Device for recovery of gas from liquid-loaded gas wells

A device for use in recovery of gas trapped by fluid and suspended solids in a gas or oil well includes a body defining a cavity with a cap at its upper end and an opening for entry of fluid at its bottom end. A lower valve controls fluid flow into, and an upper valve controls flow out of, the cavity. Pressurized gas pushes downward on fluid in the cavity in a compression stroke which closes the lower valve and opens the upper valve. Gas is exhausted from the cavity during an exhaust stroke. An effluent line allows exit of the fluid and suspended solids during the compression stroke. A probe line provides electrical power to a pair of probes for initiating and halting entry of the stream of pressurized gas into the cavity.

FIELD OF THE INVENTION

The invention relates to the field of hydrocarbon production and more particularly to production of gas from liquid-loaded gas wells containing suspended solids such as sand and/or silt.

BACKGROUND OF THE INVENTION

It is well known that oil and gas wells have a finite lifetime and that the production rate of an individual well will decrease gradually until resource extraction no longer becomes profitable or until regulations mandate that production from the well must be suspended.

In most cases, as oil and gas wells mature, production volumes decrease as the bottomhole pressure decreases. This results in produced fluids from the reservoir reaching a critical velocity that eventually does not permit the liquids to reach the surface without some form of artificial lift. When these liquids aren't completely removed from the well with the oil and gas production from the reservoir, they build up in the well, causing the oil and gas to flow intermittently, lowering production and eventually killing the well. This is phenomenon is known as “liquid-loading.” Liquid loading is particularly problematic for conventional artificial lift equipment when the liquids contain significant volumes of particulates such as fine mud, sand and silt.

PCT Publication No. WO2010/009496 describes a gas displacement pump for use in pumping liquids for recovery of oil from stripper wells.

U.S. Pat. No. 5,074,758 describes a pump for moving liquids or slurries which is particularly adapted to move dangerous and corrosive liquids.

U.S. Pat. No. 5,373,897 describes a pneumatic underground fluid recovery device for use in a well to pump underground fluids therefrom.

U.S. Pat. No. 6,027,314 describes a pneumatically powered submersible fluids pump with a casing activator.

There remains a need for a solution to address and improve the rate of production and ultimate reserve recovery from oil and gas wells loaded with sandy, silty, muddy liquids. In most cases the particulate material in wells producing these types of liquids in conjunction with oil and gas causes conventional rotating or reciprocating artificial equipment to fail prematurely. Currently, the problems caused by sand, mud and silt are addressed using siphon string technology.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, there is provided a device for use in recovery of gas trapped by fluid and suspended solids in a gas or oil well, the device comprising a body defining a cavity with a cap at its upper end and an opening for entry of fluid at its bottom end, the device including a lower valve for controlling flow of fluid into the cavity and an upper valve for controlling flow of the fluid and suspended solids out of the cavity, the cap having a plurality of lines passing therethrough and into the cavity, the lines comprising: a) a gas line for providing a stream of pressurized gas to push downward on fluid in the cavity in a compression stroke which closes the lower valve and opens the upper valve, the gas line further used to exhaust contained gas from the cavity during an exhaust stroke when infiltration of fluid into the cavity raises the fluid level in the cavity; b) an effluent line for allowing exit of the fluid and suspended solids during the compression stroke; and c) a probe line for providing electrical power to a pair of probes for initiating and halting entry of the stream of pressurized gas into the cavity.

In certain embodiments, the upper valve and the lower valve are both located below the pair of probes.

In certain embodiments, the probes are spaced vertically apart within the cavity in an arrangement having an upper probe for sensing an upper fluid level to trigger initiation of the compression stroke and a lower probe for sensing a lower fluid level to trigger initiation of the exhaust stroke.

In certain embodiments, the cavity further contains a plurality of baffles for halting upward movement of the suspended solids in the fluid as the fluid rises during the exhaust stroke.

In certain embodiments, each one of the plurality of baffles is supported by one or more of the plurality of lines in the cavity.

In certain embodiments, the plurality of baffles is three baffles.

In certain embodiments, the baffles are leaf-shaped and include openings for holding the one or more of the plurality of lines.

In certain embodiments, the leaf-shaped baffles are rotated with respect to each other to provide partial transverse blockage of the cavity at different cross sectional areas of the cavity.

In certain embodiments, one of the openings is configured to hold the effluent line and another one of the openings is configured to hold the probe line.

In certain embodiments, the baffles are supported by or formed integrally with the cavity's sidewall.

In certain embodiments, the effluent line terminates at the upper valve and the upper valve includes an upper ball seat and an upper check ball, wherein the upper valve is closed when the upper check ball is positioned in the upper ball seat during the exhaust stroke and wherein the upper valve is open when the upper check ball floats above the upper ball seat during the compression stroke.

In certain embodiments, the lower valve is supported by an extension of the body which extends below the upper valve and the lower valve includes a lower ball seat and a lower check ball, wherein the lower valve is closed when the lower check ball is positioned in the lower ball seat during the compression stroke and wherein the lower valve is open when the lower check valve floats above the lower ball seat during the exhaust stroke.

In certain embodiments, the extension of the body which extends below the upper valve is a tube.

Another aspect of the present invention is a device for use in recovery of gas trapped by fluid and suspended solids in a gas or oil well, the device comprising a body defining a cavity with a cap at its upper end and an opening for entry of fluid at its bottom end, the device including a lower valve for controlling the flow of fluid into the cavity and an upper valve for controlling the flow of fluid out of the cavity, the cap having a plurality of lines passing therethrough and into the cavity, the lines comprising: a) a gas line for provision of a stream of pressurized gas to push downward on fluid in the cavity in a compression stroke which closes the lower valve and open the upper valve, the gas line further used to exhaust contained gas from the cavity during an exhaust stroke when infiltration of fluid into the cavity raises the fluid level in the cavity; b) an effluent line for allowing exit of fluid suspended solids during the compression stroke; c) a probe line for provision of electrical power to a pair of probes for initiating or halting the provision of gas pressure to the cavity; and d) a bubble tube line for determining pressure in the device.

In certain embodiments, the bubble tube line is configured to be switched to a cleaning line for injection of a second stream of pressurized gas into the device.

In certain embodiments, the device further comprises an adapter attached to the bottom end of the body, the adapter configured for attachment of a pair of nested tubes including an inner tube and an outer tube, the adapter having an opening leading to a channel in the adapter's inner sidewall, wherein the bottom end of the bubble tube is placed at the opening to transmit gas from the bubble tube into a space between the outer tube's inner sidewall and the inner tube's outer sidewall.

In certain embodiments, the inner tube and the outer tube are attachable to the adapter by threading.

In certain embodiments, the upper valve and the lower valve are both located below the pair of probes.

In certain embodiments, the probes are spaced vertically apart within the cavity in an arrangement having an upper probe for sensing an upper fluid level to trigger initiation of the compression stroke and a lower probe for sensing a lower fluid level to trigger initiation of the exhaust stroke when the fluid level rises.

In certain embodiments, the cavity further contains a plurality of baffles for halting upward movement of the suspended solids in the fluid as the fluid rises during the exhaust stroke.

In certain embodiments, each one of the plurality of baffles is supported by one or more of the plurality of lines in the cavity.

In certain embodiments, the plurality of baffles is three baffles.

In certain embodiments, each of the baffles is leaf-shaped and includes one or more openings for holding the one or more of the plurality of lines.

In certain embodiments, the leaf-shaped baffles are rotated with respect to each other to provide transverse blockage of the cavity at different cross sectional areas of the cavity.

In certain embodiments, the one or more openings includes a first opening configured to hold the effluent line, a second opening configured to hold the probe line and a third opening configured to hold the bubble tube line.

In certain embodiments, the baffles are supported by or formed integrally with the cavity's sidewall.

In certain embodiments, the effluent line terminates below the adapter at the upper valve and the upper valve includes an upper ball seat and an upper check ball, wherein the upper valve is closed when the upper check ball is positioned in the upper ball seat during the exhaust stroke and wherein the upper valve is open when the upper check ball floats above the upper ball seat during the compression stroke.

In certain embodiments, the lower valve is supported by the inner tube of the body which extends below the upper valve and the lower valve includes a lower ball seat and a lower check ball, wherein the lower valve is closed when the lower check ball is positioned in the lower ball seat during the compression stroke and wherein the lower valve is open when the lower check valve floats above the lower ball seat during the exhaust stroke.

Another aspect of the present invention is a system for recovery of gas trapped by fluid and particulate matter in a gas or oil well, the system comprising: a) a device as described herein wherein the cap is attached to an upper tube for protecting the plurality of lines extending upward from the cap and the plurality of lines is covered by a single protective covering forming an umbilical cable above the cap; and b) a wellhead for sealing the well; wherein the plurality of lines extend out from the wellhead, wherein the probe line is connected to a source of electricity, the gas line is connected to a source of pressurized gas and the effluent line is connected to a fluid storage unit.

In certain embodiments, the wellhead includes a means for gripping the umbilical cable to support the device in the well.

In certain embodiments, the means for gripping the umbilical cable is a set of slips.

In certain embodiments, the wellhead is sealed from the well to prevent loss of gas or fluid as a result of potential leakage of the effluent line or the gas line.

In certain embodiments, the system further comprises a means for sealing the device from the upper tube.

In certain embodiments, the upper end of the protective tube is connected to a fishing unit for attachment of a lifter for withdrawal of the device from the well.

In certain embodiments, the fishing unit comprises a fishing neck attached to a top portion of the protective tube and an overshot tube connected to the fishing neck, the overshot tube having a restricted diameter portion for attachment of the lifter.

