RU2610045C2 - Method and device for alignment of steam assisted gravity drainage with vibration-wave effect on productive formation in horizontal wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: group of inventions relates to oil industry and can be used for increasing oil recovery of productive formations in development of deposits of high-viscosity oil and industrial bitumen using steam assisted gravity drainage. Method of combining steam assisted gravity drainage with vibration-wave effect on productive formation in horizontal well conditions, which comprises laying in an interval of productive formation a pair of two-head horizontal wells, one above other, each consisting of two vertical shafts interconnected by horizontal section and including casing, laid from one head to other and perforated within horizontal section. Furthermore, wells comprise two oil-well tubing (OWT), laid inside casing pipe within vertical shafts and ending with shanks in beginning of horizontal section of well, before perforated section of casing pipe. Upper well is injection well and serves for feeding steam into productive formation, and lower well is a producer well and serves for pumping product. Horizontal section of casing pipe is insulated on both sides by packers installed on ends of OWT. Injection well is mounted on both ends with OWT, immediately behind packers, flow generators of pressure fluctuations, front surface to each other. Volume half-wave resonator is formed from horizontal section of casing pipe, enclosed between flow generators. Steam is pumped into injection well via OWT and all steam is pumped via flow generators. Pressure fluctuations are generated in steam flow. Frequency of generating pressure for steam supply via each OWT is controlled separately. System of waves travelling towards each other is generated in volume resonator. Pressure fluctuations are directed to productive formation through perforations in casing.

EFFECT: technical result is intensification filtration of formation fluid in pore channels due to formation of pressure oscillations of certain frequency in formation interval with developed liquid communication when pumping steam via oil-well tubing into injection well.

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Description

Method and device for combining steam-gravity drainage with a microwave exposure to the reservoir in horizontal wells.

The invention relates to the oil industry and can be applied in the development of high-viscosity oil fields by double-well horizontal wells using the method of steam gravity drainage (SAGD) to increase the fluidity of the oil. It provides intensification of formation fluid filtration due to the formation of a field of elastic vibrations in the interval of a productive formation with developed fluid communication.

A known method of generating pressure waves at the bottom of the well (see patent No. 96118034) when washing with technical fluids, in which a flow generator (PG) is installed at the end of tubing (tubing), fluid is pumped into the tubing, fluid is pumped through the steam generator, generated pressure fluctuations inside the GHG and form elastic pressure waves behind the GHG inside the casing.

Oil production wells are periodically cleaned from solid deposits on the walls and in the perforation holes of the casing and eliminate blockage of the bottomhole zone (decolmate) by pumping various technical fluids. It was noted that the presence of pressure fluctuations in the injected fluid helps to achieve a better result.

The most effective methods of creating pressure fluctuations at the bottom of the well with the help of steam generators installed directly in the place where they are most in demand, i.e. at the lower end of the tubing. With this method of generating pressure fluctuations, all the fluid is pumped through the GHG, which in one way or another creates pressure fluctuations in the fluid flowing through it, forming a field of elastic waves inside the well, spreading its effect through the perforation holes to the adjacent area of the formation. The pumped liquid is then, if necessary, either pumped back through the annulus, or enters the reservoir.

The rigid construction of the steam generator and the absence of moving parts during operation is their advantage.

The disadvantage of GHGs stems from their advantage - a rigid structure makes it difficult to reconfigure them to a different resonant frequency without a significant change in the entire structure

A known method of thermal wave action on a reservoir, including simultaneous thermal and wave action due to injection into the well of the coolant through the SG pressure fluctuations installed in the well (see patent No. 2244813).

To increase the fluidity of high-viscosity oil through a single-mouth horizontal well, water vapor is injected into the formation. All steam is passed through a steam generator installed at the bottom of the well. Pressure oscillations are generated at a frequency corresponding to the natural frequency of the reservoir. Thus, the thermal effect on the formation is combined in order to increase the fluidity of highly viscous oil with a microwave action, which makes it possible to increase fluid mobility in the immediate vicinity of the source of pressure fluctuations.

The disadvantage of this method is the small size of the area covered by the influence of the wave field, limited by the direct proximity to the source of pressure fluctuations.

A known method of producing highly viscous oil, in which a pair of horizontal wellbore wells are laid in the interval of a productive formation, one above the other, each consisting of two vertical shafts interconnected by a horizontal section, and including: a casing pipe laid from one well to the other and perforated into the limits of the horizontal section; and two tubing (tubing), laid inside the casing within the vertical shafts and ending with shanks at the beginning of the horizontal section of the well in front of the perforated section of the casing; of which the upper well is injection and serves to supply water vapor to the reservoir, and the lower well is producing, and serves to pump the product, and the horizontal section of the casing is isolated on both sides by packers installed on the tubing shanks (see patent No. 2287677) .

