RU2781983C1 - Method for developing high-viscosity and bituminous oil deposits - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry and can be used in the development of deposits of high-viscosity and bituminous oil. The method for developing a high-viscosity and bituminous oil field includes the construction of a horizontal production well and an injection well located above and parallel to the production well, creating a permeable zone between the wells by injecting a coolant - steam - into both wells, injecting steam into the injection well, withdrawing products from the production well. At the same time, changes in temperature and pressure at the intake of the deep-well pump are monitored. When the downhole pump reaches a pressure of 0.1 MPa and a temperature of 118°C and above, or a pressure of 0.2 MPa and a temperature of 131°C and above, or a pressure of 0.3 MPa and a temperature of 141°C and above, or a pressure of 0 .4 MPa and temperatures of 149°C and above, or pressures of 0.5 MPa and temperatures of 156°C and above, the dryness of the injected steam is reduced to 80-89%. When the downhole pump reaches a pressure of 0.1 MPa and a temperature of 107°C and below, or a pressure of 0.2 MPa and a temperature of 120°C and below, or a pressure of 0.3 MPa and a temperature of 130°C and below, or a pressure of 0 .4 MPa and temperatures of 138°C and below, or pressures of 0.5 MPa and temperatures of 145°C and below, the dryness of the injected steam is increased to 95-97%.

EFFECT: increasing the efficiency of developing paired horizontal wells by maintaining the rate of well heating, maintaining trouble-free operation of wells using the steam gravity method.

1 cl, 1 tbl, 4 ex

Description

The invention relates to the oil industry and can be used in the development of deposits of high-viscosity and bituminous oil.

A known method of operating a double-headed horizontal well (patent RU No. 2159317, IPC E 21 B 43/20, publ. 20.11.2000), including the opening of a productive formation saturated with high-viscosity oil or bitumen, a horizontal wellbore and its fastening with a casing production string, equipment mouth, perforation and development of the well. After the installation of equipment for the extraction of hydrocarbons at the second wellhead, the well is developed and production from the wellheads is started, and when the waterflood contour approaches the packer installation site, the tubular space of the production string in the interval of the packer installation is blocked, for example, with a polymer plug, and the wellhead located on the side opposite to the direction of movement the waterflood circuit is used to inject a liquid or gaseous agent to maintain reservoir pressure, and the opposite wellhead is used to produce hydrocarbons

The known method has a low lifting efficiency of viscous oils or bitumen, as it is characterized by a discrete mode of product lifting, which is associated with the use of the natural energy of the formation.

Also known is a method of developing a deposit of high-viscosity oil or bitumen (patent RU No. 2246001, IPC E 21 B 43/24, publ. to the other, together with packers for installing the latter in the roof of the productive formation, lifting and supplying oil to the flow line at one of the wellheads. The wellhead sections of the production string are connected to each other by a ground section in the form of an arcuate pipeline with an identical inner diameter to form a closed channel, the said ground section of which is fixed on the support frame of the drive unit. To do this, an additional column is placed in the production string, which acts as a tubing in the underground part and has perforations for communication with the reservoir. In the cavity of the additional column at equidistant distances from each other, a system of cylindrical elements is installed, interconnected by means of power rods to form a closed traction system. Sections of the underground part of the tubing string from the wellhead to the boundaries of the perforation section of the production string, together with the said cylindrical elements, form piston pump pairs. During operation, the system of cylindrical elements is forced to move by means of a drive unit with continuous successive displacement of oil from the tubing string by means of the above-mentioned piston pump pairs).

The known method does not allow to develop a reservoir with high oil recovery due to the low flow of high-viscosity formation fluids into the well.

The closest is the method of developing an oil-bitumen deposit (patent RU No. 2287677, IPC E 21 B 43/24, publ. 20.11.2006), including the construction of horizontal double-head production wells and a production injection well located above and in parallel, creating a permeable zone between wells due to the injection of water vapor into both wells, after the creation of a permeable zone, steam is supplied only to the injection two-head horizontal well, and production is taken from the production two-head horizontal well, while the degree of dryness of the injected steam alternates periodically, first steam is injected with a high degree of dryness until the injectivity of the injection well is increased of a double-headed horizontal well and the proportion of steam in the withdrawn production, and then steam of a small degree of dryness is injected, the volume of which is determined by the increase in injection pressure, which is maintained not exceeding the opening pressure of vertical fractures, and the production is taken along the production double-head horizontal well until the productive formation is completely depleted.

