Background Art Methods and devices of the above mentioned general type are known in the art. One of such methods is disclosed for example in U. S. patent no. 5,105,889. The device disclosed in this reference includes a set of axially vertically aligned pipes of different diameters and length, representing a multiparameteric hydrodynamic system which establishes a certain precalculated bottomhole pressure below the device, in order to decrease gas blockage of the near bottomhole zone of the formation and to provide a stable fluid flow to the surface. A forced fluid degassing takes place the device, creating a two-phase gas-liquid emulsion in order to provide a sufficient fluid lift within the well. The device disclosed in this patent has however certain limitations. A pressure differential depends on the calculated diametrical parameters of the pipes, which correspond to current values of parameters of the flow and the formation. Such stringent dependency restricts the adaptability of the device to changing reservoir and well conditions. Geometrical sizes of the pipes on which the efficiency of the device depends are based on such data as reservoir and bottomhole pressure, reservoir collecting properties, physical oil and gas characteristics, etc. The data may not accurately correspond to the actual current conditions resulting in an impaired efficiency of the bottomhole device. In the calculations some operational procedures can not be taken into consideration such as completion and shut-in of an adjacent well, thus impairing well parameters and affecting performance of the well with the bottomhole device.

There is however a long period of time from the date when the well and the parameters are taken, than the sizing calculations of the device are performed, and the device is manufactured and installed in the well. During this time the parameters may change and the calculations will be inaccurate.

Another method and device is disclosed in U. S. patent 5, 752, 570. In accordance with this patent, bottomhole pressure is automatically maintained higher than a current saturation pressure of the formation fluid with gas in the near bottomhole zone of the formation, regardless of fluctuations of fluid pressure in the formation, in order to create fluid flow with minimum gas content. Once the bottomhole pressure decreases, the device automatically creates conditions for formation of a fluid flow into the device with an increased speed. Nearly monophase flow is transformed within the device into a finely dispersed gas-liquid flow, in order to provide its lift to the wellhead. The device disclosed in this reference automatically adjusts bottomhole pressure to a desired level, simultaneously providing a pressure drop, in order for the fluid to degass within the transforming area, according to the device inlet pressure at the bottomhole.

However, in the process of oil field development, operational conditions change as well as the inflow performance curve corresponding to a current well operation, and the sensing element of the device disclosed in this reference will no longer maintain the same optimal well operation, since its calibration was based on the previous well information parameters. Also, in the device disclosed in this reference, the regulation is performed by means of changing an inlet diameter of the device, which is based on extremely little movement of its elements. Besides in case of unstable well operation, the regulating system may acquire automatic fluctuations. Calculations have proven that in some wells a space between the inner nozzle surface and the outer surface of the regulating cone of the device reduces approximately 0.01 inch. With such a small space even a trace of sand in the fluid can jam the regulating unit and stop the well. Since the pressure difference depending on the movement of the regulating cone has a non linear characteristic and is a function of fixed power of the diameter of the regulatable cross-section, it impedes precise regulations.

The device for intensification of hydrocarbons production disclosed in U. S. patent no. 5, 105, 889 also has some disadvantage : ;. The special landing seat is needed for each well and is to be adapted fcr each particular device, so that for installation of removal of the seat lifting and lowering of the whole tubing is needed, which naturally involves additional time, labor and expenses. The landing seat decreases a cross-section of the bottomhole of the well posing substantial difficulties when it is necessary to perform other procedures, for example measuring. The landing seat can be connected only at one piece of the tubing which is at the bottomhole of the well. In the known device rubber O-rings are provided between the device and the landing seat to ensure hermetic stability. They cause some difficulties when the device is installed and they are not completely reliable.

The elastic fixing element of the device formed as a collet which is located downstream of the device is susceptible to mechanical fractures and other defects, which decrease the service life and reliability of the whole device.

The collet must be destroyed when the device is lifted from the well and its parts are left in the bottomhole and pollute the latter. In the event of extensive exploitation in corrosive areas of the well bottomhole, the properties of the collet material change and stability can be lost. As a result, lifting of the device to the surface with conventional equipment can be impossible and the well in this situation is completely incapacitated. The device can not be used in the hydrocarbons well with a multi-purpose nipple at the bottomhole for installation and removal of different well devices and measuring equipment.

