Method and Apparatus for Increasing Well Productivity

Abstract

This patent application discloses method and apparatus to cut an extended slot connecting a well to a substantial cross section of a desired producing formation whereby material can flow freely between the formation and the wellbore and at least partially overcome the flow limitations of low permeability formations without the environmental issues associated with hydraulic fracturing. It is further disclosed that the connection between said slot and the formation may be further enhanced by explosive or combustive processes that rapidly generate gas pressure within the large surface area of the slot, thereby changing its characteristics and forcing open additional fractures into the cross section of formation exposed to the slot. The method may significantly increase the recoverable percentage of natural gas from low permeability deposits such as shale and coal.

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         21 . A method for increasing well productivity by cutting an extended slot, connecting the well to a substantial cross sectional area of a desired producing formation so that flow of resources between the formation and the well is substantially increased, comprising:
 a. a well having a single wellbore path with one starting point and one distal end point, such that a drilling pipe may pass through entire length of said well,   b. an abrasive cutting member attached to at least one pipe, with said pipe extending to earth surface,   c. means for manipulating said abrasive cutting member within said wellbore path by movement of said pipe,   d. means for urging said abrasive cutting member against sidewall of said wellbore and deeper into said slot in said sidewall,   whereby said slots may be extended tens to hundreds of feet deep along an extended length of said wellbore.   
     
     
         22 . A method for increasing well productivity as in  claim 21  additionally comprising means for adjusting total friction during operation by changing the operating position of said at least one pipe and said attached abrasive cable within said single borehole to change the total arc of contact between said abrasive cable and said single wellbore,
 whereby total friction may be dynamically adjusted as needed during operation so that said attached abrasive cable will not become stuck by friction as is likely in prior art. 
 
     
     
         23 . The method of  claim 21  additionally comprising means for reducing friction of said pipe and attached tensile member against wellbore, such as a drilling fluid having high lubricity. 
     
     
         24 . The method of  claim 21  additionally comprising; that said single wellbore path follows a curved path through said desired producing formation and said means for urging said abrasive cutting member against said sidewall of said wellbore and extending said slot into a subterranean formation, further comprises an abrasive cable tensioned and reciprocated along said curved path. 
     
     
         25 . The method of  claim 21  additionally comprising; extending said borehole through a laterally curved path so as to produce a slot that varies in orientation between horizontal and vertical. 
     
     
         26 . The method of  claim 21  additionally comprising; drilling said well with one or more lateral boreholes, branching off first said wellbore, wherein said lateral boreholes are blind holes and said extended slot is formed along each lateral,
 whereby multiple said slots, may be formed in multiple blind holes extending from said well. 
 
     
     
         27 . A method for increasing well productivity as in  claim 21 , comprising the additional steps of:
 a. creating at least one said slot that has a substantially planar surface area of at least 10,000 square feet,   b. providing a combustible mixture within said slot at a predetermined pressure such that when ignited, said mixture may generate a deflagration gas pulse of suitable pressure, rise time and duration within said slot, and acting against said planar surface area of said slot to at least temporarily alter the orientation of the fracture gradient,   c. providing at least one suitably positioned ignition source,   whereby said gas pulse is created against said planar surface area of said slot such that a plurality of fractures substantially perpendicular to said planar surface area may be created.   
     
     
         28 . A method for increasing well productivity as in  claim 21 , additional comprising; means for forming a downhole heat exchanger within said slot, such as extending a pipe substantially through the length of said well wherein said pipe pulls at least one smaller tubing pipe into said extended slot and providing tension means of controlling position of multiple said tubing pipes within said extended slot. 
     
     
         29 . The method of  claim 28 , additionally comprising means for gathering heat from an extended area wherein at least one first said slot having said downhole heat exchanger means, and additionally comprising at least one second said slot with a passage and pumping means to pump water from first said slot to second said slot,
 whereby resulting hydrostatic gradient urges groundwater flow carrying heat from the surrounding formation into first said slot.   
     
     
         30 . A method for increasing well productivity by increasing the cross sectional area of a desired producing formation exposed to a well, comprising:
 a. forming a single wellbore having a substantially smooth curved path, such that a drill pipe may extend through the entire length of said single wellbore,   b. introducing at least one pipe having an attached abrasive cable, into said single wellbore, such that said at least one pipe, extends substantially from the surface to at least near said curved path and said attached abrasive cable extends at least through a portion of said curved path,   c. tensioning said attached abrasive cable with a tensioning means, at least within said at least a portion of said curved path, such that said tension urges said attached abrasive cable laterally into the sidewall of said wellbore and on into said formation,   d. reciprocating said pipe within said single wellbore with a reciprocation means, such that said attached abrasive cable is also drawn back and forth along said at least a portion of said curved path of said single wellbore to cut a slot,   whereby a slot exposing at least 10,000 square feet of formation surface area may be created even at great depth with a single hole, without costly precision drilling of intersecting wellbores or fishing of a cutting device through an intersection as in prior art.   
     