The disadvantages of this method are the high material and energy costs for the construction of two-headed horizontal wells associated with the need for additional drilling, casing, cementing and arrangement of the second wellhead. Also, in the known method, the range of the degree of steam dryness is not indicated, and therefore it is quite difficult to implement the method and achieve the required rate of heating and, as a result, oil recovery.

The technical objectives are to increase the efficiency of development of paired horizontal wells by reducing the unit costs of steam generation, maintaining the rate of well warm-up, maintaining trouble-free operation of wells using the steam gravity method.

Technical problems are solved by the method of developing a field of high-viscosity and bituminous oil, including the construction of a horizontal production well and an injection well located above and parallel to the production well, the creation of a permeable zone between the wells by injecting a coolant - steam into both wells, injection of steam into an injection well, selection of products from production well.

What is new is that they monitor changes in temperature and pressure at the suction of the deep pump, when the pressure at the suction of the deep pump reaches 0.1 MPa and a temperature of 118°C and above, or a pressure of 0.2 MPa and a temperature of 131°C and above, or pressure 0.3 MPa and a temperature of 141°C and above, or a pressure of 0.4 MPa and a temperature of 149°C and above, or a pressure of 0.5 MPa and a temperature of 156°C and above, the dryness of the injected steam is reduced to 80-89%, at reaching at the suction of the deep pump a pressure of 0.1 MPa and a temperature of 107°C and below, or a pressure of 0.2 MPa and a temperature of 120°C and below, or a pressure of 0.3 MPa and a temperature of 130°C and below, or a pressure of 0, 4 MPa and temperatures of 138°C and below, or pressures of 0.5 MPa and temperatures of 145°C and below, the dryness of the injected steam is increased to 95-97%.

The method for developing paired horizontal wells producing high-viscosity oil is carried out in the following sequence.

In a high-viscosity oil field, pairs of horizontal wells are drilled, namely horizontal production wells and injection wells located above and parallel to the production wells. Production wells are equipped with temperature and pressure control devices.

A permeable zone is created between the injection horizontal well and the production horizontal well by injecting the coolant - steam into both wells along the tubing string from the inlet and outlet sections. Steam enters the zone between wells through cracks. There is an accelerated heating of the formation. After the pressure is removed, the fractures close and the heat coverage of the formation increases. After creating a permeable zone, the coolant is pumped only into the injection well.

Changes in thermobaric conditions are monitored - changes in temperature and pressure at the intake of the deep pump. Upon reaching the critical values of the upper (with an increase in temperature) and lower (with a decrease in temperature) temperature limits at the inlet of a deep-well pump at certain pressure values, the dryness of the steam is changed. The critical values of the upper and lower temperature limits are determined based on the permissible values of the upper temperature limit at the inlet of the deep pump - T1 and the lower temperature limit - T2 at the inlet of the deep pump (see table).

When the downhole pump reaches a pressure of 0.1 MPa and a temperature of 118°C or more, or a pressure of 0.2 MPa and a temperature of 131°C or more, or a pressure of 0.3 MPa and a temperature of 141°C or more, or a pressure of 0 .4 MPa and temperatures of 149°C and above, or pressures of 0.5 MPa and temperatures of 156°C and above, the dryness of the injected steam is reduced to 80-89%.

When the downhole pump reaches a pressure of 0.1 MPa and a temperature of 107°C and below, or a pressure of 0.2 MPa and a temperature of 120°C and below, or a pressure of 0.3 MPa and a temperature of 130°C and below, or a pressure of 0 .4 MPa and temperatures of 138°C and below, or pressures of 0.5 MPa and temperatures of 145°C and below, the dryness of the injected steam is increased to 95-97%.

