Patent Publication Number: US-6209651-B1

Title: Well production apparatus and method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method of enhancing fluid and gas recovery from a well. In particular, the invention relates to enhancing oil and gas recovery from a well in an environmentally friendly manner. 
     2. Related Art 
     It is of some importance to discuss the background of the oil and gas recovery process in order to best appreciate the invention. An oil or gas pool requires a reservoir rock that is porous and permeable and a trap to contain the oil or gas. The oil or gas travels from its source into and through the reservoir rock to the trap. 
     The trap usually is an impermeable rock which encloses above the reservoir rock. Due to buoyancy and time, the less dense oil or gas migrates to the top of the trap, displaces the salt water, and remains in the trap. Thus, several layers form including gas at the top, then light oils, heavier oils, oil and saltwater mixtures and saltwater at the bottom. 
     Each well has inherent flow characteristics. The type of trap and geographical formation make up part of the natural flow characteristics of a pool of gas and oil. Common types of traps are dome, structural traps (created by relationships involving faults), and stratigraphic traps (resulting from variations in the layers, or strata). 
     Sedimentary rock usually forms reservoir rocks under certain conditions. Most reservoir rocks consist of sandstone or limestone due to their permeable and porous characteristics. 
     Most wells are drilled via a rotary bit method as is known in the art. When the drilling reaches oil-bearing formations the limits of the field are determined via formation samples and running well logs, a casing pipe is installed with production piping lowered into the casing which is used to withdraw the fluids through perforations in the casing. 
     Initially, the rate of the flow and the pressure and volume of the well are controlled by special pipings and gate valves—called a “Christmas tree”—installed above ground. Production begins when the optimal depth of the well is determined, at which point the pump is set to such depth to allow optimum exploitation of the well. The recovery of oil and gas requires the use of separation equipment. Natural gas must be separated from the liquid petroleum and salt water. 
     Initial production is usually through the mechanism of primary recovery, wherein the oil and gas field&#39;s own pressure drives the oil or gas to the surface. Over time, the pressure in the field drops. The oil must be pumped up to maintain production levels and difficulty resides in knowing what depth and for how long the pumping must be maintained for economic viability. A common drawback is that pumping the well causes removal of unwanted saltwater from the well because it has a tendency to mix with the oil and gas as it enters the perforations in the casing as the reservoir decreases. While some of the gas is utilized in conventional methods, a great deal of gas is wasted and placed into the atmosphere during the separation process due to their design as illustrated in FIG.  4 . 
     Presently, about one-quarter to one-third of the oil is recovered through pumping, depending on the characteristics of the field. Natural gas recovery is usually much higher due to its natural properties of removal. 
     Expensive secondary and tertiary recovery methods are employed to increase recovery. Secondary recovery injects water or gas into the field to restore pressure and increase the proportion of petroleum removed from the field. Tertiary recovery injects steam, acids, carbon dioxide, detergents into the well to heat the oil, especially where it is “heavy” and flows poorly. These methods are not as desirable as primary methods. 
     It is desirable to employ less expensive recovery techniques while maximizing recovery in an environmentally acceptable manner. There exists a need for removing oil and gas from a reservoir in a manner such that the reservoir water substantially remains in the well. There is also a need to reduce waste of natural resources. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object to enhance oil and gas recovery from a well. 
     It is a further object to reduce expenses associated with oil and gas recovery. 
     It is another object to prevent theft or loss of oil and gas from the well site. 
     It is still another object to recover oil and gas in an environmentally acceptable manner. 
     It is yet another object to reduce waste of natural resources. 
     Accordingly, the present invention is directed to an apparatus for use in a well having a pressure control device operatively associated with the well for controlling pressure within the apparatus and the well. The pressure control device includes, but is not limited to, a compressor and submersible pump operably connected thereto. 
