CA2829630A1 - Crossover valve system and method for gas production - Google Patents
Crossover valve system and method for gas production Download PDFInfo
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- CA2829630A1 CA2829630A1 CA 2829630 CA2829630A CA2829630A1 CA 2829630 A1 CA2829630 A1 CA 2829630A1 CA 2829630 CA2829630 CA 2829630 CA 2829630 A CA2829630 A CA 2829630A CA 2829630 A1 CA2829630 A1 CA 2829630A1
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 82
- 238000000034 method Methods 0.000 title claims abstract description 13
- 239000012530 fluid Substances 0.000 claims abstract description 34
- 230000004913 activation Effects 0.000 claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 26
- 238000004891 communication Methods 0.000 claims abstract description 12
- 238000002347 injection Methods 0.000 claims abstract description 9
- 239000007924 injection Substances 0.000 claims abstract description 9
- 238000003780 insertion Methods 0.000 claims abstract description 5
- 230000037431 insertion Effects 0.000 claims abstract description 5
- 235000009508 confectionery Nutrition 0.000 claims description 9
- 230000037361 pathway Effects 0.000 claims description 4
- 239000007789 gas Substances 0.000 description 73
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 7
- 210000002445 nipple Anatomy 0.000 description 5
- 230000004888 barrier function Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 230000003213 activating effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000779 depleting effect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
- E21B43/121—Lifting well fluids
- E21B43/122—Gas lift
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Safety Valves (AREA)
Abstract
A crossover valve assembly for insertion into production tubing, or integral with production tubing, includes an outer housing, an inner production tube, a pilot section responsive to external pressure to open an activation passage above a pre-determined pressure, a power section responsive to pressure in the activation passage to open an injection opening; and a crossover valve responsive to pressure in the injection opening to open a crossover port, allowing fluid communication from outside the outer housing to within the inner production tube. A method of producing a vertical, deviated or horizontal gas well having an annular space defined by a well casing and a concentrically disposed production tubing, wherein an upper annulus exists above a packer isolating the annulus, includes the steps of (a) opening a communication path through the tubing into the upper annulus, and if necessary, removing any fluid in the upper annulus, (b) landing at least one crossover valve within the production tubing above the packer and exposed to the upper annulus; and (c) injecting gas into the annular space to open the crossover valve and enter the production tubing, wherein the injected gas lifts liquids in the production tubing to the surface.
Description
Crossover Valve System and Method for Gas Production Field of the Invention [0001] The present invention is directed to a valve for use in production from gas wells with low flow pressures and inconsistent production line pressure.
Background [0002] Gas wells, and in particular sour gas wells with varying quantities of H2S are produced throughout the Western Canada Sedimentary Basin. While reservoir pressures are depleting, the remaining gas volumes left in the reservoir are usually significant. The challenge is to produce the remaining reserves with low flow pressures and inconsistent production line pressures.
Background [0002] Gas wells, and in particular sour gas wells with varying quantities of H2S are produced throughout the Western Canada Sedimentary Basin. While reservoir pressures are depleting, the remaining gas volumes left in the reservoir are usually significant. The challenge is to produce the remaining reserves with low flow pressures and inconsistent production line pressures.
[0003] Sour gas wells are completed with a packer in place to isolate the sour production from the annular space between the well casing inside diameter and the outside diameter of the production tubing. The packer prevents sour gas from entering the annulus and corroding the casing string, which is the barrier between the wellbore and any adjacent ground water or aquifer. Additionally, the annulus above the packer is typically filled with inhibited brine solution to enhance corrosion protection and provide an additional barrier preventing migration of sour gas into the annulus.
[0004] All gas wells will produce a quantity of liquid which is unloaded during gas production. Liquid loading is a symptom of the well's inability to unload liquids that are naturally produced during the production life of the well and is the most common cause of production decline in a gas well. In addition to liquid loading, there are a number of other reasons why wells will not produce at the maximum level. If a number of wells are drilled into the same reservoir and the gas is depleted at a faster that normal rate, the competitive drainage of the reservoir will reduce production. In a compartmentalized reservoir, where reservoir size is limited because of lack of connectivity between the permeable parts of the formation, there may be production issues. Also, production may be limited because of formation damage caused to the near well bore while drilling the well or on subsequent work over with a service rig or natural near well bore damage may also be caused by liquid loading or natural scaling effects of the produced well effluent.
[0005] When a well is initially drilled, it is typically in a virgin part of the reservoir, and therefore reservoir pressures and volumes are usually quite high. The surface production lines that will transport the gas and liquids are operated at pressures that allow the well to flow to surface. The difference between the surface lines pressure and the flowing bottom hole pressure of the well will dictate how much the well can flow. Other factors also relate directly to this such as gas density, friction effect, liquid density and depth of the well. As the well ages and flowing bottom hole pressure depletes, the well will experience reduced flow capability.
[0006] It is well known that liquid loading affects gas production when gas velocity drops below the level necessary to carry liquid droplets upwards. Critical gas velocity is a function of flowing pressure, fluid and gas density, droplet size, surface tension, temperature and pipe diameter.
[0007] One method of increasing gas velocity is to change tubular size or decrease surface pressure; the effect on the wells ability to unload liquid is dramatic when such solutions are applied. However, these solutions will only last as long as the bottom reservoir pressure can produce against the new conditions.
[0008] Unfortunately for most sour gas wells, the option to change tubulars or decrease surface pressures are often uneconomic and the well is abandoned long before its usable reserves are depleted. The cost to change out tubulars is high in terms of cost (rig, safety equipment, pump trucks etc.) and the potential damage to the formation, which may occur as the well has to be killed using a fluid whose hydrostatic weight has to equal or overcome the shut in reservoir pressure. In many cases the depth of the well and the low reservoir pressure will not hold a full column of kill fluid and the fluid will fracture into the formation face, causing damage that cannot be repaired.
