Abstract:
An apparatus for separating a mixture of liquids of differing specific gravities in a wellbore is disclosed along with a method of installation and operation thereof. This device separates water from hydrocarbons prior to hydrocarbon extraction in order to decrease disposal costs of waste water. The device is designed to be compatible with existing oil wells that have been abandoned because of lack of profitability caused by a high water to oil ratio. The device may also be installed in new wells with a high water concentration.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to water and liquid hydrocarbon separators and specifically to water and liquid hydrocarbon separators that separate fluids underground. 
       BACKGROUND OF THE INVENTION 
       [0002]    Oil wells often produce multiple fluids in addition to oil. Typically, water seeps into subterranean oil reservoirs as the oil is being removed, and is eventually pumped to the surface along with the oil. This water must be separated from the oil before the oil can be used. Once the water has been separated from the oil, the water must be disposed of in a safe and environmentally friendly manner. Water disposal costs typically include storage, shipping, processing, and associated personnel costs. 
         [0003]    When a well has produced a significant portion of its oil reserve, additional water often begins to seep into the reservoir, causing a significant decrease in oil to water ratio. This increase in water causes increasing water disposal costs and decreasing oil yield. When the costs of water disposal outweigh the income from the oil production, the oil well is considered unprofitable and is capped, often with a significant amount of oil remaining in the well. 
         [0004]    Several methods of separating water and oil both above and below ground have been created. However, the present methods each require either expensive equipment, active management, or both. 
         [0005]    Therefore, what is needed is an apparatus for separating a mixture of liquids of differing specific gravities in a wellbore. The apparatus should employ a relatively inexpensive process to separate water from valuable liquid hydrocarbons underground, before any liquids have been drawn to the surface, to reduce or eliminate water disposal costs. Furthermore, other desirable features and characteristics of the present invention will become apparent when this background of the invention is read in conjunction with the subsequent detailed description of the invention, appended claims, and the accompanying drawings. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention advantageously fills the aforementioned deficiencies by providing an apparatus for separating a mixture of liquids of differing specific gravities in a wellbore. The apparatus decreases costs associated with continued exploitation of an oil well. 
         [0007]    In one particular embodiment of the present invention, a wellbore that has been capped and abandoned due to high water content is reopened and the present technology is installed. A separation member is selected to have a specific gravity greater than the crude oil present in the well but less than water. The separation member then floats in the interface between the crude oil and water layers. Pressure from a pressure regulating member above the wellbore then repeatedly forces water out of the wellbore while retaining the crude oil for extraction. 
         [0008]    In another embodiment, the present technology is installed into an operating well with a high water concentration. A separation member is selected to have a specific gravity greater than the crude oil present in the well but less than water. The separation member then floats in the interface between the crude oil and water layers. A pressure regulating member is configured to monitor the pressure in the wellbore and reduce pressure when an experimentally determined pressure is measured. Pressure from then pressure regulating member above the wellbore repeatedly forces water out of the wellbore while retaining the crude oil for extraction. An extraction member is also present to automatically extract the separated crude oil when the time between periods of increased pressure is reduced to an experimentally determined desired level associated with the particular wellbore. 
         [0009]    In still another embodiment, a new well is drilled and the present technology is installed thereto. A separation member is selected to have a specific gravity greater than the crude oil present in the well but less than water. The separation member then floats in the interface between the crude oil and water layers. A pressure regulating member is configured to monitor the pressure in the wellbore and reduce pressure when an experimentally determined pressure is measured. Pressure from then pressure regulating member above the wellbore repeatedly forces water out of the wellbore while retaining the crude oil for extraction. An extraction member is also present to automatically extract the separated crude oil when the time between periods of increased pressure is reduced to an experimentally determined desired level associated with the particular wellbore. 
         [0010]    The present invention now will be described more fully hereinafter with reference to the accompanying drawings, which are intended to be read in conjunction with both this summary, the detailed description, and any preferred and/or particular embodiments specifically discussed. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of illustration only and so that this disclosure will be thorough, complete and will fully convey the full scope of the invention to those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The drawings contained herein exemplify one of the embodiments of the claimed invention. It should be noted that the invention is not limited to the embodiment shown. The embodiment shown is purely an example, and the invention is capable of many variations of said embodiment. In the drawings, 
           [0012]      FIG. 1  illustrates a side view of a pressure regulating member located on top of a wellbore lined with a wellbore casing. 