     The apparatus further includes a buoyant tubing member of a diameter to fit within casing of the well yet contain the submersible pump therein. The tubing member has an enclosed first end positionable down hole and includes a plug axially displaced from the first end and sealably disposed in the tubing member forming an air chamber between the first end and the plug. The tubing member has an open second end and preferably includes a plurality of orifices in a side adjacent the second end. Further, the tubing member includes a fluids composition sensor and transmitter connected thereto for transmitting a signal indicative of fluid composition. The apparatus includes a receiver operably disposed in the well which receives the signal and is connected to a computer-based device for manipulating the signal and generating a control output for controlling the pressure in the well via the compressor. The apparatus further includes a gas fluids separator in the casing of the well. 
     A method of enhancing oil and gas recovery in a conventional well is provided, wherein the well has a fluid zone of a first heavier density, another fluid zone of a second lighter and gas zone of a lighter density than said fluid zone densities, and wherein the well has perforated casing disposed in the well, production piping disposed in the casing, a submersible pump disposed in said casing which is operatively connected to the production piping. The method includes the steps of carrying out a first phase of separating heavier fluids from lighter fluids in casing of a well, and pumping first phase fluids from the casing, wherein the first phase fluids include in large part lighter fluids with smaller part heavier fluids. 
     Other objects and advantages will be readily apparent to those skilled in the art upon viewing the drawings and reading the detailed description hereafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic of an embodiment of the present invention employed in an existing well site. 
     FIG. 1 a  shows a part of FIG. 1 in an enlarged manner. 
     FIG. 1 b  shows another part of FIG. 1 in an enlarged manner. 
     FIG. 2 is a cross section of a production piping used in the present invention. 
     FIG. 3 is a schematic of another embodiment of the present invention employed in an existing well site. 
     FIG. 3 a  shows a part of FIG. 3 in an enlarged manner. 
     FIG. 3 b  shows physical relationship of parts of FIG.  3 . 
     FIG. 4 depicts a prior art in the field. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings in FIGS. 1,  1   a,   1   b  and  2 , an embodiment well production apparatus is generally referred to by the numeral  10  and is employed at an oil and gas well site  12 . Existing at the well site  12  there is a casing  14  disposed in a hole H. Production piping  13  is disposed in the casing  14 . The production piping  13  has annular channels  15  (See FIG. 2) which communicate with conduit  24  which in turn connects to gas pressure tank  90 . The production piping  13  extends into the casing  14  through a packer (not shown) and centralizer  21  to connect to a submersible pump  22 . 
     Below the surface S, there exist many types of geological formations, but in the case of an oil and gas formation, there exists a field of production which includes gas G, oil O and salt water W. Gas G is mainly found in the gas formation zone. Oil O is mainly found in the oil bearing zone below the gas G and salt water W in the salt water formation zone below the oil O. 
     A controller  16  is provided on the surface S which includes a computer based device with operating software thereon which is used to operate the apparatus  10  at the well site  12 . The controller  16  is typically equipped with a communications link, such as a modem conduit, such that remote control of the controller  16  is available as well as exchange of information concerning the function of the apparatus  10  and characteristics of the well site  12 . In this regard, the controller  16  includes software to detect theft and/or parts failure and generate a communications signal to a remote location for immediate dispatching of personnel. 
     A compressor  18  is provided and operatively connected to the controller  16  and to the pump  22 . As will be apparent by the description herein, the controller  16  can cause the compressor  18  to change pressure within the apparatus  10  and for example, remove or add gas G from and to the casing  14  thus affecting level of fluids, particularly oil, in the formation as well as aiding in separation of fluids. The compressor  18  is connected to a gas vacuum tank  26  via conduit  27 , to conduit  36  via conduit  29 , and to conduit  20  via conduit  25 . 
