Wells – Processes – Electric current or electrical wave energy through earth for...
Reexamination Certificate
1998-08-14
2001-12-11
Neuder, William (Department: 3672)
Wells
Processes
Electric current or electrical wave energy through earth for...
C166S249000, C166S177600
Reexamination Certificate
active
06328102
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the transport of a target substance from an earth formation, and may find commercial application in the recovery of hydrocarbons from a wellbore or in environmental clean-up operations.
2. Description of the Prior Art
Hydrocarbons are likely to remain a critical component of this nation's economy. While the oil and gas industry expends considerable sums in the exploration and development of new fields, the industry also recognizes that a large amount of unproduced hydrocarbons remain in formations which have already been discovered and produced. Many older formations have been subjected to workover operations, wherein the hydrocarbon-bearing formations were fractured, water-flooded, and subjected to various chemical treatments. Even in those formations in which substantial sums have been expended on secondary recovery operations, the industry recognizes that substantial deposits remain. This has given rise to a tertiary recovery industry, wherein various techniques are utilized to stimulate the formation and generate the production of additional hydrocarbons therefrom. For example, a variety of techniques exist in which the formation is subjected to electrical or thermal stimulation which allows for the additional production of hydrocarbons. For example, various prior art techniques include the stimulation of the formation using microwave radiation. Alternatively, electrodes can be placed in the formation in order to stimulate production utilizing electrical currents. Alternatively, a thermal element can be located within the wellbore which elevates the formation temperature, resulting in increased production, in particular in fields which have hydrocarbon deposits which tend to congeal and clog the flow pathways and wellbore.
The present invention is also directed to environmental clean-up operations of both subsurface and surface locations. In the prior art, considerable amounts are expended to contain and clean-up undesirable contamination which may reside in a subterranean or surface location. Contaminates may include extremely hazardous materials, such as toxic substances, as well as less hazardous materials such as petroleum based chemicals. Prior art clean-up operations are often very expensive operations to undertake and may involve the excavation, removal, and replacement of surface earth formations. Such projects are of a massive scale, requiring considerable investment of manpower, equipment, and time. For spills that occur in relatively populous regions, there are very few options, since the contaminate soil may present long term hazards to the aquifer or other water supplies adjacent or beneath the contaminated soil. Any improvement in technology that may reduce the investment in dollars, manpower, equipment, and time would be welcome in the industry.
SUMMARY OF THE PRESENT INVENTION
It is one objective of the present invention to provide a method for utilizing the piezoelectric effect for aiding in the transporting of target substances within an earth formation.
It is yet another objective of the present invention to provide a method which utilizes either or both of the direct and the converse piezoelectric effect to mechanically stimulate at least one earth formation to increase the permeability of the medium, increase the local temperature in the medium, and to enhance the permeability of a preselected volume of the medium.
Additionally, it is another objective of the present invention to provide a method for piezoelectric-induced transport within a particular earth formation, in a manner which allows an operator to control the directional is orientation of an enhanced permeability within the earth formation.
Yet another objective of the present invention is to provide a method of utilizing a piezoelectric effect to sequentially deform an earth medium and produce the effect of a peristaltic fluid pump to directionally transport fluids within a target formation.
These and other objectives are achieved as is now described. A method is provided for enhancing the transport of a target substance in a particular surface and/or subsurface earth formation. The method includes a number of method steps. An earth formation is identified which has a particular, desirable piezoelectric property. The earth formation bears a target substance which is to be separated or removed from the earth's formation. In one commercial implementation, the target substance may include hydrocarbons or other downhole substances which are commercially valuable or which should be removed for other reasons. Either both of the direct and converse piezoelectric effects are utilized. When the converse piezoelectric effect is utilized, a voltage is applied to at least a particular portion of the earth formation. The voltage develops mechanical stress in the particular earth formation utilizing the piezoelectric property, in particular utilizing the converse piezoelectric effect. The mechanical stress causes changes in the earth's formation which facilitate removal of the target substance. Alternatively, or supplementally, the direct piezoelectric effect may be utilized by supplying a vibration or sonic energy source mechanically coupled to the earth formation. Finally, at least one removal process is utilized in combination with utilization of the piezoelectric property to transport at least a portion of the target substance away from the particular earth formation. In the context of the commercial implementation of hydrocarbon recovery, the removal process may be any conventional or novel process for directing hydrocarbons to the surface, and may include pumping or water flooding operations.
In one preferred embodiment of the present invention, the utilization of the converse piezoelectric effect generates mechanical stress in the earth formation which alters the permeability of the earth formation. Additionally, the mechanical stress develops a local temperature increase in the affected formation. The impact of the electrical field, mechanical stress, and the temperature increase results in changes which affect the permeability of the target substance and which result in an advantageous increase in the permeability which allows the target substance to be removed from the earth formation. This may be supplemented by the application of vibratory or sonic energy to the formation.
In alternative embodiments of the invention, the piezoelectric effect may be applied to the earth formation in a manner which develops permeability which has a controllable directional orientation. This is accomplished by applying either a stimulating voltage and/or a vibration or sonic source to the earth formation in a manner which either varies the piezoelectric effect with respect to time or location within the surface or subsurface earth formation. In this manner, the permeability may be controlled in time and direction in order to allow for preferential flow of subterranean fluids which may carry the target substance. Additionally, and alternatively, a plurality of stimulating energies may be applied in a predetermined pattern with respect to time to a plurality of portions of surface or subsurface earth formations in order to sequentially deform the earth formations in a manner which evacuates fluid due to a resulting peristaltic pump fluid action.
In the preferred embodiment of the present invention, analysis is performed of the surface or subsurface earth formation which contains a target substance in order to determine the presence of a piezoelectric effect and the magnitude of the piezoelectric effect within the formation. Additionally, the earth formation which contains the target substance may be studied in order to determine the one or more resonant frequencies associated with the material. The resonant frequencies may be utilized during stimulation operations in order to maximize the application of the piezoelectric effect to the earth formation. The determination of the optimum frequency or frequencies of
Hunn Melvin A.
Neuder William
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