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IPC classes for russian patent Water-flooded reservoir development method (variants) (RU 2259473):
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FIELD: oil reservoir development, particularly for developing water-flooded ones.
SUBSTANCE: method involves withdrawing oil through production wells and ejecting working substance through ejection wells. To prevent water ingress from well bore into oil-saturated formation area formation is perforated in water-oil interface zone so that lower part of oil-saturation formation interval and upper part of water-flooded formation interval are penetrated. This provides oil relative permeability retention in oil-saturated formation area. To prevent formation mudding during initial perforation thereof drilling is performed in depression, balance and repression modes with pressure of not more than 3 MPa. As far as oil is depleted perforation interval is extended towards oil-saturated formation area.
EFFECT: possibility to retain oil relative permeability of oil-saturated formation area.
2 cl, 2 dwg
The invention relates to the oil and gas industry, and in particular to methods development of flooded oil fields.
Known methods of development of flooded oil fields [1,2,3,4], including the selection of oil through the production wells and the injection of working agent through injection.
With the aim of reducing water abstraction through production wells into injection pump water or sedimentation solutions for capping the most permeable or fractured porous portions of the formation or such operations are performed at the same time as through injection or through production wells.
Also known the way of the development of oil deposits [5], including the injection of water into injection wells, oil extraction through dobyvaya wells and the hydrophobicity of the water of the reservoir, the injection into the producing well fluids to restore permeability oil reservoir, for example, selectively water isolating oil-based solutions, with subsequent change of direction of product formation during its selection.
There is a method of developing oil deposits [6], including the injection of water into injection wells, oil extraction through mining, the hydrophobicity of the reservoir, and the oil is taken deep pumps. the rich for changing the direction of movement of the products in its selection down the shank below the perforated zone [prototype].
The disadvantage of the prototype is the need of the installation of the shank by hanging below the pump or below the packer.
The present invention is the preservation of the relative permeability of the reservoir oil without the use of liners.
Task one option is achieved by the fact that by way of development of waterlogged deposits of oil, including the injection of water into injection wells, oil extraction through production wells, preserving the relative permeability of oil, according to the invention a primary opening of the reservoir by drilling carried out in a mode of depression or equilibrium, and the selection of oil is carried out of the perforation interval width from 1 to 1.5 m, produced in the area of oil-water section, with the width of the perforation interval, coinciding with the oil-saturated part of the reservoir is not more than 75% and the rate of opening of the upper part of the oil-saturated interval of the reservoir, and the lower part - flooded reservoir interval, moreover, as reserves carry out the expansion of the perforated interval in the direction of the oil-saturated part of the formation.
The task of another variant is achieved by the fact that by way of development of waterlogged deposits of oil, including the injection of water into injection wells, oil extraction through production wells, preserving the relative permeability of oil, which according to the invention a primary opening of the reservoir by drilling carried out in the mode of repression is not more than 3 MPa, and the selection of oil is carried out of the perforation interval width from 1 to 1.5 m, produced in the area of oil-water section, with the width of the perforation coinciding with the oil-saturated part of the reservoir is not more than 75 % and the rate of opening of the upper part of the oil-saturated interval of the reservoir, and the lower part - flooded reservoir interval, while as reserves carry out the expansion of the perforated interval in the direction of the oil-saturated part of the formation.
The interval for perforation choose a width from 1 to 1.5 m and the width of the perforation interval, coinciding with the oil-saturated part of the reservoir is not more than 75%.
When selecting products from the formation through the perforated intervals water from flooded (washed) of the reservoir, and the oil from the oil-saturated part of the formation.
The oil received in the wellbore, due to the lower density POPs up and fills the annular space between the production column and deflated equipment above the suction products.
The water in the wellbore accumulates below the point of suction products by gravity separation processes.
Place suction supplied from the reservoir into the wellbore, is located in the lower part of the pump casing. And when deflated the shank place suction products serves as the inlet of the bottom h and shank (shank are called fixed below the pump tubing).
Located in the borehole water in the process of stopping wells penetrating the perforation interval, reduces permeability of oil in the oil-saturated part of the reservoir. This increases permeability of water leads to the formation of a cone of water during operation and to decrease the content of the share of oil in selected products.
