RU2705652C1 - Injection device for thermal isolation of injection well in permafrost zone - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry, namely, to construction of oil and gas wells in permafrost conditions. Proposed device comprises production string, cooling device, temperature control and monitoring unit. Cooling facility is made in the form of coil pipes, spiral-like casing installed in casing pipe in cement stone of casing string, connected to cooling unit installed at wellhead. Temperature control sensors are arranged in cement stone in the area of cooling coil tubing coils.

EFFECT: improved well integrity and automation of heat insulation process.

1 cl, 1 dwg

Description

Technical field

The invention relates to the oil industry, namely the construction of oil and gas wells in permafrost.

State of the art

A well-known design of wells in permafrost conditions, containing a production casing with spiral guide lights made on it, a conductor, an additional casing associated with ground equipment, including a refrigerant supply device. An additional column is placed in the annular space between the borehole wall and the conductor. (AS USSR No. 440483, IPC Е21В 3/00, publ. 0.01.05)

The disadvantage of the analogue is the need to install another column, which increases the diameter of the conductor, and which, in turn, leads to the use of bits of a very large diameter (difficult to make, therefore, very expensive) and leads to higher construction costs. The invention by A.S. No. 440483 has another additional column for placement of permanent or temporary sensors, which further complicates the design of the well and increases the cost of construction and maintenance.

A METHOD FOR THERMAL INSULATION OF AN EXPRESSIVE WELL is known in the patent literature (RF patent No. 2120540, IPC ЕВВ 36/00, publ. 10/20/98). The invention can be used in the production of highly viscous oil using thermal methods of stimulating the formation. In this method, after installing a tubing (tubing) in a cased well with a packer, a separation pipe is installed between it and the casing, having inlet and outlet fittings at the wellhead. After the coolant is supplied to the tubing, the heat-insulating agent is pumped through the annular channels formed by the separation pipe. As the latter, inert or accompanying gases, flushing liquid, oil, etc. can be used. The method allows you to adjust the temperature in the insulation zone by changing the volume or the swaying speed of the agent and quickly intervene in the process when an emergency occurs.

The method is as follows (see drawing to the patent prototype). A packer is installed on the lower end of the tubing and lowered into a well cased by a string until the packer is placed above the roof of the reservoir. Between the casing and tubing, concentrically the latter, establish a separation pipe, the lower end of which is located in the immediate vicinity of the packer. Heat carrier is pumped from the wellhead through wellhead fittings, and a heat-insulating agent is supplied through the fittings, which passes through the annular channels formed by the dividing pipe, goes out through the fittings, and heat is removed from the casing. Equipment for controlling the temperature of the insulating agent is installed on the output armature.

The disadvantages of the prototype is the complexity of the design of the well — it is necessary to install another pipe, which reduces the size of a possible tubing (reducing the debit of the well) or requires an increase in the diameter of the conductor (the use of bits of very large diameters and casing pipes of very large diameters).

Disclosure of the invention

The objective of the invented invention is to expand the arsenal of means for thermal insulation of an injection well in the permafrost zone, to eliminate the disadvantages of the prototype, namely, to increase the support / stability of the well and to automate the thermal insulation process.

The above task is solved using the features specified in the claims, common with the prototype, such as a Device for thermal insulation of an injection well in the permafrost zone, containing a production casing, cooling means, temperature control and control unit, and distinctive essential features, such as cooling means made in the form of pipe-coils spiral mounted on the casing of the conductor in the cement stone of the casing connected to the refrigeration unit, installed at wellhead, wherein the sensors monitor temperature in the cement stone placed near the pipe-coil cooling means.

The above set of essential features allows you to get the following technical result: increase the lining / stability of the well and automation of the thermal insulation process.

The utility model is illustrated in the drawing, where in FIG. The scheme of the proposed design is presented.

A device for maintaining well stability in the permafrost zone (Fig), contains a production casing 1, cooling means, a control and temperature control unit 2. The cooling means is made in the form of coil tubes 3, helically mounted on the casing 4 of the conductor 9 in a cement stone 5 columns connected to a refrigeration unit 6 installed at the wellhead. The temperature control sensors 7 are placed in a cement stone 5 in the area of the pipe-coils 3 cooling means. Position 8 indicates the permafrost zone, and position 9 the conductor of the well.

The device operates as follows.

When constructing a well before launching, casing pipes 4 are used, which are planned to be placed in the permafrost zone 8, on which coil pipes 3 and temperature control sensors 7 are helically mounted. When screwing casing pipes 4 of conductor 9 to each other, fragments of pipe coils are also connected between by myself. The temperature control sensors 7 are interconnected for connection to the control and monitoring unit 2. The required number of casing pipes 4 with coils 3 is lowered into the well, then the conductor 5 is cemented in a known manner. The pipes of the coil pipes located in the column head are connected via pipelines to the refrigeration unit 6. Connect the temperature control sensor circuits to the control unit 2.

During the construction and operation of the well in the permafrost zone 8, thermal regulation is carried out automatically by pumping refrigerant through the coil pipes 3 from the refrigeration unit 6. The flow rate of the refrigerant depends on the temperature measured by the control sensors 7.

The automatic removal of heat arising from the drilling fluid during construction or formation gas during the operation of the well by the refrigerant prevents the thawing of permafrost 8 and, changing the profile of the well.

Compared with the prior art, the proposed solution allows to reduce the number of drilling stages and the time of well drilling, since there is no need to lower and cement an additional string to form a space for coolant movement, since the coil pipes are pre-installed on the casing.

In addition, temperature control sensors are also pre-installed on the “first” (lowest) casing pipe with a coil and on the “last” (highest) casing pipe with a coil. When connecting the casing pipes to each other, the coils of the two pipes are connected and the electrical circuits (signal and power, if necessary) of the temperature control sensor are connected. Thus, the casing descends at a time already prepared for work as a cooling element. There is no need to drill and lower an additional column to accommodate temperature control sensors.

From the description and practical application of the present invention, other particular forms of its implementation will be apparent to those skilled in the art. This description and drawings are considered as material illustrating the invention, the essence of which and the scope of patent claims are defined in the following claims, a combination of essential features and their equivalents.

Claims (1)

A device for thermal insulation of a injection well in the permafrost zone, comprising a production casing, a cooling means, a control and temperature control unit, characterized in that the cooling means is made in the form of coil pipes mounted spirally on a conductor casing in a cement casing stone connected to a refrigeration unit installed at the wellhead, the temperature monitoring sensors being placed in a cement stone in the area of the cooling means coil tubes.

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