RU2749703C1 - Method for developing layer of ultra-viscous oil by uniform vapor-gravity action - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry and can be used in the development of layers of ultra-viscous oil by the method for steam-gravity action. A method for developing an ultra-viscous oil reservoir by uniform steam-gravity action is proposed, including drilling and arrangement of a pair of parallel horizontal wells, where the horizontal shaft of the injection well is placed above the horizontal shaft of the producing well, descent of casing strings into the horizontal wells, cementing of the annulus, perforation, steam injection into the injection well and uniform heating of the steam chamber due to controlled steam injection and changes in the heating zones, taking into account the thermograms obtained during steam injection, selection of products from the production well. In this case, the annular space along the entire length of the horizontal injection well bore through the perforation holes in the casing string is discretely isolated by local placement of heat-resistant plugging material in it, thereby dividing the horizontal injection well bore into intervals of 20-100 m. A flexible steam pipe is lowered into the injection well, the shoe of which is equipped with packers to prevent steam from escaping into the well space behind the packers and beyond the intervals of the trunk, a perforated pipe is placed between the packers to pump steam into the formation. Moreover, the perforated branch pipe is made with a length not exceeding the distance between the intervals of the shaft. The injection of steam into the injection well and the uniformity of the heating of the steam chamber are regulated by moving in the casing along the horizontal trunk of the shoe of the specified steam pipe with a perforated branch pipe at a speed of 0.1-1 m/s and stopping between intervals for the heating time of 6-48 hours.

EFFECT: increased coverage and coefficient of oil recovery of the reservoir due to the uniform heating of the reservoir along a pair of wells through the use of a movable steam line.

1 cl, 1 dwg

Description

The invention relates to the oil industry and can be used in the development of super-viscous oil formations by the method of steam-gravity action.

There is a known method for the development of a field of heavy oil or bitumen with regulation of the selection of well production, including the construction of an upper injection well and a lower production well with horizontal sections located one above the other, pumping a coolant through a horizontal injection well with heating the formation, creating a steam chamber and selecting products by a pump through a horizontal production well with a decrease in production in the zones of the presence of temperature peaks, carrying out uniform heating of the steam chamber. According to the known method, during the construction of wells, their horizontal sections are equipped with filters installed opposite the zones of the productive formation, and in the production well the filters are made in the form of breaking the productive formation into zones of sections, inside which the pump shank is placed with temperature-dependent valves made in the form of elastic collars filled with material expandable with increasing temperature, installed outside the liner between the inlet openings and located opposite the corresponding filter sections with the possibility of their tight shutdown when the temperature of the produced heavy oil or bitumen rises to 0.5-0.9 from the temperature at which the coolant breaks through into the horizontal section of the production well from the horizontal section of the injection well (RF patent No. 2407884, class Е21В 43/24, publ. 27.12.2010).

The disadvantage of this method is the lack of the possibility of uniform heating of a heterogeneous reservoir, leading to a decrease in coverage with a thermal steam effect. As a result, the oil recovery of the productive formation remains low.

