Advanced gas injection method and apparatus liquid hydrocarbon recovery complex

Abstract

The invention provides for injecting of high-pressure miscible natural gas directly into a newly opened or previously produced liquid hydrocarbon reservoir to saturate liquid hydrocarbons to improve their mobility to flow toward and into producing wells. Concurrent injection of gas, miscible or otherwise, into the hydrocarbon zone's gas cap supplies additional pressuring effects to aid the resaturation process. Downhole float operated injectors are improved to operate at high pressures maintained within the wellbore to assure liquid hydrocarbon flow completely out of the formation. The improved injector system then senses the difference between liquid and gas and closes its valve to retain the gas within the wellbore. Rejected gas is redirected into the reservoir's gas cap for its continued benefits. Two liquid-producing systems utilize: 1) a liquid column and backpressure valve or, 2) an extended-float-length injector to permit the injector's float to open at high differential pressures created by maintaining the wellbore at pressure above liquid saturation levels.

What is claimed is:  
     
         1 . A system for increasing liquid hydrocarbon recovery from a downhole formation through an injection tubing string, comprising: 
 a vertical wellbore opened both into the gas cap and the liquid hydrocarbon zones with horizontal boreholes and/or perforations;    the injection tubing string from its connection to the surface compressor down the vertical wellbore to be open-ended by the selected opened liquid hydrocarbon zone;    a packer selectively positioned above the downhole liquid hydrocarbon formation for sealing a well annulus outward from the injection tubing string;    a bridge plug placed previously at an optimum level below the liquid hydrocarbon zone to isolate the choice injection area;    injecting high pressure miscible natural gas from the surface compressor through injection tubing string below packer out the vertical tubing's open end directly into the open horizontal borehole(s) and/or perforations, compressing high-pressure natural gas into the selected liquid hydrocarbon zone(s), where it enters solution with the liquid hydrocarbon to increase its pressure and reduce its viscosity, thereby increasing its mobility, to be produced under high pressure.    
     
     
         2 . The system as defined in  claim 1 . to inject miscible and/or other gases from surface at high pressures through a well annulus into existing gas cap formations through horizontal borehole(s) and/or perforations above the tubing packer and in communication with underlying liquid hydrocarbon formations.  
     
     
         3 . A method of increasing liquid hydrocarbon recovery from a downhole formation through an injection tubing string, comprising: 
 a vertical wellbore annulus with horizontal borehole(s) and/or perforations indirect communication with the liquid hydrocarbon zone(s);    positioning the injection tubing string from its connection to the surface compressor down the vertical wellbore open ended by the opened liquid hydrocarbon zone;    positioning a packer above the liquid hydrocarbon zone for sealing the well annulus outward from injection tubing string;    setting a bridge plug at an optimum level(s) below the selected liquid hydrocarbon zone(s), isolating the chosen injection area;    injecting high pressure gas from surface compressor through injection tubing string below packer out the vertical tubing's open end directly into the open horizontal borehole(s) and/or perforations compressing gas deep into the liquid hydrocarbon zone(s) to enter solution with the liquid hydrocarbon;    establishing increased pressure and viscosity reduction, increasing liquid hydrocarbon mobility through high pressure gas going into solution with liquid hydrocarbon to be recovered under a maintained high pressure level; and    maintaining gas cap(s) and liquid hydrocarbon zone(s) under high pressure forward to the production and recovery process of this invention.    
     
     
         4 . The method as defined in  claim 3 , further comprising: 
 injecting miscible gas and/or other gases through the well's upper annulus above top packer into the horizontal borehole(s) and/or perforated gas cap overlying the liquid hydrocarbon zone, and establishing increased overall formation gas cap pressure by surface compressor injection to increase efficiency of miscible gas injection into the lower liquid hydrocarbon zone.    
     
     
         5 . The method as defined in  claim 4 , further comprising: 
 enhancing gravity flow of lower liquid hydrocarbons' flow movement on into producing wellbores by maintaining high gas cap pressure throughout the formation maintaining the selected hydrocarbon formation(s), both liquid hydrocarbon zone(s) and gas cap(s), under high pressure forward to the production and recovery process of this invention.    
     
     
         6 . A system for enhancing liquid hydrocarbon recovery from a downhole formation through an injection tubing string, comprising: 
 a vertical wellbore opened both into the gas cap and the liquid hydrocarbon zone(s) with horizontal borehole(s) and/or perforations;    a packer positioned between the liquid hydrocarbon zone(s) and the gas cap on the injection tubing string for sealing the well annulus outward from the tubing string, thereby isolating the gaseous hydrocarbon zone(s) from the liquid hydrocarbon zone(s);    previously having set a bridge plug at an optimum level below selected liquid hydrocarbon zone(s) for isolating chosen injection area;    the flowing of natural gas from the formation's opened gas cap(s) through the annulus above the top packer directly into a surface compressor;    the surface compressor compressing the flowing gas cap(s') gas under high pressure into the injection tubing string;    the injection tubing string, open-ended at the lower part of the vertical wellbore near the horizontal borehole(s) and/or perforations, injecting high pressure compressed natural gas directly into the open liquid hydrocarbon zone(s); and    injected high pressure natural gas entering liquid hydrocarbon zone and going into solution with the liquid hydrocarbon, adding pressure and solution gas energy to the liquid hydrocarbon, thereby increasing its mobility and decreasing its viscosity with its own compatible gas cap(s') natural gas.    
     