[0009] Surface pressure may be reduced by using a compressor to reduce the flowing wellhead pressure in the wellbore. The cost is directly related to the size of compressor required to have sufficient suction pressure that allows the well to unload liquid with the elevated velocity required to produce the gas to the gathering system lines.
Most compressors for sour gas are required to have numerous safety shutdown systems, expensive coolers to reduce the heat of compressed gas and noise emission controls.
Most compressors for sour gas are required to have numerous safety shutdown systems, expensive coolers to reduce the heat of compressed gas and noise emission controls.
[0010] Artificial lift in these wells is difficult to implement. Most types of downhole mechanical or electrical pumps do not work well in a high gas environment due to gas locking and cavitation. The costs of the modifications or additional completion components required to adapt the pumping systems to efficient operation in high gas ratio environments can also be prohibitively expensive.
[0011] Therefore, there is a need in the art for an innovative and economical solution to produce gas from these aging reservoirs.
Summary of The Invention [0012] In one aspect, the invention comprises a valve as part of an operational system that uses reservoir energy and injected sweet gas to activate a plunger up and down the well bore and acts as interface between the produced liquid and produced gas, there by unloading all liquid to surface. The plunger may be cycled numerous times throughout the day and is the frequency of cycling is only dependent on how much gas is available for each cycle.
Summary of The Invention [0012] In one aspect, the invention comprises a valve as part of an operational system that uses reservoir energy and injected sweet gas to activate a plunger up and down the well bore and acts as interface between the produced liquid and produced gas, there by unloading all liquid to surface. The plunger may be cycled numerous times throughout the day and is the frequency of cycling is only dependent on how much gas is available for each cycle.
[0013] Therefore, in one aspect, the invention comprises a method of producing a vertical, deviated or horizontal gas well having an annular space defined by a well casing and a concentrically disposed production tubing, said well having an upper annulus and a lower producing zone open to the production tubing, wherein the upper annulus is isolated from the lower producing zone by a packer, comprising the steps of:
(a) opening a communication path through the tubing into the upper annulus, and if necessary, removing any inhibited fluid in the upper annulus;
(b) landing at least one crossover valve within the production tubing above the packer and exposed to the upper annulus; and (c) periodically injecting gas into the annular space to open the crossover valve and enter the production tubing, wherein the injected gas lifts liquids in the production tubing to the surface.
In one embodiment, the at least one crossover valve is deployed on a continuous or jointed tubing string or by wireline, within the production tubing.
100141 In another aspect, the invention may comprise a crossover valve assembly for insertion into production tubing, comprising:
(a) a pilot section comprising an outer housing and an inner production tube disposed concentrically within the housing, defining an annular space therebetween, a pilot valve assembly within the annular space and comprising a valve seat and a pilot piston moveable between a closed position and an open position, a pilot chamber exposed through a pilot opening in the outer housing, a spring for biasing the pilot piston towards the closed position;
(b) a power section comprising an outer housing and an inner production tube disposed concentrically within the housing, defining an annular space therebetween, a power valve assembly disposed within the annular space and comprising a valve seat, a valve mandrel and an activation piston, wherein the valve mandrel and an activation piston are moveable between a closed position and an open position, wherein the power section defines an activation chamber;
(c) an activation fluid passage between the pilot chamber and the activation chamber which is closed when the pilot piston is in its closed position and open when the pilot piston is in its open position, and wherein fluid pressure in the fluid passage moves the activation piston and valve mandrel to their open position;
(d) a crossover fluid passage through the power section outer housing and the power section inner production tube which is closed when the activation piston and the valve mandrel are in their closed position; and (e) an equalization fluid passage between the activation chamber and through the power section outer housing, which equalization passage is more restrictive than the activation fluid passage.
[0015] In another aspect, the invention may comprise a crossover valve assembly for insertion into production tubing, or integral with production tubing, comprising:
(a) an outer housing;
(b) an inner production tube;
(c) a pilot section responsive to external pressure to open an activation passage above a pre-determined pressure;
(d) a power section responsive to pressure in the activation passage to open an injection opening; and (e) a crossover valve responsive to pressure in the injection opening to open a crossover port, allowing fluid communication from outside the outer housing to within the inner production tube.
In one embodiment, the pre-determined pressure is set by means of a coil spring, or a gas spring, or both a coil and gas spring, acting within the pilot section. The power section may comprise an equalization pathway open to outside the outer housing, which equalization pathway is more restrictive to gas flow than the activation passage.
[0016] In another aspect, the invention may comprise a system for producing a vertical, deviated or horizontal gas well having an annular space defined by a well casing and a concentrically disposed production tubing, said well having an upper annulus and a lower producing zone open to the production tubing, wherein the upper annulus is isolated from the lower producing zone by a packer, comprising:
(a) a communication path through the tubing into the upper annulus;
(b) at least one crossover valve within the production tubing above the packer and exposed to the upper annulus through the communication path; and (c) a surface gas injector and a gas supply for injecting gas into the annular space to open the crossover valve and enter the production tubing.
In one embodiment, the system may further comprise a plunger for reciprocating within the production tubing. The system may further comprise a surface controller for controlling the gas injector, wherein the controller is responsive to a signal indicative of one or more of the following: the position of the plunger, pressure in the annulus, pressure or gas flow in the production tubing.
Brief Description of The Drawings [0017] In the drawings, like elements are assigned like reference numerals.
The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention. The drawings are briefly described as follows:
[0018] Figure 1 is a schematic representation of a wellbore with an upper annulus and lower producing zone, sectioned vertically along its length and depicting the crossover valve thru tubing completion.