The closest in technical essence to the proposed method is a method of developing a field of heavy oil or bitumen with regulation of the injection of a coolant into a well, including the construction of an upper injection well and a lower production well with horizontal sections located one above the other, injection of a coolant through a horizontal injection well with heating the formation , creating a steam chamber and withdrawing products through a horizontal production well, in which thermograms of the steam chamber are taken, the state of its heating is analyzed for the uniformity of heating and the presence of temperature peaks, and taking into account the obtained thermograms, uniform heating of the steam chamber is carried out, changing the heating zones, during the construction of wells their horizontal the sections are equipped with filters, at the mouth of the injection well, the pipe string for pumping the coolant is equipped with a pipeline with a valve, and the pipe string outlet openings are placed in the filter, breaking it into a zone They are warmed up in such a way that they exclude the breakthrough of the coolant into the production well through a warmer zone, regulate the supply of the coolant depending on the thermogram of the steam chamber taken in the production well. In the known method in the injection well, the filter is hermetically divided into two heating zones, made in its initial and final sections, and the outlet openings of the pipe string in it are divided into two groups and made opposite the corresponding heating zones of the formation, the coolant is pumped into the formation along the pipe string through the filter first into the final zone of the productive formation heating, and as the final zone warms up, the injected steam volume is redistributed between the initial and final zones of the productive formation heating, a rod string with a plunger is lowered into the pipe string in the injection well, in the process of pumping the coolant the space between the pipe string and the string the rods at the injection wellhead are sealed, the rod string with the plunger is placed opposite the first group of pipe string outlet openings made at the same level along the pipe string perimeter with an increase in their throughput at an angle of 270 ° between the smallest and largest outlet openings with the possible their alternate opening and closing, and the second group of holes is made in the form of an open end of the pipe string, while the coolant is pumped at a constant flow rate of steam supplied to the pipe string of the injection well, the ratio of the volumes of the pumped coolant in the initial and final zones of heating the coolant is changed by changing supplying the volume of the coolant to the first heating zone by means of limited rotation from the wellhead of the rod string with a plunger at an angle ranging from 25 ° to 270 ° relative to the first group of outlet openings of the pipe string (RF patent No. 2469187, cl. E21B 43/24, publ. 12/10/2012 - prototype).

The known method makes it possible to regulate the heating of the formation by pumping steam only at the heel and toe of the horizontal wellbore, the middle part of the horizontal wellbore remains unregulated. As a result, the oil recovery of the productive formation remains low.

The proposed invention solves the problem of increasing the oil recovery of a productive formation.

The problem is solved by the fact that in the method of developing a super-viscous oil reservoir with a uniform steam-gravity action, including drilling and arrangement of a pair of parallel horizontal wells, where the horizontal injection wellbore is placed above the horizontal wellbore of the production well, lowering casing strings into horizontal wellbores, cementing the annular space, perforation , steam injection into the injection well and uniform heating of the steam chamber due to controlled steam injection and changes in the heating zones taking into account the thermograms obtained during steam injection, product selection from the production well, according to the invention, the annular space along the entire length of the horizontal injection well through the perforations in casing is discretely isolated by local placement of heat-resistant grouting material in it, thereby the horizontal wellbore of the injection well is divided into intervals of 20-100 m, into the injection a flexible pipe steam line is run down the well, the shoe of which is equipped with packers to prevent steam from escaping into the well space behind the packers and beyond the borehole intervals, a perforated branch pipe is placed between the packers for steam injection into the formation, and the perforated branch pipe is made with a length not exceeding the distance between the borehole intervals, steam injection into the injection well and the uniformity of heating of the steam chamber is controlled by moving in the casing along the horizontal bore of the shoe of the specified steam pipeline with a perforated nozzle at a speed of 0.1-1 m / s and stopping between intervals for a heating time of 6-48 hours.

The essence of the invention.

The oil recovery of a super-viscous oil reservoir developed by the method of steam-gravity drainage is significantly influenced by the uniformity of heating of the steam chamber. However, the existing technical solutions do not fully allow the accomplishment of this task. The proposed invention solves the problem of increasing the oil recovery of a productive formation. The problem is solved as follows.

FIG. 1 shows the layout of horizontal production and injection wells in a vertical section of the productive formation. Designations: 1 - steam injection well, 2 - oil-saturated production formation, 3 - production well, 4 - casing, 5 - perforations, 6 - annulus, 7 - heat-resistant plugging material (insulation), 8 - steam pipe shoe, 9 - flexible tubing (steam pipe), 10 - shoe packer 8 of the steam pipeline 9, 11 - perforated branch pipe, 12 - conductor, 13 - day surface, 14 - top of productive formation 2, 15 - packer to isolate the space between the conductor 12 and casing string 4, 16 - winch, 17 - pump, 18 - heat-resistant cement in the annulus of the casing 12.

The method is implemented as follows.

Construction and preparation for operation of a pair of parallel horizontal wells is carried out, and the horizontal bore of the steam injection well 1, ending in the productive formation 2, is placed above the horizontal bore of the production well 3, also ending in the productive formation 2 (Fig. 1). Wells in the horizontal part of the wells are equipped with casing strings 4, the annular space is cemented and reopened, receiving perforations 5.