In certain embodiments, each one of the plurality of lines is separated from the protective covering within the wellhead and extends from the top of the wellhead as a separate line.

In certain embodiments, each of the separate lines is each sealed at its respective opening at the top of the wellhead.

In certain embodiments, the wellhead includes a production pipe connected to a gas pipeline and the gas line is connected via a three-way valve to the gas pipeline and a compressor, the three-way valve for switching between input of compressed gas into the gas line for the compression stroke and exhaust of gas back into the pipeline during the exhaust stroke.

In certain embodiments, each one of the plurality of lines is formed by an upper line and a lower line connected at connection points located above the cap of the separator, the connection points providing a means for disconnecting each of the upper lines from their corresponding lower lines and withdrawing each of the upper lines from the well while the lower lines remain associated with the separator device in the well.

In certain embodiments, at least one of the connection points represents a weak point with respect to disconnection of all of the upper lines from their corresponding lower lines.

In certain embodiments, the weak point comprises a connector with a locking spring mechanism having a variable locking set point which, when exceeded allows breakage of the weak point to allow the upper lines to be withdrawn from the well.

In certain embodiments, each of the pair of probes is supported within the cavity by a connection to the cap.

In certain embodiments, the connection to the cap is made by threaded cap attachments configured to be threaded into the body of the cap with electrically conducting connector pins extending therethrough for forming a connection of the upper probe line with the pair of probes.

Another aspect of the present invention is a method for removing fluid and suspended solids from a gas or oil well to promote production of gas from the well, the method comprising: a) installing a system as described herein in the well; b) injecting the stream of pressurized gas into the well in the compression stroke to displace liquid into the effluent line leading out of the well until the level of the fluid and suspended solids in the well reaches a lower limit indicated by the lower probe; c) halting the pumping of the gas and allowing the liquid to infiltrate into the well in an exhaust stroke until the level of the fluid and suspended solids reaches an upper limit indicated by the upper probe; and d) repeating steps b) and c) in sequence.

In certain embodiments, the method further comprises collecting data indicating bottom hole pressure, fluid production volumes and gas production volumes to assess the performance of the well.

In certain embodiments, the method further comprises conducting rate transient analysis from the data, the rate transient analysis providing a means for modelling a rate of gas production decline in the well.

In certain embodiments, step a) is performed by conveying the device into the well using a coiled tubing unit, wherein the coiled tubing unit grips and drives the umbilical cable as the umbilical cable is conveyed into the well.

Another aspect of the invention is a wellsite installation for controlling production of gas from a gas or oil well, the wellsite installation comprising: a) a system as described herein; b) a control panel for controlling and measuring: i) flow of produced gas out of the system; ii) flow of the stream of pressurized gas into the system; and iii) flow of the fluid and suspended solids out of the system; and c) a remote terminal unit for collection of data obtained at the control panel.

Another aspect of the present invention is a gas collection network comprising a plant for receiving and compressing gas produced from a plurality of wellsite installations as described herein, the plant including a compressor for compressing the produced gas transferred from the wellsite installations and a water tank for storing the fluid and suspended solids transferred from the wellsite installations.

In certain embodiments, the plant further comprises a master terminal unit for analysis of the data collected at the control panel.

In certain embodiments, the gas collection network further comprises a dehydrator located at the plant to remove water vapor from the produced gas.

In certain embodiments, the gas collection network further comprises a master terminal unit in data and control communication with the remote terminal unit, the master terminal unit having a user interface displaying data from the control panel including downhole pressure, casing pressure and flow rate.

In certain embodiments, the gas collection network further comprises a fluid line to transmit the fluid and suspended solids to the plant for storage.

In certain embodiments, the gas collection network further comprises a gas recycling line to transmit gas from the dehydrator at the plant to the wellsite installation as the source of the stream of pressurized gas for generating the compression stroke.

DETAILED DESCRIPTION OF THE INVENTION

Rationale

Reservoir pressure depletion resulting from hydrocarbon production eventually leads to insufficient velocity in the well to allow a gas well to unload produced fluids. As the fluid level in the vertical wellbore rises, the hydrostatic pressure of the fluid restricts the flow of gas to surface, and production diminishes. Attempts to address this problem have typically been prone to early failure or prohibitively expensive, or both. Consequently, liquid-loaded wells are often abandoned before all recoverable reserves have been produced.

An additional problem encountered by gas producers in Canada is that when production at a gas well drops below 2 barrels of oil equivalent per day (BOEPD) the operator must post a performance bond with the Energy Regulator of the particular provincial jurisdiction in accordance with a regulatory framework known as Licensee Liability Rating Legislature. If gas production falls to zero in a given well, the bond can be as high as $60,000 per well. If the operator does not post the bond, the Energy Regulator is authorized to shut in the well. The operator must then provide $60,000 to abandon the wellbore and the facilities. With the later issuance of a reclamation certificate, the operator, upon presentation of the reclamation certificate will be released from the bond. This process can take longer than five years in some cases. Including the shut-down costs, a Licensee Management Rating equal to one can require as much as $120,000 in capital per well with $60,000 required for payment of the bond and $60,000 to actually abandon the well and reclaim the wellsite and access road.

It would be advantageous for gas production companies to increase gas production and recover more reserves before ultimately being faced with a Limited Liability Rating situation.

About 85 million years ago, a huge inland sea covered the middle of North America. For example, the location of Writing-On-Stone Provincial Park on the Milk River in southern Alberta, would have been located on this very large and stormy sea. Sand was deposited on the shore which, over millions and millions of years, slowly compacted to become sandstone rock. This became part of the Milk River Formation. There are a number of regions in this area with high numbers of low-producing gas wells and most of these wells are liquid-loaded.

A well becomes liquid loaded when the fluid velocity in the well falls below 10 feet per second. Dewatering these wells with conventional tools is problematic due to the nature of the silt and mud in the fluid produced with the natural gas. A siphon string provides a near-term solution to this problem because it is constructed of plastic with a smaller inside diameter than most of the shelf steel tubing strings. These plastic strings have a lower coefficient of friction and are less expensive when compared to steel strings. However, a more robust and effective system for recovering gas from liquid-loaded gas and oil wells is desirable.

Overview and Advantages of the System and Method

The system and method described herein separates gas from liquids in liquid-loaded wells using a separator device provided with downhole probes to determine when the device is filled with fluid and when it is empty. When the inner cavity of the separator device is full of fluid produced from the reservoir, an upper probe recognizes the liquid level at or near the top of the device and triggers the injection of external pressurized gas in a compression stroke to displace the fluid into an effluent line where it is pushed out of the well by positive gas displacement. The fluid is moved using the pressure of the injected gas and as such does not rely upon reservoir pressure. This fluid in the effluent line moves directly to a water tank. The silt or other suspended solids in the fluid may be separated from the fluid and sold as a value-added fertilizer or fill product. The lower level of fluid in the casing will allow greater volumes of gas to infiltrate into the casing annulus from the perforations and diffuse upward to the wellhead where it is conveyed out of the well and into a pipeline according to conventional processes.

The amount of pressure required to move the fluid into the effluent line depends on the specific gravity of the fluid and the depth of the separator device. The fluid produced in the wellbore is moved to the surface without the benefit of reservoir pressure and minimum velocity restrictions that cause liquid loading. This fluid is subsequently produced directly to the water disposal tank. Sending fluids directly to the production tank at a central plant instead of the gas gathering system connected to the plant reduces the pipeline pigging frequency by about 5-fold and frees up operating personnel to allow them to conduct predictive maintenance at the wells and the plant equipment.

When the fluid is moved out of the separator device via the effluent line, the fluid level drops until a lower threshold is recognized by a lower probe. At this threshold, the injection of pressurized gas is stopped and the infiltration of fluid from the well into the separator device is allowed to proceed in an exhaust stroke until the fluid level rises once again (pushing gas out of the cavity of the device via the gas line) to the top probe which once again triggers the injection of pressurized gas to initiate another compression stroke. The gas exhausted is delivered back to its original source, which, in certain embodiments, is a gas pipeline leading to a processing plant. A relatively small volume of gas is recycled back to the well to repeat the cycle. The frequency of cycle depends on the productive capability of the reservoir.

One advantage provided by the system and method is that it reduces the frequency of pigging required to keep the gas-gathering lines fluid free.

Another advantage is that inflow performance and productivity of a wellsite installation with the separator device and system becomes stable and depletion is more predictable extending the recoverable reserve life of a well when the fluid level is constantly below the perforations connecting the reservoir to the wellbore.

Another advantage is that the system is amenable to operation in an information network of data analytics, such that a single field operator can monitor hundreds of wells online. The operator then only deals with wells that do not meet production expectations. Trouble shooting and repairs can be done from the computer terminal in most cases. This reduces labor costs and time required for maintenance.

Another advantage is that geothermal energy transferred by the fluids from the reservoir to the surface by the system is used to heat the inside of the wellhead shelter. This reduces the need to use methanol to avoid freezing of liquid lines and obviates the need for service companies to thaw frozen lines.

Another advantage is that with operation of the system, the majority of fluid and gas separation occurs downhole at the perforations of the well and this minimizes a need for surface separators. This reduces the surface footprint and reduces the chances of spills which would impact the environment. Eliminating surface separators reduces property taxes.

Another advantage is that the separator device is deployed in a well by using a conventional coiled tubing rig with conventional chains and an injector to grip and lower the umbilical cable containing the lines required for operation of the separator device. Furthermore, conventional coiled tubing injection rigs are lighter and are not subject to seasonal restrictions as are other types of service rigs and drilling rigs.