[0019] Figure 2 is a schematic representation of the crossover valve device sectioned along its length to reveal all of the working components.
[0020] Figure 3 is a detailed view of area A shown in Figure 2, showing the power section valve assembly.
[0021] Figure 4 is a detailed view of area B of Figure 2, showing the pilot section valve assembly.
[0022] Figure 5 is a tranverse cross-sectional view along line C-C in Figure 2.
[0023] Figure 6 is a cross sectional of the crossover valve of Figure 2, shown with the pilot valve assembly in its open position.
[0024] Figure 7 is a cross sectional of the power section of the crossover valve of Figure 2, shown with the power valve assembly in its open position.
[0025] Figure 8 is a cross sectional of the power section of the crossover valve of Figure 2, shown with the RCV valve in its open position.
Detailed Description Of Preferred Embodiments [0026] When describing the present invention, all terms not defined herein have their common art-recognized meanings. To the extent that the following description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention.
[0027] The apparatus of the present invention is designed to facilitate production of gas wells with low flow pressures and/or inconsistent production line pressure, and sour gas wells in particular. The term "fluid" is used herein as comprising both liquids and gases.
[0028] As shown in Figure 1, a producing gas well comprises a casing string (1) and a production tubing string (2). A packer (3) provides a seal between the tubing outside diameter and the casing inside diameter, The packer prevents cross-flow of produced liquids and gas above the packer and protects the casing from corrosion usually associated with H2S, as the casing is the only barrier between the wellbore and the surrounding natural formation.
100291 Many sour gas well sites are equipped with high pressure, sweet fuel gas for instrumentation operation. This source gas may also be an excellent medium for annular circulation gas.
[0030] In one aspect, the invention comprises a method of producing natural gas from an isolated zone, such as a sour gas zone, by thing injected sweet gas to lift liquids in the production tubing to the surface. In general terms, in another aspect, the apparatus of the present invention comprises a crossover valve device, which opens in response to pressure in the casing annulus, to permit fluid flow from the annulus into the tubing string.
[0031] The valve (10) comprises a number of tubular elements (11) assembled together to define an internal production flow path and an outer housing (12). In one embodiment, the valve comprises a pilot section (13) and a power section (14), connected by a pup joint (16) defining a fluid passage (17). In one embodiment, the valve (10) is adapted to be run on wireline, or on continuous or jointed tubing string. In one embodiment, the valve may be an integral component of a tubing string.
[0032] The pilot section comprises a concentric sliding pilot piston (18), a pilot valve seat (20) and an annular pressure opening (22) in the outer housing (11). In its closed position, as shown in Figures 2 and 4, the downhole end of the pilot piston (18) is seated against valve seat (20), closing off the pup joint fluid passage (17). The pilot piston (18) is appropriately sealed with seals which slide against the inner surface of the housing (11) and the outer surface of the inner tubing.
[0033] The pilot piston (18) is biased towards its closed position by a coil spring (26), or a gas spring (28), or a combination of a coil spring and a gas spring. As shown in Figure 2, a pilot pressure chamber (28) is filled with an inert gas such as nitrogen through a valve (24), and resists upward movement of the pilot piston. The casing pressure required to open the pilot valve must overcome the closing pressure, which is the sum of the gas pressure in chamber (28) and the pressure exerted by the coil spring. When the annular pressure drops below the closing pressure, the pilot valve will close.
[0034] When the pressure applied through the pressure opening (22) overcomes the closing pressure, the pilot piston (18) is urged upwards as fluid fills the pilot chamber (23) until the casing pressure equals the closing pressure exerted by the coil spring and the gas spring.
[0035] This fluid in the pilot chamber (23) then travels downwards through the pup joint fluid passage (17) and enters the power section (14), activating the power piston (30) which is also a sealed concentric sliding piston. In one embodiment, the power piston is biased in a closed position by a coil spring (31).
[0036] The power piston (30) pushes against a mandrel (32) having a valve face (34) which is seated against an injection gas inlet (36) through the outer housing. The injection gas inlet may be provided in a circumferential groove (38) around the outer housing which has an angled conical section. The valve face (34) has a matching conical section which sealingly engages the gas inlet when closed.
[0037] As injected gas (G) in the casing annular space enters the power section (14) through gas inlet (36), it proceeds through the valve between the lower tubular (11A) and the outer housing (12) until it reaches the cross-over valve or RCV valve (50), where it unseats the RCV valve (50), and through crossover port (52) and enters the internal flow path of the valve (10). The RCV valve (50) is biased upwards by a coil spring (51), the force of which is overcome by the injected sweet gas pressure. The RCV valve is shown seated (closed) in Figure 7 and unseated (open) in Figure 8.
[0038] When the annular pressure outside the valve drops below the closing pressure of the pilot section, the pilot piston (18) will be urged towards its closed position, and eventually seating against the valve seat (20), and initiating the valve closure sequence. If the annular pressure continues to drop, the fluid in the pilot chamber (23) and in the pup joint fluid passage (17) is allowed to slowly equalize to the annular pressure through a restrictive bypass (42) which exists between the lower tubular (11A) and the outer housing (12) around the power piston (30). The closing pressure exerted by the power section coil spring (31) is then sufficient to return the power piston (30) to its closed position, as the pressure equalizes.
When the power piston returns the closed position, the valve face (34) closes the injection gas inlet (36). The RCV valve (50) will then close and the valve (10) again isolates the annular space from the production tubing.
[0039] The restrictive bypass (42) is always open, but provides sufficient resistance to gas flow to allow gas pressure from the pilot section to open the power piston, while allowing equalization within a reasonably short period of time, in one embodiment, in the order of a few minutes.
