Gas compressor unit for oil wells

Abstract

A gas compressor unit for an oil well includes a base (101), a motor (104), a cylinder (110), and a double-acting piston that is driven by a crank linkage to move within the cylinder. A valve frame (122) is attached to the base, the valve frame having a first frame port (124) and a second frame port (126), the first frame port connected by a first flexible conduit (125) to a first gas inlet / outlet port (120) of the cylinder, the second frame port connected by a second flexible conduit (127) to a second gas inlet / outlet port (121) of the cylinder; a discharge leg (128) having a pair of discharge check valves (130a, 130b) and a discharge leg port (131) between the discharge check valves, and a suction leg (129) having a pair of suction check valves (132a, 132b) and a suction leg port (132) between the suction check valves. The gas compressor unit also includes a liquid separator (134) having a first end connected to the suction leg port (132) and a second end connected to a suction hose (137), and a vent line (141) connected to a relief valve (142, 143) and between the liquid separator and the discharge leg port (131).

Description

[0001] BACKGROUND

[0002] RELATED U.S. APPLICATION DATA

[0003] This application is a continuation-in-part of U.S. Patent Application No. 15 / 911,754, filed March 5, 2018, which claims priority to Argentine Patent Application No. P20170101354, filed May 19, 2017. TECHNICAL FIELD

[0004] The present invention relates to the field of machines, devices and equipment used in the oil industry, and more particularly, to a gas extraction and transmission unit for oil wells that allows reducing the pressure in the well annulus according to the amount of gas contribution of the oil well, thus increasing the production of fluids from the well annulus. It should be emphasized that this gas compressor unit is completely independent of the systems commonly used for oil extraction, such as AIB (Spanish acronym for Independent Compressor Unit) rod pumps, PCP, electric submersible pumps, "plunger lift" pumps, etc., which in turn allows regulating the pressure required inside the oil well. BACKGROUND

[0005] AIB rod pumps are well known in the oil industry, and are known to allow mechanical extraction of crude oil from oil wells. Rod pumps are commonly used in many oil fields, and depending on the size of the pump, it is possible to produce between 5 cubic meters and more than 50 cubic meters of a mixture of crude oil and water in 24 hours. The size of the pump is also determined by the depth and weight of the crude oil to be extracted, where the deeper the extraction, the more energy is required to move a greater length of the fluid column. A connecting rod crank mechanism converts the rotational movement of the motor into a reciprocating vertical movement that moves the pump rod, and produces a typical stroke movement. Thus, the AIB rod pump allows the extraction of crude oil from the oil well.

[0006] As mentioned above, crude oil is accompanied by water and gas in the oil field. However, the gas in the oil well is a major problem for the extraction of oil. This can occur due to the excessive pressure of the gas inside the oil well, more particularly in the annular space located between the casing and the tubing. The presence of excessive gas pressure significantly reduces oil production. As a result of the above, some devices have been developed that allow the extraction of gas from the well annulus to reduce the pressure and allow normal production of crude oil. Currently, beam rocker compressors are used in mechanical pumping for gas transmission, which are installed and operate in conjunction with AIB rod pumps, use large pistons, and extract gas depending on the number of strokes performed by the AIB.

[0007] However, while it has proven practical in the art to use beam-type rocker arm compressors, they suffer from limitations in oil production. One of these limitations is that extraction of gas is performed depending on the movement of the head of the AIB, so if the compressor requires some type of maintenance, the AIB should first be stopped to perform said maintenance, which causes a waste of time and loss of production. Furthermore, while the gas pressure in the well annulus can change, the conventional compressor will continue to extract the same amount of gas in each stroke, so the gas pressure inside the well will be significantly modified, positively or negatively affecting the oil production.

[0008] A pumping or compressor unit of the above type is disclosed in US patent 4,530,646 to McCoy, in which a cylinder is connected between a stationary pivoting lower end and a walking beam 18 that oscillates about a horizontal axis. The walking beam 18 is part of a conventional pumping unit 12 in which the walking beam 18 oscillates at its upper middle portion, one end of which is connected to a drive assembly 24 and the opposite end is connected to a horsehead 22 to reciprocate the pump inside the well to pump oil from the well. Thus, the cylinder assembly 34 and the piston rod assembly 36 operate under the movement of the walking beam 18, which is structured according to the need to extract oil. In other words, the need for gas extraction by the cylinder assembly 34 is different from the need to extract oil, which can reach an operating range that is detrimental to one aspect.

[0009] For example, the speed of the reciprocating motion of the piston of McCoy is limited to that of the oil pump for extracting oil. In addition, McCoy cannot control the well pressure because the oil pump cannot be stopped, nor can it reduce its speed, all of which are detrimental to the oil extraction operation.