Another advantage is that the system containing the bubble tube provides a means for conducting rate transient analysis and as a result, remaining recoverable reserves currently calculated by production decline analysis can be verified and calculated using modern rate transient methods. The optional bubble tube feature of the system which is described herein below provides a means for continuous measurement of bottomhole pressures, and continuous producing fluid levels. The data from the continuous bottomhole pressure measurement is used to determine the best drilling spacing to recover unswept reserves in the reservoir. In addition, the bubble tube feature provides a conduit for cleaning of the device and the annulus of the well with high pressure gas to break up larger solid masses that can accumulate in the wellbore when producing into the downhole separator.

Another advantage relating to the capability of conducting rate transient analysis is that new drill spacing units can be determined based on pressure draw down analysis to drain unswept reserves. Surface drilling footprints based on having fewer wells present helps the environment and the economics of developing gas reserves.

Definitions

As used herein, the term “wellhead” refers to the combined components at the surface of a well that provide the structural and pressure-containing interface for the production equipment. The functions served by the wellhead include, but are not limited to: providing a means for pressure sealing and isolation of the casing at the surface, providing a means for attachment of equipment such as a blowout preventer, a Christmas tree, a well pump and/or a separator device according to the invention, and providing a means for accessing the well itself, during workover operations for example. A wellhead is also used to connect the wellhead blowout preventer during workover operations using a coiled tubing rig or conventional service rig.

As used herein, the term “umbilical cable” refers to a cable holding the lines which are used to support and operate the separator device of the invention in a gas well.

As used herein, the term “casing” refers to a pipe inserted into a drilled hole and cemented in place. Casing is installed to protect fresh water formations, isolate a zone of lost returns or isolate formations with significantly different pressure gradients. Casing is usually manufactured from plain carbon steel. After it is installed and cemented in place, it is perforated with holes at various intervals to permit fluids and hydrocarbons under static pressure in the reservoir to be produced into the wellbore and eventually to the surface.

As used herein, the term “packer” refers to a device for sealing a wellbore or a section thereof. A packer will have an initial smaller diameter which is expandable to seal the wellbore or section thereof. Packers employ flexible, elastomeric elements that expand. The two most common forms are the production or test packer and the inflatable packer. The expansion of the former may be accomplished by squeezing the elastomeric elements (somewhat doughnut shaped) between two plates, forcing the sides to bulge outward. The expansion of the latter is accomplished by pumping a fluid into a bladder, in much the same fashion as a balloon, but having more robust construction.

As used herein, the term “weak point” refers to a position along a length of a cable or pipe which is expressly provided as a break point of the cable or pipe when a pre-determined pulling force is exerted upon that cable or pipe. A weak point may be provided by alteration of the materials forming the cable or pipe at the desired position, or may be provided by an expressly designed mechanical connection structure designed to disengage when the pre-determined pulling force is met and exceeded.

As used herein, the term “perforation” refers to a tunnel created in the casing to the reservoir formation, through which oil or gas enters for production.

As used herein, the term “line” refers to any conveyance structure or combination of connected conveyance structures providing a basic conveyance function over a distance. Accordingly, the related term “gas line” refers to a conduit providing conveyance of gas into and out of the separator device of the invention, the related term “effluent line” refers to a conduit for conveying effluent in the form of fluid away from the separator device of the invention, the related term “probe line” refers to an electrical conduit for providing electricity to each member of a pair of probes which detect the presence of fluid for the purpose of controlling compression and exhaust strokes of the separator device, and the related term “bubble tube line” refers to a conduit for providing gas into the separator device for the purpose of pressure measurements and for the purpose of cleaning the separator device and the annulus of the well.

As used herein, the term “compression stroke” refers to the half cycle of the separator device wherein gas is injected into the device to force liquid and silt out of the cavity of the device via an effluent line.

As used herein, the term “effluent” refers to fluid and suspended solids discharged from the separator device according to certain embodiments of the invention.

As used herein, the term “exhaust stroke” refers to the half cycle of the separator device wherein gas injection is halted and liquids enter the cavity of the device.

As used herein, the terms “water” and “fluid” are used interchangeably and refer to water in any mixture state that may be encountered in a liquid-loaded gas well as a result of infiltration from the formation into the well. The mixture may include oil, dissolved gases, dissolved mineral salts and suspended solids, including, but not limited to, mud, sand, and silt and precipitated mineral salts.

As used herein, the term “baffle” refers to any structure provided in a cavity or channel to block and/or impede the flow of fluids and/or particulates contained therein.

As used herein, the term “rate transient analysis” refers to analysis of continuous production and flowing pressure data to characterize a reservoir for the purposes of determining remaining reserves and developing resource extraction strategy which may be done through infill drilling or enhanced recovery techniques.

As used herein, the term “fishing” refers to the application of tools for removal of objects stuck in a wellbore, which require retrieval using “fishing tools.”

As used herein, the term “pigging” refers to the act of forcing a device through a pipeline for the purpose of displacing or separating fluids and for cleaning or inspecting the pipeline. Pigging will reduce back pressure at each wellhead and this will optimize production volumes.

As used herein, the term “bubble tube” refers to a conduit used for injection of a gas into a well or into equipment installed in a well at a controlled rate for the purpose of continuous measurement of downhole pressure. A bubble tube system provides the ability to measure downhole pressure while having complete isolation from the well fluid media by measuring the flowing pressure on surface of a gas bubbling at the bottom of a capillary tube in a well. The measurement instrument can be located potentially thousands of feet from the bottom of a well. This isolation makes the bubble tube system suitable for use in wells with corrosive, acidic, hazardous, liquids at very hot temperatures. It is intrinsically immune to surface foam, pH, conductivity, temperature, turbulence, viscosity, and solids content.

Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present invention.

Overview of the Separator System

One aspect of the present invention is a separator device constructed for use in a system for separation and recovery of gas trapped in a gas well by fluid and particulate matter such as fine mud and/or silt. To facilitate a discussion of the separator device, the separator system will first be discussed in general terms, followed by a more detailed description of the features of the device itself.

Turning now toFIG. 1, there is shown a cross-sectional illustration of one embodiment of a system100for recovery of oil and gas trapped in a gas well by fluid and particulate matter in accordance with the present invention. The system100is deployed in the casing5of an oil or gas well and includes a separator device110which is deployed below the perforations7in the casing5. The device110is formed by a hollow cylindrical body112with a cap114attached to the open top of the body112. The cap114has openings to allow passage of a plurality of lines that provide specific functions for the separator device110as described hereinbelow. The central line in this embodiment of the separator device110is the effluent line116. On the far left of the effluent line116is the gas line118which acts as a dual purpose gas compression and exhaust line. The gas line118terminates immediately beneath the cap114. Between the gas line118and the effluent line116is the probe line120. To the right of the effluent line116is the bubble tube line122.

The features and functions of the four lines116,118,120and122will now be briefly described. The effluent line116carries fluid and suspended solids out of the well on the compression stroke when the separator device110is operating. The gas line118provides pressurized gas into the separator device110during the compression stroke and exhausts gas out of the device110during the exhaust stroke. The probe line120is an insulated electrical line to provide power to the probes126and128which sense fluid levels in the separator cavity124as described in more detail below. The bubble tube line122provides a means for continuously measuring downhole pressure and for cleaning the bottom of the device110and the annulus of the well as described in more detail below.

It is advantageous to make the lines116,118,120and122rigid to avoid kinking and the various problems associated therewith. Therefore, pipes formed of steel or other similarly rigid material or metal alloy are used as the effluent line116, the gas line118and the bubble tube line122. In most embodiments, the probe line120is a combination of wires protected by insulation. In one example embodiment, the diameter of the effluent line116is about 0.75 inches, the diameter of the gas line118is about 0.5 inches and the bubble tube line122is about 0.375 inches. These dimensions have been found to be appropriate for one embodiment of a cylindrical separator device with a body112having an inner diameter of about 3.188 inches. The skilled person will recognize that these dimensions are indicative of one embodiment and may be altered if desired for any reason pertaining to improvement of any aspect of operation of the separator device110. Such alternative embodiments with alternative dimensions are within the scope of the present invention.

To retain clarity inFIG. 1, the probe line120is shown as being attached to an upper probe126and a lower probe128(both shown with black circles inFIG. 1). Alternative embodiments have a probe line120which is booted and connected by a tight fitting to the upper and lower probes126and128, each mounted separately in the top end of the pump body. This arrangement is shown inFIGS. 3A and 3B. Still other embodiments have probes each supported by two distinct probe lines. All of these alternative embodiments are within the scope of the invention. The upper and lower probes126and128are provided to identify two different levels of fluid in the cavity124which are reached during regular cycling of the separator device110as described in more detail herein below. Examples of such sensors include but are not limited to, conductivity sensors, tuning fork sensors, optical sensors and dielectric sensors. Any sensor capable of sensing the presence of a liquid may be adapted for use as a probe for use with the present invention and such alternatives can be constructed by the skilled person routinely, without undue experimentation.

In certain embodiments, the probe line120is insulated with an abrasive resistant coating such as polyethylene to prevent electrical shorting. Such coatings are known to the skilled person and can be applied appropriately without undue experimentation.

InFIG. 1, it is seen that the bubble tube line122extends out of the bottom of the separator body112. The bubble tube line122is included in this embodiment of the system in order to provide a means for measurement of the reservoir pressure for the purpose of performing rate transient analysis in accordance with known bubble tube pressure measurement methods and also to provide a means for cleaning the separator device110and the annulus of the well by sweeping the bottom of the separator device110with high pressure gas. To provide this dual function, a bubble tube line valve is provided (as described herein below with reference toFIG. 2) with appropriate connections in accordance with known methods. Alternative embodiments do not include a bubble tube line. In the embodiments that do not include a bubble tube line, the separator device110may be provided with a different means for monitoring pressure in the separator device, if desired.

