RU2578137C1 - Method for development of high-viscosity oil deposit - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention can be used in the development of deposits of heavy oil. A method of high-viscosity oil field development involves drilling vertical and inclined horizontal injection wells, injection of working agent through the injection wells and selection of oil through production wells. Vertical wells drilled at a distance of 1-10 m from the face inclined horizontal wells. Vertical well is perforated from the top layer to the level of 1-2 meters above the water contact OWC. For separation of the perforation interval vertical well bore at two intervals in the vertical wellbore packer is set in the range below the top layer of 4 m and up to 5 m OWC. In vertical wells installed is equipment that allows to regulate the injection of steam at each interval of a vertical well. Trunnion well is equipped with temperature sensors. In the initial period of inclined horizontal well and vertical well steam injection is performed to create a hydrodynamic connection between wells and warming their bottom zones. After warming face zones obliquely horizontal well transferred by extraction, and the vertical well is converted to injection. According to the testimony of temperature sensors determine the interval break of steam. A break of steam close to the bottom of the trunnion hole injection is stopped in the lower range of vertical well, with a couple of breakthrough closer to the point of entry into the reservoir inclined horizontal wells stop pumping into the upper range of vertical well. After aligning the temperature readings in pan horizontal well injection intervals in the vertical well is resumed. Vary the amount of coolant in the vertical injection well and the selection of the liquid from the slope of a horizontal well to reduce the rate of steam breakthrough in pan horizontal well and resize the steam chamber.

EFFECT: enhanced oil recovery, reduced water production, the decrease in displacement agent injection, pressure maintenance, lack of lowering the temperature of formation fluid, heated by pumping the coolant in the production well bore, which facilitates its ascent to the surface.

1 cl, 1 ex, 1 dwg

Description

The invention relates to the oil industry and may find application in the development of deposits of high viscosity oils or bitumen under thermal influence.

A known method of developing a reservoir of highly viscous oil (patent RU No. 2334095, IPC E21B 43/24, published in Bulletin No. 26 09/20/2008), including drilling vertical injection wells and horizontal production wells, pumping a working agent through injection wells and taking oil through producing wells. The horizontal wellbore of the producing well is carried out at 1.5-2.5 m above the bottom of the reservoir and is perforated. Above the horizontal well of the producing well, 3.5-4.5 m is placed the bottom of the vertical injection well, perforated in the range of 0.5-1.5 m from the bottom. A vertical injection well is placed from a vertical wellbore of a producing well at a distance greater than 2/3 of the length of the horizontal section of the producing well, up to the end of the horizontal wellbore, with steam alternating with air being used as an agent.

The disadvantage of this method is the likelihood of a quick breakthrough of the coolant due to the small distance between the bottom of the producing and injection wells (3.5-4.5 m). In this regard, high costs and low efficiency. The method is not suitable for the development of deposits with an inclined oil-water contact.

The closest in technical essence and the achieved result is a method of developing a highly viscous oil reservoir (patent RU No. 2506417, IPC E21B 43/16, published in bulletin No. 4 of 02/10/2014), including drilling vertical injection wells and inclined horizontal production wells, the injection of the working agent through injection wells and the selection of oil through production wells, characterized in that they determine the level of water-oil contact - oil-and-gas production, producing an inclined horizontal well from the mouth to the bottom; 2-3 m above the level of the oil-water supply, a vertical injection well is drilled with a bottom position above the bottom of the producing well 5-8 m higher, the production well is perforated along the entire length of the inclined section, the vertical injection well is perforated in the formation zone in the direction of the mouth of the producing well, in stages as the breakthrough of the working agent or flooding of the product is above 95%, the bottom of the producing deviated horizontal well is cut off above the breakthrough or flooding zone, and the opening area of the injection well is cut from the bottom by 1 / 3-1 / 2 of the whole th length thereof, in the formulation of the entire mouth area extracting generated obliquely horizontal well is transferred under injection of working fluid.

The disadvantages of the method are the uneven heating of the drainage area of the horizontal production well, the likelihood of a quick breakthrough of steam injected into the vertical injection well to the bottom of the producing horizontal well.

The technical objectives of the proposed method are to ensure the operability of the steam-gravity drainage technology in the reservoir with an inclined oil-water contact, to reduce the water cut of the produced products from the reservoir, to prevent the coolant from breaking into the producing well, to reduce the cost of eliminating the construction of an additional horizontal injection well.

Technical problems are solved by the method of developing a highly viscous oil deposit during thermal exposure, including the drilling of vertical injection wells and inclined horizontal production wells, pumping a working agent through injection wells, and taking oil through production wells.