           [0013]      FIG. 2  illustrates a cut away view of a wellbore containing an apparatus for separating a mixture of liquids of differing specific gravities. 
           [0014]      FIG. 3  illustrates a graph showing internal pressure patterns of the separation chamber  22  of the wellbore casing  11  caused by the pressure regulating member  10  over time. 
       
    
    
       [0015]    The first digit of each reference numeral in the above figures indicates the figure in which an element or feature is most prominently shown. The second digit indicates related elements or features, and a final letter (when used) indicates a sub-portion of an element or feature. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIG. 1  illustrates a side view of a pressure regulating member  10  located on top of a wellbore lined with a wellbore casing  11 . The liquid hydrocarbon mixture present in the wellbore casing  11 , as discussed below, is responsive to pressure changes caused by the pressure regulating member  10 . The pressure regulating member  10  may be any machine that uses any industry standard means to selectively change pressure in the separation chamber  22  of the wellbore casing  11  as discussed below. In the preferred embodiment, the pressure regulating member  10  is any industry standard system comprising a compressor, relief valve, and a pressure monitoring system, whether manual or automated, and being capable of selectively forcing a gaseous composition into the wellbore casing  11  and removing said gaseous composition from the wellbore casing  11 . The pressure regulating member  10  should constantly measure the internal pressure in the wellbore casing  11  and add pressure, remove pressure, or maintain a constant pressure based on experimentally determined time values and pressure patterns of the specific wellbore as described in  FIG. 3  below. In an alternate embodiment, the pressure regulating member  10  does not measure the internal pressure of the wellbore casing  11  and changes pressure in cycles based solely on time. This embodiment is not preferred however, because a pressure regulating member  10  without a pressure monitoring system may increase pressure for periods in excess of the optimal amount of time for a given well resulting in increased equipment wear or reduce pressure after periods which are less than the optimal amount of time for a given well resulting in an inefficient process for reasons explained more fully below. 
         [0017]    It should be noted that  FIG. 1  is intended to illustrate the position of the pressure regulating member  10  with respect to the wellbore casing  11 . The pressure regulating member  10  as depicted in  FIG. 1 . is present for illustrative purposes and is not intended to depict a functioning compressor and relief valve combination. As mentioned above, any compressor and relief valve combination that performs the above listed functions may be a pressure regulating member  10 . 
         [0018]      FIG. 2  illustrates a cut away view of a wellbore containing an apparatus for separating a mixture of liquids of differing specific gravities. In the present embodiment, the reduced pressure caused by the pressure regulating member  10  allows a mixture of liquids of differing specific gravities to be forced into the wellbore casing  11  by pressure from a known oil bearing zone through a plurality of production perforations  11 A in the wellbore casing  11 . In the preferred embodiment, the mixture of liquids of differing specific gravities comprises a mixture of liquid hydrocarbons, such as crude oil, and water and will hereinafter be referred to as the liquid hydrocarbon mixture. The production perforations  11 A are positioned in the wellbore casing  11  to correspond to known oil-bearing zones where liquid hydrocarbon mixtures are located. 
         [0019]    Upon entering the wellbore casing  11 , the liquid hydrocarbon mixture enters an isolation chamber  28 , created by the wellbore casing  11 , a pair of isolation members  26 , and the flow member  20 . The isolation chamber  28  prevents the liquid hydrocarbon mixture from mixing with water leaving the device through disposal perforations  11 B as discussed below. In the preferred embodiment, the isolation members  26  are industry standard isolation packers, but any similar device may be substituted. The isolation members  26  are positioned to form a plurality of seals  26 A with the flow member  20  and a plurality of seals  26 A with the wellbore casing  11  to prevent any liquid contained in the isolation chamber  28  from mixing with liquid in the separation chamber  22  or the disposal chamber  210 . 