The specific design features such as the lower fastening, the presence of collet, etc. limits the possibility of necessary variations with use of the Venturi tubes.

Disclosure of the invention Accordingly, it is an object of the present invention to provide a method of and a device for production of hydrocarbons, which avoids the disadvantages of the prior art.

More particularly, it is an object of present invention to provide a method of and a device for production of hydrocarbons by means of automatic setting and maintaining a bottomhole pressure at an optimal level and fluid flow within a wide range of their parameters without the necessity of replacing the device.

It is also an object of present invention to provide a method of and a device for production of hydrocarbons which allow a self-regulating operation with regulation of a multi-phase flow under changing formation conditions and with varying fluid parameters.

It is also an object of present invention to provide a method of and device for production of hydrocarbons, which are characterized of smooth characteristics of regulation of hydraulic resistance to a fluid flow, capable of a smooth, flexible and precise regulation of the system well-formation within a wide range of well flow rates.

Still another object of present invention is to avoid generation of sound speeds of the flow in the device within a calculated range of yields.

Also, it is an object of present invention to provide a device for intensification of hydrocarbons production, which ensures efficient lifting, lowering, prolongation of service life, and exploitation in the well.

Accordingly, it is an object of present invention to provide a method of production of hydrocarbons comprising the steps of producing a flow of hydrocarbon-containing formation fluid from a formation at a bottomhole of a well, automatically maintaining a pressure of the optimum formation fluid at the bottomhole of the well at a level sufficient for maintaining the flow of the formation fluid from the formation at the bottomhole of the well towards a we)) head by changing a parameter of a flow passage of an automatically maintaining means arranged in the well ; in response to changes in properties of the formation and formation fluid and performing the changing of the parameter of the flow passage of the automatic maintaining means in response to a difference of a formation fluid flow parameter upstream and downstream of said automatic maintaining means.

In accordance with another feature of the present invention, a device for production of hydrocarbons from a well having a bottomhole and a wellhead and communicating with a formation, the device has means for producing a flow of hydrocarbon-containing formation fluid from the formation at the bottomhole of the well ; means for automatically maintaining a pressure of the formation fluid at the bottomhole of the well at a level sufficient for maintaining optimum the flow of the formation fluid from the formation at the bottomhole of the well to the wellhead by changing a parameter of flow passage of said automatic maintaining means arranged in the well in response to changes in properties of the formation and the formation fluid ; and means for detecting a difference of a formation fluid flow parameter upstream and downstream of said automatic maintaining means, so that the parameter of the flow passage of said automatic maintaining means is changed in dependence on said differences of a formation fluid flow parameter upstream and downstream of said automatic maintaining means.

A further feature of present invention resides, briefly stated, in a device for intensification of hydrocarbons production which comprises a substantially tubular body adapted to be arranged inside a well tubing and having an axis and a plurality of passages arranged one after the other in an axial direction and having different diameters, so that hydrocarbons can flow from a bottomhole of the well successively through said passages toward a wellhead, the body having at least a tubular portion which is provided inside with at least one of the passages and is provided outside with means for fixing the one portion and therefore the body to the well tubing, the body also having another portion axially spaced from at least one portion and provided inside with at least one of the passages and outside with means for sealing the another portion relative to the well tubing.

It is still a further object of present invention to provide a system for hydrocarbons production which comprises a well tubing ; and a device for intensification of hydrocarbons production, the device including a substantially tubular body adapted to be arranged inside a well tubing and having an axis and a plurality of passages arranged one after the other in an axial direction and having different diameters so that hydrocarbons can flow from a bottomhole of the well successively through the passages toward a well head, the body having at least a tubular portion which is provided inside with at least one of the passages and is provided outside with means for fixing the at least one portion and therefore the body to the well tubuing, the body also having another portion axially spaced from at least one portion and provided inside with at least one of the passages and outside with means for sealing the another portion relative to the well tubing.