New is that a vertical well is drilled at a distance of 1-10 m from the bottom of an inclined horizontal well, a vertical well is perforated from the top of the formation to a mark 1-2 m above the oil hole, to separate the interval of perforation of a vertical well into two intervals in a vertical well, a packer is installed in the interval below the formation roof by 4 m and above the OWC by 5 m, equipment is installed in the well to control the injection of steam in each interval of the vertical well, an inclined horizontal well is equipped with temperatures sensors, in the initial period, steam is injected into the inclined horizontal and vertical wells to create a hydrodynamic connection between the wells and heated their bottom-hole zones, after heating the bottom-hole zones, the inclined horizontal well is put into production, and the vertical well is turned into injection, according to the temperature sensors interval of steam breakthrough, when steam breaks closer to the bottom of an inclined horizontal well, the injection is stopped in the lower interval of a vertical well, when breakthrough ara closer to the entry point of the inclined horizontal well, the injection is stopped in the upper interval of the vertical well, after aligning the temperature readings in the horizontal well, the injection is resumed in the intervals of the vertical well, the volume of coolant pumped into the vertical well is changed, and the fluid is taken from the inclined horizontal well to reduce the speed steam breakthrough in an inclined horizontal well and changes in the growth rate of the steam chamber.

The drawing shows a layout of a vertical injection well and an inclined horizontal production well.

The method of developing deposits of high viscosity oil is as follows.

In the reservoir 1, the level of water-oil contact (WOC) 2 is determined, if the level of WOC 2 ′ is inclined, then its inclination angle is determined. Then they drill and equip an inclined horizontal borehole 3 with a bottom face above the level of BHK 2 by at least 2-3 m.

An inclined horizontal well 3 is perforated over the entire interval of the productive formation 1. In the case of developing a reservoir with an inclined level of OWC 2 ′, an inclined horizontal well 3 is drilled above the level of OWC 2 ′ at least 2-3 m from it. Next, a vertical well 4 is drilled at a distance 1-10 m from the bottom of an inclined horizontal well 3 along its axis. The distance from the bottom of the vertical well 4 to the bottom of the inclined horizontal well 3 is set greater than the permissible deviation from the design point during drilling (radius of the tolerance circle). A vertical well 4 is perforated from the top of the formation to a mark 1-2 m above the oil hole. In a vertical well 4, a packer 5 is installed in the interval below the top of the formation 1 by 1/4 of the oil-saturated interval of the formation 1 and above the OWC by 1/4 of the oil-saturated interval of the formation 1 to divide the perforation interval of the vertical well 4 into the upper 6 and lower 7 intervals. Equipment is installed in the vertical well 4, which allows to regulate the steam injection in the upper 6 and lower 7 intervals of the vertical well 4. The inclined horizontal well 3 is equipped with temperature sensors 8 for monitoring the temperature along the bore of the horizontal well 3. After the horizontal and 3 horizontal wells are set to 4 steam is injected into both wells to create a hydrodynamic connection between the wells and warm their bottom-hole zones. As a working agent, steam is used, for example, with a temperature of 180-250 ° C and a dryness of 0.7-0.9 units. After heating the bottom-hole zones of an inclined horizontal 3 and vertical 4 wells, an inclined horizontal well 3 is transferred to produce liquid, and a vertical well 4 to steam injection. According to the temperature sensors 8 in an inclined horizontal well 3 control the steam chamber and determine the interval of steam breakthrough. The temperature at which steam breakthrough (steam breakthrough temperature) is recorded in the range is determined as 85-95% of the vaporization temperature of the injected water at reservoir pressure. When fixing in sensors 8 in the interval of an inclined horizontal well 3 temperatures above the temperature of steam breakthrough, it is believed that steam breakthrough occurred in this interval. When the steam breaks closer to the bottom of the inclined horizontal well 3, the injection is stopped at the lower interval 7 of the vertical well 4, when the steam breaks closer to the entry point of the inclined horizontal well 3, the injection is stopped at the upper interval 6 of the vertical well 4, after the inflow profile is aligned, the injection into the intervals 6 and 7 resume. The volume of coolant pumped into the vertical well 4 and the selection of fluid from the inclined horizontal well 3 are changed to reduce the rate of steam breakthrough in the inclined horizontal well 3 and the growth rate of the steam chamber. If low temperature is detected in the sensors 8 of the inclined horizontal well 3, then the injection of steam into the vertical well 4 is increased or the liquid withdrawal from the inclined horizontal well 3 is reduced. If the high temperature is detected in the sensors 8 of the inclined horizontal well 3, the steam injection into the vertical well 4 is reduced.

