Abstract:
A method of recovering product from a fracture below a surface, said method including:
       a. providing a first well that may be stimulated or has been stimulated at a first predetermined depth within a formation;   b. stimulating said well resulting in at least one fracture in said formation; said fracture having at least one initiation point and at least one distal point; wherein said at least one initiation point is proximate said stimulated well and said at least one distal point is distant said stimulated well;   c. providing at least one non-stimulated well, proximate said first well at a second predetermined depth in said formation and contacting said at least one distal point of said at least one fracture; said at least one non-stimulated well further including at least one access point to capture product from said at least one fracture in said formation;
 
capturing said product from said fracture through said at least non-stimulated well, and recovering said captured product optionally at said surface.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to the field of horizontal hydrocarbon exploration and development wells and field development methods. In particular, the invention relates to increasing product recovery, in particular hydrocarbon recovery from fractures proximate fractured wellbores, preferably hydraulic fractured wellbores, through subsurface rock formations. More specifically, the invention relates to a non-treated, preferably non-hydraulic fractured substantially deviated wellbore, wherein said non-treated substantially deviated wellbore is non-treated during product recovery, proximate a fracture treated, preferably a hydraulic fractured treated substantially deviated wellbore to allow for recovery of product, in particular hydrocarbons from fractures in said rock formations and methods for using same. 
       BACKGROUND OF THE INVENTION 
       [0002]    Commercial extraction of reservoir product, such as oil and/or gas or combinations thereof, from certain subsurface rock formations requires a wellbore extending through the formation to a reservoir. In order to increase recovery of oil and/or gas or combinations thereof from rock formations and reservoirs, wellbores are stimulated, in one instance through hydraulic fracturing resulting in a hydraulic fracture in the formation surrounding the wellbore. Typically wellbores are drilled in a pattern that benefits the most from the dominant hydraulic fracture direction. Wellbores are placed side by each, in one example, in a substantial pitchfork fashion, such that wellbores are evenly spaced at a distance or proximity that permit efficiency in drainage of hydrocarbon fluid or gas, contained in the reservoir and fracture, into said wellbore. 
         [0003]    If wellbores are drilled too far apart, an increasingly large portion of the desired reservoir product is left behind in the reservoir, and in particular the fracture. It is well documented in the oil and gas industry that each hydraulic fracture, while intersecting reservoir rock at great distances from the wellbore; does not effectively produce oil and gas from the entire length of the fracture. It is accepted that up to 66% or more of the created fracture length will not contribute significantly to production. In other words, only 34% of the fracture may be contributing to overall hydrocarbon production. 
       SUMMARY OF THE INVENTION 
       [0004]    The following terms are used herein to better understand the present invention. Hydrocarbon fluid means gas, oil or combinations thereof that may also include other components, such as water used when fracturing a wellbore. 
         [0005]    Induced fracture means a fracture induced by any means including stimulating a wellbore using fracture stimulating techniques, including hydraulic fracture stimulating techniques. 
         [0006]    Non-stimulated (passive) wellbore means a wellbore that is not directly stimulated via said wellbore in order to stimulate fractures or hydrocarbon production but captures hydrocarbon fluid or product from fractures originating from a stimulated wellbore. The term non-stimulated (or passive) also means stimulated (or fractured) less than a stimulated well, preferably substantially non-stimulated (non-fractured), more preferably not stimulated (not fractured). The term also means not only less frequency of stimulation (fracturing), but also partial stimulation (fracturing) of a wellbore. The term non-stimulated also means that the well or wellbore is non-stimulated at and/or during the time of capturing product according to the process described herein. 
         [0007]    Product means any product contained in a rock formation or subterranean formation such as hydrocarbon or the like. In other instances, solute from a salt mining operation, such as sodium chloride and/or potassium chloride or other minerals dissolved from said rock formation, including geothermal heated water or steam. 
