RU2612385C1 - Method for thermal action on formation - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method for thermal action on formation comprises studying of the formation physical parameters, determining in-situ pressure of the formation and the pressure of the formation of fractures in the formation, construction of a horizontally directed well barrel containing a sealed heater filled with coolant in a circulating heat exchanger form, liquid heating in the well barrel is carried out via pumping of a coolant preheated on the surface in the heater. When heating formation in the well, pressure is maintained at least at the level of the initial formation pressure and not exceeding the pressure forming fractions in the collector via releasing of gas from the well and liquid from the well lower level. The directional barrel is constracted upward the bottom of the well with an incline, excluding downward the bottom of the well parts, but not more than 30° in relation to horizon, and the heater does not reach the bottom of the well from 1/4 to 3/4 of the length of directional well barrel.

EFFECT: restoration of the hydraulic connection of the formation with the well, increase in oil recovery from heavy oil formations and well capacity, resumption of operation of unprofitable oil, natural gas, fresh, mineral and thermal waters wells, ecological safety.

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Description

The invention relates to mining and can be used for heat treatment of a productive formation with highly viscous oil, restoration of hydraulic connection between a formation and a well, increase in oil recovery from highly viscous oil and production rates, as well as the resumption of unprofitable wells for oil, natural gas, fresh, mineral and thermal waters.

There is a method of developing a reservoir of high viscosity oil (patent RU No. 2379494, ЕВВ 43/24, published on January 20, 2010) using a pair of horizontal injection and production wells, the horizontal sections of which are placed parallel to one another in the vertical plane of the reservoir, equipped with a pump compressor pipes that allow simultaneous injection of coolant and selection of products, injection of coolant, heating of the reservoir with the creation of a steam chamber, selection of products through a production well through a pump compression pipes and control of technological parameters of the formation and the well, characterized in that the ends of the tubing strings are located at opposite ends of the conventionally horizontal section of the wells, heating of the productive formation begins with steam injection into both wells, heats the inter-well zone of the formation, reduces the viscosity of highly viscous oil, and the steam chamber is created by pumping a coolant, propagating to the upper part of the reservoir with an increase in the size of the steam chamber, in the process of product selection In addition, from time to time, 2-3 times a week, they determine the mineralization of the water being taken in by way, analyze the effect of changes in the mineralization of the water being taken in on the uniformity of heating the steam chamber, and taking into account the changes in the mineralization of the water being taken in, the steam chamber is uniformly heated by adjusting the coolant injection or product selection wells until a stable mineralization value of the associated water is reached.

The disadvantages of this method are:

- a narrow scope associated with the inability to use to increase the productivity of formations with fresh, mineral and thermal waters;

- complex control over the process of steam gravity (PGV), requiring stopping the selection process for the analysis of its mineralization;

- large non-production costs associated with heating the coolant (practically not decreasing with increasing temperature in the heated formation) to high temperatures for injection into the formation, where it mixes with the products of the formation and with which it rises to the surface (at least 80% of the coolant in the produced products ), after which a lot of money is spent on separating the coolant from the production of the formation;

- high pressure injection of the coolant (up to 20-40 MPa) into the reservoir, which can cause a breakthrough of the coolant in the aquifers and / or absorbing strata, which may lead to the inability to use the method or violate the environmental situation in underground water sources;

- it is impossible to analyze the parameters of the injection well without stopping its operation;

- oil recovery factor does not exceed 40% due to the formation of zones with a relatively small initial reservoir with low reservoir resistance and mudding due to high pressure exposure of the reservoir sections that are not in zones with low reservoir resistance, which excludes their further extraction using wells;

- the need to build expensive additional pairs of injection and producing horizontal wells, since the use of horizontal wells with a length of more than 200-250 m and a diameter of more than 140 mm does not affect the heating efficiency due to the formation of zones with low formation resistance in the formation;

- high financial and material costs, the use of expensive equipment operating at high pressures, and the need to build at least one pair of horizontal sections of the injection and production wells.