The novel features which are considered as characteristic for the present invention are set forth in particular in the appended daims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

Brief Description of the Drawings Figure 1 is a view showing a method of and a device for production of hydrocarbons in accordance with the present invention ; Figure 2 is a view showing illustrating characteristic curves for regulation of production of hydrocarbons by the method and the device in accordance with the present invention ; Figure 3 is a view schematically showing a device for intensification of hydrocarbons production which is formed in accordance with one embodiment of the present invention and arranged in a well tubing provided with a nipple ; Figure 4 is a view showing a device for intensification of hydrocarbons production which is formed in accordance with another embodiment of the present invention and installed in a well tubing provided with a tubing collar, and Figure 5 is a view showing a device for intensification of hydrocarbons production which is formed in accordance with a third embodiment of the present invention and arranged in a smooth well tubing without a tubing nipple or a tubing collar.

Best Mode of Carrying Out the Invention A device in accordance with the present invention includes a known well tubing which is identified with reference numeral 1 and arranged a well. A flow of hydrocarbon-containing formation fluid flows through the well tubing 1 from a bottomhole near a formation to a wellhead.

A device for automatically maintaining a pressure of the formation fluid at the bottomhole of the well at a level sufficient for maintaining the optimum flow of the formation fluid from the formation at the bottomhole of the well to the wellhead in accordance with the present invention includes a set of interconnecting elements located in the well tubing 1. The device is fixed to the well tubing 1 by a locking element 2 which is installed hermetically in the well tubing at a certain depth. The device has a body which is identified with reference numeral 3 and attached to a bottom part of the locking element, for example by threaded connection. A plurality of pipes 4 are provided inside the body 3. The device further has a double-acting cylinder-piston unit including a cylinder 5 and a piston 7 with a piston rod 6 reciprocatingly movable in the cylinder 5. The cylinder 5 is connected to the lower part of the body 3.

The upper part of the cylinder above the piston 7 or downstream of the piston as considered in direction of flow of the formation fluid is provided with a port 8 through which the fluid from the bottomhole can flow into the interior of the cylinder 5 above the piston 7. The fluid flow entering the upper part of the cylinder 5 above the piston 7 has a pressure P, which is applied to the piston 7 from above. The lower part of the cylinder 5 has a port 9 located below the piston 7 or downstream of the piston 7 as considered in direction of flow of the formation fluid. The port 9 is connected by a connecting pipe 10 to a space above the device 4,5,6,7. The port 9 is filled with the formation fluid having a pressure Pz which is applied to the lower surface of the piston 7 from below.

The device is further provided with a balancing spring 11 which can be located inside or outside of the cylinder 5, above or below it, in accordance with the well conditions. A cylinder needle 12 is attached to the piston rod 6 coaxially with the set of the pipes 4. During the reciprocating movement of the piston 7 in the cylinder 5, the needle 12 is displaced within a lower pipe of the multi-pipe set of the inventive device, along the axis of the device. During the displacement of the needle 12 within an inner opening of the lower pipe of the device, a length of an annular passage formed around the needle 12 changes.

Finally, a central support 13 operates as a bearing for a cantilever part of the needle and as an upper stop for the stroke of the piston rod 6.

The method in accordance with the present invention is performed and the device in accordance with the present invention operates in the following manner.

During the operation of a well, the formation parameters, such as formation pressure, gas, oil and water saturation, phase permeability as well as fluid parameters, such as water-oil and gas-oil ratio, viscosity, surface tension, etc. change. In the oil industry it was necessary to replace the equipment in the well with a new equipment having characteristics corresponding to the current formation and fluid parameters. With the method and device in accordance with the present invention no replacement of the equipment is needed. The device automatically maintains a pressure of the formation fluid at the bottomhole of the well at a level sufficient for maintaining the optimum flow of the formation fluid from the formation at the bottomhole of the well to the wellhead. The device in accordance with the present invention provides automatic adjustment of its parameters in response to the changing formation parameters and fluid properties.

