RU2735009C1 - Method for development of ultraviscous oil deposit by thermal methods at a late stage - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil-producing industry. Method for development of ultraviscous oil deposit by thermal methods at a late stage of development involves pumping of steam into upper injection wells, heating of productive formation with creation of steam chamber, extraction of oil through lower production wells, at the late stage of development, termination of steam injection, pumping of hot water into the formation and extraction of products, note here that steam injection to upper injection wells is stopped, while lower production wells are converted to injection of hot water at temperature of 40-65 ° C. Initially, after geophysical surveys through observation wells, the deposit is drilled in rows of parallel paired horizontal producers and injection wells, directed towards similar corresponding wells from adjacent row with holding distance between bottoms, excluding steam and / or hot water from one well into another. After transferring to the lower horizontal production wells hot water injection, geophysical survey is carried out in observation wells to determine oil-saturated zones of the formation, in which additional production horizontal wells are drilled in the overhead part of the productive formation between the faces of previously drilled horizontal wells at distance of 1-3 m from the roof of the productive formation.

EFFECT: high efficiency of heat action, maximum possible extraction of residual ultraviscous oil from the reservoir part of the productive formation, avoiding fast flooding of production additional wells at a late stage of development.

1 cl, 1 ex, 2 dwg

Description

The invention relates to the oil industry and is aimed at increasing the technological efficiency of developing super-viscous oil deposits at a late stage of development by injecting hot water into the deposit.

There is a known method of developing a reservoir of high-viscosity and super-viscous oil by thermal methods at a late stage of development (patent RU No. 2611789, IPC Е21В 43/24, publ. 03/01/2017, bull. No. 7) According to the invention, according to the refined geological data, a section of the deposit with a large formation, with the help of thermobarometric studies for a number of control, observation and production wells, the steam chamber is delineated, its lowest and highest in absolute value marks are determined, steam injection is stopped, wells are selected for injecting waste water and gas; hot waste water is pumped into the wells with perforation having a level corresponding to the lower boundary of the steam chamber, injection wells located in the dome zone of the steam chamber are transferred to nitrogen injection. By injecting liquid and gaseous agents, the reservoir pressure is increased to the initial one, and fluid is withdrawn from the production wells.

The disadvantage of this method is the high probability of a breakthrough of the injected gaseous agent into the perforation interval of the production wells, the need to inject large volumes of gas into the steam chamber in order to increase the reservoir pressure to the required values, large material and economic costs for gas production and its injection into the reservoir.

A known method for the development of fields of high-viscosity oil or bitumen (patent RU 2582256 C1, IPC E21B 43/24, publ. 20.04.2016, bull. No. 11), including the construction of pairs located one above the other horizontal production and injection wells, as well as additional horizontal wells, pumping a coolant through the upper injection wells with heating the reservoir and creating a steam chamber, product selection due to steam-gravity drainage through the producing wells and monitoring the state of the steam chamber. An additional well is built between the production and injection wells. The solvent is pumped through the additional well at intervals into the least warm-up zones.

The disadvantages of this method are:

- firstly, its application on heavy oil or natural bitumen deposits arises the need to drill injection and production wells at an extremely small distance of about 5 m from each other and the need to drill an additional well between them, which is extremely difficult from the point of view of drilling technology;

- secondly, the method implies supplying a solvent to the formation, which implies additional costs;

- thirdly, this method is ineffective at the late stage of development of super-viscous oil deposits.

There is also a known method for the development of superheavy oil or natural bitumen deposits (patent RU 2643056 C1, IPC E21B 43/24, publ. 01/30/2018, bulletin No. 4), which provides for drilling a horizontal production well near the bottom of the formation, drilling above it in the same vertical plane parallel to the production well of the horizontal injection well at a distance that provides the possibility of creating a hydrodynamic connection between the wells to initiate the drainage process, injecting steam into the injection well and withdrawing fluid from the production well, drill an additional injection well above the horizontal injection well parallel to it in the vertical plane at a minimum distance from the top of the reservoir, taking into account the technical ability to maintain the well trajectory without drilling through the overlying rocks, the moment of establishing a hydrodynamic connection between the upper injection and production wells is recorded, after which steam injection into the lower injection is stopped well and start pumping steam into the upper injection well before the end of the period of production of the displacement element.