[0040] The valve (10) will open at annular pressures above the closing pressure, and will close when the annular pressure drops below the closing pressure. In one embodiment, the closing pressure of the pilot section of the valve is adjusted by adjusting the strength of the coil spring and the gas spring, if both are used. The selected closing pressure may be determined by considering the well depth, annulus volume available and gas/liquid ratios. In one embodiment, the low pressure closure will be set significantly higher than the minimum tubing pressure, thereby ensuring no sour gas in the production tubing can escape into the annulus through the valve (10). For example, the low pressure closure may be set at 500 kPa over the minimum tubing pressure. This is important in the absence of the inhibited annulus fluid to prevent sour gas migration into the annulus. In addition, the valve may be equipped with two isolation mechanisms (or barriers) between the tubing ID where sour gas resides and the annulus which is required to remain sweet.
[0041] In one embodiment, the gas spring can be charged to a very high pressure before use in the field, and can then be adjusted to a desired pressure for the particular downhole conditions it will encounter before installation downhole. The coil spring provides a fixed closing pressure, while the gas spring may provides a variable customizable closing pressure.
[0042] Therefore, in one embodiment, the crossover valve comprises three actuating components, the pilot section, the power section and the RCV valve, which interact by gas pressure and not physical linkage.
[0043] In operation, and with reference to Figure 1, a bottom hole check valve (8A) is placed into the bottom of production tubing string, which functions to prevent gas injected from surface entry into the formation when the well is completed, but does allow gas flow from the formation into the tubing string, [0044] The cross-over valve (10) assembly can be run using wire line techniques or coiled or jointed tubing techniques that are well known in the industry and need not be further described here. If an existing sliding sleeve is part of the production string, it may be opened.
Alternatively, the tubing may be perforated above the packer (3). The valve is landed above the isolation packer (3), level with an open sliding sleeve or with tubing perforations. The valve is located in between two thru-tubing pack-offs (4, 5) which isolate the production tubing above and below the valve. Any gas from the annulus can only enter the production tubing through the valve (10). Suitable anchor and packer configurations are described in co-owned U.S. Patent No. 7,347,273 B2, the entire contents of which are incorporated herein by reference (where permitted).
[0045] Any inhibited fluid in the annulus may be removed using conventional means, such as by circulation of nitrogen gas.
[0046] Once the dovvnhole equipment has been installed and any inhibited fluid has been removed, a sweet gas compressor (102) can compress low volume gas from the instrument supply line (104) and inject it down the casing tubing annulus. Once the annular pressure exceeds the closing pressure of the crossover valve (10), the injected sweet gas (G) will pass through the valve (10) into the production tubing, overcome the flowing bottom hole pressure, and cause the bottom check valve (8A) to close. Thus, all the sweet annular gas (G) will move upwards in the production tubing. This will increase the gas velocity to above the critical rate and drive any liquid column in the production tubing to the surface.
[0047] Once the liquid column is produced, the pressure in the annulus may be reduced, closing the valve while maintaining a positive pressure differential against the tubing. With the liquid hydrostatic column removed from the well bore, the well can now produce to full potential through the bottom check valve (8A). The production cycle is repeated when the annular gas column has reached the required pressure to open the crossover valve (10) again.
[0048] A plunger assembly (not shown) may be introduced into the tubing string to allow the well to be operated at lower gas velocities. The plunger acts as an interface between the liquid column and the injected gas. Because the plunger is a dynamic seal with close tolerance between the plunger body and the tubing wall (as opposed to perfect seal), it still requires velocity to move the liquid up hole, however the cross sectional area of the plunger coupled with the gas velocity trying to pass the outside creates a differential pressure from below which drives the plunger and the liquid column to surface.
[0049] In one embodiment, the system may comprise electronic monitoring and pressure recording to determine when the system operates, such as, for example, by using a PLC
(Programmable Logic Controller) with various analog and digital inputs and outputs, which can read and record signals from external sensors such as pressure transducers. These transducers constantly sample the well pressures and will signal the PLC
control box to open casing valves to flow or shut in. The PLC may also have a proximity switch which detects the plunger arrival at surface and records times and flows. With these electronic instruments and control the well can be left with no human intervention once the flow cycles are set into the controller. These set pressures and times can be adjusted to suit the changing well conditions.
[0050] Alternate means exist of completing this production workflow including, but not limited to a locking and sealing mandrel assembly (as is well known in the art) to engage and seal in an existing selective profile nipple integral to the production tubing string. This would replace the tubing packer (5) depicted in Figure 1. This completion is possible if a selective profile nipple exists and is easily accessible in the wellbore relative to the location of the communication ports through the production tubing wall. In another alternative, the tool string may be landed across an open sliding sleeve providing communication through the wall of the tubing from the annulus. All of the elements of the tool string may be designed to pass through the largest standard selective profile nipple size in order to easily facilitate landing said tool string across an existing sliding sleeve (equipped with profile nipple) or below an existing profile nipple in the event that complex wellbore geometry is encountered.
(a) opening a communication path through the tubing into the upper annulus, and if necessary, removing any inhibited fluid in the upper annulus;
(b) landing at least one crossover valve within the production tubing above the packer and exposed to the upper annulus; and (c) periodically injecting gas into the annular space to open the crossover valve and enter the production tubing, wherein the injected gas lifts liquids in the production tubing to the surface.
In one embodiment, the at least one crossover valve is deployed on a continuous or jointed tubing string or by wireline, within the production tubing.
