RU2287676C1 - Method for extracting a deposit of highly viscous oil - Google Patents

Abstract

FIELD: oil industry, possible use during extraction of a deposit of highly viscous oil.

SUBSTANCE: in accordance to method, well is drilled with horizontal shaft. Horizontal shaft of well is driven by descending profile through all of productive bed. In drilled well, casing string is mounted, perforated in interval of product well. Behind-pipe space is cemented from ceiling of product bed to mouth of well. Tubing string perforated in lower portion is lowered into casing string. Packer is mounted in lower part of perforation interval between tubing strings. Along additional tubing string, cementing material is fed, and then a heat carrier. Product is extracted from product well through perforation of casing string and perforation of tubing string, perforated in interval of productive bed. Product is transported to mouth along circular inter-pipe space between columns of tubing strings. Extraction of product is continued until sharp decline of well debit. Tubing strings are serially lifted or lowered to new deposits upwardly up to ceiling or downwardly down to shoe of productive bed and operations are repeated until full depletion of productive bed.

EFFECT: increased oil yield due to increased coverage of bed by processing agent during serial processing of whole bed.

1 ex, 1 tbl, 4 dwg

Description

The invention relates to the oil industry and may find application in the development of a highly viscous oil field.

A known method of developing an oil field, including drilling a vertical well, launching two columns of tubing, pumping coolant through the inner string of tubing and sampling through the annulus of oil (RF Patent No. 2206728, class E 21 V 43/24, publ . June 20, 2003).

The main disadvantage of this method is the low oil recovery coefficient due to the small coverage of the formation by the impact of the area.

Closest to the proposed invention in technical essence is a method of developing an oil field, including drilling wells with a horizontal wellbore, installing a perforated casing string in a drilled well, cementing the annulus to a horizontal wellbore, lowering tubing strings to the casing to the perforation interval in the terminal parts, centering them in the casing using a packer, supplying coolant through the tubing string behind the packer, from boron product through the perforation of the casing at the beginning of the horizontal section and transporting it to the mouth through the annular annular space (RF Patent No. 2067168, CL E 21 In 43/24, publ. 09/27/96 - prototype).

The main disadvantage of this method is the low coverage of the formation along the section. In addition, when a displacing agent breaks into the production interval, it is not possible to adjust the coverage of the formation, both by section and by area.

The objective of the invention is to increase oil recovery by increasing the coverage of the formation with an agent of influence during sequential development of the entire formation.

The problem is solved in that in a method for developing a highly viscous oil field, including drilling a well with a horizontal wellbore, installing a casing perforated in the interval of the producing formation, cementing the annulus from the roof of the producing formation to the wellhead, lowering the tubing to the interval perforations in the end part, setting the packer, coolant supply through the tubing string, product selection through casing perforation at the beginning Along the horizontal section and transporting it to the mouth along the annular annulus, according to the invention, the horizontal wellbore is drawn in a downward direction through the entire reservoir, as a tubing string, a tubing string perforated in the lower part and a perforated tubing string in the bottom tubing pipes lower the additional tubing string, put the packer at the bottom of the perforation interval between the columns tubing pipes, plugging material is pumped through an additional tubing string, and then the coolant, product is taken from the reservoir through the perforation of the casing string and perforation of the tubing string perforated in the interval of the reservoir, transport the product to the mouth through the annular annulus between the tubing strings, the selection of the product is carried out until the well production rate decreases to the minimum cost-effective level, successively imayut string of tubing to the new location of the producing formation upward to the roof and the operation is repeated to completely deplete the producing formation.