A known method for the development of deposits of heavy and ultra-viscous oils (patent RU No. 2387818, ЕВВ 43/24, publ. 04/27/2010), including the injection of steam into the reservoir, heating the reservoir with the creation of a steam chamber, the combined injection of steam and hydrocarbon solvent and selection of products, characterized the fact that a hydrocarbon solvent is a mixture of hydrocarbons of the limiting aliphatic and aromatic series, the main component of which is benzene, and the combined injection of steam and a hydrocarbon solvent is carried out after reaching the temperature in the steam chamber is not less than the phase transition temperature of the mixture of steam and hydrocarbon solvent with the temperature in the steam chamber not lower than the temperature of the phase transition of the steam-hydrocarbon solvent mixture.

The disadvantages of this method are:

- a narrow scope associated with the inability to use to increase the productivity of formations with fresh, mineral and thermal waters;

- complex control over the process of steam-gravitational impact (PGW), which requires stopping the selection process for the analysis of its mineralization;

- large non-production costs associated with heating the coolant (practically not decreasing with increasing temperature in the heated formation) to high temperatures for injection into the formation, where it mixes with the production of the formation and with which the formation rises to the surface (at least 80% of the coolant in the produced products), after which a lot of money is spent on separating the coolant from the formation products;

- high costs for the use of hydrocarbon solvent, since it is used as a percentage of the injected steam (3-20 t / h);

- high pressure injection of the coolant (up to 20-40 MPa) into the reservoir, which can cause a breakthrough of the coolant in the aquifers and / or absorbing strata, which may lead to the inability to use the method or violate the environmental situation in underground water sources;

- it is impossible to analyze the parameters of the injection well without stopping its operation;

- the need to build expensive additional horizontal injection wells, since the use of horizontal wells with a length of more than 200-250 m and a diameter of more than 140 mm does not affect the heating efficiency due to the formation of zones with low formation resistance in the formation;

- oil recovery factor does not exceed 45% due to the formation of zones with a relatively small initial reservoir with low reservoir resistance and mudding due to high pressure exposure of reservoir sections that are not in zones with low reservoir resistance, which excludes their further extraction using wells;

- high financial and material costs, the use of expensive equipment operating at high pressures, and the need to build at least one pair of horizontal sections of the injection and production wells.

There is a method of increasing oil recovery by exposure to the bottomhole formation zone by ultrasonic radiation (ultrasound) (patent RU No. 2353760, ЕВВ 43/16, 43/24, 28/00, publ. 04/27/2009), which consists in simultaneous vibration and thermal effects, characterized the fact that ultrasonic radiation is directed from the ground part of the well into the well through the tubing of the well, along the stem of the well pump and along the submersible waveguide located in the tubing and / or in the gap between the tubing and casing, air ystvie performed during oil production from the well without stopping, and ultrasound power density supplied to the waveguides are selected in the range from 0.1 to 10 kW / cm ^2.

The disadvantages of this method are:

- a narrow scope associated with the inability to use to increase the productivity of formations with fresh, mineral and thermal waters;

- also a narrow scope associated with the need to select the column used for ultrasound transmission, with almost the same acoustic and electrical parameters of all its pipes and the formation with fairly uniform parameters along the entire opening length to eliminate the effect of “attenuation” of ultrasound during transmission through the pipe string and impact on the reservoir;

- it is necessary to use special expensive equipment (cables, sensors, relays, control panels, connection nodes, etc.), designed for the high power consumed by the ultrasound generator;

- it is impossible to analyze the parameters of the well and select products without stopping the operation of the ultrasound generator;

- high energy costs with a relatively small coverage of the reservoir, which significantly increases the time (not less than 20 times compared with the PGW) before the start of industrial development.

The closest in technical essence is the method of heat treatment of the bottom-hole zone of the well (patent RU No. 2266401, ЕВВ 43/24, publ. 12/20/2005), including filling part of the body of the electrode heater with water, sealing it, placing it in the well and heating the bottom-hole zone of the well, characterized in that the upper part of the casing is filled with inert gas at an initial pressure p ₁ and after placing the casing in the bottomhole zone of the well, water is heated to the working supercritical temperature T ₂ , while the pressure p ₁ is determined from the dependence:

,

,

where p ₂ is the working pressure inside the heater body corresponding to the temperature T ₂ , Pa;

T ₁ - initial water temperature, K;

V is the volume of the heater body, m ³ ;

V ₂ - the working volume of water at a pressure p ₂ and a temperature T ₂ , m ³ ;

V ₁ - the volume of water at a pressure p ₁ and a temperature T ₁ , m ³ .