         [0020]    The flow member  20  further comprises a plurality of production valves  20 A and disposal valves  20 B. In the preferred embodiment, the flow member  20  is a section of tubing connecting the isolation chamber  28 , the separation chamber  22 , and the disposal chamber  210 . The production valves  20 A should be one-way valves that allow the liquid hydrocarbon mixture to be received into the flow member  20  from the isolation chamber  28 , but do not allow liquid to flow out of the flow member  20  and back into the isolation chamber  28 . The disposal valves  20 B should be one-way valves that allow liquids to flow out of the flow member  20  and into the disposal chamber  210 , but not flow from the disposal chamber  210  into the flow member  20 . This configuration of valves causes the liquid hydrocarbon mixture to enter the flow member  20  during periods of reduced pressure from the pressure regulating member  10 . Furthermore, water and other liquids that have been separated through the process discussed below leave the flow member  20  through the disposal valves  20 B during periods of increased pressure from the pressure regulating member  10 . Due to the fact that hydrocarbons have a lower specific gravity than water, most of the liquid settling near the disposal valves  20 B, being the first liquid to enter the disposal chamber  210  during periods of increased pressure, is mostly comprised of water. 
         [0021]    Due to the fact that hydrocarbons have a lower specific gravity than water, the hydrocarbon mixture will naturally rise to the top flow member  20 , through the receiving member  21 , and be received into and contained by the separation chamber  22  during periods of reduced pressure. Inside the separation chamber  22 , the hydrocarbon mixture will naturally separate into layers of hydrocarbons of varying specific gravities hereinafter referred to as the crude oil layer  23 . The crude oil layer  23  will float on top of the water layer  24 . The natural separation process will create an interface  27  between the two liquids. For this process to occur, the liquid hydrocarbon mixture must be contained in the separation chamber in an undisturbed state until the liquids have separated. 
         [0022]    A separation member  25  is positioned inside the separation chamber  22 . The separation member  25  is selected to comprise a specific gravity that is greater than the crude oil layer  23  but is less than the water layer  24 . The separation member  25  will naturally sink to the bottom of the crude oil layer  23  but will float on top of the water layer  24 . A separation member  25  with the proper specific gravity will naturally float in the interface  27  between the two liquids. Since the crude oil layer  23  may comprise different compounds in different wells, the separation member  25  may have a different specific gravity in different wells or in different embodiments. Also, in embodiments where different liquids are to be extracted, the separation member  25  should be selected to have a specific gravity greater than the liquid to be extracted and less than the liquids that should remain in the wellbore and be flushed through the disposal valves  20 B. 
         [0023]    A receiving member  21  is positioned inside the separation chamber  22  and connected to the flow member  20 . The liquid hydrocarbon mixture flows from the flow member  20  and into the separation chamber  22  during periods of reduced pressure in the separation chamber  22 . Once the liquid hydrocarbon mixture has separated into the crude oil layer  23  and the water layer  24 , the pressure regulating member  10  increases the pressure in the separation chamber  22 . When the pressure begins to increase due to action by the pressure regulating member  10 , the water layer  24  is forced through the receiving member  21 . When most of the water layer  24  has been forced into the flow member  20 , the separation member  25  which was floating in the interface  27  is received by the receiving member  21 . The receiving member  21  and the separation member  25  should be shaped so that a seal is created when the separation member  25  is received by the receiving member  21  during periods of increased pressure inside the separation chamber  22 . The seal between the separation member  25  and the receiving member  21  prevents the liquid in the crude oil layer  23  from reentering the flow member  20 . When the seal between the separation member  25  and the receiving member  21  is created, most of the liquid remaining in the separation chamber  22  consists of compounds with specific gravities that are less than the specific gravity of the separation member  25 , crude oil in most embodiments. 
         [0024]    It should be noted that the receiving member  21  and the separation member  25  may comprise many different variations other than those expressly shown in  FIG. 2 , and this disclosure is intended to cover and does cover those variants. The only requirement is that the separation member  25  must be capable of floating in the interface  27 , and the separation member  25  and the receiving member  21  should prevent liquid flow from the separation chamber  22  to the flow member  20  when the separation member  25  is received by the receiving member  21 . 