The features of the invention are:

1. drilling a horizontal wellbore;

2. installation of perforated casing in the interval of the productive formation;

3. cementing the annulus from the roof of the reservoir to the wellhead;

4. descent into the casing string of the tubing string to the perforation interval in the end part;

5. setting the packer;

6. coolant supply through the tubing string;

7. product selection through perforation of the casing at the beginning of the horizontal section;

8. transportation of the product to the mouth through the annular annulus;

9. holding a horizontal wellbore with a downward profile through the entire reservoir;

10. as a tubing string, the use of perforated tubing at the bottom of the tubing string;

11. the descent into the perforated at the bottom of the tubing string of the additional tubing string;

12. setting the packer in the lower part of the perforation interval between the columns of the tubing;

13. for an additional column of tubing pumping the plugging material, and then the coolant;

14. product selection from the reservoir through perforation of the casing string and perforation of the tubing string perforated in the interval of the reservoir;

15. transportation of the product to the mouth along the annular annular space between the columns of the tubing;

16. product selection to reduce well production to a minimum cost-effective level;

17. successive raising (lowering) of the tubing string to new locations up to the roof (down to the bottom) of the reservoir and repeating operations until the reservoir is fully developed.

Signs 1-8 are common with the prototype, signs 9-17 are the essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

When developing a highly viscous oil reservoir, part of the recoverable reserves remains in the reservoir due to the low impact of the reservoir. The objective of the invention is to increase oil recovery by increasing the coverage of the formation by exposure during the sequential development of the entire formation.

Figure 1-4 shows a diagram of the implementation of the proposed method: figure 1 - the operation of posting a horizontal barrel, figure 2 - the operation of lowering the string of tubing, figure 3 - the operation of the injection of plugging material and coolant, in fig. 4 - operation for lifting the tubing string to a new location and working out the formation.

Legend: 1 - reservoir; 2 - perforated casing; 3 - perforation interval; 4 - centralizer; 5 - the first column of tubing; 6 - intervals of perforation; 7 - the second additional column of tubing; 8 - packer; 9 - cuff; 10 - plugging material; 11 - coolant; 12 - the developed interval of the reservoir.

The method is carried out in the following sequence.

A horizontal well with a downward profile is drilled at a highly viscous oil field, i.e. with the intersection of the entire section along the strike of the reservoir 1 at an antiaircraft angle of 80 to 90 ° (Fig. 1). In the drilled well, a casing 2 is installed, perforated with holes 3, the annulus is cemented to the beginning of the horizontal section. Then, inside the casing 2, a tubing string 5 is mounted on the centralizers 4, with perforations 6 (FIG. 2) and cuffs 9. The second additional tubing string 7 is lowered into the tubing string 5 and centered in the string tubing 5 using a packer 8. Between the casing 2 and the tubing string 5 in the interval of perforation 3 set the cuff 9.

In the tubing string 7, injection (Fig. 3) of plugging material 10 is carried out, the required volume to increase the coverage of the formation by the influence of the coolant. As the plugging material 10, liquid glass, a polymer with a thermal stabilizer, etc. can be used. Next, the coolant is pumped into the end of the horizontal well under the design pressure above the in-situ pressure of the productive formation 1. At the same time, alternating changes in pressure gradients along the streamlines from the end of the horizontal section are created to the intervals of perforation of the tubing string due to the creation of pressure from the injection side (shuttle repression process the impact of depression on the perimeter of the placement). All this, as follows from the physical nature of the process, leads to an increase in the coverage of reservoirs by exposure due to oil displacement, both by area and by section of the reservoir, and to intensify production of the product. After holding the calculated duration, the product (oil) is taken through the perforation interval 6 along the annulus of the tubing strings 5 and 7. The coolant pumping, holding and product selection cycles are repeated until the flow rate decreases below the minimum cost-effective. Then the columns of the tubing 5 and 7 are raised to a new location (Fig. 4) above the worked out interval 12 and the cycles are repeated.