[0010] US patent application publication US 2015 / 0233368 Al to Gallaway discloses a gas compressor comprising: a motor; a pinion operatively coupled to the motor; a rack driven by the pinion; at least one inlet gas connection; at least one outlet gas connection; and a piston and piston rod reciprocating within a compressor cylinder. The piston rod is coupled to the rack, whereby gas entering the compressor cylinder through the at least one inlet gas connection can be compressed within the cylinder by the piston and can be expelled from the cylinder through the at least one outlet gas connection. The pump of Gallaway operates in a horizontal position and is installed in a skid.

[0011] One disadvantage of the Gallaway appears to be its durability over time. When working 24 hours and subjected to constant cyclic loads on the tooth flanks, all moving parts (i.e. pinion, rack, bearings, seals, washers) are subject to wear. The Gallaway requires lubrication, which is a critical point in the drive. It must be checked and replaced regularly, which is a critical point as the lubricating oil mixes with the gas passing through the package of the axial reciprocating shaft. In addition, the Gallaway is limited to a small range of speeds. In the case of speeds greater than 20 rpm, a more robust, more powerful system must be provided to avoid premature damage. The Gallaway is also limited in the power transmission of the rack and pinion assembly, so a high power of the geared motor is required to handle a high pressure range.

[0012] US Patent Application Publication US 2007 / 0251379 Al to Lund, which was granted US Patent 7,721,641, discloses an air compression apparatus comprising: a frame; a tank; a motor drive mechanism operatively connected to a motor; and at least one piston assembly operatively connected to the motor drive mechanism and configured to move within a corresponding cylinder mounted to the frame. The piston assembly includes: (1) a piston body; (2) a piston rod having a hollow bore for receiving external air and connected to the motor drive mechanism and the piston body. Upward travel of the piston body caused by the motor drive mechanism opens a piston valve and allows ambient air to be drawn into the cylinder through the hollow bore, and downward travel of the piston body closes the piston valve to compress air within the cylinder. The motor drive mechanism includes an engine exhaust system that moves a pulley by a belt, which is connected to the piston rod.

[0013] More specifically, as disclosed in column 11 of the above cited US patent 7,721,641, the cylinder 130 not only provides lateral oscillation, but also vertical oscillation of the cylinder relative to the crank 120 as the crank rotates. The vertical oscillation movement of the cylinder 130 relative to the crank 120 results in a controlled variation of the velocity of the piston 140 relative to the cylinder 130 and the compressed air load within the cylinder, thereby providing a controlled variation of the leverage exerted by the crank 120 against the compressed air load. When the piston 140 retracts towards the top of the cylinder 130 during part of the rotation of the crank 120, a valve (not shown) at the bottom of the piston 140 is pulled open by the action of the vacuum created in the bottom chamber of the cylinder 130, so that ambient air then enters the bottom chamber through the hollow piston rod 170 and the open valve. When the piston 140 has reached the top of its stroke, the valve at the bottom of the piston closes, the air in the bottom chamber is compressed by the downward movement of the piston 140 and is driven through a check valve 180 into the pressure tank 102 or into the cylinder 130 chamber above the piston 140. During the downward travel of the piston 140, a valve 142 at the top of the piston allows air to enter the upper chamber through the hollow piston rod 170.

[0014] It is clear that Lund discloses a structure that compresses only the air that enters through the hole in the piston rod 170, wherein the valve at the piston 140 directs the entering air to the upper chamber or the lower chamber of the cylinder. That is, only one input is provided for air, which cannot operate to allow the gas to enter and exit through different separate input and output ports. Lund is not designed for pumping gas from an oil well and directing the gas to a circulation loop or a gas production pipeline and / or the associated reservoir.

[0015] For the above reasons, it would be convenient to have a new device, apparatus, machine or instrument that allows the extraction of gas from an oil well without affecting the production of crude oil, and also allows repeated extraction of gas depending on the pressure present in the oil well. SUMMARY

[0016] Therefore, it is an object of the present invention to provide a compressor unit for an oil well that allows the extraction of gas independently of the AIB rod pump.

[0017] It is another object of the present invention to provide a compressor unit that allows the maintenance of a constant gas pressure in the oil well, since the compressor unit has a pressure switch, a pressure transmitter and a frequency converter that control the speed of the piston depending on the gas flow to be extracted.

[0018] It is another object of the present invention to provide a compressor unit that, due to its structural configuration, has a longer useful life and efficiency of the compressor unit due to less maintenance and repairs.

