RU2405929C1 - Method for development of reservoir of high-viscous oil - Google Patents

Abstract

FIELD: oil and gas production. ^ SUBSTANCE: method includes lowering concentrically arranged internal and external pipe strings into casing string. External string is arranged as heat-insulated and is lowered below depth of paraffin crystallisation start. Packer is installed above reservoir. Internal pipe string is manufactured as composite, made of upper part with lower nipple and tail with packer arranged as through, which are lowered and installed in well prior to lowering of pipe string. Upper part of internal pipe string is equipped with submersible pump and valve arranged below channel with adjustable pressure, which communicate internal space of upper part with internal space of external heat-insulated string at a certain pressure. Upper part of internal pipe string is lowered down to tight inlet of nipple into packer passage. Coolant pumping is carried out into heat-insulated external pipe string with coolant bleed via annular space. Oil is bled along internal pipe string with the help of submersible pump. In order to pump coolant into reservoir, annular space is isolated at wellhead, and as certain pressure of valve opening is achieved, coolant through channels and along internal pipe string is pushed into near-bottom zone of reservoir. In order to pump chemical reagent, upper part of internal pipe string is lifted up to outlet of nipple from packer passage. Chemical reagent is supplied through external pipe, passage of packer and tail of internal string into near-bottom zone of reservoir. ^ EFFECT: reduction of costs for realisation of method and possibility to bleed high-viscous oil from reservoir with low reservoir pressure. ^ 1 dwg

Description

The invention relates to the oil and gas industry, in particular to the development of a highly viscous oil formation using heat and reagents for lifting and displacing highly viscous oil containing a large amount of asphalt-resin-paraffin substances.

A known method of producing highly viscous oil (RF patent No. 2206728, IPC 8 ЕВВ 43/24, published in Bulletin No. 17 of 06/20/2003), including the descent into the casing string of the tubing to the perforation interval, feeding it coolant, product rise along the annulus, while two tubing strings are lowered into the casing, the first is lowered to the beginning, and the second through the first to the end of the perforation interval and the coolant is fed through it, and the pump is pumped into the space between the casing and the first -compressor pipes supply gas, the product is lifted in the space between the tubing strings, after ensuring a given injectivity, the product is stopped rising, the coolant is pumped to the calculated value, while the gas supply is continued, the space between the tubing strings is filled with it and maintained in this state, then the well is stopped for thermocapillary impregnation until an intensive decrease in fluid mobility in the bottom-hole zone begins, pressure in the well is relieved, incoming in it, to reduce the flow rate obtained in the natural regime of the formation, the cycle of pumping the coolant and product selection is repeated until a zone with a mobile fluid is created with the producing well, after which the well is transferred to the injection, and the selection of products is carried out through the producing well, while the selection of products produced by swabbing or supplying gas to the annular spaces, and the producing well is operated as an injection-producing well until a zone with moving fluid is created, after which it is not Euodias in mining.

The disadvantages of this method are:

- firstly, the high costs and low efficiency of the production of high-viscosity oil containing a large amount of asphalt-resin-paraffin substances, since heat from the coolant supplied through the second tubing string through the products to be lifted and gas supplied is transferred to the rocks to heat behind the casing, and is also removed from the well to the surface with a coolant, raised together with the reservoir products;

- secondly, during the cyclic injection of the coolant and the selection of products from the well, the energy consumption for raising the oil increases, which are associated with an increase in viscous friction due to a decrease in the temperature of the oil being raised and an increase in its viscosity as it rises to the surface of the earth, which leads to production difficulties oil, shutdowns of production wells and a decrease in the overhaul period of wells.

The closest in technical essence is a method of producing highly viscous oil (RF patent No. 2296856, IPC 8 ЕВВ 43/24, published in Bulletin No. 10 of 04/10/2007), which includes lowering into the casing string of tubing strings located concentrically, the flow of coolant and the rise of oil through the annulus, characterized in that the casing string is sequentially lowered with the packer at the end, tubing with closed and open ends, and the casing string is lowered below the depth the beginning of crystallization of paraffin, tubing with a closed end to this depth, and tubing with an open end so that they form a gap between tubing with a closed end, while the coolant is fed into tubing with an open end , oil is lifted along the annulus of heat-insulated and tubing pipes with a closed end, chemicals and coolant when processing the bottom-hole formation zone are fed through the same annulus the carrier is supplied with a sealed well, while the space between the casing and the insulated strings is filled with gas, and the interval for the onset of paraffin crystallization is determined by measuring the temperature along the wellbore.