Concrete example

The Ashalchinskoye field of high-viscosity oil is being developed. At the Ashalchinskoye field with highly viscous oil located at a depth of 90 m, represented by heterogeneous formations with a thickness of 20-30 m with a temperature of 8 ° C, a pressure of 0.5 MPa, an oil saturation of 0.70 units, a porosity of 30%, and a permeability of 0.265 μm ² , with oil having a density of 956 kg / m ³ and a viscosity of 10206 MPa · s, a horizontal well with a downward profile is drilled. Drilling a horizontal section of the downward profile with a length of 400 m is carried out along the strike of the reservoir 1 (Fig.1). A casing 2 is installed in a drilled well, perforated with holes 3 to 25 meters above the end of the horizontal section, the annulus is cemented to the beginning of the horizontal section. Then, inside the casing string 2, a tubing string 5 perforated every 20 m is installed (FIG. 2), equipped with centralizers 4 and cuffs 9, a second additional tubing string 7 is lowered into it, and centered in the tubing string 5 using a packer 8. Through the tubing string 7, the plugging material 10 is injected (FIG. 3) - liquid glass with a volume of 5 m ³ , then the coolant is pumped - steam with a temperature of 320 ° C into the end of the horizontal shaft under by 4.0 MPa, which is higher than the in-situ pressure of the productive formation 1. Steam is supplied until the viscous fluid is liquefied to flow around the wellbore 2. The estimated steam volume is 5000 tons.

After thermocapillary impregnation of the estimated duration (10 days), through the perforation interval 6, products are selected along the annulus of the tubing strings 5 and 7. When the temperature of the produced fluid decreases to 50 ° C, steam injection is resumed in a horizontal well. In the future, cycles of steam injection into a horizontal well continue to alternate with the selection of the product (oil) from it until the flow rate decreases below the minimum cost-effective. A sign of the development of the bottom-hole zone of the well is a sharp decrease in oil production - less than 3 tons / day and an increase in water cut to 98%. Then the tubing columns 5 and 7 are raised to a new location (FIG. 4) above the worked out interval 11, the plugging material (liquid glass) is pumped in, steam is pumped in and the selection is started. The development is repeated intervalwise throughout the entire section of the downhole well. The site is operated until the design oil recovery reaches 28%.

When using the method, it is possible to treat the formation from the roof of the reservoir to the sole, depending on the geological structure and properties of the oil. With low formation anisotropy and significant oil viscosity, interval processing is carried out from the roof to the bottom of the formation. With significant fragmentation, processing is performed from the bottom of the formation.

Due to the sequential development of the entire horizontal wellbore interval, the coverage of the formation increases by exposure, and all sections of the bottom-hole formation zone around the well are evenly generated and, as a result, oil recovery is significantly increased. Comparison of the effectiveness of the proposed method are shown in table 1.

From the table it follows that the proposed method allows to extract an additional 162.5 thousand tons of oil.

The application of the proposed method will increase the oil recovery of highly viscous oil from the reservoir.

Table 1 Technical and economic effectiveness of the proposed method Indicators Prototype The proposed method Balance reserves, thousand tons 650 650 The average oil flow rate, t / day 10 twenty The coefficient of coverage of the reservoir impact, unit 0.10 0.70 The coverage coefficient of the formation by water flooding, d.ed. 0.60 0.80 The displacement factor, unit 0.50 0.50 Oil recovery ratio, unit 0,03 0.28 Recoverable oil reserves, thousand tons 19.5 182 Additional oil production, thousand tons - 162.5 The value of additional oil production, million rubles - 812.5 Costs, million rubles - 50,0 National economic effect, million rubles - 762.5

Claims (1)

A method for developing a highly viscous oil field, including drilling a well with a horizontal wellbore, installing a casing perforated in the interval of the producing formation, cementing the annulus from the roof of the producing formation to the wellhead, lowering the tubing string into the casing to the perforation interval in the terminal part, setting packer, coolant supply through the tubing string, product selection through perforation of the casing at the beginning of the horizontal section and its transportation to the mouth along the annular annular space, characterized in that the horizontal wellbore is carried out in a downward direction through the entire reservoir, as a tubing string perforated in the lower part of the tubing string, inside perforated in the bottom of the string tubing, lower the additional tubing string, place the packer at the bottom of the perforation interval between the tubing string, the plugging material is pumped through an additional tubing string, and then the coolant, the product is taken from the reservoir through the perforation of the casing string and the tubing of the tubing perforated in the interval of the reservoir, the product is transported to the mouth along the annular annulus between the tubing columns pipes, the selection of the product leads to a sharp decrease in the flow rate of the well, successively raise the tubing string for new months opolozheniya productive formation upwardly to the roof and the operation is repeated to completely deplete the producing formation.

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