An increased differential pressure between the formation and the bottomhole pressure usually results in increased oil flow rates. However, in formations with high gas-oil ratio, a decrease in bottomhole pressure causes formation oil degassing in the near bottomhole zone of the formation, increase in oil viscosity, reduction of the formation oil permeability and as a result, reduction of the formation productivity. Further reduction of bottomhole pressure may result in a decrease of oil flow rate rather than an increase.

The valve pressure is optimal when its subsequent decrease leads not to an increase of the yield but instead to a decrease of the yield. The optimum pressure will change in time according to change of parameters of fluid and formation. Maintenance of an optimum bottomhole pressure by means of the inventive device in the formations with gas and water coning provides for the maximum oil flow rates with minimum gas and water flow rates.

In the beginning of the operation of the inventive device, the needle 12 is completely introduced into the lower pipe 4 of the pipe set. In some cases it can be not completely introduced, and in other cases it can be completely withdrawn from the lower pipe, depending on the well and formation conditions. After installation of the device and starting of the well, the phase oil permeability, in the near bottomhole zone of the reservoir increases and as a result the oil flow rates also increase. In response, the pressure differential within the device grows. The piston 7 is displaced in the cylinder 5, and in turn it displaces the needle 12. The piston 7 is under a pressure differential P,-P2. The piston 7 is balanced by the spring 11 such that the initial movement of the piston connected with the needle 12 starts when a force generated by the pressure differential exceeds a force of the pre-compressed spring: APS = (P1-P2) S>Fspr, wherein S is a cross-sectional area of the piston.

Before any movement of the piston, the pressure differential within the device corresponds to the initial hydraulic resistance, with the cylinder needle pushed into the lower pipe. After the increase of the flow rate to a certain level when its further growth may cause extremely rapid increase of pressure differential within the device, the needle 12 starts to pull down from the lower pipe 4. When APS < F, wherein Fv is the force of the spring, the hydraulic resistance of the device reduces, maintaining bottomhole pressure at an optimum level. Such dependence of the bottomhole pressure and the movement distance is based on certain computer simulators which calculate a pressure distribution in the reservoir, well and in the device. Operational characteristic of the spring is calculated in accordance with the above mentioned considerations.

When the cylinder needle 12 is completely pulled out of the lower pipe, the hydraulic resistance of the device is minimal. Such resistance corresponds to a resistance of the whole system of the pipes having a round cross-section. The pressure differential within the device in response to a further increase of flow rates will be based on a constant (minimal) hydraulic resistance of the lower pipe, as well as another pipe, and further pipes of the multi-pipe system. It is important that after the needle 12 starts to pull down from the lower pipe, the lower pipe becomes a system of two pipes, including a round pipe and a coaxial pipe. If the flow rates decrease due to some changes in the reservoir and fluid parameters and reduction of the reservoir pressure, the needle 12 will start moving back into the lower pipe so as to adjust the hydraulic resistance of the device to an optimum level in order to maintain optimum bottomhole pressure and maximum oil flow rates according to the current conditions of the reservoir, reservoir pressure, and fluid parameters.

Due to the above described self-regulation the inventive device can operative efficiently in a wider range of reservoir and fluid parameters varying with time without the necessity to remove the device from the well.

When the method is performed and the device in accordance with present invention, they provide an increase in oil well production and recovering index by maintaining stable fluid flow rates at an optimum (maximum) level according to current reservoir condition, fluid parameters and recovery method. A considerably prolonged duration of the well life operating due to the inventive device is provided without the necessity to replace the device. An improved regulation of parameters of the system reservoir-well due to the flexible, smooth and precise device operation is achieved within a wide range of pressure levels, fluid flow compositions and flow rates. Numerous wiretine operations on the device installation/removal in order to replace pipe system due to the change of reservoir and fluid parameters and lift conditions are dispensed with. The geometrical parameters of the device automatically adjust in response to changing formation and fluid parameters. There is no fluid flow rate limitation when the fluid speed within the device reaches a sound velocity. Also, the regulation is performed as a two stage regulation when necessary, in particular a rigid regulation in the beginning uninterruptedly transforming into a smooth and flexible regulation of fluid flow hydraulic resistance at the end.

An example for designing the device in accordance with the present invention with a movable needle is presented hereinbelow.

