Well bore fluid redistribution and fluid disposal

Abstract

Redistribution of fluids present in well bore environments is disclosed. In some embodiments, the invention may be the redistribution of water produced in a coal bed methane well. The redistribution of water from one aquifer (27) to another aquifer in accordance with the present invention is also disclosed. Furthermore, the injection of a reservoir formation (39) with water, and in some embodiments as a flood of the reservoir formation, in accordance with the present invention is also disclosed. Each of the embodiments of the present invention is disclosed as methods and processes as well as one or more device or apparatus. Such processes and tools may avoid the requirement for surface discharge of water produced in a well bore and may minimize the regulatory costs associated with such water handling. Methods of compliance, water disposal, aquifer recharge, transfer of water from one aquifer to another, and obtaining a permit are also disclosed.

Description

TECHNICAL FIELD[0001]The invention relates to the redistribution of fluids produced in well bore environments. The invention in some embodiments are technologies addressing surface discharge of water produced in wells such as those producing coal bed methane and in petroleum oil and gas wells. The invention may be particularly applicable wherein costs associated with regulatory compliance are to be minimized.BACKGROUND[0002]Methane gas may be produced in the mining of coal. Coal formations naturally produce methane gas. For example, methane gas may be produced by dewatering activities of the mining process. Methane gas that is contained in the coal formation may be biogenic (generated by biologic organisms) or oragenic (generated by organic decomposition of coal) origin.[0003]Recovery of the methane gas present in coal formations is a major source for the modern coal bed methane (CBM) industry. The recovery of such methane gas frequently involves the removal of water from the coal b...

AI Technical Summary

Benefits of technology

[0021]One object of the present invention may be to address and perhaps avoid discharging water produced by coal bed methane wells to the surface. Still another object of the invention may be to address compliance with water discharge rules. Another object of the invention may be to address and minimize regulatory costs associated with redistributing water produced by coal bed methane wells. Yet a further object of the invention may be to redistribute water from one geologic section to another, such as from one aquifer to another aquifer. An additional object of the invention may be to provide a water flood of a geologic section, such as a formation reservoir.

Problems solved by technology

If the intake is set too high in the well, water from the formation may not be sufficiently produced.

If the intake is set too low, water from the formation may not be sufficiently produced and the water may no longer float the coal fractures (keeping them open), possibly negatively affecting gas desorption or possibly inhibiting the flow of gas out of the coal seam.

The quality of the produced water may vary from better than some bottled waters to poor, possibly depending on proximity of the coal bed methane well to the coal aquifer recharge area.

However, water quality problems may occur after the water reaches the surface and travels for any distance.

At some point in the drainage, these salts may begin to accumulate, thus possibly reducing the discharged water quality.

The discharged water may become impaired because the discharged water may acquire salts along its path to tributaries.

This impaired water may ultimately commingle with unimpaired water and may eventually degrade the fresh water supply.

However, the NPDES permit acquisition process may involve significant drawbacks for coal bed methane producers, including the possibility of a substantial time and financial investment for the producer in obtaining the permit and the possibility of a denial of the permit.

However, traditional re-injection methods may not have been economically viable to re-inject a high volume of produced water from a large number of wells.

The drilling costs of each well may detract from economic viability of traditional re-injection methods.

Furthermore, some formations may already contain a substantial amount of water, thus requiring large pump pressures to exceed the fracture rate of these formations in order to inject the additional waters.

Traditional re-injection methods, furthermore, may be cost prohibitive given surface equipment and processes required.

However, facility and treatment costs may be prohibitively expensive.

Other traditional re-injection techniques involve drilling an additional well or wells near an existing coal bed methane well for re-injection into a shallow aquifer system, but again these attempts may not have been economically viable due to the added costs of the additional wells as well as equipment and pumping costs to re-inject the water back into the formations.

Yet other attempts have involved using the produced water for irrigation, but the expenses involved in irrigation (for example, the capital outlay for an irrigation system and the treatment of soils to prevent souring) may have been so high as to be economically unsustainable.

Still attempts may have involved the use of large leach-fields to dispose of water, but it may have been that relatively low permeability soils such as tight clay soils hindered the percolation process.

However, this technique may be dependent on certain pressure ranges to work properly and may perhaps require a time cycle controller to switch a valve when water reaches a set height or time.

The technologies of the above referenced patents and other similar technologies may also be limited in application to brine water disposal for oil and gas reservoirs and not particularly addressing the complexities of redistribution of fresh water into a fresh water system or the corresponding environment.

Furthermore, the complexities associated generally with oil and gas reservoirs and traditional production equipment may actually lead those in the field away from thoughts of more efficient and less mechanically complex techniques, and particularly given the differences in the production environment.

Accordingly, a need may exist to avoid the NPDES permit system altogether, thus possibly streamlining the permit procedure and potentially reducing costs.

Secondary and tertiary recovery is the recovery of oil or gas, or combinations thereof, in production-depleted reservoirs exhibiting low pressure or low flow rates, such that production is not economical or too much gas or water is present.

For example, if there is no readily available source of CO2 near the production facility (miscible displacement), it may be that a CO2 flood may not be economically viable.

Such surface facilities may ultimately increase the operating cost of the field, perhaps reducing the economic viability of the operation.

Those skilled in the art may not have fully appreciated the nature of the problems and challenges involved.

As a result, attempts to meet these needs may not have effectively solved one or more of the problems or challenges here identified.

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