     
         7 . A method of enhancing liquid hydrocarbon recovery from a downhole formation through an injection tubing string, comprising: 
 a vertical wellbore annulus with horizontal borehole(s) and/or perforations in direct communication with both the liquid hydrocarbon zone(s) and the gas cap(s);    positioning the injection tubing string from its connection to the surface compressor down into the vertical wellbore, where injection tubing string is open-ended by the open liquid hydrocarbon zone(s);    positioning a packer above the selected liquid hydrocarbon zone(s) for sealing a wellbore annulus outward from the injection tubing string;    previously having set a bridge plug at an optimum level below a selected hydrocarbon zone, isolating the chosen injection area;    flowing natural gas off the formation's gas cap through the well annulus above the top packer directly into the surface compressor;    the surface compressor injecting high pressure gas into the injection tubing string past the optimally set top packer, compressing gas out of the open-ended tubing directly into the opened horizontal borehole and/or perforated selected liquid hydrocarbon zone(s);    establishing increased pressure and viscosity reduction, increasing the liquid hydrocarbon's mobility through high pressure miscible natural gas going into solution with its own compatible liquid hydrocarbon; and    maintaining high gas pressure on the entire selected hydrocarbon formation's liquid hydrocarbon zone(s) and gas cap(s) through on to production and recovery process.    
     
     
         8 . The method as defined in  claim 7 , further comprising: 
 maintaining a high gas cap pressure when the gas cap is lowered in volume and pressure by the surface compressor injecting miscible and/or other gases into the gas cap.    
     
     
         9 . An improved downhole injector for positioning downhole within or below a liquid hydrocarbon recovery zone in a vertical wellbore to permit all liquids, under all conditions, to freely pass from a downhole formation through the injector, first through a sand screen filter, then through an opened double shutoff valve, then through a check valve, and on into a production tubing string, while positively, under all conditions, preventing any free gases from passing through the injector into the production tubing string, the injector comprising: 
 an injector housing having an double shutoff valve, having a main tip and port seat with a small, {fraction (3/16)}∴, being of a 0.0276″ cross-sectional area, pilot tip and port seat, affixed thereto;    a liquid responsive float, open at the top and closed at the bottom, connected to the double shutoff valve by means of the pilot valve working stem, movable within the injector housing, subject to buoyancy created by permanent liquid surrounding the float in the injector housing;    a double shutoff valve member movably responsive to the up and down movement of the float, thereby opening and closing the double shutoff valve as float fills or empties with liquids;    a liquid discharge 1″ pipe leading from double shutoff valve through the float with fin-like guides extending from it to help center float without friction contact, discharge 1″ pipe making into injector's head at production tubing connection;    a vertical slotted filter screen on the liquid and gas inflow entry on the upper injector housing, the vertical slots having increments of 0.001″, the vertical slotted filter screen preventing selectively-sized sand and/or debris particles from entering the injector housing; and    a check valve directly above injector head tubing outlet fro preventing liquids from returning to injector.    
     
     
         10 . The improved injector as defined in  claim 9 , wherein the filter screen has vertical entry slots, thereby preventing sand particles from plugging screen slots by constantly entering the same horizontal slot area as in prior art, thereby multiplying screen rib entry areas for improved sand settlement outside of the screen area into the vertical wellbore annulus.  
     
     
         11 . The improved injector vertical slotted screen, as defined in  claim 10 , having a reinforced pipe base with multiports for excessive high pressure collapse resistance and the vertical slotted screen with its pipe base being variable in section lengths to accommodate low volume to high volume high pressure liquid inflow rates while screen sections will be threaded on their pipe base for connecting threaded collars in approximate lengths of 20′ to 30′.  
     
     
         12 . The improved injector as defined in  claim 9 , wherein the float is substantially extended, as needed, in section lengths by connecting threaded collars and reinforced threaded float ends to add float opening weight with increased float closing buoyancy in order to open injector's double shutoff valve at all variable excessively high pressures.  
     