         [0008]    According to one aspect of the invention, there is provided a method of recovering a product, preferably hydrocarbon (gas, oil and combinations thereof) fluids from a reservoir below a surface, preferably normally not recoverable through a induced fracture proximate a stimulated substantially horizontal wellbore at a first predetermined depth in a formation, said method comprising: 
         [0000]    providing at least one stimulated substantially horizontal wellbore at a first predetermined depth in a formation; wherein said stimulation results in at least one induced fracture, preferably more than one induced fracture, in said formation, preferably in said reservoir, proximate said at least one stimulated substantially horizontal wellbore; said at least one induced fracture having at least an initiation point proximate said at least one stimulated substantially horizontal wellbore and at least one distal point, distant said at least one stimulated substantially horizontal wellbore;
 
providing at least one non-stimulated wellbore, preferably stimulated less than said stimulated wellbore, more preferably substantially non-stimulated, proximate said stimulated wellbore at a second predetermined depth in said formation, preferably substantially parallel to said stimulated wellbore, wherein said at least one non-stimulated wellbore further comprises at least one access point to capture product, preferably hydrocarbon from said formation, capturing said product, preferably hydrocarbon fluids from said at least one fracture, and recovery said captured product, preferably hydrocarbon fluids at said surface. In one embodiment, said first and second predetermined depths are substantially the same. In another embodiment, said first and second predetermined depths are substantially different. Preferably said at least one non-stimulated wellbore is proximate said at least one distal point of said at least one induced fracture, more preferably said at least one non-stimulated wellbore is in contact with said at least one induced fracture, preferably transverses said at least one induced fracture.
 
         [0009]    According to another aspect of the invention, there is provided a product recovery system, preferably a hydrocarbon recovery system comprising: 
         [0000]    at least one stimulated substantially horizontal wellbore at a first predetermined depth in a formation; wherein said stimulation results in at least one fracture proximate said at least one stimulated substantially horizontal wellbore;
 
at least one non-stimulated wellbore, preferably stimulated less than said stimulated wellbore, more preferably substantially non-stimulated, proximate said stimulated wellbore at a second predetermined depth in said formation, preferably substantially parallel to said stimulated wellbore, wherein said at least one non-stimulated wellbore further comprises at least one access point to capture product, preferably hydrocarbon from said formation of said at least one stimulated wellbore.
 
         [0010]    According to yet another aspect of the invention, there is provided a diagnostic method and system to determine the location of subsurface fractures, said diagnostic method and system comprising: 
         [0000]    providing at least one stimulated substantially horizontal wellbore at a first predetermined depth in a formation; wherein said stimulation results in at least one fracture, preferably more than one fracture, proximate said at least one stimulated substantially horizontal wellbore;
 
introducing at least one marker or tracer, preferably a Gama emitting tracer or the like into said at least one stimulated substantially horizontal wellbore, such that said tracer enters at least one fracture, preferably more than one fracture, proximate said stimulated wellbore;
 
providing at least one non-stimulated wellbore, preferably stimulated less than said stimulated wellbore, more preferably substantially non-stimulated, proximate said stimulated wellbore at a second predetermined depth in said formation, preferably substantially parallel to said stimulated wellbore, wherein said at least one non-stimulated wellbore further comprises at least one access point to capture said at least one marker or tracer from said formation, capturing said at least one marker or tracer from said at least one fracture, and mapping the location and path of said marker or tracer to identify the location of said at least one fracture in said formation, resulting in information to map said at least one fracture, preferably more than one fracture, within a discrete fracture network, (DFN), mapping processes known in the industry. Said diagnostic method may reveal improvements in fracture design such that the induced fracture process in the actively stimulated wells can be achieved more efficiently while considering all resources, natural and capital (e.g., water, sand, hydrocarbon energy sources, and currency investment).
 
         [0011]    Furthermore, there is provided a method of monitoring wellbore parameters, preferably pressure in the at least one non-stimulated wellbore, preferably stimulated less than said stimulated wellbore, more preferably substantially non-stimulated, preferably before, during and after the stimulation of at least one stimulated wellbore. Preferably said monitoring indicating the interval when a fracture, produced by the stimulation of the at least one stimulated wellbore, comes in contact with, preferably intersects with, the at least one non-stimulated wellbore. Preferably said pressure is monitored with devices, preferably pressure sensors or gauges proximate said non-stimulated wellbore, preferably within said wellbore. In one embodiment, said pressure is monitored via a surface pressure gauge. This information, preferably knowledge of this interval may be used to improve fracture design processes in a manner similar to the above marker and tracer process. In addition, logging the drilled open hole with imaging logs to visualize natural fractures before the wellbores are drilled, and then after they are fracture stimulated to visualize the location the created fractures contact, preferably intersect the non-stimulated wellbore, may assist in understanding how fractures grow and propagate. 