The bottom of the body112of the separator device110is attached to an adapter130. The function of the adapter130is to provide a means for attachment (for example, by threading) to two nested tubes, an outer tube132and an inner tube134which is nested within the cavity of the outer tube132. The bubble tube line122may extend through the adapter130and into the space between the nested tubes132and134, or it may be simply placed adjacent to an opening in the sidewall of the adapter130, which extends via a channel into the space between the inner sidewall of the outer tube132and the outer sidewall of the inner tube134. This arrangement will be described in more detail hereinbelow with reference toFIG. 7.

Returning now toFIG. 1, it is seen that residing within the cavity of the inner tube134are an upper valve136and a lower valve138. The specific structure and operation of particular embodiments of these valves will be discussed in more detail hereinbelow with reference toFIGS. 3A and 3B. For the purposes of this general discussion, it is to be understood that during the compression stroke of the separator device110which is initiated when the upper probe126senses the fluid level at its position, pressurized gas enters the cavity124via the gas line118. The fluid level in the cavity124is forced downward under this gas pressure. This causes the lower valve138to close and also causes the upper valve136to open, thereby allowing entry and flow of fluid into the effluent line116which is connected to the upper valve136. On the exhaust stroke, which is initiated by the lower probe128sensing that the fluid level has dropped to its position, the entry of pressurized gas into the cavity124via the gas line118is halted. This allows the fluid level in the cavity124to rise again as a result of fluid infiltration from the reservoir as a result of the removal of fluid from the well. Gas remaining in the gas line118is vented to the gas-gathering pipeline and reaches pressure equilibrium with the gas-gathering pipeline. With the reduced pressure, valve136closes and valve138opens. Fluid enters the bottom of the inner tube132and opens the lower valve138to enter the inner tube134. The hydrostatic pressure of the fluid in the effluent line116keeps valve136closed and the fluid level gradually increases in the cavity124until it reaches the upper probe126thereby triggering the next compression stroke. The separator device110will continue to cycle in this manner as long as fluid enters the cavity124from the reservoir. The rate of filling of the cavity124of the separator device110is variable and depends upon the unique deliverability characteristics of each wellbore in a particular reservoir.

The skilled person will recognize from this description that the separator device110operates at a rate which matches the rate of infiltration of fluid into the reservoir and thus, the volumes of gas injected to drive the operation of the separator device110are matched to the requirements of the reservoir.

It is to be understood that the fluid level in the separator device110and the well will be at its lowest level when the separator device cycle is at the bottom of the compression stroke. Because the fluid level is low at this point, the hydrostatic head pressure of the column of fluid is low and more gas is able to escape from the reservoir via the perforations7in the casing5of the well. In certain situations, the fluid level will be below the perforations of the well and the reservoir pressure at the perforations will now be at the same pressure as the pressure of the gas gathering line. Therefore, in this situation, gas is produced uninhibited by a hydrostatic head of fluid and it moves to the surface gas gathering line via the wellhead168.

One of the problems addressed by certain aspects of the present invention is the removal of fluid containing suspended solids such as fine mud and silt. Such suspended solids will quickly clog the effluent lines of conventional reciprocating or rotating artificial lift equipment. While the separator device of the present invention operates on the general principle of positive gas displacement of fluids, there is still significant potential for particulate matter such as silt or fine silicate mud particles to enter the gas line118on the exhaust stroke. Therefore, in certain embodiments, the cavity124of the separator device110is provided with a plurality of baffles to interrupt the upward movement of fluid and particulates in the cavity124during the exhaust stroke. This interruption of flow causes the particulates to drop downward and thus, fouling of the gas line118is prevented.

The skilled person will recognize that baffles may be attached to or otherwise integrally formed in the inner sidewall of the cavity124. A more effective solution is provided as shown inFIG. 1by constructing a set of baffles148a,148band148ceach having a means for attachment to one or more of the lines in the cavity124. This simplifies the construction of the body112. In addition, if the baffles148a,148band148care substantially equally spaced and supported by each one of the three lines that extend down the majority of the length of the cavity124, the structure of each baffle acts as a centralizer, keeping the three lines116,118and120parallel and generally straight. The specific structure of a specific embodiment of set of baffles248a,248band248cis described herein below with reference toFIGS. 4A, 4B and 5. The skilled person will recognize that alternative arrangements are possible wherein the baffles are supported by only one of the three lines which extend down the majority of the length of the cavity124. Such alternative embodiments are within the scope of the invention.

Returning now toFIG. 1, the features of the system100external to the separator device110which are located above the cap114will now be described. As noted above, four lines including the effluent line116, the gas line118, the probe line120and the bubble tube line122extend upward through openings in the cap114. The connectors152,154,156and158are located above the cap114. In certain embodiments, the effluent line116, the gas line118, and the bubble tube line122are continuous lines extending through the cap114to the surface via the wellhead168and the only line with a connector is the probe line120.

The area above the cap114is provided with a protective pipe160which is connected to the cap114by a threading mechanism, for example. A sealing means designated herein as umbilical isolation packer150is placed in the protective pipe160above the cap114to isolate the upper part of the system100from the separator device110because it is advantageous to restrict fluid from entering this upper part of the system100.

To facilitate assembly of the system100in stages, it is advantageous to terminate each of the four lines116,118,120and122extending above the cap114and to connect each of these lines to upper lines (having the same reference numerals) via connectors152,154,156and158. The upper lines are then collected and encased in a sheath of protective elastomeric material to provide a single umbilical cable162which extends upwards in the cavity of the protective pipe160.

It is advantageous to provide the umbilical cable162with as much strength as possible because it is subjected to significant force of gravity on its cumulative weight when being deployed into a well by a conventional coiled tubing unit which grips and injects the umbilical cable into the casing. It has been determined that the structural strength of the umbilical cable162is improved significantly if the four lines116,118,120and122contained therein are twisted into a repeating helical pattern prior to covering with the protective material. In one embodiment, the helical pattern for the four lines116,118,120and122repeats at intervals ranging between about 8 to about 14 inches.

In the embodiment ofFIG. 1, the system is provided with a means for withdrawal of the separator device110from the well. The skilled person will recognize that this means for withdrawal is not required for operation of the separator device and therefore should be considered an optional feature. To provide the withdrawal mechanism of this embodiment, the upper end of the protective pipe160is provided with a means for connection (for example, by threading) to a fishing neck166which itself is provided with a means for connection to an overshot for connection to a lifter (not shown). The fishing neck166includes a set of slips and packers (not shown) for securely grasping the umbilical cable162. This provides a convenient integral mechanism for retrieval of the separator device110when it requires maintenance or when gas recovery operations are complete.

The system100also includes a wellhead168which allows passage of the umbilical cable162while sealing the well. An intermediate section of the wellhead168is provided with a set of umbilical slips170to grip and support the umbilical cable162and an umbilical packer172above the slips to provide further sealing of the well at the wellhead168. An advantageous feature of this particular embodiment is that the four lines (effluent line116, gas line118, probe line120and bubble tube line122) are separated from the umbilical cable162within the body of the wellhead168and emerge from the wellhead as separately sealed distinct lines116,118,120and122. This feature enhances the security of the wellhead168. Detailed views of a specific wellhead embodiment268are described herein below with reference toFIGS. 9A to 9E.

Returning now toFIG. 1, it is seen that above the wellhead168, the effluent line116removes fluid from the system100. The fluid is sent to a tank (not shown inFIG. 1) and the suspended solids are allowed to settle and then can be separated. In some cases, the suspended solids are silt or other organic matter which can be used as an agricultural product or fill, for added value. Generally the recovered solid will require chemical treatment to be used for agricultural applications.

Referring now toFIG. 2, where the same reference numerals are used to indicate the same features, there is shown a schematic flow diagram indicating how fluid and gas flows through and out of the system100. The flow of fluids is shown with solid arrows and the flow of gas is shown with dashed line arrows. In this simplified schematic view of the system100, the view of the separator device110is simplified relative to the view ofFIG. 1. The effluent line116, the gas line118, the probe line120, the bubble tube line122, and the wellhead168are shown.

Gas and fluid enters the casing5of the well from the perforations7. The fluid moves downward and enters the separator device110. The gas moves upward within the casing annulus and exits the well via a conventional port on the right side of the wellhead168. This produced gas enters a gas meter176and is then directed into the gas gathering pipeline174the gas meter sends a signal to the remote terminal unit (not shown) which determines volumes of gas produced.

The fluid entering the separator device110is conveyed out of the well via the effluent line116during the compression stroke of the separator device110. During proper functioning of the separator device110the effluent line116is always filled with fluid and the direction of flow is out of the separator device110on the compression stroke with no flow on the exhaust stroke. The effluent line116emerges from the well and, in this particular embodiment, is sent to a water tank178either on site or conveyed to a tank at a remote location.

Gas is removed from the pipeline via a branch conduit182and sent to a compressor184to pressurize the gas for the compression stroke of the separator device110. For efficient functioning of at least some of the embodiments of the system100described herein, a pressure range between about 800 to about 1200 psi is used. The pressurized gas follows conduit186to a 3-way valve188. On a compression stroke of the separator device110, the 3-way valve188will be open between conduit186and the gas line118and thus the pressurized gas moves down via the gas line into the separator device110where it pushes fluid into the effluent line116.

On the exhaust stroke, the flow of pressurized gas into the gas line118is shut off by the 3-way valve188which switches to an exhaust conduit190. This exhaust gas conduit190is joined to the gas pipeline174. The exhaust stroke is at the same pressure as the gas pipeline174and the length of time for the exhaust cycle depends on the rate of reservoir fluid production into the separator device110.