The disadvantages of this method are:

- firstly, high material costs for drilling an additional horizontal well in the top of the productive formation above each pair of horizontal wells;

- secondly, this method is ineffective at the late stage of the development of super-viscous oil deposits.

The closest in technical essence and the achieved result is a method of developing super-viscous oil deposits by thermal methods at a late stage of development (patent RU 2673934 C1, IPC E21B 43/24, publ. 03.12.2018, bul. No. 34), including steam injection into injection wells , heating the reservoir with the creation of a steam chamber, oil withdrawal through the production wells, at a late stage of development, the termination of steam injection, determination of the parameters of the steam chamber, injection of hot water into the reservoir and product selection, characterized in that a pair of wells with thermobaric conditions in the upper injection well below the vaporization temperature in reservoir conditions, with a reduction in oil production rate to 1-3 tons / day, after which steam injection into the upper well is stopped, the lower well is transferred to water injection with a volume of 30-80 m ³ / day with a temperature of 40-65 ° С, and the upper one is launched for selection of the formation products.

The disadvantages of this method are:

- firstly, there is a high probability of rapid flooding of the upper horizontal well due to the close location of the lower horizontal well;

- secondly, the inability to develop residual reserves from the upper part of the reservoir.

The technical objectives of this proposal are to increase the efficiency of thermal impact with the maximum possible recovery of residual super-viscous oil from the top of the productive formation (in the upper part of the reservoir) with the exception of rapid watering of additional production wells at a later stage of development, which leads to a decrease in material and economic costs due to savings on the elimination of production stops due to product flooding.

Technical problems are solved by the method of developing a super-viscous oil reservoir by thermal methods at a late stage of development, including steam injection into injection wells, heating of a productive formation with the creation of a steam chamber, oil withdrawal through production wells, at a late stage of development, termination of steam injection, injection of hot water into the reservoir, and product selection, steam injection into the upper well is stopped, the lower well is transferred to hot water injection with a temperature of 40-65 ° C.

What is new is that initially, after geophysical surveys through observation wells, the deposit is drilled out in rows of parallel paired production and injection wells directed towards similar corresponding wells from an adjacent row with keeping the distance between the bottom holes, excluding the breakthrough of steam and / or hot water from one well to another, and after transferring the lower horizontal wells to injection, geophysical studies are carried out in observation wells to determine the oil-saturated zones of the formation, in which additional horizontal production wells are drilled in the top of the productive formation between the bottoms of previously drilled horizontal wells at a distance of 1 - 3 m from the top of the productive formation.

FIG. 1 shows the layout of horizontal wells in the reservoir (top view).

FIG. 2 shows the layout of horizontal wells in the reservoir (side view).

The method is implemented as follows.

The method of developing reservoir 1 (Fig. 2) of super-viscous oil deposits by thermal methods at a late stage of development includes the initial drilling along a sparse grid with observation wells (not shown), through which geophysical studies are carried out to determine the structure of reservoir 1 and its oil saturation. According to the results of these studies, reservoir 1 of the reservoir is drilled out in rows of parallel paired production 2 and injection 3 wells directed towards the similar corresponding wells 4 and 5 from the adjacent row, keeping the distance L between the bottom holes, excluding the breakthrough of steam and / or hot water from one well 3, 5 , 2 or 4 to another 5, 3, 4 or 2, respectively. Steam is injected into horizontal injection wells 3 and 5, heating of productive formation 1 with the creation of a steam chamber (not shown), oil withdrawal through production wells 2 and 4. At a later stage of development, steam injection and production are stopped, while steam injection into upper wells 3 and 5 (Figs. 1, 2), and lower wells 2 and 4 are transferred to hot water injection with a temperature of 40 - 65 ° C. At the same time, geophysical studies are carried out in observation wells to determine the oil-saturated zones 6 of reservoir 1, in which additional horizontal production wells 7 are drilled (Figs. 1, 2) in the top part of the productive reservoir 1 between the bottoms of previously drilled horizontal wells 1, 3, 4 and 5 at a distance of 1 - 3 m from the top of the productive layer 1.