         [0025]    When the pressure in the separation chamber  22  is increased after the hydrocarbon mixture has separated into layers, the water from the water layer  24  is forced through the receiving member  21  and received by the flow member  20 . During periods of increased pressure, pressure from the separation chamber  22  forces the water in the flow member  20  to flow through the disposal valves  20 B and into the disposal chamber  210  of the wellbore casing. The liquid contained in the disposal chamber  210  is isolated from the isolation chamber  28  by the isolation members  26 . The isolation member seals  26 A prevent the water leaving the disposal valves  20 B from mixing with the liquids in the isolation chamber  28  and reentering the flow member  20  through the production valves  20 A. The production valves  20 A prevent the water contained in the flow member  20  from reentering the isolation chamber  28 . The water in the disposal chamber  210  of the wellbore casing  11  leaves the disposal chamber  210  through disposal perforations  11 B in the wellbore casing  11  and enters a disposal zone in the earth. 
         [0026]    It should be noted that in some cases, the oil bearing zone is located below the lower isolation member and the disposal zone to be used is located beside or around the wellbore casing and above the lower isolation member. In this case, the present invention can perform the same function by reversing the direction of the flow allowed by the production valves  20 A and the disposal valves  20 B of the flow member  20 . In this case, the production valves  20 A, isolation chamber  28 , and production perforations  11 A as depicted function as disposal valves, disposal chamber, and disposal perforations, respectively. Meanwhile, in this embodiment, the disposal valves  20 B, disposal chamber  210 , and disposal perforations  11 B as depicted function as production valves, isolation chamber, and production perforations, respectively. In this embodiment, the overall function of the device remains the same, however, the liquid hydrocarbon mixture enters the device from a lower portion of the wellbore casing and the remaining water layer is allowed to exit the device and enter the disposal zone from a higher portion of the wellbore casing. 
         [0027]    The operation of the present invention is summarized hereinafter. The pressure regulating member  10  is manipulated to decrease the pressure in the separation chamber  22 , and maintain said pressure at a constant level. The pressure regulating member  10  may be manipulated by a person or by an automated system. The reduced pressure created by the pressure regulating member  10  allows the liquid hydrocarbon mixture to enter the isolation chamber  28  from the oil bearing zone through production perforations  11 A in the wellbore casing  11 . The reduced pressure then allows the liquid hydrocarbon mixture into the flow member  20  through the production valves  20 A, through the receiving member  21 , and into the separation chamber  22 . The constant reduced pressure in the separation chamber  22  allows the liquid hydrocarbon mixture to separate into a crude oil layer  23  and a water layer  24  once the liquid in the system reaches a steady state. The separation member  25  then floats in the interface  27  between the two liquids. After the liquids have separated, the pressure regulating member  10  is manipulated to increase the pressure in the separation chamber  22  and force the water layer  24  through the receiving member  21 , into the flow member  20 , through the disposal valves  20 B, into the disposal chamber  210 , out of the disposal perforations  11 B and into a disposal zone. The increased pressure from the pressure regulating member  10  also forces the separation member  25  to form a seal with the receiving member  21  which prevents the crude oil layer  23  from escaping from the separation chamber  22 . The pressure regulating member  10  may then be manipulated again to reduce the pressure in the separation chamber  22  and start the process again. Each time the process goes through a cycle, more crude oil is available in the separation chamber. Once the desired amount of water-free separated crude oil is present in the separation chamber  22 , the crude may be extracted by an extraction member  29 . The extraction member  29  may be any standard technology capable of pumping oil to the surface of the earth from a wellbore. 
         [0028]    It should be noted that the extraction member  29  as depicted in  FIG. 2 . is intended to illustrate the lower portion of a pipe which would be connected to a pump on the surface. However, any industry standard methods of oil extraction may be used. 
         [0029]    The preferred method of installation of the apparatus for separating a mixture of liquids of differing specific gravities in a wellbore is disclosed hereinafter. In the preferred embodiment, a wellbore that has been previously capped due to a high water to oil ratio must first be obtained. All existing equipment should be removed from the wellbore with the exception of the wellbore casing  11 . Any repairs needed to restore the integrity of the wellbore casing  11  should be completed. In an alternate embodiment, a new well is drilled in a location with a high water to oil ratio and a wellbore casing installed. In another alternate embodiment, a well that is currently in use may be converted to use the present process in the manner disclosed herein. 