The skilled person will recognize that in certain embodiments, the 3-way valve188may be electrically linked to the probe line120so that the probes which control the timing of the compression and exhaust strokes of the separator device110also control the 3-way valve188. Such an arrangement can be constructed by the skilled person without undue experimentation. The probe line120is connected to an electrical source199to provide power to the probes which are responsible for switching between the compression and exhaust strokes of the separator device110.

In addition to providing the source of pressurized gas for driving the compression stroke of the separator device110, the compressor184provides compressed gas to the bubble tube line122via conduit192when the bubble valve194is open between conduits192and the bubble tube line122. The bubble valve194is also connected to a source of high pressure cleaning gas196via conduit198. When the bubble tube line122is connected to conduit198, high pressure gas is pumped into the bubble tube line122and streams outward at the bottom of the separator device110between the nested tubes formed by the outer tube132and the inner tube134(seeFIG. 1) the constriction of flow caused by this arrangement causes the injected gas to uniformly sweep the bottom of the separator device110to obtain effective cleaning of the annulus defined by the inner sidewall of the casing5as well as the bottom valve138of the separator device110. A more detailed embodiment incorporating this feature is described in more detail herein below with reference toFIG. 7.

Operation of the Separator Device

A more detailed description of the operation of the separator device110will now be described with reference toFIGS. 3A and 3B, where the same reference numerals used inFIGS. 1 and 2are retained.

Continuing with the same arrow flow scheme ofFIG. 2, the flow of gas is shown with dashed arrows and the flow of fluid is shown with solid arrows.

FIG. 3Aschematically illustrates the flow of fluid and gas through the separator device110during the compression stroke of the separator device110. Pressurized gas flows into the separator device110via the gas line118and pushes down on the fluid level in the cavity124of the separator device110, as indicated by the dashed arrows. The fluid flows downward under this pressure. This particular embodiment of the separator device110is provided with two ball valves136and138. Alternative embodiments employ other types of valves. In certain embodiments, the ball valves136and138include balls140and144formed of plastic such as polyurethane and ball valve seats142and146formed of hard materials such as ceramics.

The fluid flowing downward under pressure during the compression stroke of the separator device110causes the lower check ball144to drop into the lower ball seat146to close the lower valve138. The upward flow of fluid from the reservoir is thus blocked. The fluid is then forced upward into the upper valve136and the downward motion of the fluid unseats the upper check ball140from the upper ball seat142to open the upper valve136. This allows the fluid to enter the effluent line116. As long as pressurized gas is injected into the gas line118, fluid will be forced upward through the effluent line116and will exit the top of the separator device110. The compression stroke illustrated inFIG. 3Acontinues until the fluid level reaches the lower probe128. When the lower probe128senses that the fluid level has dropped to or below its location, the compression stroke is halted and the exhaust stroke begins as illustrated inFIG. 3B.

FIG. 3Bschematically illustrates the flow of fluid and gas through the separator device110during the exhaust stroke of the separator device110. The flow of pressurized gas that flows into the separator device110via the gas line118during the compression stroke is now stopped. As a result, the fluid level in the cavity124gradually rises (as shown by the solid arrows) in the cavity124of the separator device110as fluid gradually infiltrates the well from the formation. The fluid enters the cavity124via the bottom of the outer tube132and then enters the inner tube134where it unseats the lower check ball144from the lower ball seat146in the lower valve138. This action allows the fluid level to move up into the cavity124. This upward movement of fluid does not have sufficient pressure to unseat the upper check ball140from the upper ball seat142of the upper valve136. As a result, the bottom entrance to the effluent line116remains closed and fluid does not move upward in the effluent line116during the exhaust stroke.

As noted above, when the fluid level in the well is low, greater volumes of gas can escape from the formation into the well and be captured as production gas at the wellhead. The rate of infiltration of fluid will be dependent upon the characteristics of the formation, and several hours may pass before the fluid level reaches the upper probe126to halt the exhaust stroke and initiate the compression stroke.

It is to be understood that as the fluid level rises in the cavity124the baffles148a,148band148cinterrupt this upward flow and the particulate matter (mud, silt and the like) present in the fluid will tend to drop downward, thereby preventing fouling of the gas line118. This also enhances the removal of the particulates from the cavity124via the effluent line116.

The effect of the fluid level increasing in the cavity124is that the pressurized gas remaining in the cavity124at the end of the compression stroke is now displaced out into the lower opening of the gas line. This exhaust gas is sent back to the pipeline as indicated by line190via the 3-way valve188inFIG. 2.

As described above, one of the functions of the bubble tube line122is to perform cleaning operations. Accordingly, in a first mode of operation, the bubble tube line122is configured to clean the lower valve138of the separator and in a second mode of operation, the bubble tube is configured to clean the area between the casing5and the separator device110. In the first mode, for cleaning the lower valve138, the cleaning operation is initiated during the exhaust stroke. In the second, mode, cleaning of the area between the casing annulus5and the separator device110is initiated during the compression stroke. This prevents gas from flowing into the effluent line116.

Features of Example Embodiments

A number of features of example embodiments of various features of the separator device and system will now be described. These features may be provided in various combinations in construction of various alternative embodiments of the present invention. While the components of the system and method described using reference numerals in the 100 series inFIGS. 1 to 3, more detailed features of the components are described inFIGS. 4 to 12using reference numerals in the 200 series and the 300 series (probes only) while the general features retain their original reference numerals in the 100 series. Features of a control system are described with reference toFIGS. 13A and 13B, which use reference numerals in the 500 series.

As noted above with respect to the baffles148a,148band148cshown inFIGS. 1 and 3, it is advantageous to provide a means for attachment of the baffles to one or more of the lines that extend through the cavity124. In certain preferred embodiments, these lines include the effluent line116, probe line120and the bubble tube line122(there is no opening for the gas line118because it terminates just below the cap of the separator device and therefore baffles are not attached thereto). Accordingly, there is shown inFIGS. 4A and 4B, one embodiment of a single leaf-shaped baffle248awith a leaf portion251aa stem portion253aand openings in the leaf portion251a. The baffle248ais dimensioned such that its total area is between about half to about two-thirds of the cross sectional area of the cavity, thereby providing a means to block upward movement of particulates such as silt and sand during the exhaust stroke.

The central opening255ais dimensioned to accommodate the effluent line116, the opening259ato the right of the central opening255ais dimensioned to accommodate the bubble tube line122, and the opening257ato the left of the central opening255ais dimensioned to accommodate the probe line120, as indicated inFIG. 4Bwhere the probe line120, the effluent line116and the bubble tube line122are shown extending from their respective openings257a,255aand259ain the leaf portion251aof the baffle248a. It is to be understood that each of the lines116,120and122is held in place by the baffle248aand thus, a plurality of such baffles will provide the advantage of acting as centralizers to keep the lines straight within the cavity of the separator device.

Referring now toFIG. 5, there is shown a set of three non-identical baffles248a,248band248c. Each of these baffles differs from the others in the placement of their respective openings255a-c,257a-cand259a-c. For example, it is seen in baffle248athat all of the openings255a,257aand259aare located in the leaf portion251a. In contrast, baffle248bhas the bubble tube line opening259bin the stem portion253band baffle248chas the probe line opening257bin the stem portion253c.

The different placement of the openings255a-c,257a-cand259a-cof each baffle248a-cis provided because it is advantageous to rotate each baffle248a,248band248cwith respect to the longitudinal axis of the separator device body. This arrangement is seen when the baffles are viewed with respect to the axes of the three lines116(effluent line axis261),120(probe line axis263) and122(bubble tube line axis265) inFIG. 5, where it is seen that each of the leaf portions251a,251band251cprovides staggered blockage of the cavity of the separator device in order to slow the upward movement of particulates in the fluid from rising at the same rate as the fluid level to facilitate removal of the particulates from the separator device via the effluent line116during the compression stroke of the separator device.

It is advantageous in certain embodiments to place the baffles such that there is approximately equal spacing between pairs of adjacent baffles. In one preferred embodiment, the separator device body is about 217.25 inches long and adjacent pairs of baffles are separated from each other in the cavity at a distance of about 71 inches with the lowest baffle located about 52.75 inches above bottom end of the separator device body.

While this preferred embodiment provides a set of baffles248a,248band248cconfigured to hold three lines in the cavity124, the skilled person will appreciate that alternative baffle sets may be provided which are configured differently. For example, in alternative separator device embodiments which do not include a bubble tube line, the baffles may be configured to be supported by only the effluent line116or only the probe line120or by both the effluent line116and the probe line120. Furthermore, the baffle set shown inFIG. 5may be modified to include additional or fewer baffles or may be used in the alternative embodiment when a bubble tube line is not included in the separator device. All of these alternative embodiments are within the scope of the invention.

The skilled person will also appreciate that baffles may also be provided in shapes other than the leaf shape described in the embodiment ofFIGS. 4 and 5. Separator devices constructed according to the principles of the present invention and provided with baffle sets having alternative square, circular or oval shapes are also within the scope of the invention.

Adapter for Connection of Nested Tubes and Bubble Tube Line—

As described hereinabove with respect toFIGS. 3A and 3B, in a preferred embodiment, the bottom of the separator device110includes nested tubes132and134which are connected to the bottom end of the separator device body112using a hollow adapter130. A specific adapter embodiment230is illustrated in two perspective views inFIGS. 6A and 6Band showing the connections to the nested tubes132and134inFIG. 7. It is seen that the adapter230includes a narrow portion provided with inner tube threads231for connecting the inner tube132and an intermediate wider portion with outer tube threads233for connecting the outer tube134. The adapter230is also provided with a recessed outer sidewall235at its upper end. This recessed outer sidewall235is dimensioned to reside within the lower end of the cavity124of the separator device body112. This recessed outer sidewall235may be provided with threads for connection to the lower end of the separator device body112(if the inner sidewall of the lower end of the body112is likewise provided with appropriate mating threads) or the connection of the adapter230to the body112may be made permanent by welding.