[0019] Another object of the present invention is to provide a gas compressor unit for oil wells, which makes it possible to control the pressure in the oil well.

[0020] Another object of the present invention is to provide a gas compressor unit for an oil well, comprising a drive system for actuating a piston-cylinder assembly, wherein the speed of the drive system can be changed by a VFD according to the oil well conditions, wherein the required pressure in the oil well can be controlled by monitoring the pressure with a transmitter and by changing the speed of the device, and wherein the gas compressor unit is completely independent of any oil pump unit operating simultaneously in the same oil well.

[0021] Another object of the present invention is to provide a gas compressor unit for an oil well, comprising a drive system for actuating a piston-cylinder assembly, wherein lubrication is not required in the drive mechanism, and wherein a pressure sensor and a safety valve are provided for an event of a sudden increase in gas in the oil well, in which case the valve opens to direct excessive pressure to an exhaust pipe spaced apart from the pump or compressor components.

[0022] Another object of the present invention is to provide a gas compressor unit for an oil well, comprising at least one compressor cylinder having at least one gas inlet connected to the oil well, at least one gas outlet, a pivoting lower end, and a double-acting piston. The drive shaft of the double-acting piston is connected to a drive motor, which may be an electric motor, a hydraulic motor, or an internal combustion engine. The drive motor is connected to a pressure transmitter, which is operatively connected to a pressure switch, which is operatively connected to the oil well.

[0023] Another object of the present invention is to provide a gas compressor unit for oil wells, comprising:

[0024] Base;

[0025] Support components in the base;

[0026] A rotary drive motor is installed in the upper end of the support element;

[0027] The output rotating shaft of the rotary drive motor;

[0028] A connecting rod having one end attached to the output rotating shaft to rotate together with the output rotating shaft and an opposite end including a first support member;

[0029] A connecting element, which is rotatably connected to the opposite end of the connecting rod via a first support member;

[0030] at least one compressor cylinder having a first end and a second end and a double acting piston, wherein the second end is pivotally connected to a support fixed in the base, the double acting piston having a drive shaft connected to said connecting element for moving the double acting piston by a reciprocating motion;

[0031] at least one first gas inlet / outlet port in the first end of the compressor cylinder;

[0032] at least one second gas inlet / outlet port in the second end of the compressor cylinder;

[0033] a valve frame attached to the base, said valve frame having a first frame port connected to the first gas inlet / outlet port of the compressor cylinder by a first flexible conduit and a second frame port connected to the second gas inlet / outlet port of the compressor cylinder by a second flexible conduit, a discharge branch having a pair of discharge check valves and a discharge branch port between the discharge check valves and a suction branch having a pair of suction check valves and a suction branch port between the suction check valves;

[0034] a liquid separator having a first end connected to the suction branch port and a second end connected to a suction hose;

[0035] an exhaust pipe connected to a safety valve and between the liquid separator and the discharge branch port. BRIEF DESCRIPTION OF DRAWINGS

[0036] For a more clear and comprehensive understanding of the present application, it has been provided in several drawings, in which the present application has been represented by way of example in one of the preferred examples, in which:

[0037] Figure 1 shows an exemplary schematic view of a gas compressor unit for an oil well according to the present application, in which the present application is shown by way of example in combination with the corresponding components installed in an oil well;

[0038] Figure 2 shows a perspective view of a gas compressor unit for an oil well according to the present application,

[0039] Figure 3 and Figure 4 shows a cross-sectional view of a gas compressor unit according to the present application, in which the direction of advancement of the piston can be observed, allowing the entry of gas and at the same time allowing the compression / discharge of gas,

[0040] Figure 5 shows a perspective view of another embodiment of the present application,

[0041] Figure 6 shows a perspective view of an embodiment of Figure 5

[0042] Figure 7 shows a perspective view of an embodiment of Figure 5

[0043] Figure 8 shows a perspective view of an embodiment of Figure 7

[0044] Figure 9 shows a detailed view of the lower section or lower end or second end of the compressor cylinder, wherein the swing mounting of the cylinder in the base is shown. DETAILED DESCRIPTION

[0045] With reference now to the attached drawings, it can be seen that the present invention comprises a new gas compressor unit for oil wells, independent of the AIB rod pump, which allows a controlled extraction of gas to keep the gas pressure inside the oil well constant, thus allowing the extraction of oil without any inconvenience. For illustrative purposes and to further enhance the understanding of the invention, Figure 1 a compressor unit is shown connected with the corresponding parts of an oil well. As mentioned above, since it is an exemplary solution, the separation distances and dimensions of the components shown are not shown to scale, so it should be understood that this is not a limitation of the invention, in fact it is properly adapted to the needs of the site.