The annular space 6 along the entire length of the horizontal borehole of the injection well 1 through the perforations 5 in the casing 4 is discretely isolated by local placement of heat-resistant plugging material 7 (for example, cement, organosilicon fluids, liquid glass, etc.), thereby the horizontal bore of the injection well 1 is divided into intervals of 20-100 m. According to research, dividing a horizontal injection well into intervals less than 20 m long is impractical, since within short distances for most reservoirs, the change in the temperature gradient of the formation is small, while with an interval length of more than 100 m, proper uniform heating of the formation is not ensured.

Then, coiled tubing (steam pipe) 9 is lowered into injection well 1 9. Shoe 8 of coiled tubing 9 is equipped with packers 10 to prevent steam from escaping into the well space behind the packers and beyond the borehole intervals and, accordingly, to provide directional steam supply. A perforated pipe 11 is placed between the packers 10 for injecting steam into the formation 2. The perforated pipe 11 is made with a length not exceeding the distance between the intervals of the wellbore.

Then, steam is injected into reservoir 2 through injection well 1. In the process of steam injection, thermograms of heating of reservoir 2 are taken with a steam chamber. The injection adjustment and the uniformity of heating the steam chamber is carried out by moving in the casing 4 along the horizontal bore of the shoe 8 of the specified flexible steam pipe 9 with a perforated nozzle 11 at a speed of 0.1-1 m / s and stopping between intervals for a heating time of 6-48 hours. This makes it possible to maintain the uniform and sufficient temperature gradient along the formation required for the production of extra-viscous oil during steam injection.

According to research, moving in the casing 4 along the horizontal bore of the shoe 8 of the flexible steam pipe 9 with the perforated nozzle 11 at a speed of less than 0.1 m / s is impractical, because the travel time may be longer than the stopping time, while at a speed of more than 1 m / s, there is a risk of equipment breakdown. When the steam pipeline 9 with a perforated nozzle 11 is stopped in each interval for a warm-up time of less than 6 hours, or more than 48 hours, for most reservoirs the temperature gradient along the horizontal wellbore turns out to be different, as a result, the formation is heated unevenly.

Production well 3 is used to select the product from formation 2.

Development is carried out until the full economically viable development of the formation.

The result of the introduction of this method is to increase the oil recovery of the productive formation.

Examples of specific execution of the method.

Example 1. Productive formations 2 of super-viscous oil deposits are represented by heterogeneous sandstones with a thickness of 20-30 m, depth of occurrence - 90 m, oil viscosity - 10000 mPa · s, average permeability - 2D (Fig. 1).

Construction and preparation for operation of a pair of parallel horizontal wells 1, 3 are carried out, the horizontal boreholes of which are completed in the productive formation 2. The horizontal bore of the steam injection well 1 is placed above the horizontal bore of the production well 3 at a distance of 6-7 m in the vertical plane. This distance is determined as the optimal distance between horizontal wellbores and is calculated from hydrodynamic modeling. The horizontal distance between the entry points into the productive formation of injection 1 and production 3 horizontal wells is 25 meters. Horizontal sections of wells are performed with a length of 500 m.

In wells 1 and 3, drilling for the jig 12 is carried out with a bit with a diameter of 295 mm. The conductor 12 with a diameter of 245 mm is lowered from the day surface 13 to a depth of 90 m - the roof 14 of the productive layer 2. The annular space of the conductor 12 is cemented with heat-resistant cement 18.

Drilling under the casing string 4 in wells 1, 3 is carried out with a bit with a diameter of 216 mm. Casing string 4 with a diameter of 168 mm is lowered into wells 1, 3, centered (not shown in Fig. 1), a secondary opening is carried out with a hydromechanical perforator type PGM-168, obtaining perforations 5. The annular space in wells 1 and 3 between the conductor 12 and the casing column 4 is isolated with packers 15.

The annular space 6 along the entire length of the horizontal wellbore of the injection well 1 through the perforations 5 in the casing 4 is discretely isolated by local placement of heat-resistant plugging material 7 (liquid glass) in it, thereby the horizontal wellbore of the injection well 1 is divided into 7 intervals of 100 m.