     
         13 . A system for recovering liquid hydrocarbons from a downhole formation through a production tubing string, comprising: 
 an improved downhole injector as defined in  claim 9  positioned downhole within or below a liquid hydrocarbon recovery zone for passing formation liquids through the injector and into the production tubing string while preventing excessively high pressure free gases from passing through the injector;    a packer positioned above the downhole injector for sealing the well annulus outward from the production tubing string at the optimum top level of the liquid hydrocarbon zone;    a gas pressure relief vent tube sealingly extending upward through the packer, said pressure relief vent tube opening at a predetermined pressure such that excessive gas pressure can be relieved through the vent tube and into the annulus of the opened gas cap formation above the packer;    a tubing pressure activated gas lift valve on an inside or outside pocket mandrel on the production tubing string directly above packer at gas cap bottom for injecting high pressure lift gas into production tubing;    a venturi jet tube directly above gas lift valve centered inside the production tubing to increase gas-velocity flow through its venturi-shaped cone to create a more efficient gas-liquid mixture and sweeping action by forming a gaseous piston to help lift the flowing liquid hydrocarbon column to next gas lift combined with venturi jet tube stage lift uphole;    one or more fluid operated gas lift valves optimally spaced on the production tubing string without venturi jet tubes to complete flowing liquid hydrocarbon process onto the surface; and    a sufficiently opened internal tubing string depth for swabbing the well, when necessary;    maintaining required high gas pressure on the entire selected hydrocarbon formation's liquid hydrocarbon zone(s) and its own wellbore annulus and gas cap(s) and its wellbore annulus throughout the entire production and recovery process of this invention.    
     
     
         14 . A method of recovering liquid hydrocarbons from a downhole formation through a production tubing string comprising: 
 providing an improved downhole injector as defined in  claim 9  and in entry communication with the production tubing string;    positioning an improved downhole injector optimally bottomhole within or below an opened horizontal borehole or perforated liquid hydrocarbon zone;    positioning a packer above an improved downhole injector for sealing a well annulus outward from the production tubing at an optimum top level of the liquid hydrocarbon zone entering the gas cap above;    providing a gas pressure relief vent tube sealingly extending upward through the packer, said pressure relief vent tube opening at a predetermined pressure setting, venting excessive gas pressure buildup to the open gas cap above;    providing a tubing fluid pressure activated gas lift valve mounted on an outside or inside pocket mandrel on production tubing string directly above top packer at optimum lower gas cap level, injecting high pressure lift gas into production tubing when predetermined tubing fluid pressure opens gas lift valve;    providing a venturi jet tube directly above gas lift valve centered inside the production tubing string for increasing gas velocity flow through its venturi-shaped cone for creating a more efficient gas-liquid mixture sweeping action when flowing to form a gaseous piston to help drive flowing liquid hydrocarbons upward;    providing additional tubing fluid pressure activated gas lift valves with venturi jet tubes optimally spaced uphole for stage-lifting deep wells;    providing additional fluid operated gas lift valves on mandrels uphole on the production tubing string without venturi jet tubes for assisting flowing liquid hydrocarbon process on out to surface separating facilities; and    providing a sufficiently deep internal production tubing string depth for swabbing well when necessary.    maintaining required high gas pressure on the entire selected hydrocarbon formation's liquid hydrocarbon zone(s) and its wellbore annulus and gas cap(s) and its wellbore annulus throughout the entire production and recovery process of this invention.    
     
     
         15 . A system for recovering liquid hydrocarbons from a downhole formation through a production tubing string, comprising: 
 an improved downhole injector as defined in  claim 9 , positioned downhole within or below a liquid hydrocarbon recovery zone for producing formation liquids through the injector and into the production tubing string while preventing high pressure free gas from passing through the injector;    a packer positioned above the downhole injector for sealing a well annulus outward from the production tubing string;    a gas pressure relief vent tube sealingly extending upward through the packer, said pressure relief vent tube opening at a predetermined pressure setting, such that excessive gas pressure can be relieved through the vent tube and into the annulus of the opened horizontal borehole and/or perforated gas cap above the packer;    a back pressure valve for retaining high pressure on the production tubing string on the surface wellhead production tubing exit port; and    a liquid column maintained in the production tubing string above the injector onto wellhead tubing backpressure valve, creating a total back pressure of gas-saturated liquid column plus surface back pressure valve setting to open at desired approximate differential needed to open injector double shutoff valve.    maintaining required high gas pressure on the entire selected hydrocarbon formation's liquid hydrocarbon zone(s) and its wellbore annulus and gas cap(s) and its wellbore annulus throughout the entire production and recovery process of this invention.    
     
     
         16 . The system as defined in  claim 15 , further comprising: 
 a total internal tubing back pressure, setting calculated using back pressure valve setting coordinated with liquid column in production tubing to prevent substantial gas volume from breaking out of solution as the liquid column reaches production tubing well surface.    
     
     
         17 . The system as defined in  claim 15 , further comprising: 
 the use of the extended float system coordinated with the internal tubing back pressure to overcome the system's limitations and help prevent gas from breaking out of solution as liquid column reaches well's surface    
     
     
         18 . The system as defined in claims  18  and  17 , further comprising: 
 flowing liquid hydrocarbon production to surface without any artificial lift system in excessively high bottomhole pressure wells with little or no rathole at lesser well depths, so that high bottomhole pressure flows liquid hydrocarbon out at the surface wellhead tubing back pressure valve discharge.