         [0012]    Preferably, said at least one non-stimulated wellbore further comprises a slotted liner. 
         [0013]    Preferably said at least one non-stimulated wellbore is not cased. 
         [0014]    In one embodiment, said at least one stimulated and said at least one non-stimulated wellbore have a common entry point from said surface. 
         [0015]    In another embodiment, said at least one stimulated and said at least one non-stimulated wellbore each has a distinct entry point from said surface. 
         [0016]    In one embodiment, said at least one non-stimulated wellbore is substantially beneath said at least one stimulated wellbore. 
         [0017]    In another embodiment, said at least one non-stimulated wellbore is substantially above said at least one stimulated wellbore. 
         [0018]    In another embodiment, said at least one non-stimulated wellbore is substantially at the same height of said at least one stimulated wellbore. 
         [0019]    In another embodiment, at least two non-stimulated wellbores are proximate said at least one stimulated wellbore, preferably substantially above and substantially below said stimulated wellbore. 
         [0020]    In another embodiment, said at least one non-stimulated wellbore is preferably stimulated less than said stimulated wellbore, more preferably substantially non-stimulated. 
         [0021]    In another embodiment, there is provided a method and system of reducing costs associated with hydrocarbon fluid recovery from below the surface, said method and system comprising any of the methods and systems disclosed herein. 
         [0022]    According to yet another embodiment, the at least one non-stimulated wellbore is an existing well previously stimulated but not directly stimulated at or during the time of the process of the present invention. In this instance, a well previously stimulated, but having been shut in or unused for a period of time, may now be the non-stimulated well recovering product proximate a stimulated well. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0023]      FIG. 1  is a depiction of a typical fractured wellbore in the field. 
           [0024]      FIG. 2  is a depiction of a non-fractured (or non-stimulated) wellbore according to the present invention above a fractured (or stimulated) wellbore. 
           [0025]      FIG. 3  is a depiction of a non-fractured (or non-stimulated) wellbore according to the present invention below a fractured (or stimulated) wellbore. 
           [0026]      FIG. 4  is a depiction of two non-fractured (or non-stimulated) wellbores according to the present invention, one above and one below a fractured (or stimulated) wellbore. 
           [0027]      FIG. 5  is a depiction of a plurality of non-fractured (or non-stimulated) wellbores according to the present invention proximate a fractured (or stimulated) wellbore and contacting a fracture resulting from the stimulation of the fractured wellbore. 
           [0028]      FIG. 6  is a depiction of tracers identified in untraced wellbores from fractures created by stimulated wellbores proximate the untraced wellbores. 
           [0029]      FIG. 7  is a depiction of a map view of wellbores in a formation. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Other aspects and advantages of the invention will be apparent from the following description and the appended claims. 
         [0031]    Referring now to  FIG. 1 , there is provided a typical fractured wellbore  23  resulting in a plurality of fractures  22  in the rock formation below the ground  19 . An entry point  20  to the wellbore  23  above the ground level is provided. In one example, a first substantially horizontal wellbore  23  is drilled into a formation. The wellbore is cased and prepared as known to a person of ordinary skill in the art, for hydraulic fracturing. Referring now to  FIG. 2 , a second wellbore  24  is drilled proximate said first wellbore  23 , particularly above said fractured wellbore  23 . In this instance, the second wellbore  24  is not prepared in the typical manner for hydraulic fracturing. Rather the second wellbore  24  is considered passive in nature. The passive wellbore  24  may be lined in any manner in order to prevent collapse of said wellbore, preferable with a slotted liner or the like or the wellbore may be left as an open hole. In one example, typical completions may require an intermediate casing set in the substantially horizontal wellbore and cemented to the surface. A passive or non-stimulated wellbore would then emanate from the end of said intermediate casing permitting flow of hydrocarbon from a reservoir in an underground formation to the surface via the intermediate casing, production tubing or production casing as per traditional completions methods employed in the hydrocarbon industry. In this instance, the passive or non-stimulated wellbore may be open hole or the open hole section may be supported to prevent collapse thereof, such as, but not limited to, a slotted liner or pre-perforated casing or casing that is similarly perforated as the stimulated wellbore. In a preferred embodiment, the production casing or liner residing in the horizontal portion of the passive wellbore would not be cemented in place. 