100141 In another aspect, the invention may comprise a crossover valve assembly for insertion into production tubing, comprising:
(a) a pilot section comprising an outer housing and an inner production tube disposed concentrically within the housing, defining an annular space therebetween, a pilot valve assembly within the annular space and comprising a valve seat and a pilot piston moveable between a closed position and an open position, a pilot chamber exposed through a pilot opening in the outer housing, a spring for biasing the pilot piston towards the closed position;
(b) a power section comprising an outer housing and an inner production tube disposed concentrically within the housing, defining an annular space therebetween, a power valve assembly disposed within the annular space and comprising a valve seat, a valve mandrel and an activation piston, wherein the valve mandrel and an activation piston are moveable between a closed position and an open position, wherein the power section defines an activation chamber;
(c) an activation fluid passage between the pilot chamber and the activation chamber which is closed when the pilot piston is in its closed position and open when the pilot piston is in its open position, and wherein fluid pressure in the fluid passage moves the activation piston and valve mandrel to their open position;
(d) a crossover fluid passage through the power section outer housing and the power section inner production tube which is closed when the activation piston and the valve mandrel are in their closed position; and (e) an equalization fluid passage between the activation chamber and through the power section outer housing, which equalization passage is more restrictive than the activation fluid passage.
[0015] In another aspect, the invention may comprise a crossover valve assembly for insertion into production tubing, or integral with production tubing, comprising:
(a) an outer housing;
(b) an inner production tube;
(c) a pilot section responsive to external pressure to open an activation passage above a pre-determined pressure;
(d) a power section responsive to pressure in the activation passage to open an injection opening; and (e) a crossover valve responsive to pressure in the injection opening to open a crossover port, allowing fluid communication from outside the outer housing to within the inner production tube.
In one embodiment, the pre-determined pressure is set by means of a coil spring, or a gas spring, or both a coil and gas spring, acting within the pilot section. The power section may comprise an equalization pathway open to outside the outer housing, which equalization pathway is more restrictive to gas flow than the activation passage.
[0016] In another aspect, the invention may comprise a system for producing a vertical, deviated or horizontal gas well having an annular space defined by a well casing and a concentrically disposed production tubing, said well having an upper annulus and a lower producing zone open to the production tubing, wherein the upper annulus is isolated from the lower producing zone by a packer, comprising:
(a) a communication path through the tubing into the upper annulus;
(b) at least one crossover valve within the production tubing above the packer and exposed to the upper annulus through the communication path; and (c) a surface gas injector and a gas supply for injecting gas into the annular space to open the crossover valve and enter the production tubing.
In one embodiment, the system may further comprise a plunger for reciprocating within the production tubing. The system may further comprise a surface controller for controlling the gas injector, wherein the controller is responsive to a signal indicative of one or more of the following: the position of the plunger, pressure in the annulus, pressure or gas flow in the production tubing.
Brief Description of The Drawings [0017] In the drawings, like elements are assigned like reference numerals.
The drawings are not necessarily to scale, with the emphasis instead placed upon the principles of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental concepts of the present invention. The drawings are briefly described as follows:
[0018] Figure 1 is a schematic representation of a wellbore with an upper annulus and lower producing zone, sectioned vertically along its length and depicting the crossover valve thru tubing completion.
[0019] Figure 2 is a schematic representation of the crossover valve device sectioned along its length to reveal all of the working components.
[0020] Figure 3 is a detailed view of area A shown in Figure 2, showing the power section valve assembly.
[0021] Figure 4 is a detailed view of area B of Figure 2, showing the pilot section valve assembly.
[0022] Figure 5 is a tranverse cross-sectional view along line C-C in Figure 2.
[0023] Figure 6 is a cross sectional of the crossover valve of Figure 2, shown with the pilot valve assembly in its open position.
[0024] Figure 7 is a cross sectional of the power section of the crossover valve of Figure 2, shown with the power valve assembly in its open position.
[0025] Figure 8 is a cross sectional of the power section of the crossover valve of Figure 2, shown with the RCV valve in its open position.
Detailed Description Of Preferred Embodiments [0026] When describing the present invention, all terms not defined herein have their common art-recognized meanings. To the extent that the following description is of a specific embodiment or a particular use of the invention, it is intended to be illustrative only, and not limiting of the claimed invention.
[0027] The apparatus of the present invention is designed to facilitate production of gas wells with low flow pressures and/or inconsistent production line pressure, and sour gas wells in particular. The term "fluid" is used herein as comprising both liquids and gases.
[0028] As shown in Figure 1, a producing gas well comprises a casing string (1) and a production tubing string (2). A packer (3) provides a seal between the tubing outside diameter and the casing inside diameter, The packer prevents cross-flow of produced liquids and gas above the packer and protects the casing from corrosion usually associated with H2S, as the casing is the only barrier between the wellbore and the surrounding natural formation.
100291 Many sour gas well sites are equipped with high pressure, sweet fuel gas for instrumentation operation. This source gas may also be an excellent medium for annular circulation gas.
[0030] In one aspect, the invention comprises a method of producing natural gas from an isolated zone, such as a sour gas zone, by thing injected sweet gas to lift liquids in the production tubing to the surface. In general terms, in another aspect, the apparatus of the present invention comprises a crossover valve device, which opens in response to pressure in the casing annulus, to permit fluid flow from the annulus into the tubing string.
[0031] The valve (10) comprises a number of tubular elements (11) assembled together to define an internal production flow path and an outer housing (12). In one embodiment, the valve comprises a pilot section (13) and a power section (14), connected by a pup joint (16) defining a fluid passage (17). In one embodiment, the valve (10) is adapted to be run on wireline, or on continuous or jointed tubing string. In one embodiment, the valve may be an integral component of a tubing string.
[0032] The pilot section comprises a concentric sliding pilot piston (18), a pilot valve seat (20) and an annular pressure opening (22) in the outer housing (11). In its closed position, as shown in Figures 2 and 4, the downhole end of the pilot piston (18) is seated against valve seat (20), closing off the pup joint fluid passage (17). The pilot piston (18) is appropriately sealed with seals which slide against the inner surface of the housing (11) and the outer surface of the inner tubing.
