RU2528757C1 - Development of low-permeability oil deposits by horizontal wells under natural conditions - Google Patents

Development of low-permeability oil deposits by horizontal wells under natural conditions Download PDF

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RU2528757C1
RU2528757C1 RU2013145724/03A RU2013145724A RU2528757C1 RU 2528757 C1 RU2528757 C1 RU 2528757C1 RU 2013145724/03 A RU2013145724/03 A RU 2013145724/03A RU 2013145724 A RU2013145724 A RU 2013145724A RU 2528757 C1 RU2528757 C1 RU 2528757C1
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horizontal
wells
well
oil
development
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RU2013145724/03A
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Russian (ru)
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Раис Салихович Хисамов
Вадим Валерьевич Ахметгареев
Рустэм Гусманович Ханнанов
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Открытое акционерное общество "Татнефть" им. В.Д. Шашина
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Abstract

FIELD: oil-and-gas industry.
SUBSTANCE: proposed method comprises drilling of parallel production and injection horizontal wells combined with multiple hydraulic fracturing of the seam. Note here that at least one production well is drilled in beds with permeability not over 2 mD. First, one horizontal well is drilled with angle between maximum major strain of the bed and direction of borehole making 30-60 degrees. Multiple hydrofrac is realised thereat. Well is put in operation. If bed pressure decreases by not over 3% a year then further development is performed under natural conditions with drilling the injection wells. Other production wells are drilled parallel with the first one in case the initial geological store of oil per one horizontal well makes at least 50 thou t at spacing between said wells not exceeding 100 m. Multiple hydrofrac is realised for all wells. Note here that the number of multiple hydrofrac stages is selected proceeding from analytic relationship.
EFFECT: higher yield owing higher coverage.
3 ex, 1 dwg