The disadvantages of this method are:

- narrow scope associated with the inability to use this method in horizontal wells due to descent on the cable;

- also a narrow scope associated with the need to conduct work near high-voltage power lines (power lines), since the generation of 1 MW of heat at a voltage of 380 V requires a current of 3700 A (which is approximately equal to the simultaneous use of 180 welding machines);

- it is necessary to use special expensive equipment (cables, sensors, relays, control panels, connection nodes, etc.) designed for high power consumed by the heater;

- an increase in the length of the electrode heater reduces the temperature by a unit of its length, which makes this method inefficient in wells with a large length of stimulation;

- high energy costs with a relatively small coverage of the reservoir, which significantly increases the time (about 15-20 times compared with even the GWP) before the start of industrial development;

- it is impossible to carry out the selection and analysis of well production without stopping the operation of the electrode heater, since for its effective operation it is necessary to install a packer in a vertical well above the formation that it affects.

The closest in technical essence is the method of thermal action on the formation (patent RU No. 2471064, ЕВВ 43/24, publ. 12/27/2012, bull. No. 36), including filling a sealed heater with a coolant, placement in the well and heating the bottom-hole zone of the well, the bottom-hole zone of the well is built in the form of a horizontally-inclined or horizontal wellbore, the heater is made in the form of a circulation heat exchanger, in which pumping preheated on the surface of the coolant is performed before placing the heat exchanger study the physical parameters of the formation, determine the in-situ pressure of the formation and the pressure of formation of cracks in the reservoir, while heating the bottom zone of the formation in the well, maintain a pressure not lower than the initial reservoir pressure of the formation and not higher than the pressure of formation of cracks in the reservoir due to the selection of gas and liquid from the well lower level.

The disadvantages of the method are:

- a decrease in the efficiency of the method due to the construction of the well without taking into account the roughness of the horizontal wellbore in the formation;

- high material costs associated with the need to build a heat exchanger in the reservoir for the entire length of a horizontally-inclined or horizontal wellbore, as they require individual development of a heat exchanger, ordering materials and manufacturing for each well;

- low efficiency at the initial stage of the implementation of the method, since only the annular space inside the well between the inner wall and the heat exchanger works to displace formation products.

The technical task of the invention is a method of thermal impact on a formation that works efficiently at the initial well stage by increasing free volume and construction, taking into account the possible curvature of the well bore with low material costs due to the possibility of using a unified heat exchanger for any of the wells.

The technical problem is solved by the method of thermal action on the formation, including the study of the physical parameters of the formation, determination of the in-situ pressure of the formation and the pressure of cracking in the reservoir, the construction of a horizontally inclined wellbore in the formation, in which a sealed heater filled with a coolant is placed in the form of a circulating heat exchanger, fluid heating in the wellbore due to pumping in the heater preheated on the surface of the coolant, and when heated the fins in the well maintain a pressure not lower than the initial reservoir pressure of the formation and not higher than the pressure of formation of cracks in the reservoir due to the selection of gas and liquid from the lower level of the well.

длины наклонно-направленного ствола скважины.What is new is that the directional well is built ascending to the bottom with a slope excluding sections descending to the bottom, but not more than 30 ° relative to the horizon, and the heater does not reach the bottom of the well for at least

length of directional wellbore.

In FIG. 1 shows a diagram for the implementation of a horizontal wellbore.

In FIG. 2 shows a section AA of FIG. one.

The method is implemented as follows.

Build a well 1 (Fig. 1) with the placement of a directional shaft 3 in the reservoir 2, in which the casing 5 is perforated 4 (or during construction, the casing is equipped with sand filters - not shown). Then a sealed heater 6 is lowered into the well 1, for example, made in the form of a pipe 7 in a pipe 8, which is filled with a heat carrier and connected to a heat generator 9, for example, to a heat exchanger or a heating boiler.