     
         31 . The method of  claim 30  wherein said single wellbore has at least a portion of said curved path within a substantially non-vertical plane between horizontal and vertical, such that at least a portion of said slot will be in said non-vertical plane. 
     
     
         32 . The method of  claim 30  wherein said curved path of said single wellbore extends from said desired producing formation back to the earth's surface and along paths that may be inclined from vertical to reduce the total included angle of said single wellbore. 
     
     
         33 . The method of  claim 30  wherein said single wellbore is a single blind hole borehole having a distal end substantially in said desired producing formation and a pipe reciprocating means for said pipe and said attached abrasive cable tensioned and external to at least a portion of said pipe and additionally comprising:
 a. said pipe that is inserted into said single wellbore at least through said curved path through said desired producing formation, 
 b. said attached abrasive cable that is attached to the lower end of said pipe and extending externally up at least through said at least a portion of said curved path, 
 c. said tensioning means is able to tension said attached abrasive cable after said pipe is inserted substantially through said curved path, 
 d. said pipe reciprocating means, such as a drilling rig, reciprocates said pipe within borehole, 
 whereby said attached abrasive cable is reciprocated along inside radius of said curved path and cuts a slot into said desired producing formation that may increase surface area exposed to said single wellbore about 100 to 1000 fold. 
 
     
     
         34 . The method of  claim 33  additionally comprising at least one of the additional steps of;
 a. extending said curved path through additional bends so as to produce a slot that may follow a pathway that varies in orientation between horizontal and vertical, 
 b. repositioning said pipe so that said abrasive cable extends through a reduced total arc of contact with said curved path to reduce total friction, 
 c. attaching said abrasive cable to distal end of said pipe such that release can be triggered from the surface. 
 
     
     
         35 . The method of  claim 30  wherein said curved path of said single wellbore is a u loop style borehole curving through said desired producing formation with both ends of said wellbore extending back along relatively straight paths to the earth's surface and additionally comprising:
 a. said tubing pipes positioned within each end of said single wellbore from substantially said ground surface to a predetermined point approximately where said slot is to be begin, 
 b. said attached abrasive cable extends at least through entire said single wellbore and longitudinally through said tubing pipes, 
 c. a gripping means on said tubing that grabs hold of said abrasive cable and holds tension but which can also release and re-grip without removing said tubing pipes from said single wellbore, 
 d. a tensioning means that tensions said attached abrasive cable to generate lateral cutting force against the sidewall of said wellbore, 
 e. a means for reciprocating tubing pipes and thus also reciprocating said attached abrasive cable within said single borehole, 
 whereby said abrasive cable saws into inside radius of said curved path of desired producing formation to cut said slot. 
 
     
     
         36 . The method of  claim 35  additionally comprising at least one of the following additional steps of:
 d. extending said curved path of u loop through a lateral curved path so as to produce a slot that may follow a pathway that varies in orientation between horizontal and vertical, 
 e. extending said tubing pipes through at least part of said curved path to reduce the total arc of contact of said abrasive cable and thereby the friction between said abrasive cable and said curved path, 
 f. providing a releasable cable gripping device on said tubing pipes such that the portion of said abrasive cable between the distal ends of said tubing pipes which is performing the cutting action can be periodically changed by releasing said gripping device and circulating said abrasive cable with a suitable means and so that new areas of said abrasive cable are exposed, 
 g. filling said slot with proppant materials, 
 h. pumping a lubricating drilling fluid through said borehole to reduce friction, 
 i. constructing multiple said slots to maximize production from a specific area of land. 
 
     
     
         37 . A method for increasing well productivity by cutting at least one extended slot from a well into a desired producing formation comprising:
 a. drilling said well with one or more lateral boreholes, as are known in the art, such that said lateral boreholes are blind holes, not intersecting with other holes,   b. extending said lateral boreholes along a curved path through said desired producing formation,   c. providing a pipe having an abrasive cable attached to its distal end and extending toward the surface, along said pipe and being external to said pipe through at least a portion of said curved path,   d. providing a tensioning means for said abrasive cable between said distal end of pipe and a point on said pipe above said distal end, such that said tension may be adjusted from the surface,   e. providing a reciprocating means, such as the stroke of a drill rig which is known in the art, for said pipe such that pipe and thereby said attached abrasive cable are reciprocated along at least a portion of said curved path,   whereby said attached abrasive cable is reciprocated along inside radius of said curved path and cuts a slot into said desired producing formation connecting said well to a cross sectional area comparably to that achieved by hydraulic fracturing.