrated using the installation shown in the drawing.

The installation includes a subsea drilling rig 1, a hollow drill pipe 2 with windows 3, a screw auger 4, a dome-shaped element 5, a heating element 6, a flexible pipe 7, a heating tank 8, a heating element 9, an underwater pipe 10, a condensate pump 11, vertical separator tank 12, gas pipeline 13, freshwater water supply 14, power station 15, warm water discharge pipe 16.

The installation works as follows. Drilling rig 1 pre-lowered into place. Production from a special vessel. Drill pipe 2 with windows, 3 and auger head 4 drills the bottom and penetrates the cavity with gas hydrate. The well can be drilled in advance during exploratory drilling. As a drilling rig, well-known drilling rigs modernized for underwater drilling can be used, for example, a domestic drilling rig of the BGA-2,3 brand (M. S. Safonov and other BGA-2,3 drilling rig - M .: Nedra, 1966). Drilling auger head 4 crushes and crushes ice of gas hydrate, pumping it under a dome-shaped element 5. The dome-shaped element 5 in the folded state, mounted on bearings (not shown) on the pipe 2, is lowered after the head 4. Inside the dome-shaped element 5, heating elements 6 are mounted, which, when lowering the dome-shaped element into the cavity with gas hydrate, are connected to the electric current and heat up. In this case, the dome-shaped element 5 is opened under the pressure of the injected gas hydrate and closes the well exit. As a result of heating, crushed ice under the dome-shaped element 5 under internal pressure enters through the windows 3 into the hollow pipe 2 and pipe 7, from where it goes on to the heated container 8.

In this tank, the second stage of heating from the elements 9 takes place, as a result of which the snow-like mass of the gas hydrate turns into a gas-liquid mixture - the pulp. The pulp under internal pressure moves through the pipeline 10 and enters the vertical container-separator 12. The latter is a large cylinder, in the upper part of which there is an expanding part - a gas holder. This part goes directly to the warm surface layers of water. In the tank 12, the last stage of heating and separation (separation) of water and gas takes place. In this case, the heat of coastal waters is used for heating. Gas accumulates in the upper part of the tank 12, from where it passes through the gas pipeline 13 to the hydroelectric power station where it is burned. Fresh water is pumped out from the bottom of the same tank by pump 11 and goes to technological needs. Waste warm water is drained through the pipeline

16. Electric cables and other communications are laid along the bottom near the main gas pipeline.

Claims (2)

Φορ-mule of invention 1. A method of underwater production of gas hydrate, including drilling and lifting along a string of pipes of products to the surface, characterized in that, in order to increase the efficiency and safety of production and transportation of gas hydrate, after grinding the gas hydrate, underwater three-stage heating is performed to obtain the final decomposition products of gas and water while primary heating is carried out while overlapping annular space with a dome-shaped element that opens under the influence of gas pressure obtained in ultate primary gas hydrate decomposition. 2. The method of pop. 1, characterized in that the third stage of heating is carried out in a separator located on the shelf.