CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser. No. 61/755,262, filed Jan. 22, 2013, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to the dewatering of gas producing wellbores including methods, devices and systems therefor and more specifically to ultrasonic devices, methods and systems therefor.

2. Description of the Related Art

Gas producing wells, such as natural gas and including those wells that have concurrent production of liquids or non-gaseous products such as water, oil or condensates, are often incapable of clearing these liquids from the well bore. This is especially true in depleted reservoirs and low-rate gas producing wells. Liquids can accumulate in the well bore as gas is produced. Accumulated liquid exerts backpressure on the producing formation such that flow of gas is reduced or completely restricted.

Natural gas producing wells can experience sporadic or permanent cessation of production if the gas flow velocity is too low to lift slugs or large drops of non-gaseous production from the wellbore. This process is known in the field as loading. Typically, the non-gaseous production comprises mineralized water which may or may not be associated with produced solids and/or hydrocarbon liquids.

Typical dewatering methods for reducing liquid accumulation in the well bore and re-establishing a viable gas production rate usually involve using the reservoir energy to lift out the liquid or by using external energy to lift it out. Reservoir energy is used by concentrating the reservoir pressure using mechanical means (i.e. plunger lift) or by taking advantage of critical flow properties (i.e. velocity strings). These methods are limited in application by the reservoir pressure and flow rates. External energy is used to activate pumps or to periodically bail, swab or perform coiled tubing cleanouts (CTC). These methods are not as limited by reservoir pressure or flow rates but may be too expensive (in the case of pumps) or technically inadequate (in the case of periodic removal methods) to be considered an optimal solution for gas producing wells including shallow gas producing wells.

A further problem with external energy sources such as down-hole pumps is that many pumping methods are labour intensive, require regular attention and generally use expensive equipment to provide an external source of lifting capacity to clear the well bore of the liquids. As a result, these technologies are cost prohibitive, and are often not economically viable for low production wells.

Other dewatering technologies have a narrow operating range, and must be suited to each individual well based on well characteristics such as water gas ratio (WGR), well pressure, and gas flow rate. This information is often unavailable, and can be highly variable over time. These technologies generally require regular attention from operations staff which can be problematic in areas of limited or restricted lease access. The narrow operating range of these dewatering technologies means that they usually fail when well conditions change in such a way that they are outside of the operating range.

Failure of these technologies results in down time and lost production, and can also require attention from operations staff in order to resume production.

A need therefore exists for a well dewatering method and system that overcomes at least one of the above mentioned shortcomings associated with existing technologies or at least overcomes at least one shortcoming inherent to existing and potential well dewatering systems further to those described above.

SUMMARY OF THE INVENTION

This invention uses an ultrasonic particle generator to create ultra fine particles of the non-gaseous production thereby allowing gas producing wells with low gas flow velocities to remain unloaded. The smaller the particle of non-gaseous production, the less velocity is required to transport it in the gas stream and out of the well bore. Devices in accordance with the invention may also potentially be used to enhance the utility of velocity string tubulars by allowing the velocity string to sit with its entrance high above the gas/non-gaseous interface thereby reducing the risk of flooding the velocity string during a period of shut-in.

An ultrasonic device and system is provided for specific application to unloading non-gaseous production (typically mineralized water which may or may not be associated with produced solids and/or hydrocarbon liquids) from gas producing wells. In one embodiment, the system comprises an ultrasonic particle generator bank, including a transformer as needed (geometry of bank varies depending on down hole configurations) with multiple ultrasonic sources for redundancy/longevity and particle formation rate control. The multiple ultrasonic sources may be powered electrically from the surface, or by other means, with a length management conveyance system. The ultrasonic sources may be buoyed at substantially optimal depth below the surface of the non-gaseous production being particlized to be dewatered.

In one embodiment, the present invention provides for an ultrasonic dewatering system for use in a gas producing well to particlize non-gaseous production for removal from a wellbore, the ultrasonic dewatering system comprising:

an ultrasonic particle generator bank for positioning in the non-gaseous production for particlizing at least a portion of the non-gaseous production, the ultrasonic particle generator bank comprising:

an ultrasonic source for positioning at or below the surface of the non-gaseous production for particlizing at least a portion of the non-gaseous production; and

a power source in communication with the ultrasonic source.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the ultrasonic particle generator bank further comprises a buoyancy control for positioning the ultrasonic source a desired depth below the surface of the non-gaseous production.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the desired depth is between about 0 mm and 4 mm.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the desired depth is about 1.0 mm or less.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the system or systems further comprise:

an electrical conveyance electrically connecting the power source and the ultrasonic particle generator bank.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the electrical conveyance further comprises a length management system for controlling the length of the electrical conveyance to maintain a length of the electrical conveyance at a length suitable to maintain the buoyancy of the ultrasonic source at the desired depth.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the ultrasonic particle generator bank comprises multiple ultrasonic sources and a transformer in communication with each ultrasonic source.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the wellbore further includes a velocity string mounted at a height that is raised above the surface of the non-gaseous production relative a typical velocity string.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the ultrasonic source is a directly coupled ultrasonic atomizer, a horn nebulizer, or a mesh nebulizer.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the wellbore is a horizontal wellbore.

In yet another embodiment, the present invention provides for an ultrasonic dewatering system for use in a gas producing well comprising a wellbore to particlize non-gaseous production for removal from the wellbore, the ultrasonic dewatering system comprising:

an ultrasonic particle generator bank in the non-gaseous production for particlizing at least a portion of the non-gaseous production, the ultrasonic particle generator bank comprising:

an ultrasonic source below the surface of the non-gaseous production for particlizing at least a portion of the non-gaseous production; and

a power source in communication with the ultrasonic particle generator bank.

In another embodiment of the ultrasonic dewatering system or systems outlined above, the ultrasonic particle generator bank further comprises a buoyancy control positioning the ultrasonic source a desired depth below the surface of the non-gaseous production.