[0033] The pilot piston (18) is biased towards its closed position by a coil spring (26), or a gas spring (28), or a combination of a coil spring and a gas spring. As shown in Figure 2, a pilot pressure chamber (28) is filled with an inert gas such as nitrogen through a valve (24), and resists upward movement of the pilot piston. The casing pressure required to open the pilot valve must overcome the closing pressure, which is the sum of the gas pressure in chamber (28) and the pressure exerted by the coil spring. When the annular pressure drops below the closing pressure, the pilot valve will close.
[0034] When the pressure applied through the pressure opening (22) overcomes the closing pressure, the pilot piston (18) is urged upwards as fluid fills the pilot chamber (23) until the casing pressure equals the closing pressure exerted by the coil spring and the gas spring.
[0035] This fluid in the pilot chamber (23) then travels downwards through the pup joint fluid passage (17) and enters the power section (14), activating the power piston (30) which is also a sealed concentric sliding piston. In one embodiment, the power piston is biased in a closed position by a coil spring (31).
[0036] The power piston (30) pushes against a mandrel (32) having a valve face (34) which is seated against an injection gas inlet (36) through the outer housing. The injection gas inlet may be provided in a circumferential groove (38) around the outer housing which has an angled conical section. The valve face (34) has a matching conical section which sealingly engages the gas inlet when closed.
[0037] As injected gas (G) in the casing annular space enters the power section (14) through gas inlet (36), it proceeds through the valve between the lower tubular (11A) and the outer housing (12) until it reaches the cross-over valve or RCV valve (50), where it unseats the RCV valve (50), and through crossover port (52) and enters the internal flow path of the valve (10). The RCV valve (50) is biased upwards by a coil spring (51), the force of which is overcome by the injected sweet gas pressure. The RCV valve is shown seated (closed) in Figure 7 and unseated (open) in Figure 8.
[0038] When the annular pressure outside the valve drops below the closing pressure of the pilot section, the pilot piston (18) will be urged towards its closed position, and eventually seating against the valve seat (20), and initiating the valve closure sequence. If the annular pressure continues to drop, the fluid in the pilot chamber (23) and in the pup joint fluid passage (17) is allowed to slowly equalize to the annular pressure through a restrictive bypass (42) which exists between the lower tubular (11A) and the outer housing (12) around the power piston (30). The closing pressure exerted by the power section coil spring (31) is then sufficient to return the power piston (30) to its closed position, as the pressure equalizes.
When the power piston returns the closed position, the valve face (34) closes the injection gas inlet (36). The RCV valve (50) will then close and the valve (10) again isolates the annular space from the production tubing.
[0039] The restrictive bypass (42) is always open, but provides sufficient resistance to gas flow to allow gas pressure from the pilot section to open the power piston, while allowing equalization within a reasonably short period of time, in one embodiment, in the order of a few minutes.
[0040] The valve (10) will open at annular pressures above the closing pressure, and will close when the annular pressure drops below the closing pressure. In one embodiment, the closing pressure of the pilot section of the valve is adjusted by adjusting the strength of the coil spring and the gas spring, if both are used. The selected closing pressure may be determined by considering the well depth, annulus volume available and gas/liquid ratios. In one embodiment, the low pressure closure will be set significantly higher than the minimum tubing pressure, thereby ensuring no sour gas in the production tubing can escape into the annulus through the valve (10). For example, the low pressure closure may be set at 500 kPa over the minimum tubing pressure. This is important in the absence of the inhibited annulus fluid to prevent sour gas migration into the annulus. In addition, the valve may be equipped with two isolation mechanisms (or barriers) between the tubing ID where sour gas resides and the annulus which is required to remain sweet.
[0041] In one embodiment, the gas spring can be charged to a very high pressure before use in the field, and can then be adjusted to a desired pressure for the particular downhole conditions it will encounter before installation downhole. The coil spring provides a fixed closing pressure, while the gas spring may provides a variable customizable closing pressure.
[0042] Therefore, in one embodiment, the crossover valve comprises three actuating components, the pilot section, the power section and the RCV valve, which interact by gas pressure and not physical linkage.
[0043] In operation, and with reference to Figure 1, a bottom hole check valve (8A) is placed into the bottom of production tubing string, which functions to prevent gas injected from surface entry into the formation when the well is completed, but does allow gas flow from the formation into the tubing string, [0044] The cross-over valve (10) assembly can be run using wire line techniques or coiled or jointed tubing techniques that are well known in the industry and need not be further described here. If an existing sliding sleeve is part of the production string, it may be opened.
Alternatively, the tubing may be perforated above the packer (3). The valve is landed above the isolation packer (3), level with an open sliding sleeve or with tubing perforations. The valve is located in between two thru-tubing pack-offs (4, 5) which isolate the production tubing above and below the valve. Any gas from the annulus can only enter the production tubing through the valve (10). Suitable anchor and packer configurations are described in co-owned U.S. Patent No. 7,347,273 B2, the entire contents of which are incorporated herein by reference (where permitted).
[0045] Any inhibited fluid in the annulus may be removed using conventional means, such as by circulation of nitrogen gas.
[0046] Once the dovvnhole equipment has been installed and any inhibited fluid has been removed, a sweet gas compressor (102) can compress low volume gas from the instrument supply line (104) and inject it down the casing tubing annulus. Once the annular pressure exceeds the closing pressure of the crossover valve (10), the injected sweet gas (G) will pass through the valve (10) into the production tubing, overcome the flowing bottom hole pressure, and cause the bottom check valve (8A) to close. Thus, all the sweet annular gas (G) will move upwards in the production tubing. This will increase the gas velocity to above the critical rate and drive any liquid column in the production tubing to the surface.