The disadvantages of this method are:

firstly, the high cost of implementing the method associated with the metal structure (three concentrically arranged pipe columns);

secondly, limited application, since highly viscous oil is produced from the well through the annular space in a fountain way, which is not applicable for a productive formation with low reservoir pressure.

The objective of the invention is to reduce the cost of implementing the method with the ability to select highly viscous oil from a reservoir with low reservoir pressure.

The problem is solved by a method of developing a highly viscous oil formation, including descent into the casing of concentrically arranged pipe strings, the outer of which is thermally insulated and lowered below the start of paraffin crystallization with the packer installed above the reservoir, the coolant flow through the annulus, the oil is lifted along the sealed column pipes, which also serves chemicals and coolant when processing the bottom-hole formation zone.

What is new is that the inner pipe string is manufactured by a team consisting of the upper part of the inner pipe string with a lower nipple and a liner with a packer, made through, which are lowered and installed in the well before the pipe string is lowered, the upper part of the inner pipe string being equipped with an additional submersible pump and located below the channel with a pressure-controlled valve, which communicate the inner space of the upper part with the inner space of the outer insulated pipe at a certain pressure, lower the upper part of the inner pipe string to the sealed inlet of the nipple into the packer passage, and the coolant is pumped into the heat-insulated outer pipe string with the coolant taken through the annulus, the oil is taken from the inner pipe string with the help of a submersible pump, it is isolated for pumping the coolant into the reservoir annular space at the mouth and when a certain valve opening pressure is reached, the coolant is forced into the prize through the channels and through the inner pipe string formation zone, for the injection of a chemical, the upper part of the inner pipe string is raised until the nipple leaves the packer passage, and the chemicals are fed through the outer pipe, the packer passage and the inner string shank into the bottomhole formation zone.

The drawing shows a diagram of a partial cutaway method.

The essence of the method is as follows.

First, the equipment is assembled in the well 1. For this, the lower part of the inner string of pipes 2, for example the tubing string, consisting of a liner 3 with radial holes 4 and a packer 5, made through, is lowered into the casing 1, and the packer is installed and the packer is installed 5 above the reservoir 6. After which the passage packer 5 is planted. Packer 5 can be of any known design, for example, based on the bottom hole 1.

Then, the outer heat-insulated string of pipes 7 is lowered into the casing 1, and its lower end is lowered below the depth of onset of paraffin crystallization, while the initial interval for crystallization of paraffin is determined by measuring temperature along the barrel of the casing 1.

Next, the upper part of the inner pipe string is lowered concentrically into the insulated pipe string 7, for example, tubing string 2, equipped with a lower nipple 8 from the bottom.

In the process of lowering the tubing 2, it is equipped with an additional submersible pump 9 and a valve 11 located below the channel 10 with a pressure-adjustable valve. The descent of the upper part of the inner pipe string, that is, the tubing string 2, continues until its stop 12 interacts with the upper end of the shank 3, while the lower the nipple 8 hermetically interacts with the shank 3.

An annular space A is formed between the casing 1 and the heat-insulated pipe string 7, an annulus B is formed between the heat-insulated pipe string 7 (inner space of the heat-insulated pipe string 7) and tubing string 2.

Thus, the equipment is assembled, after which they begin to carry out the proposed method.

Before the selection of high-viscosity oil from the reservoir 6, the viscosity characteristics of the oil are reduced in the reservoir conditions and its flow into the well 1 is improved. To do this, coolant, for example steam or hot water, is pumped into the reservoir 6 to heat the highly viscous oil in the bottom-hole zone of the reservoir 6.

Open the shutoff member 13 and close the shutoff members 14 (annulus) and 15. Start to pump the coolant, for example using steam or hot water, through the shutoff member 13 into the annulus B (the inner space of the insulated outer pipe string 7), from where the coolant enters the annulus A, since they are interconnected.

As the coolant is injected, the pressure in the annulus A and the annulus B spaces rises and when the design pressure, for example 10 MPa, is reached, the pressure-controlled valve 11 opens and the coolant from the annulus B through the channel 10 made in the tubing string 2 enters the lower part of the nipple 8 and then through the radial holes 4 of the liner 3 and the under-packer space 18 of the well 1 penetrates into the reservoir 6 with high-viscosity oil, heating it. The process of pumping the coolant into the reservoir 6 continues the estimated time, after which the pressure is released in the annulus A and annulus B spaces, while the pressure-controlled valve 11 closes.