The inner sidewall237of the adapter230is provided with an opening designated herein as the bubble tube entrance239(seeFIG. 6A) which holds the bubble tube line122in place. The bubble tube entrance239leads to a channel in the inner sidewall237of the adapter230which ends in an intermediate opening designated herein as the bubble exit port241. Because the bubble exit port241is located at an intermediate position between the inner tube threads231and the outer tube threads233, when the nested tubes134and132are connected to their respective threads231and233, the bubble exit port241is located in the space between the inner tube134and the outer tube132.

As indicated by the dashed arrows inFIG. 7, the provision of the bubble exit port241between the nested tubes132and134provides enhanced uniformity of flow of high pressure gas into the bottom of the separator device110because the flow of gas from the bubble tube entering the space between the outer sidewall of the inner tube134and the inner sidewall of the outer tube132becomes dispersed around the circumference of the bottom of the separator device110. This is particularly advantageous for uniform cleaning of the separator device110and the annulus of the well.

Control Ball Valves—

As described hereinabove, the separator device includes a pair of valves which control the movement of fluid during the compression and exhaust strokes. During the compression stroke, the lower valve is closed and the upper valve is open to force fluid up into the effluent line and out of the well. During the exhaust stroke, the lower valve is open and the upper valve is closed to allow fluid to infiltrate into the separator device cavity. In one preferred embodiment, both valves reside within the inner tube of the nested tubes described above. A cross sectional illustration of this arrangement is shown inFIG. 8which also shows how the bottom end of the separator device body112is connected to the adapter230. The probe line120, the effluent line116and the bubble tube line122are shown inside the cavity124. The outer tube132and the inner tube134are connected to the lower end of the adapter230with additional sealing provided by o-rings245and247, respectively.

It is further seen in the embodiment ofFIG. 8that the effluent line116extends through the cavity of the adapter230into the cavity of the inner tube134. The end of the effluent line116is attached to the upper valve cap236and the upper valve body249with an intervening o-ring243. The upper check ball240rests in the curved upper ball seat215at the bottom of the upper valve body249. The bottom of the upper valve is provided with an upper valve bottom cap211which has an opening that permits entry of fluid during the exhaust stroke of the separator device.

The lower valve body217is fixed to the bottom end of the inner tube134. The lower valve body217includes a curved lower ball seat213and the lower check ball244sits in the lower ball seat213when the valve is closed during the compression stroke of the separator device. The lower valve body217has a lower valve bottom cap219attached thereto, which has an opening that permits entry of fluid into the cavity during the exhaust stroke of the separator device.

In certain embodiments, both check balls are constructed of polyethylene or other material with similar properties and their respective seats are identically constructed of ceramic material, or other material with similar properties.

According to certain aspects of the invention, the separator device system includes a wellhead for preservation of well pressure and reinforced support of the lines required for operation of the separator device. As described hereinabove, the bubble tube line122is optional in certain embodiments of the separator device. However, inFIGS. 9A to 9Ewhich illustrate various views of one embodiment of a wellhead268which is configured to hold a bubble tube line122as well as the effluent line116, the gas line118and the probe line120.

FIG. 9Ashows a perspective view of a partially constructed wellhead consisting of a lower wellhead body269with a production pipe271extending therethrough. The production pipe271is open to a gas pipeline and provides a passage of produced gas to the gas pipeline (not shown) which leads away from the well. It is also seen inFIG. 9Athat the umbilical cable162extends into the space above the lower wellhead body269and the four lines contained in the umbilical cable162are separated.

FIG. 9Bshows a perspective view of the partially constructed wellhead after installation of an upper wellhead body273on top of the lower wellhead body269. The four separated lines (116,118,120and122) extend from the open top of the upper wellhead body273. Also shown inFIG. 9Bis a side valve275in the upper wellhead body273. The purpose of the side valve275is to provide a means for bleeding any excess pressure or fluid buildup in the upper well body273which could occur in the event of fluid or gas leaks within the cavity of the upper wellhead body273. The upper wellhead body273contains a polyurethane seal to isolate the umbilical cable162from the umbilical slips and allow gas production to flow from the umbilical cable and casing annulus via the valve installed on the production pipe271into the metering system in the wellhead valve box (not shown). The upper wellhead body273contains the well's flowing and shut in pressure in a closed system when the separator device is filling with reservoir fluid during the exhaust stroke.

FIG. 9Cshows a perspective view of the completed wellhead268. Additional components added in this view are a housing279which is provided with channels to accommodate the upwardly extending lines116,118,120and122. A top nut277is placed over the housing279and is threaded thereto. Each individual line is provided with a sealing element and a connector for connection to outwardly extending lines for conveyance of electricity, pressurized gas, bubble tube gas and effluent.

FIG. 9Dshows a top view of the wellhead for the purpose of indicating a cross section along lines L-L of the wellhead. The cross section is shown inFIG. 9E. This cross section shows the umbilical cable162extending through the wellhead and separating into the effluent line116and the bubble tube line122. These lines extend out of the top of the wellhead268through respective channels in the housing279. It is seen that within the cavity of the upper wellhead body273the effluent line116and the bubble tube line122are sheathed in the umbilical cable162, which is supported by a set of umbilical slips270and umbilical packers272. The umbilical slips281are located within and are retained by the inner sidewall of the lower wellhead body271and are provided with inner ridges to form a stronger gripping interface with the outer sheath of the umbilical cable162. The umbilical packers272reside within the upper wellhead body273and provide an additional sealing feature to prevent loss of fluid or gas from the wellhead268if leaks occur below the wellhead268.

In this particular embodiment, lines116,118,120and122are sealed separately in housing279to act as a redundant seal in case of failure of the polyurethane seal between the umbilical cable162downhole at the top of the separator device and the fishing neck fails and allows fugitive gas to travel up the umbilical cable in the space between the lines116,118,120and122. These lines are roped and twisted during the manufacturing process of umbilical cable162and then a polyethylene jacket is applied. Each individual line is sealed because, in some embodiments there is sufficient free space between the lines to allow produced gas to travel to the surface and be released to the environment. Valve275on the upper wellhead273can be opened periodically to verify that bottom seals remain intact. Normally the pressure in the upper wellhead body cavity is zero.

In certain embodiments, the wellhead is compatible with injection of a 1.625 inch umbilical cable into the well for deployment and operation of the separator device system into the well. In certain embodiments the wellhead is rated for 600 ANSI and appropriate for gas wells having a surface pressure up to 1,440 psi.

In certain embodiments, the umbilical packer units272are further provided with sealing features to retain a sealed wellhead in the event of leakage of gas or fluid from fluid or gas lines below the wellhead.

One embodiment of the umbilical cable is shown inFIG. 10in cross section. The outer body of this particular embodiment of the umbilical cable is a flexible sheath formed of high density polyethylene with an outer diameter of about 1.625 inches. This embodiment of the umbilical cable262holds a stainless steel effluent line216with an outer diameter of about 0.75 inches, a stainless steel gas line218with an outer diameter of about 0.5 inches, a probe line220covered with insulation of cross-linked polyethylene with a polyurethane jacket to an outer diameter of about 0.393 inches, and a stainless steel bubble tube line222with an outer diameter of about 0.375 inches.

To enhance the rigidity of the umbilical cable262for protection against the forces of high pressure gas, four filler rods285a,285b,287aand287bare provided to partially fill the spaces between the effluent line216, the gas line218, the probe line220and the bubble tube line222. In this embodiment, the two large diameter filler rods285aand285bhave outer diameters of about 0.24 inches and the two smaller diameter filler rods287aand287bhave outer diameters of 0.18 inches. In this embodiment the filler rods are formed of twisted polypropylene. The remaining space of the cavity of the umbilical cable262is occupied by fibrillated polypropylene filler289. Advantageously, a binder tape291is provided between the outer surface of the fibrillated filler289and the inner surface of the outer sheath281.

This embodiment of the umbilical cable is designed to protect the functional lines within the cable from the high pressure of gas infiltration into the annulus of the well from the perforations of the well and from high pressure gas injected through the bubble tube line222during a cleaning operation. In addition, significant force is imparted within the separator cavity during the transition from the compression stroke to the exhaust stroke. The lines and filler rods of this embodiment of the umbilical cable262are twisted in a helical pattern along the length of the umbilical cable262to enhance the rigidity of the cable.

Connectors for the Effluent Line, the Gas Line and the Bubble Tube Line—

The inventor of the present invention has recognized that operation of downhole equipment in a typical liquid-loaded gas well increases the chances that such equipment will become stuck in the well from time to time due to the volumes of silt and sand present in the well. With respect to certain embodiments of the separator device of the present invention, the inventor has also recognized that the presence of integrally connected equipment above the separator and extending to the surface, would complicate fishing operations aimed at removing the separator from the well if and when it becomes stuck. Therefore, certain embodiments of the invention include provision of the probe line, the gas line, the effluent line and the bubble tube line each in two parts with connections made a location above the cap of the separator and below the umbilical cable, as shown in a general manner by connectors152,154,156and158ofFIG. 1. A means for conveniently disconnecting these lines above the separator body to allow withdrawal of the lines prior to initiation of fishing operations is also included in some embodiments.