Concrete example

The proposed method for developing a highly viscous oil deposit was tested at the Ashalchinskoye field with the following geological and physical characteristics:

the average total thickness of the reservoir is 12 m;

oil saturated layer thickness - 10 m;

the value of the initial reservoir pressure is 0.45 MPa;

initial reservoir temperature - 8 ° C;

oil density coefficient in reservoir conditions - 0.970 kg / m;

coefficient of dynamic viscosity of oil in reservoir conditions - 27351 MPa · s;

coefficient of dynamic viscosity of water in reservoir conditions - 1.3 MPa · s;

the value of the average core permeability in the reservoir is 2660 microns;

the value of the average core porosity in the reservoir is 0.3 d.

An inclined horizontal well 3 with a length of an inclined horizontal section of 400 m was positioned above the inclined level of BHK 2 ′ at a distance of 2.5 m. The inclined horizontal well 3 communicates with the formation through a slotted filter in the entire production interval.

Vertical well 4 was located at a distance of 1 m from the bottom of an oblique horizontal well 3 along its axis. Vertical well 4 was perforated from the roof to the level of 1 m above the level of the oil-well. The vertical well was divided by packer 5 into two intervals 6 and 7 at a distance of 5 m from the top of the formation.

After equipping the inclined horizontal 3 and vertical 4 wells, a working agent was pumped through them in the amount of 3.5 thousand tons each to achieve the required level of heating of the bottom-hole zones. As a working agent, steam was used with a temperature of 191 ° C and a dryness of 0.9 units. After heating the bottom-hole zones of both wells 3 and 4, the directional horizontal well 3 was transferred for production, and the vertical well 4 for steam injection.

When steam breaks closer to the bottom of an inclined horizontal well 3, steam injection to the lower interval 7 of vertical well 4 stops, when steam breaks closer to the entry point of the inclined horizontal well 3, injection stops to the upper interval 6 of vertical well 4, after alignment of the inflow profile intervals 6 and 7 resumed. During the 15-year period of operation of the element, the lower interval 7 of the vertical well 4 was blocked 45 times, the upper interval 6 of the vertical well 4 was blocked 15 times. The steam breakthrough rate was controlled in an inclined horizontal well by changing the coolant injection volumes from 50 to 85 tons / day in a vertical well and taking 60-100 tons / day of fluid from an inclined horizontal well.

The presented method, as well as the prototype method, were modeled in the CMG software package of the STARS module at the facility with the same geological and physical characteristics for different operating conditions. From the obtained calculations, the advantage of the method over the prototype was also revealed: a reduction in the percentage of water cut in the produced products from the reservoir, the exclusion of a breakthrough of the coolant in the producing well, cumulative oil production is higher than by the prototype by 10-15%.

The proposed method allows us to solve technical problems, such as ensuring the operability of steam gravity drainage technology in reservoirs with an inclined WOC, reducing the water content of produced products from the reservoir. The breakthrough of the coolant in the production well is eliminated, which makes it possible to avoid a drop in the achieved pressure in the developed formation and thereby ensure a high flow of products into the production well. Costs are reduced by eliminating the construction of an additional horizontal injection well.

Claims (1)

A method for developing a highly viscous oil deposit, including drilling vertical injection and inclined horizontal production wells, pumping a working agent through injection wells and extracting oil through production wells, characterized in that a vertical well is drilled at a distance of 1-10 m from the bottom of an oblique horizontal spine, vertical well perforate from the top of the formation to the mark 1-2 m above the oil-water contact - VNK, to separate the interval of perforation of a vertical well into two intervals vertically a packer is installed in the well in the interval below the formation roof by 4 m and above the OWC by 5 m, equipment is installed in the well that allows to regulate the steam injection in each interval of the vertical well, the inclined horizontal well is equipped with temperature sensors, in the initial period, the inclined horizontal and vertical wells are steam injection to create between the wells a hydrodynamic connection and heating their bottom-hole zones, after heating the bottom-hole zones, an inclined horizontal well is transferred to production, a vertical well is turned on for injection, according to the temperature sensors, the interval of steam breakthrough is determined, when steam breaks in the interval closer to the bottom of an inclined horizontal well, injection is stopped in the lower interval of a vertical well, when steam breaks in the interval closer to the entry point of the inclined horizontal well, the injection is stopped in the upper interval of the vertical well, after leveling the temperature readings in an inclined horizontal well, injection into the intervals of the vertical well is possible lyayut alter the volume of coolant pumped into vertical well bore fluid and the selection of the inclined horizontal wells to reduce vapor breakthrough velocity in the horizontal well and obliquely changes the size of the steam chamber.

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