RU2669647C1 - Method of mining deposit of high viscous and super viscous oil by thermal methods at late stage of mining - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil- producing industry. Method of mining a reservoir of high viscous and super viscous oil by thermal methods at a late stage of mining includes the construction of horizontal wells located one above the other, injection of steam into the upper injection well, warming up the reservoir with the creation of a steam chamber, extraction of oil through the lower production well, injection of the produced water into the injection well after reaching the design value of the residual oil saturation and cancellation of steam injection. Wells are equipped with temperature and pressure monitoring devices at building. After reaching the higher than 10 ratio of the injected steam volume to the selected oil volume, injection of the produced water into the injection well and cancellation of steam injection is carried out after the controlled reduction of steam injection into the injection well with the help of control devices that exclude a sharp decrease in pressure of more than 0.05 MPa/day and a temperature of more than 1 °C/day in the steam chamber to the temperature of steam formation of water at reservoir pressure.EFFECT: completion of wells with thermal impact without destroying the structure of the formation with simultaneous reduction of costs.1 cl, 1 dwg

Description

The invention relates to the oil industry, in particular to methods for developing high-viscosity oil fields using heat at a late stage of development.

A known method of developing deposits of highly viscous and viscous oil by thermal methods at a late stage of development (patent RU No. 2611789, IPC ЕВВ 43/24, C09K 8/592, published 01.03.2017 in bull. No. 7), including injecting steam into injection wells, warming up the productive formation with the creation of a steam chamber, oil extraction through production wells, at a late stage of development, stopping steam injection, nitrogen injection into the steam chamber and simultaneously produced water into the formation, while the absolute mark of the plantar and roofing part is determined before water and nitrogen are injected a straight chamber, and simultaneously produced water is pumped into the formation below the absolute elevation of the sole part of the steam chamber through assessment and control wells located at the boundary of the circuit formed by the steam chamber.

The disadvantage of this method is the large material costs for the construction of additional appraisal wells in the flooded sections of the reservoir. In addition, nitrogen injection can facilitate rapid cooling of the steam chamber and steam condensation, which can lead to a sharp decrease in pressure in the steam chamber and the destruction of the formation structure. The injection of produced water below the absolute elevation of the sole of the steam chamber can lead to a breakthrough of water to the bottom of the producing well.

The closest in technical essence is a method of developing a highly viscous oil field (patent RU No. 2486334, IPC ЕВВ 43/24, C09K 8/592, published on June 27, 2013 in Bulletin No. 18), which includes injecting steam into an injection well, heating the reservoir with the creation of a steam chamber, the selection of oil through the production well, the injection of produced water into the injection well after reaching the design value of the residual oil saturation and canceling the steam injection, while determining the concentration of bicarbonate ions in the produced water, there are produced water with a concentration of bicarbonate ions of at least 3 g / l, and when the concentration of bicarbonate ions in produced water is less than 3 g / l at a temperature in the steam chamber above 100 ° C, urea is additionally introduced into the produced water, after reduction temperatures in the steam chamber below 100 ° C, sodium carbonate or ammonium carbonate or sodium or potassium hydrogen carbonate are introduced into the produced water, decomposing with the release of carbon dioxide under the action of heat accumulated in the steam chamber.

The disadvantage of the invention is the use of carbon dioxide, which at high formation temperatures is an aggressive corrosive agent, including initiating the precipitation of water-insoluble compounds of calcium carbonate in the underground and surface equipment of the well. With a large development of the reservoir and the formed steam chamber, the use of a large amount of reagent is necessary to generate the estimated gas volume, which makes this method economically disadvantageous. Uncontrolled injection of steam can contribute to the rapid cooling of the steam chamber and the condensation of the steam, which leads to a sharp decrease in pressure in the steam chamber and the destruction of the formation structure.

The technical task of the proposal is to reduce costs when completing wells at a late stage of development during thermal exposure without destroying the structure of the reservoir.

The technical problem is solved by the method of developing a reservoir of high-viscosity and super-viscous oil by thermal methods at a late stage of development, including the construction of horizontal wells located one above the other, injection of steam into the upper - injection - well, heating of the reservoir with the creation of a steam chamber, oil extraction through the lower - producing - well, injection of produced water into the injection well after reaching the design value of the residual oil saturation and canceling the steam injection.

What is new is that during the construction of the well they are equipped with temperature and pressure control devices, and after reaching the ratio of the injected steam volume to the extracted oil volume of more than 10, the associated water is injected into the injection well and the steam injection is canceled after a controlled reduction in the steam injection into the injection well with control devices that exclude a sharp decrease in pressure - more than 0.05 MPa / day - and temperature - more than 1 ° С / day - in the steam chamber up to the temperature of water vaporization during formation pressure.

The figure shows a diagram of the implementation of the method.

The method is implemented in the following sequence.