A two-wellhead injection well is built along the arch of the productive formation, and a two-wellhead is produced along the bottom of the formation. Each well has vertical, inclined and horizontal sections and consists of a casing and two tubing (tubing). The casing pipe is stretched from one wellhead to another and is perforated over a horizontal section. Two tubing are located inside the casing along both vertical sections and end at the beginning of the horizontal section, from the mouths, immediately before the start of the perforated section of the casing.

For the initial heating of the formation, steam is supplied through both wells. Create a permeable zone between the wells, create a steam chamber above the injection well. After that, the steam supply through the production well is stopped and molten oil is extracted through it. The steam supply through the injection well continues during the production period.

The disadvantage of this method is the pinching of part of the oil in the pore channels of the formation by the resulting water condensate and, as a result, incomplete oil recovery.

A device is known for generating pressure fluctuations in a steam stream (see US Pat. No. 6,029,746), consisting of a chamber containing an inlet nozzle and an outlet located coaxially with a certain interval.

A flow generator device consists of two relatively independent parts: a jet generator of primary pressure oscillations and a resonator chamber. The inlet nozzle, the steam jet and the outlet form a jet generator of primary pressure oscillations, which is a self-contained part of the device and functions even in the absence of a resonator chamber, although the amplitude of the generated primary pressure oscillations is very small. But if you install a jet generator of primary pressure oscillations inside a tuned resonator chamber, then the amplitude of pressure oscillations inside the resonator will increase many times.

Widespread are various downhole devices that partially convert the supply pressure into pressure fluctuations in the steam stream injected into the formation. The most suitable devices for this purpose are flow generators of pressure fluctuations that do not have moving parts and convert the kinetic energy of the flow into vibrational energy due to the shape of the channel. The device is screwed into the sleeve at the lower end of the tubing and all the steam supplied to the formation is pumped through it.

A device for vibrating exposure to a reservoir (see US Pat. No. 4,041,984) is closest in technical essence and taken as a prototype consisting of: a cylindrical chamber with two parallel covers on both sides; an inlet nozzle located in the center of one cap on the axis of the cylindrical chamber; and an outlet with a sharp edge, located coaxially with the inlet nozzle on the axis of the cylindrical chamber in the center of the other cover.

At the lower end (tubing), a device is mounted, which is a flow generator of pressure fluctuations installed in the “downstream” direction. The GHG is an axisymmetric body and consists of: a hollow cylindrical chamber with two caps, in which an inlet nozzle (in the front "downstream" cover) and an outlet (in the rear "downstream" cover) are located. The device generates pressure fluctuations in the flowing fluid injected into the reservoir and generates a system of successive pressure fluctuations or elastic waves (field of elastic vibrations) propagating inside the well and further in the bottom-hole zone of the reservoir.

The disadvantage of the device taken as a prototype is the high reflectivity of its entire surface, since all parts are machined from steel and without special processing of the front surface have a high reflectivity.

The aim of the present invention is to increase oil recovery in reservoirs containing highly viscous oil and natural bitumen.

This goal is achieved by the fact that in the method of combining steam gravity drainage with a microwave exposure to the reservoir in horizontal wells, in which in the interval of the reservoir there are a pair of double-mouth horizontal wells, one above the other, each consisting of two vertical shafts connected by a horizontal section and including: casing laid from one mouth to another and perforated within a horizontal section; and two tubing pipes (tubing), laid inside the casing within the vertical shafts and ending with shanks at the beginning of the horizontal section of the well, in front of the perforated section of the casing, of which the upper well is injection and serves to supply water vapor to the reservoir, and the lower well is producing, and serves to pump out the product, and the horizontal section of the casing is isolated on both sides by packers installed on the tubing shanks in the injection well mounted on both shanks of the tubing, immediately behind the packers, flow generators of elastic vibrations, facing each other, create a volumetric half-wave resonator from a horizontal section of the casing enclosed between flow generators, inject steam into the injection well through the tubing and pump all the steam through flow generators generate elastic vibrations in the steam stream, regulate the frequency of generation of elastic vibrations by the steam supply pressure for each tubing separately, form a traveling system in the volume resonator they are facing each other waves, and pressure fluctuations are directed into the reservoir through the perforation holes in the casing.

Or they form a standing wave in the cavity resonator from two waves traveling towards each other, while setting the generation of both waves traveling towards one another at one of the highest natural frequencies of the cavity resonator.

Or they form a system in a volume resonator of two waves traveling towards each other with nodes and antinodes slowly moving along the cavity, for this purpose, the generation of both waves traveling towards one another is set to close frequencies.

