RU2500880C1 - Device for heat insulation of wells in permanently frozen ground - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device contains heat transfer tubes-containers with refrigerating fluid, which are connected to the housing and placed inside intermediate column; well is equipped with thermal couple, temperature control and registration unit and an element consisting of conducting cable and housing made as a solid cylindrical ring or its segments with Peltie thermoelectric modules installed inside.

EFFECT: prevention of caving, maintenance of well stability.

7 dwg

Description

The invention relates to the gas and oil industry, in particular to cooling devices for boreholes, and is intended for the operation of wells in areas of cavernous, permafrost (IMF).

Known stabilizer for plastic-frozen soils with year-round operation [patent RU No. 2231595, IPC E02D 3/115, publ. October 1, 2002] for accumulating cold at the base of engineering structures, including the underground and ground parts of a tubular sealed enclosure filled with refrigerant, the underground part of which is an evaporator, and the above-ground part is a condenser having thermoelectric modules in the form of Peltier elements.

In this stabilizer, the Peltier module is used exclusively for the circulation of the refrigerant and is not directly related to the cooling of the MMP.

A known method of thermal insulation of the wellhead of a producing well in permafrost and a device for its implementation [patent RU No. 2127356, IPC ЕВВ 36/00, publ. 03/10/1999]. A heat-insulating element is placed around the upper section of the pipe string, along the length of which heat-transfer tube containers are installed. Using these tube containers carry out heat removal from the insulating element. Seasonally operating thermostabilizers are installed with the possibility of extraction and replacement into tube containers placed directly behind the directional pipe. These thermostabilizers carry out the transfer of natural cold from air to the border of the heat-insulating element - permafrost. The number and relative position of the container tubes and thermostabilizers along the perimeter of the direction pipe is determined by solving the two-dimensional non-stationary heat equation. The computational domain is a sectional segment whose plane is parallel to the surface of the earth. The value of the computational domain can vary from 1 × 1 m to 30 × 30 m, and the step of dividing into elementary blocks is uneven and can vary from 0.01 to 5 m.

Closest to the invention in technical essence is a system for stabilizing permafrost around a producing well [US patent No. 3763931, IPC ЕВВ 43/00, 1973]. In this system, around the upper section of the production well, a pipe string of a heat-insulating element is placed along the length of which heat-transfer tube containers are connected by a casing. With their help, heat is removed from the heat insulating element.

However, these methods are not sufficiently reliable to provide thermal insulation of the permafrost in the wellhead zone of the producing well, since their use does not take into account possible seasonal temperature differences.

The technical result of the proposed invention is to prevent the formation of dips, maintaining the stability of the well.

The technical result is achieved in that in a device for thermal insulation of a well in permafrost, containing heat transfer tubes-containers with refrigerant, connected by a casing, located inside the intermediate column, it is new that the well is additionally equipped with a thermocouple, a temperature control and recording unit, as well as an element consisting of a conductive cable-cable and a housing made in the form of a continuous cylindrical ring or its segments, inside of which there are thermoelectric Kie Peltier modules.

The invention is illustrated by drawings. Figure 1 shows the temperature graph when moving the container tube to the wall of the intermediate column; figure 2 is a temperature graph during installation of the element; figure 3 is an element consisting of a housing made in the form of a continuous cylindrical ring, inside which there are Peltier thermoelectric modules, and a conductive cable-cable; figure 4 - an element consisting of a housing made in the form of segments of a cylindrical ring, inside which there are Peltier thermoelectric modules, and a conductive cable-cable; figure 5 shows the layout of the well; Fig.6 is a section aa in Fig.1, when the housing of the element is made in the form of a continuous cylindrical ring; Fig.7 is a section aa in Fig.1, when the housing of the element is made in the form of segments of a cylindrical ring;

The device contains an element consisting of a housing 1 made in the form of a continuous cylindrical ring or its segments, inside which Peltier thermoelectric modules 2, a thermocouple 3, conductive cable-cables 4, tube containers 6 with circulating refrigerant 7, heat-insulating material 9 are installed, filling annular space between production 8 and intermediate 5 columns, control unit and temperature registration 10.

Figure 1 shows the temperature graph when moving the container tube to the wall of the intermediate column without an element containing Peltier thermoelectric modules. It can be seen from this graph that during well operation in summer, a positive temperature (T> 0) will go beyond the outer surface of the intermediate string, which will lead to a loss of well stability due to thawing of the permafrost. In the winter season, the negative temperature will drop below the temperature of the IMF, due to the increase in the distance between the insulation and the production casing.

A decrease in temperature in the winter is a positive effect, and an increase in temperature in the summer is undesirable. To eliminate the increase in temperature in the summer, the column is equipped with an element with a housing 1 made in the form of a continuous cylindrical ring or its segments, inside which Peltier 2 thermoelectric modules are installed.

When an element is installed as a result of the Peltier effect, the temperature graph of the summer period will have a negative value on the outside of the column, and on the inside it will be positive (figure 2), and due to an increase in temperature between the surface of the container tube and the Peltier module, free or forced refrigerant circulation, which is an effective way to maintain the temperature of the IMF along the entire length of the well.

A device for thermal insulation of a well in permafrost rocks works as follows.

An element with a housing 1 made in the form of a continuous cylindrical ring (Fig. 3) or its segments (Fig. 4), inside which Peltier thermoelectric modules 2 are installed, and the thermocouple 3 is lowered using conductive cable cables 4 (Fig. 5) into intermediate column 5 (figure 5, 6, 7) and placed on the inner surface of the column to a depth where there are IMF zones. Depending on the power of the IMF, the height of the element is selected. Zones, thickness and depths of MMP distribution are determined by known methods, for example, by drilling parametric wells with coring and its subsequent investigation. Next, lower the tube-containers 6, which are filled with circulating refrigerant 7. The number of tube-containers and the depth of their installation depend on the specific conditions of the distribution of IMF. Heat-insulating material 9 is pumped into the annular space between production 8 and intermediate 5 columns. Then, a well operation process is carried out.

Thermocouple 3 (figure 4), located between the intermediate column 5 and the element, captures the temperature change of the IMF and sends a signal to the control unit and register the temperature 10 located at the wellhead. From the control unit 10, through cables 4, an electric current of a certain power is supplied to the element with Peltier thermoelectric modules 2. Peltier modules 2 cool the housing 1 from the outside, as a result of which the IMF is cooled and heated from the inside. Tube containers 6 with circulating refrigerant 7 create heat dissipation from the hot side of the housing 1 to provide the maximum temperature difference between the outer and inner surfaces of the element.

In winter, the element operates as an additional source of electricity, since the tube-containers 6 provide the necessary cooling of the permafrost. As a result of the temperature difference between the IMF and the container tube 6, an electric current will arise, which flows through the cable cables 4 to the control unit 10, which contains an electric energy converter (not shown). The electric energy Converter is designed to control the parameters of the electric energy coming from the element through the cable cables 4.

A device for thermal insulation of a well in permafrost rocks prevents the formation of dips and maintains the stability of the well.

Claims (1)

Device for thermal insulation of a well in permafrost, containing heat transfer tubes-containers with refrigerant, connected by a casing located inside the intermediate column, characterized in that the well is additionally equipped with a thermocouple, a temperature control and recording unit, and also an element consisting of a conductive cable-cable and housing made in the form of a continuous cylindrical ring or its segments, inside of which Peltier thermoelectric modules are installed.

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