         [0032]    When the first wellbore undergoes stimulation, in this case, hydraulic fracturing stimulation, the passive wellbore is available to capture hydrocarbons not necessarily recoverable through the stimulated wellbore (as best seen in  FIGS. 2-5 ). The passive wellbore, through the slotted liner, or the like, captures hydrocarbon, which may consist of gas, liquid or a combination of the two and other components, such as fracturing fluid, and the captured hydrocarbon is then collected, preferably at the surface level, using conventional collection means, via completion equipment commonly employed and so designed to handle product or fluid, being any produced gas, hydrocarbon or other non-hydrocarbon containing liquid such as water consisting of fracturing fluid, formation water, salt brine or other mineral rich water, or hydrocarbon liquids such as oil, condensate or any combination of said fluids. 
         [0033]    Referring now to  FIG. 3 , there is provided a stimulated or fractured wellbore  23  with a non-stimulated wellbore  25  below said fractured wellbore  23 . 
         [0034]    In this instance, the passive or non-stimulated wellbore  25  will capture hydrocarbon, which may consist of gas, liquid or a combination of the two and other components, such as fracturing fluid from the fractures substantially below the fractured wellbore  23 . 
         [0035]    Referring now to  FIG. 4 , there is provided a configuration of a non-stimulated wellbore  24  above a stimulated wellbore  23 , and a non-stimulated wellbore  25  below the stimulated wellbore  23 . As can be seen, the important aspect of the invention is the location of the non-stimulated wellbore proximate the stimulated wellbore is that the non-stimulated wellbore contacts the fractures  22  resulting from stimulating wellbore  23 . 
         [0036]    Referring now to  FIG. 5 , there is provided a configuration where  4  non-stimulated wellbores  24 ,  25 ,  26  and  27  are situated proximate a stimulated wellbore  23 , wherein the wellbores  24 ,  25 ,  26  and  27  contact the fractures  22  resulting from the stimulation of the wellbore  23 . 
         [0037]    Although the above depicts several configurations of non-stimulated wellbores proximate a stimulated wellbore, the configuration is dependent on the formation and field where the wellbore is to be drilled and may vary according to the needs of the operator. 
         [0038]    Furthermore, although the above depicts the capture of hydrocarbons, any product may be captured, depending on the type of product desired 
         [0039]    In comparison when conventional techniques are used, i.e. the first and second wellbores are hydraulically fractured, significant time, water and cost are expended. 
         [0040]    Typically a fractured wellbore requires the use of 250,000 litres of fuel, more or less, throughout a typical hydraulic fracturing operation. 
         [0041]    A wellbore of 2500 m-length requires 15 to 25 employees 72 hours minimum as well as equipment rental for preparation and fracturing. 
         [0042]    The following provides typical material and equipment used in fracturing (stimulating) a wellbore in the field, based on a hypothetical wellbore that is drilled, completed and hydraulic fracture stimulated (“frac”) with a typical high rate waterfrac with 200 metric tonnes (“MT”) sand. 
         [0043]    Wellhead treating pressure, 65 MPa, range 40 to 65 MPa; 
         [0044]    Fluid injection rate, 15 m 3 /min, range 10 to 20 m 3 /min; 
         [0045]    Number of fracs per wellbore, 20 each; 
         [0046]    6 to 9 days from first frac to turn over to completion per wellbore; 
         [0047]    Casing and cement for horizontal wellbore cost included in price to drill. 