[0046] Thus, according to Figures 1 to 4 the compressor unit for oil wells of the present invention is denoted by the general reference numeral 1 and comprises at least one compressor cylinder 2 having an upper portion 3 and a lower portion 5, an upper sealing cover 4 being mounted on the upper portion 3 and a lower sealing cover 6 being mounted on the lower portion 5, both the upper sealing cover 4 and the lower sealing cover 6 being fixed to the cylinder 2 by means of respective bolts, pins or similar fixing elements. Likewise, said compressor cylinder 2 comprises an upper gas cylinder inlet / outlet mouth 7 provided in the upper portion 3 and a lower gas cylinder inlet / outlet mouth 8 provided in the lower portion 5.

[0047] ​​​Inside, the compressor cylinder 2 comprises a double-acting piston 9, the drive shaft 10 of which passes through the upper sealing cover 4 and has a proximal end with a connection element 11 provided with a support 12 on which a connection shaft 13 is fixed, said connection shaft 13 allowing the connection between said drive shaft 10 and a respective connecting rod 14 connected to a drive motor 15- reducer 16 through a shaft 17 of a reducer 16. The drive motor 15 can be an internal combustion engine, a hydraulic motor or an electric motor, but it is preferably an electric motor, which is operatively connected to a pressure switch 18 for setting or establishing the start / stop pressure, through a pressure transmitter 41 for controlling the speed of said drive motor-reducer, and is operatively connected to the oil well, more specifically to the annular space between the casing and the extraction pipeline. In this way, the pressure in the oil well can be regulated without any inconvenience, which is not possible with any conventional equipment of the prior art, since they operate with beam pump strokes and do not have a way to regulate the pressure required inside the oil well.

[0048] The pressure transmitter 41 measures the pressure in the annulus and adjusts the rotational speed of the motor so that the piston moves at a higher or lower speed inside the compressor cylinder. This allows the extraction of gas according to the gas pressure present in the annulus. By way of example, but not limiting the present invention, if the pressure present in the annular space exceeds the maximum pressure limit required to allow the extraction of oil, the pressure transmitter 41 sends a signal to the variable speed drive of the motor so that it rotates at a higher speed, generating a greater speed in the piston movement, thus extracting a greater amount of gas from the annulus to reduce the pressure present in the annulus. Likewise, the use of the pressure transmitter makes it possible to know the pressure in the annulus and maintain the ideal pressure in the annulus on a constant basis. Accordingly, due to the arrangement of the pressure switch and the pressure transmitter, the pressure required in the oil well can be regulated according to the operating conditions at that moment.

[0049] In itself, the connecting rod 14 provides a linear eccentric movement with respect to the drive shaft 10 of the piston 9, which moves longitudinally inside the compressor cylinder 2, to allow the entry of gas and at the same time also the compression and discharge of the gas. When said drive shaft 10 performs a linear eccentric movement, it causes the compressor cylinder 2 to pivot in an inclined manner. To facilitate the inclined movement of the compressor cylinder 2, a pivoting lower end is provided, comprising a lower arm 19 provided with a support 20 through which a shaft 21 passes, the ends of which are fixed to respective transverse support plates (not shown) provided with supports (not shown), which are mounted on a frame (not shown) that supports the overall structure of the unit of the present invention. In this way, the pivoting from the lower end is allowed, accompanied by the linear eccentric movement of the drive shaft 10 and the inclined movement of the compressor cylinder 2.

[0050] In another aspect, the present application comprises at least one main gas inlet 22 connected to the well annulus and at least one main gas outlet 23 connected to the gas production line and / or the associated reservoir. Although according to Figures 1 to 4 the directions shown, it has been shown that the main gas inlet 22 is on the right side while the main gas outlet is on the left side, this does not mean that the present application is limited to the described configuration, other arrangements can also be considered and used without any inconvenience.

[0051] The main gas inlet 22 bifurcates and opens into a lower gas inlet 24 connected through a one-way check valve 25 to the lower gas cylinder inlet / outlet 8 of the lower portion 5 of the compressor cylinder 2 and an upper gas inlet 26 connected through another one-way check valve 27 to the upper gas cylinder inlet / outlet 7 of the upper portion 3 of the compressor cylinder 2. Accordingly, the present application has a lower gas outlet 28 connected through a one-way check valve 29 to the lower gas cylinder inlet / outlet 8 and an upper gas outlet 30 connected through another one-way check valve 31 to the upper gas cylinder inlet / outlet 7, both of which extend and connect to the main gas outlet 23.