         [0030]    A plurality of production perforations  11 A should be created in the wellbore casing  11  at locations adjacent to the known oil bearing zones. A plurality of disposal perforations  11 B should be created in the wellbore casing  11  at locations adjacent to a disposal zone. An isolation member  26  fitted to the lower portion of the flow member  20 D is then installed in the wellbore casing  11  between the production perforations  11 A and the disposal perforations  11 B, creating the disposal chamber  210 . The lower portion of the flow member  20 D should be positioned so that the disposal valves  20 B are positioned in the disposal chamber  210 . A second isolation member  26  fitted to the upper portion of the flow member  20 C should then installed in the wellbore casing  11  in a location above the highest production perforation  11 A. The isolation members  26  should be installed in the wellbore casing  11  in such a way that the upper and lower portions of the flow member  20 C are connected through a seal assembly  20 F. The installation of the second isolation member  26  should create the separation chamber  22  above the production perforations  11 A and an isolation chamber  28  in the portion of the wellbore casing  11  comprising the production perforations  11 A with the production valves  20 A of the flow member  20  inside said isolation chamber  28 . The flow member  20  should also be connected to the receiving member  21  as discussed above. A separation member  25  selected to comprise the characteristics described above is then placed in the separation chamber  22 . The pressure regulating member  10  and the extraction member  29  are then installed into the wellbore. The device may then be operated in the manner discussed below. It should be noted that the direction of the production valves  20 A and the disposal valves  20 B should be reversed prior to installation in cases where the disposal zone is above the lower isolation member and the production zone is below the lower isolation member as discussed above. 
         [0031]      FIG. 3  illustrates a graph showing internal pressure patterns of the separation chamber  22  of the wellbore casing  11  caused by the pressure regulating member  10  over time. All times noted in  FIG. 3  may vary depending on the characteristics of a given wellbore, the relative concentration of liquid to be separated, and the type of liquids to be separated. Therefore, no exact times have been given and  FIG. 3  is not to scale. The times noted in  FIG. 3  are illustrative only and should not be construed as limiting. 
         [0032]    When the present invention is initiated, the pressure regulating member  10  reduces pressure in the separation chamber  22  to allow the liquid hydrocarbon mixture into the chamber and allow the mixture to separate into a crude oil layer  23  and a water layer  24 . After sufficient time has elapsed for the hydrocarbon mixture to separate as discussed hereinabove, shown as Time  30 , the operator or operating program responsible for manipulating the pressure regulating member  10 , manipulates the pressure regulating member  10  to increase pressure in the separation chamber  22 . The exact Time  30  varies from well to well and should be determined by specific calculation and/or experimentation. 
         [0033]    After Time  30 , the pressure regulating member  10  increases the internal pressure in the separation chamber  22  causing water to be forced into the flow member  20  and out of the wellbore as discussed above. When substantially all the water layer  24  has been forced into the flow member  20 , the separation member  25  is received by the receiving member  21  at Time  31 . At Time  31  a seal is created preventing the crude oil layer  23  from leaving the separation chamber  22 , and preventing transmittal of the increasing pressure outside of the separation chamber  22  through the flow member  20 , causing a rapid increase in the internal pressure of the separation chamber  22 . 
         [0034]    At time  32 , the operator or operating program of the pressure regulating member  10  recognizes that the water layer  24  has left the separation chamber  22 , shown by the rapidly increasing internal pressure, and begins reducing the pressure from the pressure regulating member  10 . The internal pressure undergoes rapid reduction until the separation member  25  loses contact with the receiving member  21  and begins to float on the hydrocarbon mixture entering from the flow member  20  at Time  33 . 
         [0035]    At Time  33  pressure from the pressure regulating member  10  reduces more slowly as the pressure begins to transmit to the downhole fluids through the flow member  20 . At Time  34 , the pressure has been reduced to a small constant amount that allows the hydrocarbon mixture to fill a portion of the separation chamber  22  and begin the next cycle of the separation process. 
         [0036]    While the present invention has been described above in terms of specific embodiments, it is to be understood that the invention is not limited to these disclosed embodiments. Many modifications and other embodiments of the invention will come to mind of those skilled in the art to which this invention pertains, and which are intended to be and are covered by both this disclosure and the appended claims. It is indeed intended that the scope of the invention should be determined by proper interpretation and construction of the appended claims and their legal equivalents, as understood by those of skill in the art relying upon the disclosure in this specification and the attached drawings.