Table. Intervals of the upper and lower temperature limits at the intake of the deep-well pump.

P - pressure at the intake of the deep pump, MPa T1 - upper temperature limit at the intake of the deep pump, °C T2 - lower temperature limit at the intake of the deep pump, °C 0.1 120.23 105.23 0.2 133.54 118.54 0.3 143.62 128.62 0.4 151.84 136.84 0.5 158.84 143.84

An increase in the temperature at the downhole pump intake and its approach to the upper temperature limit at the intake of the downhole pump indicates that the boundary of the steam chamber is approaching the production well, which, in turn, leads to pump failure, steam breakthrough and unproductive heat loss. Therefore, the dryness of the injected steam is reduced to 80-89% (for example, from the degree of steam dryness of 95-97%, it is reduced to a value of 80-89%). A decrease in temperature at the downhole pump intake and its approach to the lower temperature limit at the downhole pump intake indicates that the steam chamber boundary is moving away from the production well, approaching the injection well, which, in turn, leads to watering the well, condensation of the steam chamber and to reduce oil production, the dryness of the injected steam is increased to 95-97% (for example, from the degree of steam dryness of 80-89%, it is increased to 95-97%).

Examples of practical application.

Example 1

At the Ashalchinskoye bitumen deposit, located at a depth of 90 m, there are heterogeneous layers 4 with a thickness of 20-30 m, formation temperature of 8 ° C, pressure of 0.5 MPa, oil saturation of 0.7 units, porosity of 30%, permeability of 2, 65 µm2, density of bitumen in reservoir conditions 960 kg/m3, viscosity 22000 Pa, drilling was carried out along the in-line grid of horizontal steam injection wells and located below production wells, equipped production wells with temperature and pressure control devices. At the initial stage, a permeable zone was created between the wells by injecting a coolant, steam with a dryness of 95% into both wells in a volume of 80 t/day for 2 months, and after the creation of the permeable zone, steam was pumped only into the injection well in a volume of 80 t/day, and from production well produced a selection of products. After operating the well for 8 months, the thermobaric conditions at the pump intake reached 131°C at a pressure of 0.2 MPa, which indicated that the boundary of the steam chamber was approaching the production well. To reduce the temperature in the steam chamber and maintain liquid and oil production levels, the dryness of the injected steam was reduced from 95% to 80%. These measures made it possible to avoid failure of the downhole pump, steam breakthrough and unproductive heat loss, as well as to avoid the loss of liquid and oil production by 20%.

Example 2

At the Ashalchinskoye bitumen deposit, located at a depth of 90 m, there are heterogeneous layers 4 with a thickness of 20-30 m, formation temperature of 8 ° C, pressure of 0.5 MPa, oil saturation of 0.7 units, porosity of 30%, permeability of 2, 65 µm2, bitumen density in reservoir conditions 960 kg/m3, viscosity 22,000 MPa, drilling was carried out along the in-line grid of horizontal steam injection wells and located below the production wells, the production wells were equipped with temperature and pressure control devices. At the initial stage, a permeable zone was created between the wells by injecting a coolant, steam with a dryness of 96% into both wells in a volume of 80 t/day for 2 months, and after the creation of the permeable zone, steam was pumped only into the injection well in a volume of 80 t/day, and from production well produced a selection of products. After operating the well for 8 months, the thermobaric conditions at the pump intake reached 118°C at a pressure of 0.1 MPa, indicating that the boundary of the steam chamber is approaching the production well. To reduce the temperature in the steam chamber and maintain liquid and oil production levels, the dryness of the injected steam was reduced from 96% to 85%. These measures made it possible to avoid failure of the downhole pump, steam breakthrough and unproductive heat loss, as well as to avoid loss of liquid and oil production by 15%.