[0052] It is worth noting that, as best shown in Figures 1 to 4 , the above-mentioned openings and bifurcations include pipes or tubes 32 and elbows 33, stop valves, connectors, flanges, seals, packing boxes, etc. Also, the main gas inlet 22 and the main gas outlet 23 have connectors 34 and are connected to the well, the reservoir / production line, respectively, by means of one or more conduits 40, such as pipes, tubes, hoses or the like. More specifically, according to Figure 1 , it can be seen that the main gas inlet 22 is connected to a suction outlet 35 from which the gas from the well annulus comes, while the main gas outlet 23 is connected to a discharge inlet 36 which opens into the gas production line and / or the associated reservoir. Furthermore, for illustrative and auxiliary purposes, some of the components of these parts commonly used in oil wells have been shown in the described Figure 1 , in order to better understand the present application. Among many others, the components shown therein are "sleeve" 37, tube 38 and rod 39.

[0053] By way of example but without limiting the present application, according to Figure 3 what is shown in the drawings, when the piston 9 moves upwards, the gas that enters through the main gas inlet 22 will open into the compressor cylinder 2 through the lower gas inlet 24 and the lower gas cylinder inlet / outlet 8. At the same time, it can be seen that the gas previously inside the compressor cylinder is compressed and discharged through the upper gas cylinder inlet / outlet 7, passing through the upper gas outlet 30 and finally through the main gas outlet 23.

[0054] On the other hand, Figure 4 In the middle, when piston 9 moves downward, the gas entering through main gas inlet 22 will enter compressor cylinder 2 through upper gas inlet 26 and upper gas cylinder inlet / outlet 7. Simultaneously, according to... Figure 3 As can be seen, the gas that previously entered the compressor cylinder is compressed and discharged through the lower gas cylinder inlet / outlet 8, through the lower gas outlet 28, and finally through the main gas outlet 23.

[0055] One-way check valves 25, 27, 29, and 31 are used to limit the direction of gas flow into and out of the cylinder, thereby preventing possible backflow of gas. Similarly, the direction of gas circulation and the main gas inlet and outlet are not limited to those described above, but can be adapted to have other configurations without any inconvenience.

[0056] according to Figures 5 to 8 The illustrated embodiment significantly improves upon this by eliminating the drawback of the long hose 40 constantly moving due to the pivoting motion of the cylinder 2. In some cases, the unit is installed 5 to 10 meters from the well, where these long hoses can be damaged by friction with the soil, leading to hose wear and potentially hazardous gas leaks due to punctures. This is not a problem that the Lund mentioned above had to face, as it receives external air through a hollow hole in the piston rod. There is no connection to any spaced-out wells.

[0057] Figures 5 to 8 Another problem addressed by the embodiments is that a venting system is necessary for any situation where the risk of unintended increased pressure in the pipe and hose circuits increases. Safety valves and pressure relief valves have been provided to control pressure in the circuits, and these valves are associated with the venting system. This is a challenge because... Figures 1-4 In the embodiments described, the circuit and gas conduit oscillate during operation due to the pivoting motion of the cylinder. Because the exhaust system cannot be close to, but must be spaced apart from, the moving parts of the motor and mechanism, it is virtually impossible to place long exhaust conduits within such moving parts. This structure would result in breakage in any oscillating long exhaust conduit.

[0058] like Figures 5 to 8As shown, the unit of this embodiment comprises a base 101 mounted on a frame or modular frame chassis 102, at least one bracket element 103 in the base 101 which can be a column or a hollow column to accommodate components, a rotary drive motor 104 mounted in the upper end of the bracket element 103. The rotary drive motor 104 comprises an output rotary shaft 105 connected to a connecting rod 106 having an end 107 attached to the output rotary shaft 105 to rotate with the output rotary shaft 105 and having an opposite end comprising a first bearing 108. A connecting element 109 is connected to the opposite end of the connecting rod 106 through the first bearing 108. As described with respect to the embodiment of Figure 1 the rotary drive motor 104 is connected to a pressure transmitter which is operatively connected to a pressure switch which in turn is operatively connected to an oil well. In addition, the rotary drive motor is an electric motor and is connected to a motor gear reducer 150.

[0059] Further, the present invention provides at least one compressor cylinder 110 having a first end 111 and a second end 112 and a double acting piston (not shown) inside the cylinder, the second end 112 being pivotally connected to a support 113 fixed inside the base 101, the double acting piston having a drive shaft 114 connected to the connecting element 109 for moving the double acting piston in a reciprocating motion. It will be appreciated that the internal construction of the compressor cylinder 110 is similar to that of the compressor cylinder 2 shown in Figure 3 and Figure 4 Further, the compressor cylinder 110 comprises an upper sealing cover 115 and a lower sealing cover 116, both being fixed to the compressor cylinder 110 by means of bolts, pins or similar fixing elements, respectively. As shown in Figure 9 the second end 112 of the compressor cylinder 110 has a lower arm 117 provided with a second bearing 118 to pivot around a shaft 119 fixedly attached to the support 113 on the base 101. This allows for a swinging or pivoting motion of the compressor cylinder 110.