Description

The invention relates to the oil industry and can find application in the development of low-permeability oil deposits by horizontal wells in natural mode by means of multiple hydraulic fracturing (carbon fracturing) in carbonate and terrigenous reservoirs.
There is a method of developing a multilayer oil reservoir in the presence of a highly permeable layer using hydraulic fracturing, pumping a displacing agent through injection wells, selecting reservoir fluids through production wells, performing hydraulic fracturing to obtain an effective hydraulic fracture. Hydraulic fracturing is carried out selectively in the zone of low permeability formations, excluding perforation of a highly permeable formation with a permeability of three or more times higher than the average for the formations, then after the design selection of oil reserves, perforation of the highly permeable formation is carried out with the subsequent operation of the latter, a trunk with vertical entry into the production facility is performed for ensuring the maximum gradient of the fracture pressure and to create the optimal fracture, while simultaneously in the discharge Well stocks perform hydraulic fracturing at low permeability intervals. Additionally, to create vertical filtration between a high-permeability interlayer, non-perforated and low-permeable, a horizontal lateral trunk is carried out in a low-permeable interval followed by interval fracturing (RF patent No. 2374435, class E21B 43/16, E21B 43/26, publ. 11/27/2009).
Closest to the proposed invention in technical essence is a method of developing deposits with low permeability reservoirs, including drilling production and injection wells, pumping water into the reservoir, displacing oil to production wells and hydraulic fracturing. Production and injection wells are drilled with horizontal shafts parallel to each other in plan with the intersection of all low-permeability formations from the roof to the bottom of the reservoir, while vertical boreholes are drilled in the arch of the structure along the identified or assumed trace of natural fracturing with the faces of these wells extending along extrapolation straight lines along relative to the horizontal shafts of injection wells, after which hydraulic fracturing is carried out in these wells, and water is injected into vertical wells, in which hydraulic fracturing was performed, and in horizontal injection wells, while the water is injected with chemicals that prevent clay particles and interlayers from swelling, and reagents to even out the injection profile, the latter being introduced into the injected water after flooding the produced product at 50-80 % Additionally, in the case of the significant areal size of the oil reservoir, the systems of the horizontal and vertical wells under consideration are constructed at different elevations of the reservoir. In the case of a floating pool, the development elements under consideration are relatively evenly distributed over the area of the pool above the surface of the oil-water contact (RF patent No. 2208140, class E21B 43/20, publ. July 10, 2003 - prototype).
A disadvantage of the known methods is the low oil recovery in the development of low permeability reservoirs with a permeability of less than 2 mD. Also, the production rates of vertical wells on low-permeability reservoirs are characterized by very low values. In the presence of backwater of marginal or bottom water, it is more efficient to conduct development on a natural regime.
The proposed invention solves the problem of increasing the oil recovery factor by increasing the coverage ratio.
The problem is solved in that in the method of developing a low-permeability oil field by horizontal wells in natural mode, including drilling parallel production horizontal wells followed by multi-stage hydraulic fracturing and product selection, according to the invention, in a formation with a permeability of not more than 2 mD, a horizontal production well is drilled with angle β between the maximum main stress of the formation and the direction of the horizontal wellbore from 30 ° to 60 °, hydraulic fracturing is carried out on it, the well is put into operation, times work is carried out in a natural mode without drilling injection wells in a mode in which reservoir pressure during development is reduced by no more than 3% per year, the remaining horizontal production wells are drilled parallel to the first in quantity, so that the specific initial geological oil reserves per horizontal well amounted to at least 50 thousand tons and the distance between the horizontal wells was not less than 100 m, multi-stage hydraulic fracturing is also carried out at all wells, the number N of multi-stage hydraulic fracturing is selected based on the condition N = 1 + L / 100, where L is the length of the horizontal wellbore, and rounded to a larger integer.
SUMMARY OF THE INVENTION
The oil recovery of a low-permeability oil reservoir is significantly affected by reservoir coverage. In general, such deposits are characterized by low oil recovery and selection rates. Horizontal technology and hydraulic fracturing can improve development efficiency. Existing technical solutions do not fully allow to perform this task. The proposed invention solves the problem of increasing oil recovery low-permeability reservoir oil deposits by increasing the coverage of the reservoir exposure. The problem is solved as follows.
Figure 1 shows the location of the producing and injection horizontal wells with multiple hydraulic fracturing. Accepted designations: 1 - productive formation of an oil reservoir, 2 - section of maximum oil-saturated thickness of the reservoir, as well as a purely oil zone, A, B - producing horizontal wells, X, Y - wells operating at another production facility, C - distance between horizontal shafts wells A and B, S tr - fractures of multiple hydraulic fracturing, δ max - direction of the maximum main stress of rocks, β - angle between the direction of the maximum main stress of rocks δ max and the direction of the horizontal wells A and B, L - length of horizontal Wells A and B.
The method is implemented as follows.
The section of oil reservoir 1 (Fig. 1), the productive formations of which are represented by terrigenous or carbonate deposits, are opened by vertical wells X and Y, according to which the structure of the reservoir is constructed. Using VAK-8 at wells X and Y, the direction of the maximum main stress of the rocks δ max is determined. As a result of research, for example, the north-east direction δ max was obtained.
The permeability of the reservoir does not exceed 2 mD. With such permeability values, according to the Decree of the Government of the Russian Federation No. 700-P, the reservoirs are classified as hard-to-recover reserves and they have reduced tax rates on mineral extraction (MET), which allows for horizontal drilling with multi-stage fracturing to be carried out efficiently from an economic point of view .