It is readily seen inFIG. 1that each of the four functional lines116,118,120and122emanates from the umbilical cable162within the protective pipe160which is covered at its uphole end by a transition piece164. Connectors152,154,156and158are provided to make connections with corresponding lines located above the cap114of the separator device110when the separator system100is deployed in a well. In one particular embodiment, the group of separators is provided with at least one connector having a weak point which, when disengaged, allows all four of the functional lines extending above the separator device to be disengaged from the separator above the cap114of the separator110. This allows deployment of fishing equipment to retrieve the separator device. (In one embodiment, shown inFIG. 1, the separator device110is provided with a fishing neck166which provides a position configured for connection of fishing equipment for retrieval of the separator device110).

In one embodiment, the weak point connection is made at any one or more of the effluent line, the gas line and the bubble tube line which in some embodiments are each represented by a rigid pipe constructed of stainless steel or other material with similar properties. In one embodiment, the probe line is represented by a combination of three wires wrapped in insulation, as indicated for example, inFIG. 10. Embodiments for connection of upper and lower parts of the probe line will be described in more detail hereinbelow.

One embodiment of a connector system having a weak point and designed for bridging an upper rigid pipe and a lower rigid pipe is shown inFIGS. 11A to 11Dand is illustrated as bridging an upper effluent line116aand a lower effluent line116b. The skilled person will recognize that the same connector system may also be used to connect upper and lower parts of the gas line and/or the bubble tube line (lines with different diameters will require receptacles with different diameters. The connector system includes an upper receptacle221apermanently attached by welding, for example, to the upper effluent line116aand a lower receptacle221bsimilarly attached to the lower effluent line116b. The connector system further includes a female connector226configured for installation into the lower receptacle221bby threading therewithin. Likewise, a male connector223is configured for installation into the upper receptacle221aby threading therewithin. In certain embodiments, the threading system may be provided by a Swagelok threading arrangement.

The lower end of the male connector223fits into the wider lower opening of the female connector226as best seen inFIGS. 11B and 11C. As shown inFIGS. 11C and 11D, the inner sidewall of the female connector226has a recess225that receives an adjustable locking spring224installed in the male connector223to provide a locking arrangement of the connection of the upper effluent line116ato the lower effluent line116b. A pre-determined withdrawal force causing deformation of the spring by withdrawing the upper effluent line116aat a pre-determined sufficient force disengages the locking spring224from the recess225and allows the upper effluent line116ato be separated from the lower effluent line116b. In certain embodiments where the separator device is deployed at a depth of about one thousand meters, the locking spring224is set to disengage from the female connector226when the withdrawal force is about 7,000 pounds. This force limit will vary according to the depth of deployment of the separator device.

This embodiment also contains a means of sealing the connection. The sealing means of this embodiment is provided by a pair of o-rings227aand227bwhich reside in a pair of corresponding grooves228aand228bformed in the outer sidewall of the male connector223.

As noted above, the purpose of separating the functional lines above the separator device is to facilitate their withdrawal prior to conducting a fishing operation to remove the separator device from the well. It is advantageous to make the process of disengagement of the upper lines from the lower lines as simple as possible. Therefore, in certain embodiments, the same connector system is used to connect the upper effluent line, the upper gas line and the upper bubble tube line to their respective lower lines (providing three separator systems for connecting upper and lower parts of the effluent line, the gas line and the bubble tube line). However, it is advantageous to provide only a single weak point because all three lines are removed simultaneously at a constant rate by a coiled tubing injector which grips and withdraws the umbilical cable within which they reside. Therefore, the locking spring and corresponding recess is omitted from two of the three connector systems used. In one such embodiment, only the effluent line is provided with the locking spring system, as shown inFIGS. 11B to 11D. This would avoid the possibility of having multiple weak points set at different disengagement limits. Therefore, in a situation where the upper lines are being removed from the well, as soon as the predetermined withdrawal force is exerted on all three of the lines (by pulling on the umbilical cable) the locking spring in the connector system of the effluent line will disengage and all three connector systems will then be disconnected simultaneously, leaving only the separator device in the well. In this embodiment and similar embodiments, the receptacle threading systems must be configured to withstand the predetermined pressure, otherwise the male and/or female connectors would become disengaged from the receptacle threading systems before the locking spring mechanism.

As noted above, the probes are provided to sense the presence of fluid levels initiate transitions between compression strokes, where fluid is forced out of the separator via the effluent line, and the exhaust strokes, where the level of fluid rises in the separator device and gas is exhausted via the gas line.

In one embodiment, electrical grounding and ungrounding of the probes initiates the transitions. Thus, during normal cycling of the separator device, when fluid reaches the upper probe, it grounds the probe and initiates the compression stroke. When fluid passes just below the lower probe, this probe is ungrounded and the exhaust stroke is initiated. Like the connectors for the effluent line, the gas line and the bubble tube line described above, it is advantageous to provide a means for conveniently engaging and disengaging the probes from the probe line so that the upper probe line (the majority of which also resides in the umbilical cable), can be withdrawn at the same time as the other upper lines, as required.

In certain embodiments, the probe line connector system is distinct from the gas and fluid line connectors described above. One example embodiment of a pair of probes is shown inFIG. 12with components identified using reference numerals in the 300 series in association with general components of a separator device identified using reference numerals in the 100 series. There is an upper probe301and a lower probe311shown in association with the cap114of the separator device. The probes301and311are similarly constructed but have different lengths with the lower probe311being longer than the upper probe301as shown. The upper ends of both probes301and311, have conducting pins302,312extending outward from the cap114. These pins are used to make plug-in electrical connections with the upper probe line (not shown). Advantageously in this particular embodiment, the connection of the pins302,312of the probes301,311to the upper probe line emanating from the umbilical cable (not shown) is made using a protective boot covering to protect the connection from moisture. The protective boot structure contains a mating receptacle for each of the pins302,312to form the electrical connection with the upper probe line.

One embodiment of the boot structure (not shown) is a Y-shaped boot (not shown) constructed of rubber or other insulating protective material which is then connected to the individual wires emanating from the umbilical cable (not shown). This Y-shaped structure is reversibly connectable to the pins302,312in a plug-in arrangement. In certain embodiments, the protective boot is a Y-shaped Kemlon K16 protector boot (Kemlon, Pearland, Tex., USA; www.kemlon.com). Advantageously, this probe arrangement is resistant to pressures as high as 20,000 psi. The protective boot structure also provides for connection of a ground wire of the probe line to a ground pin320which is attached to the cap114to provide the grounding function required by the probes301,311.

In this particular embodiment, the probes301and311are installed within the body of the cap114of the separator device by threaded cap attachments305,315which allow the upper pins301,311to extend outward from the cavity124of the body112of the separator device. As such, both probes are conveniently threaded to the cap114before the cap114is connected to the body112of the separator device. The threaded cap attachments305and315are each provided with a corresponding seal306,316such as an o-ring and are each provided with lower hex nut portions to allow up to about 85 foot-pounds of torque during tightening of the cap attachments305and315into the body of the cap114such that the upper pins302and312extend upward from the upper surface of the cap114.

It is seen inFIG. 12that the lower probe311has a total length greater than that of the connector body304of the upper probe301in order to place the lower probe near the bottom of the separator device where it defines the lower boundary of fluid level in the separator at the end of the compression stroke. Lower connector pins303and313are located at the lower termini of the connectors301and311are exposed for sending the presence of fluid.

In this particular embodiment, both probes301and311have rigid cylindrical bodies304,314advantageously constructed of a corrosion-resistant alloy, such as Inconel or other similar material. Advantageously the threaded cap attachments305and315are formed of the same material as the probe bodies304and314.

It is seen inFIG. 12that the probe body314of the lower probe311is permanently attached (by electron beam welding for example) to a protective tube317such as a stainless steel tube, for example. This tube317is shown in cross section to show that the conducting wire318is held within the tube317and makes a connection to the lower pin313. The interior of the tube317is provided with insulation319. A similar arrangement exists in the upper probe301but is not shown in cross section inFIG. 12.

In one embodiment, the upper probe301has a total length of about 5.96 inches and the lower probe311has a total length of about 240 inches with the majority of its length provided by the protective tube317as shown. Additionally, the outer and inner diameters of the protective tube317are about 0.375 inches and about 0.25 inches, respectively.

Certain embodiments of the invention include a control system.FIGS. 13A and 13Billustrate one embodiment of such a control system. In this illustration, the flow of gas is indicated by a dashed line, the flow of fluid is indicated by a solid line and the transmission of data is indicated by a dot-dashed line. The wellsite installation500aof this particular embodiment includes a gas well502with a separator device504connected to a wellhead506and a data and valve control panel508connected thereto. The control panel508includes a series of valves and sensors that measure pressure and control the flow of gas to and from the separator504and measure the flow of fluid produced by the separator504during the separation process. The control panel508also measures the volumes of gas produced by the well502. Data relating to the measurements described above are measured in the control panel508. The wellsite installation500asends produced gas from the well502to the control panel508via gas conduit541and then to a compressor603at the plant600via conduit543a. Data are collected at the control panel508and sent to the remote terminal unit510via data conduit549and then to the master terminal unit601at the plant600via conduit551a.

The control panel508is in data communication with the remote terminal unit510which includes a transmitter for sending data to a master terminal unit601at the central plant600. The master terminal unit601also has a transmitter for sending command instructions such as instructions to initiate separator cleaning operations and/or software updates to the remote terminal unit510for controlling or reprogramming the control panel508.