In a device for vibrating a microwave on a reservoir, consisting of: a cylindrical chamber with two parallel covers on both sides; an inlet nozzle located in the center of one cap on the axis of the cylindrical chamber; and an outlet with a sharp edge, located coaxially with the inlet nozzle on the axis of the cylindrical chamber in the center of the other cover, the cover with the outlet made with a diffusing front surface.

The proposed method allows you to combine the steam-gravity effect on the reservoir with the microwave action by pumping all the steam supplied through the tubing to the injection well through flow-through generators of pressure fluctuations.

In FIG. 1. shows a spatial arrangement of a pair of double-well wells in the reservoir. A horizontal section of the injection well is highlighted. The sixth harmonic of a standing wave inside the casing of an injection well is schematically depicted.

In FIG. 2. shows a diagram of the mutual arrangement of a pair of flow generators inside a two-well horizontal injection well. It is shown that flow generators are installed in a horizontal section of the well.

In FIG. 3. The installation diagram of the flow generator and packer in the well is shown. Shown are the structural elements of the injection well.

In FIG. 4. The scheme of the flow generator of pressure fluctuations in the assembly is shown. All the main details of the device are presented: a resonator chamber, an inlet nozzle, a steam jet, an outlet.

The essence of the proposed invention is as follows.

A method of producing highly viscous oil and natural bitumen using steam gravity drainage (SAGD) technology using a pair of dual well horizontal wells (see Fig. 1) is considered. Oil-saturated reservoir 1 is located between the impermeable layers: the roof 2 and the bottom 3. Injection well 4, as well as production well 5, consists of two vertical columns, two inclined sections and a horizontal section in the interval between the vertical columns.

Throughout the length of both wells, from one wellhead to the other, casing pipes 6 and 7 are extended (see Fig. 2). On the horizontal sections of the wells, the casing pipes are perforated 8. Inside the casing pipes on the vertical sections of the wells, tubing 9 and 10 are installed. Each tubing breaks off at the beginning of the horizontal section of the well, from its mouth, in front of the perforated section of the casing. The tubing 9 of the injection well 4 ends with shanks (see patent CA 1304287).

In the upper, injection, double-well borehole 4, flow generators 11 are mounted on the shanks 12 (see FIG. 3) of both tubing 9 and generate pressure fluctuations in the fluid flow. The steam is pumped into the well only through the tubing, while all the steam passes through the GHG and then fed into the reservoir. In the well, at the ends of the tubing, immediately before the GHG, packers 13 are installed that separate the horizontal perforated section of the casing from the rest of the casing. The cylindrical chamber, bounded by the inner surface of the casing and GH at the ends, is a volumetric half-wave resonator, the natural frequencies of which (main and higher) are determined only by the length of the chamber in the longitudinal direction, i.e. interval between generators, and do not depend on chamber volume.

When steam passes through the GHGs, periodic pressure fluctuations are generated in the flow, which form a system of successive elastic waves at the GHG outlet. Pressure fluctuations propagate inside the well in the form of a plane harmonic wave, as in a waveguide, since the wavelength λ is much greater than the diameter of the well casing.

Each of the two generators forms a plane harmonic wave in the cavity resonator traveling inside the tube in the direction of the opposite generator. A traveling wave is not reflected from the front surface of the opposite generator. Thus, waves traveling in opposite directions propagate inside the cavity: a direct wave directly emitted by the generator and a wave from the opposite generator. Pressure fluctuations excited by the waves inside the cavity resonate through the perforation holes in the reservoir in the form of repeated shocks, facilitating the movement of fluids through the capillaries of the reservoir.

The half-wave cavity resonator is so arranged that half of the length of a standing wave of double amplitude is always placed inside it: from a traveling wave and reflected with a shift by π; corresponding to the fundamental frequency of the natural oscillations of the resonator. But there are also higher fashions. On the front surfaces of the generators there will always be antinodes of standing wave pressure with such a design. In this case, the higher harmonics will also be multiple located in the interval between the generators.

Paragraph 2 of the formula states the case when a standing wave of two direct waves running from the generators towards each other is formed inside the cavity resonator. In this case, the wave traveling from the second generator will be reflected for the first generator, and, conversely, the wave traveling from the first generator will be reflected for the second generator. In this case, phasing of the waves, i.e. adjust the phase generation so that there is no phase displacement or is 2π (360 °). Such waves are called in-phase. The amplitude of the oscillations in such a wave is equal to the sum of the amplitudes of the two waves.

In clause 3, the case is stated when an in-phase standing wave of two direct waves running from the generators towards each other is formed inside the cavity resonator. Moreover, the frequency of their generation differs by a small amount. This leads to a slow movement of the nodes and antinodes of the standing wave along the axis of the resonator and allows you to affect the entire length of the formation. The amplitude of the oscillations along the length of the casing, however, also slowly varies in magnitude from the difference to the sum of the amplitudes of both waves.

