HISTORY OF THE VoV

HISTORY OF THE VoV

Background of the Invention:

Our valves are used in recharge wells, injection wells, water banking wells, PAT (pump and treat) wells, vadose zone wells and salt water barrier wells. This invention is generally directed to flow control devices for use in water wells. The VoV (Variable Orifice Valve) continuously regulates the flow of water during periods of recharging. During recharging the water in the column or drop pipe is controlled to prevent air from being entrained or trapped in the fluid flow and carried into the aquifer. Entrained air can adversely effect the recharge efforts, through air-fouling, bio-fouling and calcite formation, by blocking the flow of water into the aquifer.

The recharge rate is determined at the time of drilling the well and provides a starting point for the design recharge rate for the valve. In most cases the recharge rate will eventually need to be increased or decreased to optimize or maximize the recharge rate and therefore, to maximize the volume of water stored. To change the recharge rate in a typical recharge well it is necessary to pull the column pipe and change the orifice plate. This is an expensive process costing $14,000 to $16,000 ('98$) and will take the well out of service.

The VoV is a device that eliminates the need to pull and replace the orifice plate to obtain a different flow rate, provides an operational procedure that eliminates cascading water and air entrainment along with the ability to maintain a minimum flow rate to maintain the bubble of injected water.

History of the Invention.

Many Water Districts and Communities have realized the need and value of maintaining the water level and storage capacity of the aquifers that provide their drinking water and other water storage. Further due to the high demand and to the variability of supply and demand, it is logical that an adequate reserve capacity of the water storage facilities be maintained to provide for extended peak demands, droughts and explosive growths in new customers. Reserve storage capacity to provide for these events in capital facilities are prohibitively expensive to construct and more difficult to justify, therefore, capital facilities typically lag behind demand.

In an effort to reduce these capital facility costs, Water Resource Engineers have become interested in the concept of replacing or storing large volumes (banking) of water in aquifers during periods of the year when both water and facility capacity are available to supply water required to recharge aquifers. The concept replacing the water pumped from the aquifer or seasonal storage is called Aquifer Storage Recovery or ASR. This scenario is an alternative to expansion of water supply, treatment, distribution and storage facilities and is quite cost effective in areas where it is technically feasible. In general, a well-based system or one that is partially well based is a system that the wells can be used for both recharge and recovery, however separate injection and production wells are preferred by some organizations. In recovery the water may require only disinfection. Recharge wells may be through existing wells or through dedicated recharge wells.

In addition to reduction in facilities expansion costs, other advantages favor recharge technology. In coastal areas reduced levels in aquifer water may permit the intrusion of salt water that can result in the destruction of the fresh water supply. In these areas, a mound of recharged fresh water is placed, through balanced flow control, in the aquifer forming a uniform curtain or barrier between the salt water and the fresh water, effectively preventing saltwater intrusion. At times this volume of water can be used to meet seasonal peak demands.

Such storage and water resource techniques have proven extremely advantageous and cost effective in areas where declining ground water levels have reduced or left wells nearly nonproductive.

Another application of this type of device is the use in ground water remediation. In areas where existing ground water supplies are threatened or have been contaminated, flow control devices like the VoV are effective in managing an effective program. Once the water is extracted and treated this type of flow control device is able to balance the flow in a series of recharge wells to provide a uniform curtain of water, placing the water in the aquifer evenly and uniformly.

Well recharging is also effective where substantial reserves are necessary to improve system reliability in the event of a catastrophic loss of a primary water supply or in communities where strategically located reserves are required to insure an adequate balance in system flows during peak demand.

Although there are obvious benefits obtained from recharging existing production water wells or in constructing new water storage recovery wells, in many applications problems have been encountered with air entrapment or entrainment in the recharge water causing air binding of the aquifer. Air binding effectively decreases the permeability of the aquifer thereby decreasing the effectiveness of the recharging operations. Such air entrainment is most frequently encountered in areas or localities where one or more of three conditions exists. These conditions may be encountered when: 1. The recharge water must drop a considerable distance from the wellhead to the static water level, 2. When the recharge flow is relatively low and, 3. Where the recharge capability of the well is relatively high. The foregoing conditions have resulted in the cascading of water in the column or drop pipe (air entrainment), thereby entrapping large quantities of air that is carried into the well and outwardly into the aquifer.

This also occurs during startup or a recharge well. The entrapped air can effectively plug or seal the aquifer, a condition known as air fouling, resulting in substantially lower permeability and storage capacity. The answer to mitigating this problem is to pump the well thereby restoring a portion of the lost capacity. We believe that it is better to prevent this situation by using the VoV.

There have been flow control devices developed by the oil and gas industry, such controllers are not suitable for down hole applications use in controlling cascading in recharge, injection or aquifer storage recovery wells. One alternative used to mitigate the air entrainment involves the use of multiple small injection tubes to place the water in the aquifer. Such alternative is possible in wells using large diameter well casing and well screens. This system is costly and generally not suitable for retrofitting existing wells and is marginal in the ability to mitigate air entrainment.

Summary of the Invention

The Variable Orifice Valve (VoV) Patent #5,503,363 & 5,618,022 or Linear Hydraulic Flow Control Device permits calibrated throttling or flow adjustments from the well head. The flow is adjusted by axially positioning a tapered piston or a tapered shaped restrictive valving portion in an orifice plate or circular opening.

This VoV is directed to a down hole flow control device for continuously regulating the flow of water during recharge, injection or aquifer storage. During recharge, the flow is controlled to prevent cascading water that would otherwise lead to air fouling or aquifer plugging through air entrapment. The VoV includes one concentric orifice connected to a tubular member that is in turn supported by stabilizing vanes and a double acting hydraulic actuator that moves a tapered piston. The orifice is stationary and piston is moved axially to vary the size of the orifice. The hydraulic actuator is controlled through two capillary hoses (1/4" I.D.) from the wellhead by a solenoid or manually operated 3-position 4-way control valve in series with a flow control valve. The hydraulic pressure is supplied to the valve by an electrically driven or manual pump. Speed of operation or movement of the valve, when using the electrical power unit is set by adjusting the hydraulic fluid flow control valve manually.

The solenoid valve may be controlled locally or by a PLC and SCADA (Supervisory Control and Data Acquisition) system from a remote location.

The VoV is connected in one of two ways:

First by being installed with the piston's needlepoint pointing up. This option provides the most stability in flow control and when the velocity in the drop pipe is below 20-25 FPS.

Second being installed with the needlepoint down. This configuration is used when the possibility of cavitation may occur. In this position the working components are upstream of the area where cavitation may occur.

The primary objective of the VoV is to provide down hole flow control for use with recharge, injection and salt water barrier wells. Wherein the flow of the recharge water is facilitated and controlled in order to eliminate a significant amount of air-fouling or well plugging through air binding from air entrainment.

It is also an objective of this VoV to provide a simple, durable and cost effective flow control for regulating the flow hydraulically, while monitoring a flow-measuring device (meter). This assures a desired well flow that can be adjusted to meet the specific static and operational pressures that are encountered or anticipated in a variety of environments.

It is a further objective of this VoV to provide down hole flow control for maximum recharge while preventing air binding in recharge and injection. Wherein minor adjustments to flow may be selectively hydraulically regulated from the wellhead.

U.S. Patents #5,503,363, #5,618,022, #5,871,200,

#6,073,906 and #6,338,466, Canada Patent #2,293,391,

Australian #748767

Plus 23 International Patents Pending.