[0047] Once the liquid column is produced, the pressure in the annulus may be reduced, closing the valve while maintaining a positive pressure differential against the tubing. With the liquid hydrostatic column removed from the well bore, the well can now produce to full potential through the bottom check valve (8A). The production cycle is repeated when the annular gas column has reached the required pressure to open the crossover valve (10) again.
[0048] A plunger assembly (not shown) may be introduced into the tubing string to allow the well to be operated at lower gas velocities. The plunger acts as an interface between the liquid column and the injected gas. Because the plunger is a dynamic seal with close tolerance between the plunger body and the tubing wall (as opposed to perfect seal), it still requires velocity to move the liquid up hole, however the cross sectional area of the plunger coupled with the gas velocity trying to pass the outside creates a differential pressure from below which drives the plunger and the liquid column to surface.
[0049] In one embodiment, the system may comprise electronic monitoring and pressure recording to determine when the system operates, such as, for example, by using a PLC
(Programmable Logic Controller) with various analog and digital inputs and outputs, which can read and record signals from external sensors such as pressure transducers. These transducers constantly sample the well pressures and will signal the PLC
control box to open casing valves to flow or shut in. The PLC may also have a proximity switch which detects the plunger arrival at surface and records times and flows. With these electronic instruments and control the well can be left with no human intervention once the flow cycles are set into the controller. These set pressures and times can be adjusted to suit the changing well conditions.
[0050] Alternate means exist of completing this production workflow including, but not limited to a locking and sealing mandrel assembly (as is well known in the art) to engage and seal in an existing selective profile nipple integral to the production tubing string. This would replace the tubing packer (5) depicted in Figure 1. This completion is possible if a selective profile nipple exists and is easily accessible in the wellbore relative to the location of the communication ports through the production tubing wall. In another alternative, the tool string may be landed across an open sliding sleeve providing communication through the wall of the tubing from the annulus. All of the elements of the tool string may be designed to pass through the largest standard selective profile nipple size in order to easily facilitate landing said tool string across an existing sliding sleeve (equipped with profile nipple) or below an existing profile nipple in the event that complex wellbore geometry is encountered.
Claims (13)
1. A method of producing a vertical, deviated or horizontal gas well having an annular space defined by a well casing and a concentrically disposed production tubing , said well having an upper annulus and a lower producing zone open to the production tubing, wherein the upper annulus is isolated from the lower producing zone by a packer, comprising the steps of:
(a) opening a communication path through the tubing into the upper annulus, and if necessary, removing any fluid in the upper annulus;
(b) landing at least one crossover valve within the production tubing above the packer and exposed to the upper annulus; and (c) injecting gas into the annular space to open the crossover valve and enter the production tubing, wherein the injected gas lifts liquids in the production tubing to the surface.
(a) opening a communication path through the tubing into the upper annulus, and if necessary, removing any fluid in the upper annulus;
(b) landing at least one crossover valve within the production tubing above the packer and exposed to the upper annulus; and (c) injecting gas into the annular space to open the crossover valve and enter the production tubing, wherein the injected gas lifts liquids in the production tubing to the surface.
2. The method of claim 1 wherein the at least one crossover valve is deployed on a continuous or jointed tubing string or by wireline, within the production tubing.
3. The method of claim 1 wherein the gas is injected continuously, and the annular pressure periodically exceeds an opening pressure of the crossover valve.
4. The method of claim 1 wherein the gas is injected periodically.
5. The method of claim 1 wherein the injected gas comprises instrumentation sweet gas.
6. A crossover valve assembly for insertion into production tubing, or integral with production tubing, comprising:
(a) a pilot section comprising an outer housing and an inner production tube disposed concentrically within the outer housing, defining an annular space therebetween, a pilot valve assembly within the annular space and comprising a valve seat and a pilot piston moveable between a closed position and an open position, a pilot chamber exposed through a pilot opening in the outer housing, and a spring for biasing the pilot piston towards the closed position;
(b) a power section comprising an outer housing and an inner production tube disposed concentrically within the outer housing, defining an annular space therebetween, a power valve assembly disposed within the annular space and comprising a valve seat, a valve mandrel and an activation piston, wherein the valve mandrel and an activation piston are moveable between a closed position and an open position, wherein the power section defines an activation chamber;
(c) an activation fluid passage between the pilot chamber and the activation chamber which is closed when the pilot piston is in its closed position and open when the pilot piston is in its open position, and wherein fluid pressure in the activation fluid passage moves the activation piston and valve mandrel to their open position;
(d) a crossover fluid passage through the power section outer housing and the power section inner production tube, which is closed when the activation piston and the valve mandrel are in their closed position and open when the activation piston and the valve mandrel are in their open position; and (e) an equalization fluid passage between the activation chamber and through the power section outer housing, which equalization passage is more restrictive than the activation fluid passage.
(a) a pilot section comprising an outer housing and an inner production tube disposed concentrically within the outer housing, defining an annular space therebetween, a pilot valve assembly within the annular space and comprising a valve seat and a pilot piston moveable between a closed position and an open position, a pilot chamber exposed through a pilot opening in the outer housing, and a spring for biasing the pilot piston towards the closed position;
(b) a power section comprising an outer housing and an inner production tube disposed concentrically within the outer housing, defining an annular space therebetween, a power valve assembly disposed within the annular space and comprising a valve seat, a valve mandrel and an activation piston, wherein the valve mandrel and an activation piston are moveable between a closed position and an open position, wherein the power section defines an activation chamber;
(c) an activation fluid passage between the pilot chamber and the activation chamber which is closed when the pilot piston is in its closed position and open when the pilot piston is in its open position, and wherein fluid pressure in the activation fluid passage moves the activation piston and valve mandrel to their open position;
(d) a crossover fluid passage through the power section outer housing and the power section inner production tube, which is closed when the activation piston and the valve mandrel are in their closed position and open when the activation piston and the valve mandrel are in their open position; and (e) an equalization fluid passage between the activation chamber and through the power section outer housing, which equalization passage is more restrictive than the activation fluid passage.