Moreover, the length of the heater 6 in the directional barrel 3 should be (empirically determined):

where L _article - the length of the directional shaft 3 of the well 1, m;

L _load - the length of the heater 6 in the barrel 3 of the well 1, m

Since heater 6 is hermetic, any high-temperature coolants, including synthetic oils (for example, Therminol by Solutia Inc., a coolant designed to operate in the range temperatures from -115 ° С to + 400 ° С in the liquid and vapor phase or similar oils from other manufacturers: BP, Shell, etc.). The heater 6 is connected to a heat generator 9 at the wellhead 1, which produces heating of the coolant and from which the pump 10 pumps the preheated coolant through the circulation heater 6, for example, the coolant is pumped into the inner pipe 7 to the plugged end 11 of the outer pipe 8, from where it the annular space of these pipes 7 and 8 rises to the surface and then goes in cycles in the heat generator 9. For more effective heating of the formation 2, the well 3 of the well 1 is recommended to build a horizon cial-sloped, rising to the bottom with a slope α with respect to the horizon, precluding downward to the bottom of the well 1 sites, but not more than 30 °, have been used to heat natural convection, which is more effective the greater the horizontal projection of the barrel. Practice for the fields of the Republic of Tatarstan shows that in order to exclude 1 sections descending to the bottom of the well, for wells with a ∅168 mm casing string, 3 should be constructed with a slope of α: at least 2 ° for carbonate and at least 3 ° 20 'for terrigenous layers. Due to this design of the barrel 3, hydraulic locks in the borehole 3 of the well 1 are eliminated. Such a structure of the wellbore 3 of the well 1 allows the heater to be placed not for the entire length of the well 2. When producing highly viscous and bituminous oils, it is recommended that prior to the placement of the heater 6, the physical parameters of the formation 2 be examined to determine the in-situ pressure of the formation 2 in the initial state and the pressure of cracking in the reservoir 2 . After the descent of the heater 6 when heating the formation 2 in the well 1 maintain the pressure recorded on the manometer 12 (taking into account the location on the mouth), not lower than the initial reservoir failure of formation 2, in order to exclude violation of the integrity of the reservoir collector 2 during the selection of its products, and not higher than the pressure, the formation of cracks in this reservoir, in order to exclude the formation of cracks with low resistance, which can cause breakthrough of steam or heated fluid, reducing the coverage and oil recovery of formation 2, and also to exclude a breakthrough into other layers (not shown), including aquifers. When working while heating the bottom-hole zone 3 when boiling the products of the formation 2, the pressure in the well 1 rises (for maximum efficiency, use the temperature for heating exceeding the boiling point of the products of the formation), which is noted on the pressure gauge 12, which shows the pressure in the well 1 taking into account the depth formation 2, and as the selection of products from formation 2, the pressure estimated by the pressure gauge 12 decreases. Assessing the readings of the pressure gauge 12, a decision is made to select the products of the formation 2 from the well 1 or to pump the pump 13 with liquid or steam into the formation 2 through the well 1, monitoring the pressure in the well 1, which is transmitted to the formation 2.

At the beginning of heating of the formation 2, the pressure in the well 1 increases due to the boiling and expansion of the liquid products of the formation 2 and the expansion of gas at the bottom of the well 1 (located at a depth of H2), which heat up along the vertical section 14 of the well 1, are selected and condensed, for example, prefabricated tank 15. In this case, light fractions of the products of the formation 2 released during the heating of the product can condense and collect in the tank 15 for further technological operations.

As it warms up and is covered by the temperature effect of the formation 2, the volume of incoming products into the well 1 increases and the power of the heater 6 is not enough to bring the fluid coming from the formation 2 to a boil. Then, the products of the formation 2 are selected using a submersible pump 16 (rod or high-temperature screw), lowered on a parallel column of pipes 17, using double-hole wellhead 18 (shown conditionally), with an input 19 located at the lowest possible level H1 of well 1 to ensure the most efficient selection of the formation of products 2.

As a result of the selection of production of formation 2 from well 1 or other production wells (not shown) covered by the thermal effects of well 1 and an increase in the coverage of the temperature effects of formation 2, in-situ pressure decreases. In order to maintain pressure in the formation 2, a liquid is pumped into it through a well 13 via a pump 13 (for example, water, water with solvents, including hydrocarbon, oil, etc.), carbonated liquid, and / or dried steam As a result, the liquid is brought to a boil under the action of the heater 6, and the gas, the generated steam and / or injected steam are additionally heated and create the pressure necessary for further development in the well 1, which acts on the formation 2. Light fractions from the produced products can be used as a hydrocarbon solvent formation 2, located in tank 15. Water with hydrocarbon solvents, oil and carbonated liquid are used when injected into formation 2 for the most efficient displacement with additional dilution m and viscous tar oils therefrom. Water and steam are used in aquifers or oil reservoirs in which a steam chamber has already been formed (shown) at the roof of the formation above the well 1 to maintain a balance between temperature, pressure and the volume of the chamber that maintains water in it in a vapor state.