[0060] According to the present embodiment, at least one first gas inlet / outlet port 120 is provided at the first end 111 of the compressor cylinder 110 and at least one second gas inlet / outlet port 121 is provided at the second end 112 of the compressor cylinder 110. A valve frame 122 is attached to the base 101, preferably to the bracket element 102 by means of a corresponding support 123 with a clamp. In Figure 8In particular, the lower and upper branches 148, 149 comprise a lower and upper tube or conduit 151, 152, respectively, which are clamped to the lower and upper support members 123. The valve frame 122 has a first frame port 124 connected to the first gas inlet / outlet port 120 of the compressor cylinder 110 by a first flexible conduit 125, and a second frame port 126 connected to the second gas inlet / outlet port 121 of the compressor cylinder 110 by a second flexible conduit 127.

[0061] Furthermore, the present invention provides a discharge branch 128 having a pair of discharge check valves 130a, 130b and a discharge branch port 131 located between the discharge check valves 130a, 130b, and a suction branch 129 having a pair of suction check valves 132a, 132b and a suction branch port 133 located between the suction check valves 132a, 132b. The discharge and suction check valves are one-way check valves, so that they are arranged as shown to define a fluid flow cycle, preferably of gas only but with some humidity or even liquid. The meaning of cycle will be defined by the movement of the piston within the cylinder, as will be disclosed below. The connections between the valves and ports are formed by respective joints, seals, pipe joints, conduits or tubes, which are shown but not precisely indicated by reference numerals in order to keep the drawing clear.

[0062] On the other hand, the present invention provides a liquid separator 134 having a first end 135 connected to the suction branch port 133 by a respective curved joint, conduit, tube, seal, union or pipe joint, and a second end 136 connected to a suction hose 137 by a tap, shut-off or stop valve 138. The suction hose 137 is connected to the oil well as the hose 40 with the suction gas outlet 35 shown in Fig. 1. Figure 1 The gas, which occasionally contains debris, water and oil, is sucked from the oil well through the suction hose 137 and directed to the separator 134, where the liquid and debris are separated and discharged through a lower conduit with a shut-off or stop valve 140.

[0063] The present invention also includes a vent pipe 141 connected to the safety valves and located between the liquid separator 134 and the discharge branch port 131. More specifically, the safety valves are a first safety valve 142 connected between the liquid separator 134 and the vent pipe 141 and a second safety valve 143 connected between the vent pipe 141 and the discharge branch port 131. Also, the present invention provides a suction pressure sensor 144 connected to at least one of the liquid separator 134 and the suction branch port 133 as shown, and a discharge pressure sensor 145 connected between the discharge hose 146 and the second safety valve 143. The discharge hose 146 is connected to a shut-off or closing valve 147 which in turn is operatively connected to the discharge branch port 131, the discharge pressure sensor 145 being connected between the shut-off or closing valve 147 and the discharge branch port 131. The connections between the ports, safety valves, sensors and vent pipe 141 are formed by respective connectors, pipe joints, seals, conduits, tubes and the like as clearly shown.

[0064] As shown, the arrangement of safety valves, sensors and vent pipe allows the release of gas and excessive pressure in case of an unexpected increase or reaching of a pressure peak within the circuit. Thus, the present invention significantly improves the safety of the installation and provides a solution to the above-mentioned drawbacks related to the movement of sensitive components in the embodiments of Figures 1-4 . The present invention also solves the problem of friction of the hoses in the soil, premature wear of the hoses and moving components.

[0065] As shown in Fig. 1, for clarity, the vent pipe has been removed, the suction check valve 132a is positioned to allow fluid to flow upwards, while the suction check valve 132b is arranged to allow fluid to flow downwards, as indicated by the arrows. On the other hand, the discharge check valve 130a is arranged to allow fluid to flow downwards and the discharge check valve 130b is mounted to allow fluid to flow upwards, as indicated by the arrows. Figure 8

[0066] In operation, 1) when the double-acting piston moves downwards, meaning that the inner chamber of the upper end of the cylinder (not shown) is expanding and thus sucks in fluid:

[0067] a) the fluid is sucked in via the hose 125 and the suction branch 129, the liquid is separated in the separator 134, the fluid flows to the suction branch port 133 and then enters the suction check valve 132a. This is because the piston compresses the fluid downwards in the lower chamber of the cylinder (not shown), the pressure generated in the lower branch 148 is higher than in the upper branch 149, therefore the fluid from the separator 134 cannot pass through the suction check valve 132b (which is closed) and is directed to the suction check valve 132a (which is open);

[0068] ​b) Fluid passes through suction check valve 132a, continues through first frame port 124, through first flexible hose 125 to first gas port 120 of compressor cylinder 110, into the upper chamber of the cylinder that is expanding, whereby first gas port 120 acts as an inlet for fluid;

[0069] c) At the other end of the cylinder, as the piston moves downward, fluid that was sucked into the lower chamber (not shown) of the compressor cylinder 110 is compressed by the piston and directed to the second gas port 121, which now acts as an outlet for fluid, which exits through the second flexible conduit 127 to the exhaust leg 128, to the second frame port 126, to the exhaust check valve 130b, through the exhaust leg port 131, through the shutoff or closed valve 147 and the exhaust hose 146.

[0070] 2) When the double-acting piston moves upward, meaning that the inner chamber (not shown) at the lower end of the cylinder is expanding, therefore sucking in fluid:

[0071] d) Fluid is sucked in through hose 127 and suction leg 129, liquid is separated in separator 134, fluid flows to suction leg port 133. Since suction check valve 132a is closed, fluid passes through suction check valve 132b, flows through conduit 151, through second frame port 126 and continues through second flexible conduit 127 into the second gas port 121 to the lower chamber of the compressor cylinder. Now, the second gas port 121 operates as an inlet port;

[0072] e) The piston follows the upward movement and compresses the fluid in the upper chamber, which is expelled through the first gas port 120, which now acts as an outlet port. Fluid is directed through the first flexible conduit 125, through the first frame port 124, and continues to flow to the exhaust check valve 130a. Fluid is expelled through the exhaust check valve 130a because it is open while the exhaust check valve 130b is closed. Fluid is finally expelled through the exhaust leg port 131 and the exhaust hose 146. In any case, as in the case of Figure 1 , the exhaust hose 146 is connected to any gas collection device.

[0073] These steps repeat cyclically with the upward and downward movement of the piston. Due to the operation of the suction check valves 132a, 132b, the fluid expelled through the exhaust hose is prevented from returning to the liquid separator 134.

[0074] By way of example but not limiting the invention, some tables are attached, which show the results obtained by the compressor unit of the invention:

[0075] Exhaust flow table: thousands of cubic feet of gas per day (MSCF / D - millions of standard cubic feet per day) under standard conditions

[0076] Calculation Formula:

[0077] 8.73 x 10 -5 x D 2 x L x RPM x Q = PS;

[0078] The calculation should be done in absolute pressure.

[0079]

[0080]

[0081] Torque Table: (Depends on pressure difference, piston diameter, and effective stroke of the piston) Newton Flowmeter

[0082] Calculation Formula:

[0083] # N-m = 4.44 x 10 2 x D 2 x L (Pd - Ps);

[0084] Where, Pressure difference: Discharge pressure Pd - Suction pressure Ps

[0085]

[0086]

[0087] Oil well testing

[0088] Before using the compressor unit of the present invention:

[0089] The selected oil well had a production of 02 BOPD x 0 BW in October 2016, and the following physical measurements were taken:

[0090]

[0091] As can be seen from the above table, the pressure without a compressor or pumping unit was 3 psi, and by using the compressor or pumping unit of the present invention, it was changed to -4 psi (negative four psi), and thus, a vacuum pressure difference allowed greater production.

[0092] Using the compressor unit of the present invention:

[0093]

[0094] One can significantly observe that the production increased from 2 BOPD (Barrels of Oil Per Day) to 8 BOPD, operating for 24 hours under the same extraction conditions as before using the compressor unit, thus obtaining a better pressure test.

[0095] In this way, the compressor unit for oil wells constituting and building the present invention, is independent of the operation of the AIB rod pump, which in turn allows to vary the piston movement speed according to the pressure present in the well annulus to extract greater or lesser amounts of gas, due to the novel arrangement of the pressure transmitter and the pressure switch. That is, the pressure is controllable, which is not possible with the conventional mechanisms of the prior art. It is important to highlight that during the oil extraction, the gas extraction cycle is continuous.