Wells X and Y are transferred to work on other objects with greater permeability. In reservoir 1, a horizontal production well A is drilled with a horizontal wellbore length L (m) and is located in maximum oil-saturated thicknesses 2. Also, section 2 is a purely oil zone. The direction of the horizontal wellbore of the producing well A and the direction of the maximum principal stress of the formation is an angle p = 30 ° -60 °. According to calculations, this range of angle β allows you to achieve the maximum value of oil recovery.
Then, in the horizontal section of well A, multi-stage hydraulic fracturing is performed, obtaining cracks S tr , in parallel with δ max . The number N of stages of multiple hydraulic fracturing is calculated by the ratio N = 1 + L / 100 and rounded to a larger integer. According to calculations, the maximum oil recovery coefficient is achieved if the number of multi-stage fracturing steps is one more than the length of the horizontal well L, at which this event is carried out, referred to 100. That is, if the length of the horizontal trunk is L = 100 m, then 2 stages of hydraulic fracturing are carried out, if L = 1000, then 11 steps.
Well A is put into operation. Development is conducted in a natural mode without drilling injection wells in a mode in which reservoir pressure during development is reduced by no more than 3% per year. Decide on the further development of reservoir 1 in natural mode without drilling injection wells. According to calculations, when the rate of reservoir pressure drop is more than 3% / year, the reservoir’s energy reserve does not allow maintaining the oil extraction rate at an economically viable level, and the final oil recovery coefficient during natural development is low.
Next, a horizontal production well B is also drilled with a length L parallel to the horizontal wellbore A with a distance between horizontal shafts C of at least 100 m.According to the calculations, at shorter distances C there is a rapid breakthrough of the injected water, which reduces oil recovery.
The total number of horizontal wells in reservoir 1 is determined on the basis that the specific initial geological oil reserves per horizontal well are at least 50 thousand tons. According to calculations, with initial geological oil reserves per well of less than 50 thousand tons, drilling horizontal wells is not economically feasible.
Oil-acid multi-stage hydraulic fracturing is also carried out at well B, the number of steps being also N and the steps being staggered as compared to the staging steps of well A. The staggering procedure allows, according to calculations, to reduce the watering rate of the producing well.
Well B is also being put into production. Development is carried out until the full economically viable development of reserves 1.
Examples of specific performance of the method
Example 1. The section of the reservoir-vaulted oil reservoir 1 (Fig. 1) with dimensions of 400 × 600 m, the productive formations of which are represented by pore-fractured carbonate deposits, are opened by vertical wells X and Y at a depth of 1395 m, according to which the reservoir structure is constructed. Using VAK-8 at wells X and Y, the direction of the maximum main stress of the rocks δ max is determined. As a result of the studies, we obtained the northeast direction δ max .
The initial reservoir pressure of the reservoir is 14 MPa, the saturation pressure of oil is 3.7 MPa, the oil-saturated power in the dome is 14 m, the permeability of the blocks is 1 mD, the permeability of the cracks is 49 mD, the porosity of the blocks is 0.074, the porosity of the cracks is 0.005, the viscosity of the oil in the reservoir conditions - 16.6 mPa · s, initial oil saturation - 0.745, initial geological reserves of the deposit - 170 thousand tons
Wells X and Y are transferred to work on other objects with greater permeability. In reservoir 1, a horizontal production well A is drilled with a horizontal wellbore length of L = 300 m and is located in maximum oil-saturated thicknesses 2. Also, section 2 is a purely oil zone. The direction of the horizontal wellbore of the producing well A and the direction of the maximum principal stress of the formation is an angle p = 60 °.
Next, on the horizontal section of well A, oil-acid multistage fracturing is carried out, obtaining cracks S tr , in parallel with δ max . The number of N stages of multi-stage fracturing is N = 1 + L / 100 = 1 + 300/100 = 4.
Well A is put into operation with a bottomhole pressure of 4 MPa. Over the two years of operation, reservoir pressure dropped by 0.42 MPa, which is 3% per year from the original. Further development is carried out in natural mode without drilling injection wells.
Then, a horizontal production well B with a length of L = 300 m is drilled parallel to the horizontal wellbore A with a distance between horizontal shafts of C = 100 m. The total number of horizontal wells in reservoir 1 is two in the calculation that the specific initial geological oil reserves per horizontal well - not less than 50 thousand tons
Oil-acid multistage fracturing is also carried out at well B, the number of N steps being also 4 and the steps being staggered as compared to the hydraulic fracturing steps of well A.
Well B is also put into operation with a bottomhole pressure of 4 MPa. Development is carried out until the full economically viable development of reserves 1.
Example 2. Perform as example 1. The site of a massive oil reservoir 1 is represented by the pore type of terrigenous reservoir, purely oil zone, the permeability of the blocks is 2 mD. Initial geological reserves of the deposit - 50 thousand tons Development is carried out by one horizontal well A. The angle between the maximum main stress of the formation δ max and the direction of the horizontal well bore A is β = 30 °. In proppant A, proppant multi-fracturing is performed.
As a result, during the development period, which was limited by watering the production well to 98%, or by achieving a minimum profitable oil production rate of 0.5 tons per day, 38.1 thousand tons of oil was produced from the site, the oil recovery ratio was 0.224. According to the prototype, ceteris paribus, 35.4 thousand tons of oil was produced, the oil recovery coefficient was 0.208, the development period was 45 years. The growth rate of oil recovery by the proposed method amounted to 0.016.
Example 3. Perform as example 1. The angle between the maximum main reservoir stress δ max and the direction of the horizontal wellbore A is β = 45 °. Efficiency is similar to example 1.
The proposed method, by increasing the coefficient of coverage of the reservoir, allows to increase oil recovery of the productive reservoir of the oil reservoir.
The application of the proposed method will solve the problem of increasing the oil recovery factor by increasing the coverage ratio.

