Method of removing materials by their disintegration by action of electric plasma

Abstract

A method of removing materials by their disintegration, especially metal tubes and non-metal materials, particularly in an area of a borehole, by thermal disintegration of materials by action of plasma created in a plasma generator, by hydrodynamic and / or gravitational removing of disintegrated materials from the area of the borehole, characterized in that a directed flow of water vapour-based plasma acts on material being disintegrated and disintegrates it by synergetic simultaneous effect of thermal action and exothermic chemical reactions.

Description

TECHNICAL FIELD[0001]The invention relates to the field of disintegration of materials, especially being parts of extractive boreholes and / or objects in them, namely by their disintegration by action of electric plasma. The invention is based on the interaction of water vapour-based plasma with disintegrated components of boreholes or objects in the borehole.BACKGROUND ART[0002]Hundreds of platforms for crude oil and natural gas production are gradually coming to the end of their lifetime. In the present, because of the insufficient profitability of exploitation in these reservoirs, their temporary or permanent shutdown is considered. The most expensive operation of these shutdowns is so-called plug and abandonment of the borehole, which is supposed to form the barrier impeding hydrocarbons to escape to the surface. As this procedure is required by legislation, plug and abandonment of the borehole provides space for innovation and increased efficacy.[0003]Around the world, these act...

AI Technical Summary

Benefits of technology

The invention is about a new technology for effectively disintegrating materials in boreholes and objects in them, such as hydrocarbons, by using plasma generated by an electric current. The technology aims to overcome the difficulties and risks associated with current methods of plug and abandonment of boreholes, such as the need for heavy drilling rigs, the risk of damaging the mouth of the borehole, and the need for expensive and frequent replacement of the tool. The technology also aims to provide a more efficient and cost-effective solution for disrupting steel casing pipes and concrete in the mining industry.

Problems solved by technology

In the present, because of the insufficient profitability of exploitation in these reservoirs, their temporary or permanent shutdown is considered.

The most expensive operation of these shutdowns is so-called plug and abandonment of the borehole, which is supposed to form the barrier impeding hydrocarbons to escape to the surface.

Plug and abandonment of the borehole represents the significant part of total costs for putting the borehole out of service.

It is difficult to mill such casings and thus the research is focused on other non-conventional, methods of their elimination.

The most difficult part consists of the first two mentioned operations, i.e. milling of the casing pipe and the concrete which are the most challenging.

However, removing of these parings may damage the mouth of the borehole.

The second disadvantage is the demand of heavy drilling rig, daily rent of which is very financially demanding.

The third disadvantage is that during the milling, the milling cutter might get damaged and stuck in the borehole, or some part of the milling cutter might get stuck in the borehole.

The disadvantage of this method is the need for heavy, and thus expensive, drilling rig and for frequent replacement of the tool because of deterioration of the tool; these features are more striking for the boreholes located in the sea.

Furthermore, the transmission of the rotary moment onto the lamellas of the milling cutter requires significantly higher structural firmness and it has higher requirements than standard drilling tools.

The disadvantages of the current method of milling the casing pipes for diverted and horizontal boreholes are the same as for the plug and abandonment of the boreholes.

The disadvantages of this solution consist in the need of an exact determination of generating mixture heat amount for total or partial removing of casing.

After ignition, it is not possible to suspend the burning of the mixture and this makes impossible to control the process while it is running.

Chemical interaction of plasma with the machined material is usually an undesirable side effect.

The disadvantage is that in these methods the streams of oxygen, heat generating dissociated gases or the stream of plasma act on the small surface and by point action, especially by melting, remove only a small amount of material.

Plasma stream cannot act planary with sufficient potency suitable for bulk removal of material.

On a short-term basis, the density of energy reaches a high level, sufficient to partially disintegrate the material, which is preferably used for perforation of casings in a borehole, but for planar removal of material it is insufficient.

The mentioned extent and way of interaction of electric arc with the disintegrated material in these patents are of point character, disintegrating a material linearly, and therefore insufficient for achieving the objective of planar removing of metal materials.

The different temperature of solidification, different thermal conductivity and thermal expansibility of metal and resulting metal oxides will lead to formation of porous structure of slag with a large number of microfissures with the internal stresses and tensions at the interfaces, which are released by disruption of the metal-oxide interface and internal mechanical cleavage of the oxide.

When solidification of material is rapid, hydrogen remains trapped in it and it can recombine to the molecular gas or in the presence of carbon to methane, which increases porosity and internal stress and thereby contributes to structural degradation of the casing being removed.

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