[0096] In addition, some advantages of the compressor unit of the present invention are:

[0097] The use of an external and independent compressor unit to replace the traditional reciprocating gas compressor CGBD (mechanical pumping), allows to further reduce the gas pressure in the well annulus, since its action is not limited by the geometry of the pumping rod unit, nor by the low GPM (<9), where the independence of the frequency of action of the compressor unit allows it to be smaller:

[0098] The compressor unit allows to maintain a constant gas pressure in the oil well, since it has a pressure switch and a pressure transmitter that controls the piston speed according to the gas flow to be extracted, the pressure is controllable:

[0099] Higher gas extraction capacity;

[0100] Increased production with less flow pressure;

[0101] Increase in recoverable reserves (vacuum inside the annulus);

[0102] Ease of installation and transport of the compressor unit;

[0103] No imbalance in the alignment and balance of the mechanical compressor unit;

[0104] Compact compressor unit overall (small size) that reduces the risk of accidents (no high work);

[0105] Ease of access to shared components;

[0106] Durability of the materials used in its manufacture;

[0107] Replacement of the compressor cylinder with another spare unit in almost 30 minutes when repairing it;

[0108] No need to stop the AIB rod pump;

[0109] The unit of the present invention is environmentally friendly, since it does not generate excessive noise;

[0110] It is not obtrusive since it occupies little physical space in the location of the oil well;

[0111] Compact compressor cylinder (less parts and flanges with uniform adjustment); improved metallurgy (high quality steel and aluminum), (in the fill box, flanges and piston) continuous seal generation;

[0112] Graphite Teflon seal with higher efficiency and durability;

[0113] Compressor accessories (horizontal check valve, elbow, ball seat, tubing, etc.) designed to work in media with gas flow;

[0114] Reduced manufacturing costs; and

[0115] The compressor unit has a longer useful life and efficiency due to less maintenance and repairs, among many other advantages.

[0116] Thus, the present invention allows to vary the piston driving according to what we want, by means of a variable speed drive that drives the motor without depending on the actuation frequency of the mechanical pump, while with the units of the state of the art it happens to depend on the actuation frequency of the mechanical pump. Accordingly, the unit of the present invention allows the compressor to be smaller, since the frequency is higher, the compressor needed is smaller, allowing to adjust the gas pressure in the well according to the desired, according to the desired regulated pressure, varying the speed of the motor that drives the compressor, thus extracting more or less gas, due to the arrangement of the pressure switch and the pressure transmitter connected to the casing.

Claims

1. A gas compressor unit for an oil well, the gas compressor unit comprising: a base, a bracket element in the base, a rotary drive motor mounted in an upper end of the bracket element; an output rotary shaft of the rotary drive motor; a connecting rod having one end attached to the output rotary shaft for rotation therewith and an opposite end including a first bearing; a connecting element rotatably connected to the opposite end of the connecting rod by the first bearing; at least one compressor cylinder having a first end and a second end and a double-acting piston, the second end being pivotally connected to a support fixed in the base, the double-acting piston having a drive shaft connected to the connecting element for moving the double-acting piston by reciprocating motion, at least one first gas inlet / outlet port in the first end of the compressor cylinder, at least one second gas inlet / outlet port in the second end of the compressor cylinder, a valve frame attached to the base, the valve frame having a first frame port connected to the first gas inlet / outlet port of the compressor cylinder by a first flexible conduit and a second frame port connected to the second gas inlet / outlet port of the compressor cylinder by a second flexible conduit, a discharge leg having a pair of discharge check valves and a discharge leg port between the discharge check valves, and a suction leg having a pair of suction check valves and a suction leg port between the suction check valves, a liquid separator having a first end connected to the suction leg port and a second end connected to a suction hose, an exhaust pipe connected to a relief valve and between the liquid separator and the discharge leg port.

2. The gas compressor unit of claim 1, wherein, the second end of the compressor cylinder has a lower arm provided with a second bearing to pivot about a shaft fixedly attached to the base in the support.

3. The gas compressor unit of claim 1, wherein, the rotary drive motor is connected to a pressure transmitter operatively connected to a pressure switch which is in turn operatively connected to the oil well.

4. The gas compressor unit of claim 1, wherein, a suction pressure sensor is connected to at least one of the liquid separator and the suction leg port.

5. The gas compressor unit of claim 1, wherein, the relief valve is a first relief valve connected between the liquid separator and the exhaust pipe and a second relief valve connected between the exhaust pipe and the discharge leg port.

6. The gas compressor unit of claim 5, wherein, a discharge pressure sensor is connected between a discharge hose and the second relief valve.

7. The gas compressor unit of claim 1, wherein, the discharge check valves and the suction check valves are one-way check valves.

8. The gas compressor unit of claim 1, wherein, the rotary drive motor is an electric motor.

9. The gas compressor unit of claim 1, wherein, the rotary drive motor is connected to a motor gear reducer.

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