Further, a flexible tubing (steam pipe) with a diameter of 60 mm is lowered into the injection well 1 inside the casing 4, capable of moving with the help of the power rods of the winch mechanism 16 along the casing 4. The shoe 8 of the steam pipeline 9 is equipped with packers 10 to prevent steam from escaping into well space behind the packers and beyond the borehole intervals. A perforated pipe 11 is placed between the packers 10 for injecting steam into the reservoir 2. The perforated pipe 11 is 20 m long.

Then, steam is injected into reservoir 2 through injection well 1. In the process of steam injection, thermograms of heating of reservoir 2 are taken with a steam chamber. The injection control and the uniformity of heating the steam chamber is carried out by moving in the casing 4 along the horizontal bore of the shoe of the specified steam pipeline 8 with a perforated nozzle 11 at a speed of 0.1 m / s and stopping between intervals for a heating period of 6 hours. These parameters are determined on the basis of modeling the development process, in which uniform heating of the formation is ensured and the formation does not have time to cool down. Moving in the casing 4 of the shoe of the steam pipeline 8 is carried out as follows. The packers 10 are "seated" in one of the intervals to prevent steam breakthrough beyond the perforated branch pipe 11. Then, after warming up the interval between the insulations (plugging material) 7, the packer 10 is "torn off", the branch pipe 11 is moved to the next interval between the insulations 7, "Fit" of packers 10. Work is repeated sequentially from one interval to another.

After an increase in the formation temperature, the viscosity of super-viscous oil decreases and flows down under the action of gravitational forces, falling into the casing 4 of the production well 3. At the same time, the product is taken by the pump 17 along the production well 3.

The development is carried out until the full economically viable development of the productive layer 2.

Example 2. Perform as example 1. The reservoir is characterized by other geological and physical characteristics and dimensions. The horizontal wellbore of the injection well is divided into intervals of 20 m. The injection control and the uniformity of heating of the steam chamber are carried out by moving in the casing along the horizontal wellbore of the steam pipeline shoe with a perforated nozzle at a speed of 1 m / s and stopping between intervals for a warm-up time of 48 hours.

As a result of the development, which was limited to achieving a water cut of the reservoir up to 98%, 32.7 thousand tons of oil were produced, the oil recovery factor (ORF) was 0.487 unit fraction. According to the prototype, all other things being equal, 29.9 thousand tons of oil were produced, the oil recovery factor was 0.445 unit units. The increase in oil recovery factor according to the proposed method is 0.042 unit fractions.

The proposed method allows you to create uniform heating of the formation along a pair of horizontal wells, respectively, to increase the coverage and oil recovery factor of the super-viscous oil formation due to the use of a movable steam pipeline.

Application of the proposed method will allow solving the problem of increasing oil recovery of a productive formation.

Claims (1)

A method of developing a super-viscous oil reservoir with uniform steam-gravity action, including drilling and arrangement of a pair of parallel horizontal wells, where the horizontal injection well is placed above the horizontal production well, lowering casing into horizontal wells, annular cementing, perforation, steam injection into the injection well and uniform heating of the steam chamber due to controlled steam injection and changes in heating zones taking into account the thermograms obtained during steam injection, product selection from the production well, characterized in that the annular space along the entire length of the horizontal injection well bore through the perforations in the casing is discretely isolated by local placing a heat-resistant plugging material in it, thereby the horizontal wellbore of the injection well is divided into intervals of 20-100 m, flexible pipes are lowered into the injection well steam line, the shoe of which is equipped with packers to prevent steam escape into the well space behind the packers and beyond the borehole intervals, a perforated branch pipe is placed between the packers for steam injection into the formation, and the perforated branch pipe is made with a length not exceeding the distance between the borehole intervals, steam injection into the injection well and the uniformity of heating the steam chamber is controlled by moving in the casing along the horizontal bore of the shoe of the specified steam pipeline with a perforated nozzle at a speed of 0.1-1 m / s and stopping between intervals for a heating time of 6-48 hours.

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