One example of a command instruction is a remotely-generated instruction by the operator to over-ride the signal probes in the separator to immediately generate either a compression stroke or an exhaust stroke. Gas is obtained via delivery line531aconnected to the wellsite installation500afrom a compressor603at the plant600the water vapor is removed from the gas by a dehydrator607prior to being routed to the control panel508at the separator installation500avia recycled gas delivery line531a. When the separator is located at a depth of 1200 feet for example, the requirement for recycled gas requirement is 1 mscf/d for each 2 bfpd produced from the effluent line (this represents only a small fraction of the produced gas of the gas gathering network from additional wellsite installations500a-dwith the majority of the produced gas being sent for gas pipeline sales via conduit633). In certain embodiments, there is a pressure sensor at the plant. If the gas recycle delivery line falls below a low pressure set point a valve opens and the compressor sends recycled gas back into the line, until the high pressure set point is reached and the delivery valve at the plant closes, waiting for the pressure in the system to fall and the cycle repeats itself.

The operator can initiate a cleaning cycle remotely using the bubble tube504. In this example, the operator reviews production data sent from the remote terminal unit510to the master terminal unit601via radio551aand relayed to the operator via the internet) and notes that the production at the well does not meet expectations. Suspecting that there is a blockage caused by clumping of particulates in the annulus of the well502, the operator enters the instruction to initiate the manual bubble tube clean out valve stroke. This instruction is transmitted via radio553ato the remote terminal unit510and then to the control panel508. The command by the operator is initiated via conduit557to switch the constant flow of bubble tube gas provided by the compressor603to the separator504via conduits535and539to gas from a high pressure gas source512. This is done by controlling a two-way valve514to draw from the high pressure gas source512via conduit537. The high pressure gas is then sent to the bubble tube in the separator504via gas conduit539. This high pressure gas emerges from the bubble tube at the bottom of the separator504and sweeps the annulus of the well502to remove the blockage.

Data collected at the control panel508and sent to the remote terminal unit510include, but are not necessarily limited to: downhole pressure measured using the bubble tube system, stroke cycles and fluid production volumes and rates, as well as gas production volumes and rates. Other sensors and regulators may be incorporated into the control panel508such as sensors for temperature and fluid density measurements. Such alternative embodiments may be constructed by the skilled person without undue experimentation. In certain embodiments, the operator may access the master terminal unit601at a remote location from the plant600via the internet (as shown inFIG. 13B). In this embodiment, the control system is used to control a plurality of additional wellsite installations500b-dand alerts are provided to the operator only in the event that data transmitted from a particular separator installation indicates that its performance has dropped below a pre-determined threshold. The parameters defining optimal and suboptimal performance may be adjusted by the operator based on the operating history of any particular well. The skilled person will recognize that such parameters may vary significantly as a result of fluid loading rates, the volumes of particulates present in the fluid and the gas reserves at any particular wellsite installation. Software for analyzing separator performance is provided with data analytics that can be programmed by the skilled person without undue experimentation.

In this embodiment, produced gas from each of the additional wellsite installations500b-dis sent to the compressor603at the plant600for subsequent dehydration, recycling and sales as shown. Additionally, fluid removed from the loaded wells is sent to the water tank605. Although not shown to preserve clarity, recycled gas is sent to each of the additional wellsite installations500b-dto drive the cycling of their respective separators and data and commands are transmitted and received at remote terminal units installed at each of the additional wellsite installations500b-d.

In certain embodiments, gas produced from the well502is measured by a turbine meter and producing pressure by a transducer, the data is sent to the remote terminal unit510for digitizing prior to being sent to the master terminal unit601. Surface gas pressure is compared to the bubble tube transducer pressure and used to calculate a fluid level. These data sets are also digitized in the remote terminal unit510prior to transmission to the master terminal unit601.

In certain embodiments, the probes of the separator504are attached by a signal cable (conduit547) directly into the remote terminal unit510. When the separator cavity is full, the probes are grounded and a circuit in the remote terminal unit510sends a signal to a solenoid in the control panel508, which in turn initiates the compression stroke. The remote terminal unit510receives this data, converts it to a fluid production volume and sends it to the master terminal unit601.

The control panel508includes a micrometer delivering bubbles of gas to the bubble tube. The downhole pressure is measured by a pressure transducer located in the control panel508and the pressure data is sent to the remote terminal unit510and then to the master terminal unit601where it is subjected to calculations for rate transient analysis to assess the performance of the well502. Additionally, the bubble tube pressure is compared to the casing gas producing pressure to calculate the fluid level. This data is also processed by the remote terminal unit510and transmitted to the master terminal unit601.

In certain embodiments, the remote terminal unit510uses a radio and antenna to send all data to the master terminal unit601. The master terminal unit601has software configured to provide an analysis of the performance of each of the separator installations in the separator network. The software calculates a production decline curve for each separator installation and is configured to provide an alert to the operator if the performance falls below a pre-determined sub-optimal level. The operator can then interpret the data and decide on actions to improve performance, such as the bubble tube cleaning operation described above.

As described above, the fluids and gases are conveyed to the plant600from the separator installations500a-d. This significantly reduces the frequency for pipeline pigging and eliminates a requirement for trucking of fluids to the plant600.

In some embodiments, the gas recycling line (exemplified by line531ainFIGS. 13A and 13B), is a polyethylene tube which is provided with a braided polyester jacket between the tube and a sheathing material to enhance its resistance to the high pressure gas travelling in this line. In certain embodiments, this braided polyester jacket increases the polyethylene tube's resistance to bursting by a factor of about 10, thereby allowing gas to be carried in the tube at pressures in the vicinity of 1,000 psi. Advantageously, this gas recycling line is contained in a trench that extends from the plant600to the wellsite installation500aand the trench also holds line543awhich carries effluent fluid from the wellsite installation500ato the water tank605at the plant600.

EXAMPLES

Example 1: Enhancement of Gas Production Rate in a Fluid-Loaded Gas Well

In this example, an existing liquid-loaded gas well of the Milk River formation in Alberta was experiencing its final phase of production using existing siphon string technology. As indicated inFIG. 14, modelling of the rate of decline of this well using the siphon string technology (solid line) indicated that it would decline to zero by approximately the year 2030. It was predicted that replacement of the siphon string technology with a wellsite installation with a separator device and related equipment according to one embodiment of the invention would double the production rate and double the lifetime of the well. The siphon string equipment was removed from the well and a wellsite installation of the present invention was deployed in its place. As indicated inFIG. 14, there was an immediate dramatic increase in the production rate and modelling of the rate of decline of the well (solid line) indicated that production would reach zero sometime after the year 2080. Therefore, the original predictions regarding the performance of the wellsite installation of the invention were generally correct.

This example indicates that the system and method of the present invention operate as intended and produce an increased rate of gas production from a liquid-loaded gas well.

Example 2: Analysis of Data Generated at a Test Wellsite Installation

In this example, analysis of data generated at the same wellsite installation described in Example 1 is described. Data were collected during the course of operation of the installation from Oct. 1, 2014 to Oct. 31, 2014. A number of parameters were investigated in order to assess the performance of the wellsite installation. Data points were obtained at 15 minute intervals to investigate volumes of gas produced, volumes of water (and silt) produced and the difference between the bubble tube pressure and the casing pressure to determine the fluid level.

FIG. 15Ais a time course of volume of gas produced (in MSCF), measured at 15 minute intervals from Oct. 1, 2014 (20141001) to Oct. 31, 2014 (20141031). It is seen that the gas production measured is relatively constant between 60 and 80 MSCF with a drop to zero occurring between October 11 and October 15, due to a system shut-down necessitated by pigging issues. It is seen that when the system was re-started on Oct. 15, 2014, the rate of gas production resumed to between 60 and 80 MSCF after a relatively brief re-equilibration period.

FIG. 15Bis a time course of the volume of fluid produced from the well (in Bbl). It can be seen the volume drops at regular intervals which indicate the transition from a compression stroke to an exhaust stroke. A drop in fluid production is seen between approximately October 11 and Oct. 13, 2014 due to the system shut-down described above. It is seen that when the system was re-started on Oct. 15, 2014, fluid production resumed.

FIG. 15Cshows two time course plots of bubble tube pressure and casing pressure. It is seen that the bubble tube pressure and the casing pressure increased during the shut-down period, as expected.

FIG. 16is a representation of a user interface displaying data processed by the control system in the form of a control window. It is seen that prominent real-time data displayed include downhole pressure, flow rate per day and casing pressure. The “readings” box includes data pertaining to accumulated gas flow, depth of water in well, number of pump strokes, volume of produced water and battery voltage. The flow of gases and fluid is illustrated. In the present view of the user interface, a compression stroke is underway, as indicated by the flow of high pressure gas (solid line) and by the exit of water (long-dashed line) from the well. Additionally, bubble tube gas (short dashed line) is flowing into the separator device. An alternative view of the user interface during an exhaust stroke would indicate that exhaust gas (double-dot-dashed line) is moving out of the well and that water is not moving from the well.

This example illustrates some of the capabilities of the control system in providing useful data to an operator regarding performance of the wellsite installation in producing gas and removing fluid from a liquid-loaded gas well. Such data provide an operator with the ability to quickly assess and address any production issues that may arise during operation of the wellsite installation.

EQUIVALENTS AND SCOPE

Other than described herein, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages, such as those for amounts of materials, elemental contents, times and temperatures, ratios of amounts, and others, in the following portion of the specification and attached claims may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains error necessarily resulting from the standard deviation found in its underlying respective testing measurements. Furthermore, when numerical ranges are set forth herein, these ranges are inclusive of the recited range end points (i.e., end points may be used).

Also, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. The terms “one,” “a,” or “an” as used herein are intended to include “at least one” or “one or more,” unless otherwise indicated.