The example is used for a well with a depth H = 5000 ft which produces Qd = 120 BBL/, with gas-oil ratio GOR = 1550 SCFIBBL and water-oil ratio WOR = 0.3, with formation pressure Pf = 2000 PSI and bubble point pressure bubble Pbp = 2100 PSI. A lift curve which reflects the dependency of change of the bottomhole pressure from the yield of oil with a diameter tubing Dt = 0.203 ft and a wellhead pressure P,,,,, = 120 PSI is represented by the curve 1 in Figure 2.

In order to maintain an optimum mode of operation of the system well-formation, as was shown by a computer simulation phase filtration in the formation, it is necessary to maintain the bottomhole pressure within the range of 850-1200 PSI with expected change of oil yield from 50 to 300'in, and GOR correspondingly from 3000 to 350'- For this example, a device which maintains the required mode is a two-pipe device which is disclosed hereinabove, with a diameter of the lower pipe D1 = 0.014 ft (4.3 mm) and length L, = 0.3 D, a diameter of the upper pipe D2 = 0.03 ft and L2 = 0. 6 f. The cylindrical needle with a diameter Di = 0.0075 ft and L1 = 0. 3 ft moves inside the lower pipe. The calculated value of the pressure difference at device in the event when the needle is completely introduced is represented by a curve 2 in Figure 2. The case which corresponds to the completely introduced needle is represented by the curve 3 in Figure 2. If the needle were introduced and immovable, then the bottomhole pressure will change in accordance with the low represented by the curve 4, even with the yields Qd < 200 BBt/D. The value of the bottomhole pressure will be Ptt < 1200 PSI, or in other words beyond the range of the adjustment.

However, the spring which is preliminarily compressed is adjusted so that the movement of the needle starts from the bottomhole pressure 900 PSI. With this situation, the value of the pressure difference at the device AP when the needle moves follows the characteristic of change represented by the curve BC. In other words, with the change of the yield from 100 to 250 BB'/Dt the bottomhole pressure changes from 900 to 1050 PSI (portion B', C'). The points C and C'corresponds to the incompletely extracted needle, and then the pressure difference at the device will be determined by the portion CD of the curve 3. Therefore, in the whole range of regulation when the well yield changes from 50 to 300 BB/,,, the pressure difference at the device changes 120 to 800 PSI (in accordance with the curved A, B, C, D, and the bottomhole pressure changes from 850 to 1200 PSI (curve A', B', C', D').

Therefore smooth regulation of the bottomhole pressure within the whole range of yield changes is performed without the replacement of the device.

A device for production of hydrocarbons in accordance with another embodiment, in particular hydrocarbons production shown in Figure 3 is arranged in a well tubing which is identified as a whole with reference numeral 101. The well tubing 101 includes a lower or upstream tubing part 102 and an upper or downstream tubing part 103 as considered in a direction of flow of hydrocarbons from a bottomhole to a wellhead. The tubing parts 102 and 103 are spaced from one another and connected by a nipple 104.

The connection can be performed for example by threads shown in the drawing.

The device for hydrocarbons production is identified as a whole with reference numeral 105. It has a hollow body 106 which forms inside a composite flow passage through which hydrocarbons flows from a bottomhole of the well toward a well head. The composite passage includes a nozzle 107 provided at a tower or inlet end of the body 106, a first passage 8 communicating with the nozzle 107, a second passage 109 communicating with the first passage 108, and a third passage 110 communicating with the second passage 109. At the upper end of the second passage 110, an opening 111 for a not shown lifting tool can be provided. As can be seen from the drawings, in the shown embodiment the diameters of the passages 108, 109, and 110 increase in the direction of hydrocarbons flow. The dimensions of the nozzle 107 and the tubes 108,109,110 are specifically selected to provide intensification of the hydrocarbons production as disclosed in detail in the above mentioned U. S. patent no. 5,105,889 which is incorporated here by means of a reference.