In formation 1 (see the figure), deposits are built up, located one above the other, producing 2 and injection 3 wells with corresponding horizontal sections 4 and 5. Horizontal sections 4 and 5 of wells 2 and 3 are located above the bottom of the producing formation 1. During construction in wells 2 and 3 have temperature and pressure monitoring devices 6 (for example, an optical fiber cable with sensors). Wells 2 and 3 are equipped with pipe columns 7 and 8, while the pipe string 8 is equipped with pumping equipment (not shown). The coolant is injected — steam — through the pipe string 7 of the horizontal section 4 of the injection well 3 until a hydrodynamic connection is formed between the corresponding horizontal sections 4 and 5 of the wells 2 and 3. This is determined using control devices 6. After the formation of a steam chamber (not shown) and creation hydrodynamic connection between wells 2 and 3 due to steam gravity drainage accumulated products (highly viscous and super-viscous oil) are taken through a pipe string 8 from a horizontal section 5 of the producing well s 2. This control over the steam chamber via lead state temperature control devices and pressure 6.

After reaching the ratio of the injected volume of steam in injection well 3 to the selected horizontal production well 2, the oil volume of more than 10, a controlled decrease in steam injection into injection well 3 is performed using control devices 6, eliminating a sharp decrease in pressure - more than 0.05 MPa / day - and temperature - more than 1 ° C / day - in the steam chamber to the temperature of water vaporization at the initial pressure in the reservoir 1. Then, 2 produced water is injected into the injection well until the steam is completely flooded howling camera.

The proposed method for developing a hydrocarbon fluid reservoir was tested at the Ashalchinskoye field. A site with the following geological and physical characteristics was identified:

- occurrence depth - 90 m;

- the average total thickness of the reservoir is 30 m;

- oil saturated layer thickness - 18 m;

- the value of the initial reservoir pressure is 0.5 MPa;

- initial reservoir temperature - 8 ° C;

- the density of oil in reservoir conditions - 960 kg / m ³ ;

- coefficient of dynamic viscosity of oil in reservoir conditions - 22140.5 mPa⋅s;

- the value of the average core permeability in the reservoir - 296 microns;

- the value of the average core porosity in the reservoir - 0.30 share units.

In a highly viscous oil 1 reservoir, a production well 2 was drilled at a distance of 2 m above the bottom of the producing formation 2. An injection well 3 was located above a production well 2 at a distance of 5 m 3 with corresponding 4 and 5 horizontal sections of 526 m. Wells 2 and 3 were equipped with a temperature and pressure control device 6. After arranging the injection 3 and producing 2 wells through the pipe string 7 of the injection well 3, the working agent was injected in the amount of 5 thousand tons. Steam with a temperature of 191 ° was used as a heat carrier and dryness fraction of 0.9 units. Steam was also injected in a volume of 5 thousand tons through a string of pipes 8 into production well 2 to create a hydrodynamic connection between wells 2 and 3. After heating the bottom-hole zone of the horizontal injection well 3, the horizontal production well 2 was converted to production, and the horizontal injection well 3 - for continuous steam injection in a volume of 80 m ³ to create and expand a steam chamber. After reaching the ratio of the injected steam volume to the extracted oil volume of more than 10 in the horizontal injection well 3, the steam injection was reduced with the help of a temperature and pressure control device 6, which excludes a sharp decrease in pressure - more than 0.05 MPa / day - and temperature - more than 1 ° С / day - in the steam chamber to a temperature of water vaporization of 153 ° C at reservoir pressure of 0.5 MPa. Then they stopped the injection of steam. 22,000 m ^{3 of} produced water were injected into reservoir 1 through injection well 3 until the water flooding of reservoir 1 was completely flooded (determined by increasing the injection pressure by more than 10%), i.e., until the steam completely condensed in the steam chamber. As a result of the measures taken, the development stage of the reservoir was completed and collapse of the reservoir was eliminated while reducing steam injection and maintaining reservoir pressure by injecting produced water without the use of expensive reagents.

The proposed method for the development of deposits of high-viscosity and super-viscous oil by thermal methods at a late stage of development allows to reduce the cost of completion of wells during thermal exposure without destroying the structure of the reservoir.

Claims (1)

A method for developing a reservoir of high-viscosity and super-viscous oil by thermal methods at a late stage of development, including the construction of horizontal wells located one above the other, injection of steam into the upper injection well, heating of the reservoir with the creation of a steam chamber, oil selection through the lower production well, injection of produced water into injection well after reaching the design value of the residual oil saturation and canceling the steam injection, characterized in that when building the wells they they are equipped with temperature and pressure control devices, and after reaching the ratio of the injected steam volume to the extracted oil volume of more than 10, the incidentally produced water is injected into the injection well and steam injection is canceled after a controlled decrease in steam injection into the injection well using control devices that exclude a sharp decrease in pressure more 0.05 MPa / day and temperatures above 1 ° C / day in the steam chamber to the temperature of water vaporization at reservoir pressure.

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