But due to the fact that the width of the perforated interval in the oil-saturated part of the reservoir is insignificant, and the amount of lifting of the cone of water is insignificant and is reversible. The main effect is achieved by the fact that due to the small width of the perforated interval opposite the oil-saturated part eliminates the possibility of water ingress from the wellbore in the perforated part of the reservoir. This preserves the relative permeability of the reservoir oil.
Graphic materials (figure 1 and figure 2) explain the essence of the invention, where figure 1 (prototype) shows the well - to-1 with the deep pump - 2 and shank - 3, launched below the perforated interval is 10. Filtering the oil comes from the oil-saturated part of the reservoir 5, and filtering water from the flooded part of the layer - 6, located below the oil-water section - 4. Above the bottom of the shank - 3 borehole filled surfaced with oil, while the perforation interval is also in contact with the oil, allowing you to maintain phase pron the water resistance of the reservoir oil. Below the bottom of the shank, the borehole is filled with water - 8. The arrow 9 indicates the direction of movement of oil and water from the perforated interval during operation of the downhole pump - 2.
2 shows the well - 1, pump 2 flow of oil comes from the oil-saturated part of the reservoir 5, and the water from the water content of the reservoir - 6. In the wellbore below the pump 2 is oil and water. But this water is not in contact with the oil-saturated part of the aquifer in the interval of absence of perforation and therefore does not reduce permeability in oil-saturated part of the reservoir. The arrow 9 indicates the direction of movement of oil and water from the perforated interval.
For successful application of the present invention, it is necessary to observe two conditions:
1. As the selection of oil due to rising oil-water partition you want to make the expansion of the perforated interval in the direction of the oil-saturated part of the formation.
2. The primary opening of the reservoir during the drilling process is carried out in the mode of depression or equilibrium. In case of failure to fulfil this condition, the repression should not exceed 3 MPa. When repression more than 3 MPa, the clogging of the reservoir does not allow effective selection without clearing the bottom-hole zone, and this is impossible without the extension of the perforation interval.
Sources of information
1. Description of the invention in which WCA No. 95103121, 6 E 21 In 43/22, 43/27, publ. in BI No. 35, 1996, "Method of developing multilayer oil fields".
2. Description of the invention the application No. 95108722, 6 E 21 In 43/20, publ. in BI No. 15, 1997, "the Way of the development of oil deposits".
3. RF patent №2103489, 6 E 21 In 43/22, BI No. 3, 1998, "Method development watered oil deposits".
4. RF patent №2113590, 6 E 21 In 43/22, publ. in BI No. 17, 1998, "a Method for developing multilayer oil fields".
5. RF patent №2085714, 6 E 21 In 43/22, publ. in BI No. 21, 1997 from 27.07.97,
6. RF patent №2173770, 7 E 21 In 43/20, publ. BI No. 26, 2001 from 20.09.2001,
1. Method development watered oil, including water injection into injection wells, oil extraction through production wells, preserving the relative permeability of oil, wherein the primary opening of the reservoir by drilling carried out in a mode of depression or equilibrium, and the selection of oil is carried out of the perforation interval width from 1 to 1.5 m, produced in the area of oil-water section, with the width of the perforation interval, coinciding with the oil-saturated part of the reservoir is not more than 75 % and the rate of opening of the upper part of the oil-saturated interval of the reservoir, and the lower part - flooded reservoir interval, while as reserves carry out extension the perforated interval in the direction of the oil-saturated part of the formation.
2. Method development of Obvodny is authorized deposits of oil, including the injection of water into injection wells, oil extraction through production wells, preserving the relative permeability of oil, wherein the primary opening of the reservoir by drilling carried out in the mode of repression is not more than 3 MPa, and the selection of oil is carried out of the perforation interval width from 1 to 1.5 m, produced in the area of oil-water section, with the width of the perforation coinciding with the oil-saturated part of the reservoir is not more than 75 % and the rate of opening of the upper part of the oil-saturated interval of the reservoir, and the lower part - flooded reservoir interval, while as reserves carry out the expansion of the perforated interval in the direction of net oil pay part of the layer.
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