Wellhead valves 20 are used to distribute the produced products of the formation 2 and inject liquid or steam and control the volumes of coolant pumped in the heater 6. To center the heater 6 relative to the walls of the casing 5 (Fig. 2) of the well 1 (Fig. 1), rigid or spring centralizers are used 21 (Fig. 2), for centering the inner pipe 7 relative to the outer pipe 8 - centralizers 22.

The placement of the heater 6 (Fig. 1) not the entire length of the barrel 3 allows you to increase at the initial stage the volume of steam generated in the well 1, at the initial stage of the method with respect to the closest analogue, which directly increases the efficiency of the proposed method, since the method is implemented by means of natural convection, the displacement force (Archimedes force) of which depends on the volume of the generated vapor (gas).

In the closest analogue, the resulting volume of steam involved in natural convection is calculated by the formula:

where V _1n - the resulting volume of steam in the barrel 3 in the closest analogue, m ³ ;

D _SLE - the inner diameter of the trunk 3 of the well 1, m;

_LOAD D - outside diameter of the heater 6 in the barrel 3, m;

L _article - trunk length 3 wells 1, m

In the proposed method, the resulting volume of steam involved in natural convection is calculated by the formula:

where V _2n - the resulting volume of steam in the barrel 3 in the proposed method, m ³ ;

D _SLE - the inner diameter of the trunk 3 of the well 1, m;

_LOAD D - outside diameter of the heater 6 in the barrel 3, m;

L _article - barrel length 3 wells 1, m;

L _load - the length of the heater 6 in the barrel 3 of the well 1, m

And the difference of the obtained steam volumes ΔV in the proposed method and the closest analogue, ceteris paribus, will be subject to the inequality [1]:

where V _1n - the resulting volume of steam in the barrel 3 in the closest analogue, m ³ ;

V _2p - the resulting volume of steam in the barrel 3 in the proposed method, m ³ ;

_LOAD D - outside diameter of the heater 6 in the barrel 3, m;

L _article - trunk length 3 wells 1, m

For well 1 with a length of 250 m, a casing diameter of 5-168 mm (inner D _well ≈0.15 m) and an outer diameter of the heater of 6-100 mm (0.1 m), the resulting volume of steam in the proposed method is greater than in the closest analogue at 26-79%.

Using the heater 6 length L _LOAD ≈180 m possible trunks 3 wells length D 1 _rms ≈240 ÷ 720 m, and the heater length L _LOAD ≈300 m in wells length D 1 _rms ≈400 ÷ 1200 m. This well construction considerably reduces 1 , since it does not require individual development of the heat exchanger 6, ordering materials and manufacturing it for each well 1.

The proposed method of thermal treatment of the formation is simple and efficient to use, environmentally friendly, does not violate the structure of the formation, allows you to work efficiently at the initial stage of the well due to the increase in free volume and construction, taking into account the possible curvature of the wellbore with low material costs due to the possibility of using a unified heat exchanger for any of the wells.

Claims (1)

The method of thermal action on the formation, including the study of the physical parameters of the formation, determination of the in-situ pressure of the formation and the pressure of formation of cracks in the reservoir, the construction of a horizontally inclined wellbore in the reservoir, in which a sealed heater filled with heat carrier is placed in the form of a circulation heat exchanger, heating the fluid in the wellbore by pumping in the heater preheated on the surface of the coolant, and when the formation is heated in the well support pressure is not lower than the initial reservoir pressure of the reservoir and not higher than the pressure of cracking in the reservoir due to the selection of gas and liquid from the lower level of the well, characterized in that the directional well is built ascending to the bottom with a slope excluding sections descending to the bottom, but no more 30 ° relative to the horizon, and the heater does not reach the bottom of the well from

before

length of directional wellbore.

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