The device of the flow generator for vibrating microwave effects on the reservoir by generating pressure waves in the volume of the horizontal section of the casing of the double-well injection well (see Fig. 4) consists of a resonator chamber 14, which is a steel pipe that is muffled at both ends by flat covers installed in parallel to each other and perpendicular to the axis of the resonator chamber. An inlet nozzle 15 is installed in the first (downstream) chamber lid, which is a small piece of a pipe of a certain bore with a smooth inlet edge and a sharp outlet edge of the flat end. An outlet 16 is formed in the second (downstream) chamber lid, which is simply drilling in a flat lid. A device of this design is called a Helmholtz inkjet generator (SGH) or a Helmholtz inkjet resonator (in the English language literature JDRH - jet drive Helmholts resonator). The front surface of the lid with the outlet is made with small corrugation. Small grooves on the surface scatter the incident wave.

The device is installed on the lower end of the tubing and its inlet nozzle is connected to the tubing channel, and the outlet is directed inside the casing of the well.

A device for generating pressure waves as follows. When steam is supplied to the tubing of a two-mouth horizontal injection well, the supplied steam flows through the resonator chamber 14 (see Fig. 4). Steam is pumped through the inlet nozzle 15 of the device, and in this case an axisymmetric jet with a perturbed periphery is formed at the outlet of the device. Vortex-like ring structures are torn off from the sharp outlet edge of the inlet nozzle at equal intervals, are carried away by the jet and hit in their motion against the sharp inlet edge of the outlet 16, forming weak primary pressure disturbances in the region of the sharp edge. The inner diameter of the outlet is 1.2 ... 1.4 of the diameter of the nozzle. Further, the jet flows into the inner volume of the well casing.

The frequency of the generation of primary pressure perturbations on the sharp edge is tuned to the natural frequency of the resonator chamber 14. In the resonator chamber, the primary pressure perturbations are amplified many times, the chamber resonates and vibrations propagate outward through the outlet 16 into the inner volume of the casing, forming a system in the volume of the casing running waves.

Having reached the opposite generator, the traveling wave is scattered by the corrugated front surface of the opposite GHG. The wave runs back from the second SG, characterized by the same frequency ω and phase ϕ. This generates a standing wave in the volume of the casing. Their amplitude can be different. With interference, the amplitude of the oscillations is added.

If necessary, it is possible to rebuild the equipment at a different oscillation frequency, a multiple of the main frequency, by changing the steam supply pressure. In this case, the position of nodes and antinodes in the casing will change, and the position of local areas of impact on the reservoir with pressure fluctuations will also change.

Claims (4)

1. A method of combining steam-gravity drainage with a microwave exposure to a productive formation in horizontal wells, in which a pair of double-mouth horizontal wells is laid in the interval of the productive formation, one above the other, each consisting of two vertical shafts connected by a horizontal section and including: casing laid from one mouth to another and perforated within a horizontal section; and two tubing pipes (tubing), laid inside the casing within the vertical shafts and ending with shanks at the beginning of the horizontal section of the well, in front of the perforated section of the casing, of which the upper well is injection and serves to supply water vapor to the reservoir, and the lower well is producing and serves to pump out the product, and the horizontal section of the casing is insulated on both sides by packers installed on the tubing shanks, characterized in that in In the production well, on both shanks of the tubing, immediately behind the packers, flow generators of pressure fluctuations, face to each other, are mounted, a volume half-wave resonator is created from the horizontal section of the casing enclosed between the flow generators, steam is pumped into the injection well through the tubing and all steam is pumped through flow generators, generate pressure fluctuations in the steam stream, regulate the frequency of generation by the steam supply pressure for each tubing separately, form a system in the volume resonator eguschih waves towards each other, and pressure fluctuations are directed into the reservoir through perforations in the casing. 2. The method according to p. 1, characterized in that a standing wave is formed in the cavity resonator from two waves traveling towards each other, while the generation of both waves traveling towards one another is tuned to one of the highest natural frequencies of the cavity resonator. 3. The method according to p. 1, characterized in that they form a system in the cavity resonator of two waves traveling towards each other with nodes and antinodes slowly moving along the length of the resonator, for this, the generation of both waves traveling towards one another at close frequencies is tuned. 4. A device for vibrating a wave on a reservoir for implementing the method according to claim 1, consisting of: a cylindrical chamber with two parallel covers on both sides; an inlet nozzle located in the center of one cap on the axis of the cylindrical chamber; and an outlet with a sharp edge, located coaxially with the inlet nozzle on the axis of the cylindrical chamber in the center of another cover, characterized in that the cover with an outlet is made with a diffusing front surface.

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