Claims (1)

  1. A method of developing a low-permeability oil field by horizontal wells in natural mode, including drilling parallel production horizontal wells with subsequent multiple hydraulic fracturing and product selection, characterized in that in producing formations with a permeability of not more than 2 mD, a horizontal production well is drilled with an angle β between the maximum main stress of the reservoir and the direction of the horizontal wellbore from 30 ° to 60 °, multiple hydra fracturing, put the well into operation, the development is carried out in natural mode without drilling injection wells in the mode in which the reservoir pressure during development is reduced by no more than 3% per year, the remaining horizontal production wells are drilled parallel to the first in quantity, based on so that the specific initial geological oil reserves per horizontal well are at least 50 thousand tons and the distance between horizontal bores is not less than 100 m, multiple wells are also carried out hydraulic fracturing, and the number N of hydraulic fracturing steps is selected based on the condition N = 1 + L / 100, where L is the length of the horizontal wellbore, and rounded to a larger integer.
RU2013145724/03A 2013-10-14 2013-10-14 Development of low-permeability oil deposits by horizontal wells under natural conditions RU2528757C1 (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2565617C1 (en) * 2014-10-13 2015-10-20 Открытое акционерное общество "Татнефть" имени В.Д. Шашина Method of development of sandwich-type oil pool using hydraulic fracturing
RU2590965C1 (en) * 2015-07-10 2016-07-10 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Method of developing oil deposits
RU2672292C1 (en) * 2018-01-10 2018-11-13 Публичное акционерное общество "Татнефть" имени В.Д. Шашина Method for oil deposit development with horizontal wells with multi-stage fracing

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RU2135750C1 (en) * 1998-12-28 1999-08-27 Батурин Юрий Ефремович Method for developing oil-gas deposit with application of hydraulic fracturing of bed
US6070666A (en) * 1998-04-30 2000-06-06 Atlantic Richfield Company Fracturing method for horizontal wells
RU2208140C1 (en) * 2002-08-15 2003-07-10 Закиров Искандер Сумбатович A method of development of oil pool with low-permeability reservoirs
RU2331761C1 (en) * 2007-10-03 2008-08-20 Антон Юрьевич Батурин Low-permeable oil reservoir development method
RU2401942C1 (en) * 2009-06-30 2010-10-20 Олег Павлович Турецкий Procedure for hydraulic breakdown of formation in horizontal bore of well
RU2432459C1 (en) * 2010-10-20 2011-10-27 Открытое акционерное общество "Всероссийский нефтегазовый научно-исследовательский институт имени академика А.П. Крылова" ("ОАО "ВНИИнефть") Procedure for development of oil deposits
RU2485296C1 (en) * 2011-12-14 2013-06-20 Открытое акционерное общество "Татнефть" имени В.Д. Шашина Method for improvement of hydrodynamic communication of well with productive formation

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US6070666A (en) * 1998-04-30 2000-06-06 Atlantic Richfield Company Fracturing method for horizontal wells
RU2135750C1 (en) * 1998-12-28 1999-08-27 Батурин Юрий Ефремович Method for developing oil-gas deposit with application of hydraulic fracturing of bed
RU2208140C1 (en) * 2002-08-15 2003-07-10 Закиров Искандер Сумбатович A method of development of oil pool with low-permeability reservoirs
RU2331761C1 (en) * 2007-10-03 2008-08-20 Антон Юрьевич Батурин Low-permeable oil reservoir development method
RU2401942C1 (en) * 2009-06-30 2010-10-20 Олег Павлович Турецкий Procedure for hydraulic breakdown of formation in horizontal bore of well
RU2432459C1 (en) * 2010-10-20 2011-10-27 Открытое акционерное общество "Всероссийский нефтегазовый научно-исследовательский институт имени академика А.П. Крылова" ("ОАО "ВНИИнефть") Procedure for development of oil deposits
RU2485296C1 (en) * 2011-12-14 2013-06-20 Открытое акционерное общество "Татнефть" имени В.Д. Шашина Method for improvement of hydrodynamic communication of well with productive formation

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2565617C1 (en) * 2014-10-13 2015-10-20 Открытое акционерное общество "Татнефть" имени В.Д. Шашина Method of development of sandwich-type oil pool using hydraulic fracturing
RU2590965C1 (en) * 2015-07-10 2016-07-10 Открытое акционерное общество "Татнефть" им. В.Д. Шашина Method of developing oil deposits
RU2672292C1 (en) * 2018-01-10 2018-11-13 Публичное акционерное общество "Татнефть" имени В.Д. Шашина Method for oil deposit development with horizontal wells with multi-stage fracing

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