The distance H between horizontal wells in the rows is selected taking into account the geological properties of reservoir 1 and the properties of the production of this reservoir 1 for maximum oil recovery (increasing the oil recovery factor - ORF). The higher the permeability of formation 1 and the less viscous oil, the greater the distance H. For example, for the Ashalchinskoye field of the Republic of Tatarstan (RT) H = 90-110 m. The same dependence on the permeability of formation 1 and the viscosity of its production at the distance L between the bottomholes of wells 2, 3 and 4, 5. For example, for the Ashalchinskoye field RT L = 70 - 80 m. The authors do not claim this.

The volumes of steam and water injection and product withdrawal are taken by calculations or empirically from those previously used in similar fields. The authors do not claim this

An example of a specific application.

On the Bolshe-Kamenskaya super-viscous oil deposit, reservoir 1 is located at a depth of 170 m, the reservoir is represented by a thickness of 15 - 25 m, reservoir temperature 8 ° C, pressure 0.5 MPa, oil saturation 0.7 unit fractions, porosity 30%, permeability 2 , 65 μm ² , the density of super-viscous oil in reservoir conditions is 960 kg / m ³ , the viscosity is 22000 mPas. Drilled after geophysical studies in observation wells in reservoir 1, counter producing 2 and 4 (Fig. 1 and 2) and located above injection 3 and 5, respectively - a pair of horizontal wells. We injected a heating agent - steam into all wells 2, 3, 4 and 5 with heating of the productive layer 1 of the deposit and creating a steam chamber. After that, steam was injected through injection wells 3 and 5 in the amount of 70 - 120 tons / day, and the product was withdrawn by means of steam-gravity drainage through production wells 2 and 4 with oil flow rates of 10 - 20 tons / day. After 10 years of operation and a decrease in the production rate to 3 tons / day for oil in producing wells 2 and 4 of the reservoir, steam injection into upper wells 3 and 5 and fluid withdrawal from lower wells 2 and 4 were stopped. Lower horizontal wells 2 and 4 were equipped for hot water injection with a volume of 70 - 80 m ³ / day with a temperature of 58 - 60 ° С. Geophysical surveys were carried out in observation wells (not shown) and the location of the oil-saturated zone 6 (Fig. 2) was determined, in which a new horizontal well 7 was drilled at a distance of 1.2 - 2 meters from the top of the productive formation 1 between the bottoms of previously drilled horizontal wells 2 (Fig. 2), 3, 4 and 5 and launched well 4 for the production of formation production. As a result of the measures taken, the oil production rate for the newly drilled well was 19 tons / day.

As a result of using the proposed method, in comparison with a similar section, the flow rate per well increased by 80%, the water cut of the product decreased from 95% to 85%. Material costs decreased by 30%.

The proposed method for the development of super-viscous oil deposits by thermal methods makes it possible to increase the efficiency of thermal action with the maximum possible recovery of residual super-viscous oil from the top of the productive formation (in the upper part of the reservoir) with the exception of rapid watering of additional producing wells at a late stage of development, which leads to a decrease in material and economic costs due to savings on the elimination of production stops due to premature watering of the product.

Claims (1)

A method of developing a super-viscous oil reservoir by thermal methods at a late stage of development, including injection of steam into the upper injection wells, heating the reservoir with the creation of a steam chamber, oil withdrawal through the lower production wells, at a late stage of development, termination of steam injection, injection of hot water into the formation and withdrawal products, while the injection of steam into the upper injection wells is stopped, the lower production wells are transferred to hot water injection with a temperature of 40-65 ° C, characterized in that initially, after geophysical studies through observation wells, the deposit is drilled out in rows of parallel paired horizontal production and injection wells, directed towards the similar corresponding wells from the adjacent row with maintaining the distance between the bottom holes, excluding the breakthrough of steam and / or hot water from one well to another, and after transferring the lower horizontal production wells to hot water injection, producing t geophysical surveys in observation wells to determine the oil-saturated zones of the reservoir, in which additional horizontal production wells are drilled in the top of the productive formation between the bottoms of previously drilled horizontal wells at a distance of 1-3 m from the top of the productive formation.

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