7. The crossover valve assembly wherein the spring for biasing the pilot piston comprises a coil spring or a gas spring, or both a coil spring and a gas spring.
8. A crossover valve assembly for insertion into production tubing, or integral with production tubing, comprising:
(a) an outer housing;
(b) an inner production tube;
(c) a pilot section responsive to external pressure to open an activation passage above a pre-determined pressure;
(d) a power section responsive to pressure in the activation passage to open an injection opening; and (e) a crossover valve responsive to pressure in the injection opening to open a crossover port, allowing fluid communication from outside the outer housing to within the inner production tube.
(a) an outer housing;
(b) an inner production tube;
(c) a pilot section responsive to external pressure to open an activation passage above a pre-determined pressure;
(d) a power section responsive to pressure in the activation passage to open an injection opening; and (e) a crossover valve responsive to pressure in the injection opening to open a crossover port, allowing fluid communication from outside the outer housing to within the inner production tube.
9. The crossover valve assembly of claim 8 wherein the pre-determined pressure is set by means of a coil spring, or a gas spring, or both a coil and gas spring, acting within the pilot section.
10. The crossover valve assembly of claim 8 wherein the power section comprises an equalization pathway open to outside the outer housing, which equalization pathway is more restrictive to gas flow than the activation passage.
11. A system for producing a vertical, deviated or horizontal gas well having an annular space defined by a well casing and a concentrically disposed production tubing , said well having an upper annulus and a lower producing zone open to the production tubing, wherein the upper annulus is isolated from the lower producing zone by a packer, comprising:
(a) a communication path through the tubing into the upper annulus;
(b) at least one crossover valve within the production tubing above the packer and exposed to the upper annulus through the communication path; and (c) a surface gas injector and a gas supply for injecting gas into the annular space to open the crossover valve and enter the production tubing.
(a) a communication path through the tubing into the upper annulus;
(b) at least one crossover valve within the production tubing above the packer and exposed to the upper annulus through the communication path; and (c) a surface gas injector and a gas supply for injecting gas into the annular space to open the crossover valve and enter the production tubing.
12. The system of claim 11 further comprising a plunger for reciprocating within the production tubing.
13. The system of claim 12, further comprising a surface controller for controlling the gas injector, wherein the controller is responsive to a signal indicative of one or more of the following: the position of the plunger, pressure in the annulus, pressure or gas flow in the production tubing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2829630 CA2829630A1 (en) | 2013-10-11 | 2013-10-11 | Crossover valve system and method for gas production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2829630 CA2829630A1 (en) | 2013-10-11 | 2013-10-11 | Crossover valve system and method for gas production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2829630A1 true CA2829630A1 (en) | 2015-04-11 |
Family
ID=52824816
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2829630 Abandoned CA2829630A1 (en) | 2013-10-11 | 2013-10-11 | Crossover valve system and method for gas production |
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| Country | Link |
|---|---|
| CA (1) | CA2829630A1 (en) |
Cited By (6)
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| US20160376880A1 (en) * | 2015-06-29 | 2016-12-29 | Welltec A/S | Downhole system for unloading liquid |
| EP3115546A1 (en) * | 2015-07-06 | 2017-01-11 | Welltec A/S | Downhole system for unloading liquid |
| CN110872940A (en) * | 2018-08-29 | 2020-03-10 | 中国石油天然气股份有限公司 | Liquid discharge device and using method thereof |
| CN111734368A (en) * | 2020-07-17 | 2020-10-02 | 宋肖萍 | Layered oil production method for petroleum |
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| CN115263253A (en) * | 2022-09-16 | 2022-11-01 | 吕远 | Large-amplitude variable bottom hole pressure mining device and method |
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2013
- 2013-10-11 CA CA 2829630 patent/CA2829630A1/en not_active Abandoned
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160376880A1 (en) * | 2015-06-29 | 2016-12-29 | Welltec A/S | Downhole system for unloading liquid |
| WO2017001401A1 (en) * | 2015-06-29 | 2017-01-05 | Welltec A/S | Downhole system for unloading liquid |
| CN107743540A (en) * | 2015-06-29 | 2018-02-27 | 韦尔泰克有限公司 | For unloading the downhole system of liquid |
| AU2016287259B2 (en) * | 2015-06-29 | 2019-03-28 | Welltec Oilfield Solutions Ag | Downhole system for unloading liquid |
| US10597989B2 (en) | 2015-06-29 | 2020-03-24 | Welltec Oilfield Solutions Ag | Downhole system for unloading liquid |
| RU2721041C2 (en) * | 2015-06-29 | 2020-05-15 | Веллтек Ойлфилд Солюшнс АГ | Well pumping system for liquid pumping |
| EP3115546A1 (en) * | 2015-07-06 | 2017-01-11 | Welltec A/S | Downhole system for unloading liquid |
| CN110872940A (en) * | 2018-08-29 | 2020-03-10 | 中国石油天然气股份有限公司 | Liquid discharge device and using method thereof |
| CN111734368A (en) * | 2020-07-17 | 2020-10-02 | 宋肖萍 | Layered oil production method for petroleum |
| CN111734370A (en) * | 2020-07-17 | 2020-10-02 | 宋肖萍 | Application method of petroleum layered oil production device |
| CN111734368B (en) * | 2020-07-17 | 2022-10-28 | 西安荣达石油工程有限公司 | Layered oil production method for petroleum |
| CN115263253A (en) * | 2022-09-16 | 2022-11-01 | 吕远 | Large-amplitude variable bottom hole pressure mining device and method |
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