     The gas vacuum tank  26  is communicably connected to an oil, gas and water separator  28 , salt water tank  30 , oil tanks  32  and  34 , gas pressure tank  90  via conduits  36 ,  38 ,  38   a,    38   b  and  38   c,  and ( 20 ,  99 ,  92  and  41 ), respectively, which connect to upper portions thereof. The gas vacuum tank  26  is used in conjunction with the compressor  18  and controller  16  to effect pressure differentials in the apparatus  10  and casing  14 . 
     The oil, gas and water separator  28  is also communicably connected to the casing  14  via conduit  31  which communicably connects to a production tubing  17  (see FIG. 2) in the production piping  13 . The production tubing  17  communicably connects to the submersible pump  22 . The oil, gas and water separator  28  further communicably connects to oil tank  32  via conduit  33  extending from a mid portion of the oil, gas and water separator  28  and to salt water tank  30  via conduit  35  extending from a lower portion of the oil, gas and water separator  28 . The oil, gas and water separator  28  also connects to gas pressure tank  90  via conduit  92 . As fluids, which by use of the present invention are predominantly oil and gas, are pumped into the oil, gas and water separator  28 , the separator  28  uses a heating process which causes substantial first phase separation. This phase separated gas is stored in gas pressure tank  90 , separated oil is stored in oil tanks  32  and  34  and separated salt water is stored in tank  30 . 
     Oil tanks  32  and  34  are communicably interconnected via conduit  37 . The oil tanks  32  and  34  have a outlet ports  40  and  42 , respectively, which connect to an oil sales conduit  45 . The oil tanks  32  and  34  will undergo further separation of oil and gas, whereby the evolving gas in another phase separation is aided via a vacuum created by the compressor  18  in the apparatus  10  and is controlled by controller  16 . In this regard, the gas is moved through the conduit  38  and is directed to gas pressure tank  90 . 
     The gas pressure tank  90  and gas vacuum tank  26  connects to the salt water tank  30  via conduits  43  and  41 . This allows removal of the fluids from the tanks  26  and  90  and returns the fluids back into the well casing  14  where they can separate. In a similar manner, another phase separation of emanating gas can be moved through the conduit  38  and directed to the tank  90 . 
     A salt water pump  80  is connected to the salt water tank  30  via conduit  82 . One end of a conduit  84  communicably connects to the salt water pump  80  and another end extends into the casing  14 , through packer (not shown), centralizers  21  and  143  and terminates below a packer  86  disposed in the bottom of the casing  14 . The salt water tank  30  has an outlet conduit  87  for draining the same. By way of the controller  16  and pump  80 , the salt water can be pumped back into the salt water formation zone. 
     The compressor  18  is powered by a natural gas powered engine which is fueled by gas emanating from the casing  14 . The compressor  18  functions to remove low pressure gas G from the gas formation zone, raise level of oil O in the oil bearing zone and in the casing  14 , and aid oil, gas and water separation by creating a vacuum in the apparatus  10  and causing flow of gas to the gas vacuum tank  26  and ultimately into the gas pressure tank  90 . Subsequently, the controller  16  uses the compressor  18  is used to increase pressure to deliver gas from the gas pressure tank  90  to a sales pipe conduit  97 . 
     Conduit  20  is operably connected to controller  16 . 
     Each of the conduits  24 ,  25 ,  27 ,  29 ,  31 ,  33 ,  35 ,  36 ,  38 ,  41 ,  45 ,  47 ,  87 ,  92 ,  95 ,  97 ,  99  is equipped with a control valve  100 ,  101 ,  102 ,  104 ,  108 ,  110 ,  112 ,  114 ,  116 ,  118 ,  117 ,  119 ,  115 ,  120 ,  122 ,  124  and  126 , respectively, which are operably connected to the controller  16 . The controller  16  actuates open and closed the valves  106 ,  100 ,  101 ,  102 ,  104 ,  108 ,  110 ,  112 ,  114 ,  116 , ( 118  and  119 ),  117 ,  115 ,  120 ,  122 ,  124  and  126  to perform a function, e.g., creating a vacuum or generating additional pressure in the casing  14 . Any inoperability or unauthorized opening or closing of flow in apparatus  10  will trigger the controller  16  to send a signal indicating the need to dispatch personnel. Additionally, the controller  16  is equipped with an automatic log software which will periodically transmit a status signal to the remote site. If the no signal is received, personnel can be dispatched accordingly. 