Example 3

At the Ashalchinskoye bitumen deposit, located at a depth of 90 m, there are heterogeneous layers 4 with a thickness of 20-30 m, formation temperature of 8 ° C, pressure of 0.5 MPa, oil saturation of 0.7 units, porosity of 30%, permeability of 2, 65 µm2, bitumen density in reservoir conditions 960 kg/m3, viscosity 22,000 MPa, drilling was carried out along the in-line grid of horizontal steam injection wells and located below the production wells, the production wells were equipped with temperature and pressure control devices. At the initial stage, a permeable zone was created between the wells by injecting a coolant, steam with a dryness of 97% into both wells in a volume of 80 t/day for 2 months, and after the creation of the permeable zone, steam was pumped only into the injection well in a volume of 80 t/day, and from production well produced a selection of products. After operating the well for 8 months, the thermobaric conditions at the pump intake reached 119°C at a pressure of 0.1 MPa, indicating that the boundary of the steam chamber is approaching the production well. To reduce the temperature in the steam chamber, the dryness of the injected steam was reduced from 97% to 89%. Further, after the operation of the next 6 months, the thermobaric conditions at the pump intake reached 106°C at a pressure of 0.1 MPa, indicating that the boundary of the steam chamber is moving away from the production well. At the same time, the water cut of the products increased to 98%. To reduce the water cut of the produced fluid, the dryness of the injected steam was increased from 89% to 95%. This measure made it possible to increase the oil production rate by 30%.

Example 4

At the Ashalchinskoye bitumen deposit, located at a depth of 90 m, there are heterogeneous layers 4 with a thickness of 20-30 m, formation temperature of 8 ° C, pressure of 0.5 MPa, oil saturation of 0.7 units, porosity of 30%, permeability of 2, 65 µm2, bitumen density in reservoir conditions 960 kg/m3, viscosity 22,000 MPa, drilling was carried out along the in-line grid of horizontal steam injection wells and located below the production wells, the production wells were equipped with temperature and pressure control devices. At the initial stage, a permeable zone was created between the wells by injecting a coolant, steam with a dryness of 97% into both wells in a volume of 80 t/day for 2 months, and after the creation of the permeable zone, steam was pumped only into the injection well in a volume of 80 t/day, and from production well produced a selection of products. After operating the well for 8 months, the thermobaric conditions at the pump intake reached 142°C at a pressure of 0.3 MPa, indicating that the boundary of the steam chamber is approaching the production well. To reduce the temperature in the steam chamber, the dryness of the injected steam was reduced from 97% to 85%. Further, after the operation of the next 6 months, the thermobaric conditions at the pump intake reached 130°C at a pressure of 0.3 MPa, indicating that the boundary of the steam chamber is moving away from the production well. At the same time, the water cut of the products increased to 98%. To reduce the water cut of the produced fluid, the dryness of the injected steam was increased from 85% to 97%. This measure made it possible to increase the oil production rate by 18%.

The proposed method for developing paired horizontal wells producing high-viscosity oil makes it possible to increase the efficiency of developing paired horizontal wells by maintaining the rate of well heating, reducing unit costs for steam generation, and maintaining trouble-free operation of wells using the steam gravity method.

Claims (1)

A method for developing a high-viscosity and bituminous oil field, including the construction of a horizontal production well and an injection well located above and parallel to the production well, creating a permeable zone between the wells by injecting a coolant - steam - into both wells, injecting steam into the injection well, withdrawing products from the production well , characterized in that they monitor changes in temperature and pressure at the intake of the deep pump, when the pressure at the intake of the deep pump reaches 0.1 MPa and a temperature of 118 ° C and above, or a pressure of 0.2 MPa and a temperature of 131 ° C and above, or pressure 0.3 MPa and a temperature of 141°C and above, or a pressure of 0.4 MPa and a temperature of 149°C and above, or a pressure of 0.5 MPa and a temperature of 156°C and above, the dryness of the injected steam is reduced to 80-89%, at reaching a pressure of 0.1 MPa and a temperature of 107°C and below at the suction of the deep pump, or a pressure of 0.2 MPa and a temperature of 120°C and below, or a pressure of 0.3 MPa and a temperature of 130°C and below, or pressure 0.4 MPa and a temperature of 138°C and below, or a pressure of 0.5 MPa and a temperature of 145°C and below, the dryness of the injected steam is increased to 95-97%.