The device 105 has a portion which is identified with reference numeral 112. This portion at its inner side forms a part of the third passage 110, and is provided on an outer side with means for fixing the portion 112 to the nipple 104. In the shown embodiment the fixing means indude a plurality of keys 113 arranged in radial slots of the portion 112 and spring-biased radially outwardly by springs 114. The keys 113 are provided with projections engageable in corresponding grooves formed in the inner surface of the nipple 104. In the shown fixed position of the device, the springs 114 urge the keys 113 radially outwardly, so that the projections of the keys 113 engage in the grooves of the nipple 104, and the device is reliably retained in the nipple. When it is necessary to remove device from the tubing, the above mentioned lifting tool engages in the opening 111, and pulls the device vertically upwardly. Due to the inclined flanks on the projections of the keys 113 and in the grooves of the nipple 104, the keys 113 are displaced radially inwardly, and the device can be withdrawn from the tubing.

The device further has another portion which is identified with reference numeral 115. The portion 115 at an inner side forms a part of the third passage 110 and on the outer side is provided with a sealing element 116. The sealing element 116 can be arranged in a groove formed in the outer surface of the portion 115. It reliably seals the portion 115 and therefore the device relative to the nipple 104. During the withdrawal of the device from the tubing, the lifting tool overcomes the frictional contact of the outer surface of the sealing element 116 with the inner wall of the nipple 104.

As can be seen from the drawing, the body 106 is composed of two body parts 117 and 118 located one after the other in the direction of flow of hydrocarbons. In the shown embodiment, the body part 118 as a whole forms the entire third passage 110 at an inner side and is provided with the fixing means 113 and the sealing means 116 on the outer side. The nozzle 107, the first tube 108, and the second tube 109 are formed in the first body part 117. The body part 117 and 118 are connected with one another for example by a thread.

Figure 4 is a view showing a further device for intensification of hydrocarbons production in accordance with a second embodiment of the present invention. The device 105 of Figure 4 is arranged in a well tubing 101'which includes a lower or upstream tubing part 102, an upper or downstream tubing part 103, and a collar 102 which connects the tubing parts 102 and 103 with one another. The connection can be formed for example by threads as shown in the drawings. The device also has the body 106 provided with the nozzle 107 and the passages 108,109,110. In this embodiment, the portion 112 of the body 106 at an inner side forms a part of the third passage 110 and on an outer side is provided with fixing means, while the portion 115 of the body 106 at an inner side forms a part of the passage 110 and at an outer side is provided with sealing means 116. The fixing means is however somewhat different. The fixing means include a plurality of locating and locking dogs 122 which in an operative position are pressed radially outwardly by flat springs 123 and have outer projections engaging in inner grooves of the collar 121. The outer projections of the locking docks 122 and the inner grooves of the collar 121 have an upper inclined flank to allow a withdrawal of the device when the lifting element engaging in the opening 111 pulls the device upwardly.

A device for intensification of hydrocarbons production in accordance with a further embodiment of the present invention shown in Figure 5 is arranged in an integral well tubing 101"having a smooth inner surface. The device also has the body 106 provided with the nozzle 107 and the passages 108, 109,110. One portion 112 of the device 105 has an inner side forming a part of the third passage 110 and an outer side provided with fixing means and another portion 115 having an inner side forming a part of the third passage 110 and an outer side provided with sealing means 116.

The fixing means include a plurality of locking members 124 which are spaced from one another in a circumferential direction and have an inner inclined surface. A corresponding part of the outer surface of the portion 112 of the body 106 has also an inclined surface corresponding to the inclined surface of the locking members 124. While the conical surface 125 is provided on an inner surface of each locking member 124 its outer surface is provided with a plurality of engaging formations which can be formed for example as small teeth. In the position shown in Figure 5, the device is displaced slightly upwardly, so that the outer conical surface of the portion 112 spreads radially outwardly the locking members 24. As a result, the outer formations 126 engage forceably with the inner surface of the well tubing 101" and fix the device in the well tubing. When it is necessary to withdraw the device from the well tubing, the device is displaced first downwardly, the inner inclined surfaces 125 of the fixing members 124 loose their radially inner support, and the locking members 124 are displaced radially inwardly. Now, the device can be withdrawn from the well tubing.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of methods and constructions differing from the types described above.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.