     A gas fluids separator  60  is provided in the well casing  14  above the gas formation zone. The gas fluids separator  60  includes an annular housing  61  having ends  62  and  64 . Each of the ends  62  and  64  is equipped with clamps  66  and  68 , respectively, for securing the gas fluids separator  60  to the production piping  13 . Spring type casing seals  71  and  73  are disposed about the housing  61  adjacent the ends  62  and  64  to prevent gas and fluids from passing between the housing  61  and the casing  14 . 
     Within the housing  61  is a spiral baffle  70  which extends therethrough and terminates adjacent open surfaces  72  and  74  of ends  62  and  64 , respectively. The open surface  72  permit the escape of gas G while the open surface  74  connects to a water drainage pipe  75  which extends into the fluids formation zone. The spiral baffle  70  has an end (not shown) which terminates adjacent the open surface  74 . Thus, as the gas G leaves the well  12  through conduit  20 , the fluids arc maintained within the casing  14  via the gas fluids separator  60 . 
     The apparatus  10  further includes a buoyant tubing member  130  of a diameter to fit within casing  14  yet movably contain the submersible pump  22  therein. The tubing member  130  is preferably made of a plastic material, such as PVC, which is less dense and hence lighter than water W. The tubing member  130  has an enclosed first end  132  positionable down hole and includes a plug  136  axially displaced from the first end  132  and sealably disposed in the tubing member  130  forming an air chamber  135  between the first end  132  and the plug  136  to aid in buoyancy. The tubing member  130  has an open second end  134  which includes a plurality of orifices  138  in a side of the tubular member  130  adjacent the second end  134 . These orifices  138  are located in an upper portion of the tubing member  130  so that substantially only oils pass into the pump  22  by virtue of tubular member  130  remaining buoyant in the water though oil fills within the tubular member  130 . 
     Further, the tubing member  130  includes a fluids composition sensors  140  which are longitudinally spaced along the side of the tubular member  130  and operatively coupled to a transmitter  142  on the tubular member  130 . The transmitter  142  includes means for transmitting a signal indicative of the fluid composition. 
     The apparatus  10  includes a receiver  144  operably disposed in the casing  14  which receives the signal from the transmitter  142  and is connected to the controller  16 . The controller  16  includes software for manipulating the signal and generating a control output for controlling the pressure in the casing  14  and/or pumping to achieve maximum flow rates. 
     The embodiment shown in FIGS. 3,  3   a  and  3   b  is directed to an apparatus  10 ′ which improves upon existing separation equipment currently employed in the field. Here, an oil, gas and water separator  28 ′ is disposed below the surface S. The oil, gas and water separator  28 ′ is large enough to serve as a holding tank for all fluids and gas. By disposing the oil, gas and water separator  28 ′ sufficiently below the surface say for example, two to ten feet, the underground temperature serves to cools the fluids and gas sufficiently to cause separation. The gas is removed from the oil, gas and water separator  28 ′ by applying a vacuum to the separator  28 ′ with the compressor  18 ′. Additional heating elements may also be employed to further increase separation if necessary, but these are believed to be minimal. An oil sales conduit  42 ′ is communicably connected to a mid section of the oil, gas and water separator  28 ′ and includes a control valve  45 ′. A salt water conduit  87 ′ is communicably connected to a bottom portion of the oil, gas and water separator  28 ′ and includes a valve  115 ′. 