Next, the selection of highly viscous oil begins with the simultaneous heating of the oil raised through the tubing string 2 with the coolant. To do this, open the locking elements 13, 14 and 15. The coolant is pumped, for example, using steam or hot water, through the shut-off element 13 into the annulus B of the well 1 to the packer 5, and then the coolant rises along the annulus A at the mouth where it is passed through the shut-off element 14 and heated, for example, by a mobile or stationary steam generator (not shown) and again fed through the shut-off element 13 into the well and thus coolant is circulated in the well to a depth of 16 paralysis of paraffin in the tubing string 2, while the pressure at which the coolant circulates in the annulus A and annulus B spaces should be less than 10.0 MPa, that is, below the opening pressure of the pressure-controlled valve 11. At the same time, any submersible pump 9 is turned on known design, for example, screw and in-pipe space 17 of the tubing string 2 (the upper part of the inner pipe string). Heated high-viscosity oil from the reservoir 6 through the radial holes 4 enters the liner 3, from where through the lower nipple 8 the oil enters the intake of the submersible pump 9, which pumps oil through the in-pipe space 17 of the tubing string 2 and lifts it to the mouth, from where the oil enters the system collection.

Moreover, starting from the depth of onset of crystallization of paraffin 6, the highly viscous oil being raised is heated from the coolant circulating in the well 1 through the tubing string 2 wall and thereby paraffin crystallization on the inner tubing 2 walls is prevented, as well as the viscosity of the oil and, accordingly, the viscosity friction when rising . In addition, due to this, the transportation of heated oil from the wellhead to the place of its collection is also facilitated.

With a decrease in the filtration characteristics of the bottom-hole zone of the productive formation 6 due to asphalt-resin-paraffin deposits in it, which is judged by the decrease in the flow rate of the well at a constant reservoir pressure, the bottom-hole zone of the formation 6 is treated with chemical reagents (solvents) of these deposits. To do this, lift the upper part of the inner column, that is, the tubing string 2 until the lower end of the nipple 8 is 3-5 meters higher than the upper end of the shank 3 (not shown), that is, until the nipple 8 leaves the passage of the packer 5. Open the shutoff member 13 and close the shutoff members 14 and 15, after which the solvent is supplied through the outer column of the heat-insulated pipes 7 through the shutoff member 14 to the annulus B, from where the solvent first enters the shank 3 and through its radial openings 4 and the under-packer space 18 flushes in bottomhole formation zone 6. pumped calculated amount of solvent and allowed to react borehole 1.

The depth 16 of the beginning of paraffin crystallization in the tubing string 2 is determined when the well is operating and there is no coolant circulation in it. To do this, a depth thermometer is lowered into the annulus B through the locking member 13 and the temperature is measured along the wellbore 1. The depth at which crystallization begins in this well 1 is determined by the known temperature of the beginning of paraffin crystallization.

The proposed method for developing a reservoir with high viscosity oil is less expensive compared to the prototype, as it has a lower metal structure, and also allows you to select high viscosity oil from the reservoir, regardless of its reservoir pressure, including from reservoirs with low reservoir pressure.

Claims (1)

A method of developing a highly viscous oil formation, including the descent into the casing of concentrically arranged pipe strings, the outer of which is thermally insulated and lowered below the depth of onset of paraffin crystallization, with the installation of a packer above the productive stratum, the flow of coolant through the annulus, the rise of oil through a sealed pipe string, which also serves chemicals and coolant during processing of the bottom-hole formation zone, characterized in that the inner pipe string is made of a prefabricated to it from the upper part of the inner pipe string with the lower nipple and the liner with the packer, made through passage, which are lowered and installed in the well before the pipe columns are lowered, the upper part of the inner pipe string being equipped with an additional submersible pump and a valve located below the channel with a pressure-controlled valve, which communicate the inner space of the upper part with the inner space of the outer insulated pipe string at a certain pressure, lower the upper part of the inner pipe string to hermetically of the nipple inlet to the packer passage, and the coolant is pumped into the insulated outer pipe string with the coolant taken through the annulus, the oil is taken through the inner pipe string using a submersible pump, to insulate the coolant in the annulus at the mouth and when a certain pressure is reached opening the valve, the coolant through the channels and through the inner pipe string is pressed into the bottom-hole zone of the formation, for the injection of chemicals the upper part is internally the first pipe string is lifted until the nipple leaves the packer passage, and chemicals are fed through the external pipe string, packer passage and the shank of the inner pipe string into the bottomhole formation zone.

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