     A gas conduit  20 ′ extends from casing  14 ′ as in a similar manner as described, with exception that the gas conduit  20 ′ extends to communicably connect with conduit  36 ′ and has control valves  108 ′ and  109 ′ therein. A conduit  99 ′ communicably connects another top portion of oil, gas and water separator  28 ′ and conduit  20 ′ and includes a control valve  126 ′ therein. A vent conduit  197 ′ is communicably connected to a top of the tank  28 ′. 
     A fluids conduit  31 ′ communicably connects to an upper portion of the oil, gas and water separator  28 ′ and communicably connects to a production tubing  17  of a production piping  13 ′ in a similar manner as described above. The fluids conduit  31 ′ includes a control valves  113 ′ and  313 ′ which are operably connected to the controller  16 ′. 
     A compressor  18 ′ is operatively disposed on the surface S of the well site. The compressor  18 ′ is communicably connected to the oil, gas and water separator  28 ′ via a conduit  36 ′ having a control valve  114 ′ therein. The compressor  18 ′ is also communicably connected to an underground pressure pipe  200 ′ via a conduit  93 ′. 
     A gas sales conduit  97 ′ connects to an upper portion of the pressure pipe  200 ′ and includes a control valve  124 ′. Another conduit  24 ′ communicably interconnects to a mid-portion of pressure pipe  200 ′ and a channel  15  of the production piping  13 ′ and includes control valves  106 ′ and  111 ′ which are connected to the controller  16 ′. Yet another conduit  202 ′ communicably interconnects a lower portion of the pressure pipe  200 ′ and the conduit  20 ′ between the valves  108 ′ and  109 ′ in conduit  20 ′, and the conduit  202 ′ includes a control valve  204 ′. A conduit  206 ′ having a control valve  208 ′ therein connects to a bottom portion of the pressure pipe  200 ′ to a sump. 
     A controller  16 ′ is operably disposed on the surface S′. The controller  16 ′ is operably connected to the control valves  45 ′,  106 ′,  108 ′,  109 ′,  111 ′,  113 ′,  114 ′,  115 ′,  126 ′,  204 ′,  208 ′ to control flow in a similar manner as stated above to control pressure within the apparatus  10 ′ and well casing  14 ′ to increase production in a more economical manner. 
     The apparatus  10 ′ also includes a tubular member  130 ′ and gas fluids separator  60 ′ which operate in a manner as described above. Fluid composition sensors  140 ′, transmitter  142 ′ and receiver  144 ′ are also provided and are operatively connected in a manner as described above. 
     A method of enhancing oil and gas recovery in a conventional well is provided. The method is used for a well having a fluid zone of a first heavier density, another fluid zone of a second lighter and gas zone of a lighter density than said fluid zone densities, wherein the well has perforated casing disposed in the well, production piping disposed in the casing, and a submersible pump disposed in said casing which is operatively connected to the production piping. The steps include carrying out a first phase of separating heavier fluids from lighter fluids in casing of a well and pumping first phase fluids from the casing, wherein the first phase fluids include in large part lighter fluids with smaller part heavier fluids. The method further calls for the steps of monitoring fluids composition in the casing of the well and controlling the pumping step in accordance with the monitoring. 
     Also, provided is the step of carrying out a second phase of separating heavier fluids from lighter fluids and transferring second phase heavier fluids back into the casing. Carrying out first phase of separating of types of fluids as well as fluids from gas is done in the casing of a well, wherein the first phase gas include in large part gas with smaller part fluids and first phase fluids include varying densities of fluids in large part lighter density than that remaining in the well. A second phase of separating gas from fluids is performed outside of the casing, wherein fluids and gas may be transferred gas back into the casing or disposed of as desired. 
     By so providing, the present invention increases recovery, reduces waste of natural resources and costs of production. The above described embodiment are set forth by way of example and is not for the purpose of limiting the present invention. It will be readily apparent to those skilled in the art that obvious modifications, derivations and variations can be made to the embodiments without departing from the scope of the invention. Accordingly, the claims appended hereto should be read in their full scope including any such modifications, derivations and variations.