         [0048]    Below lists the typical equipment and materials expended per stimulated wellbore: 
         [0049]    40,000,000 liters water; 
         [0050]    4,000 MT sand; 
         [0051]    40,000 liters polyacrylamide friction reducer; 
         [0052]    120,000 liters 15% HCl acid with additives for corrosion protection; 
         [0053]    9 to 40 bridge plugs; 
         [0054]    500 to 1,500 jet perforation charges; 
         [0055]    250,000 liters of diesel fuel for pumping and blending equipment; 
         [0056]    800 to 1600 megawatts (“MW”) hydraulic pumping equipment plus 10 to 20 MW standby pumping equipment; 
         [0057]    10 to 18 m 3 /min blending equipment plus 100 percent backup on location; 
         [0058]    On location-storage equipment and transport from mine of 2000 to 4,000 MT of sand, (fuel for transport not included); 
         [0059]    Wireline equipment for running and setting bridge plugs and perforating casing 
         [0060]    Coiled tubing equipment with bottom hole drilling assembly for drilling up bridge plugs 
         [0061]    Total completion cost per stimulated wellbore, $7,000,000.00 USD. 
         [0062]    Total cost to drill a wellbore (non-stimulated), $3,500,000.00 USD. 
         [0063]    Therefore, according to the present invention, there is a method and system provided for considerable savings for each wellbore (in one aspect there is a potential savings of up to 50% for each wellbore) that is not stimulated but still captures the product from a fracture (stimulated or natural), in particular one resulting from a stimulated wellbore proximate the non-stimulated wellbore. Other savings include, but are not limited to, reduced manpower time, reduced environmental impact of fuels used in stimulating a wellbore, reduced use of water, sand acid, bridge plugs, proppants, expendables, rented equipment and diesel fuel, as well as increased percentage product recovery. 
         [0064]    Additionally production will be realized without the additional costs of cementing in production casing, perforating, pumping hydraulic fracture treatments, and then placing plugs to isolate perforations, then perforating again on up the wellbore. These stimulation costs can be nearly as much as or exceed the cost of drilling the wellbore. In addition, placing such a wellbore in the path of created hydraulic fractures from adjacent wells provides an opportunity for diagnostics and surveillance of fractures intersecting the passive wellbore. 
         [0065]    The passive wellbore, or capture wellbore, is a wellbore that is drilled neighbouring other more conventional substantially horizontal wellbores that will be or have been stimulated for production through hydraulic fracture stimulation processes. The passive or capture well would normally be drilled at the same time (or after) as the other wells in a parallel or substantially parallel orientation to other wells such that hydraulic fractures created in the adjacent stimulated wellbores will contact, preferably intersect the passive wellbore, in such a manner that the passive wellbore will benefit from the hydraulic fracture stimulation of the other wells in the field or on pad. In one embodiment, the well will be drilled in between wells in the same direction and in the same length, but apart from the other fractured wells, or active wells, spaced at a distance close enough to be certain hydraulic fractures will contact, preferably intersect the passive well. The passive well, in one embodiment will be completed open hole, in another embodiment, the open hole section will be supported by a slotted liner, or pre-perforated casing, or casing that is similarly perforated as an active well, preferably the passive well will not be cemented in place as is the current practice in many horizontal fracture stimulated wells. 
         [0066]    The advantages of the passive wellbore of the present invention are discussed above, but the primary purpose is to increase production from a hydraulic fracture stimulated reservoir with lower impact on the environment, and ultimately less cost spent per e 3 m 3  of natural gas or m 3  of oil and/or natural gas liquids, or other product contained in rock. A passive well is not stimulated directly with a hydraulic fracture treatment which has environmental impact implications much in the news for several years now. The industry has been challenged with reducing the use of surface water, chemicals used to treat the water for hydraulic fracture purposes, and reducing the carbon impact of burning diesel and natural gas to drive high pressure pumping equipment. This is a green process in that the hydrocarbon produced from a passive capture well will be at a far lower cost in surface water and energy consumed, and reduced disposal requirements, e.g. 20 to 25% of the water returned after fracturing, that will be contaminated with fracturing chemicals and salts, metals and radio nuclides. 
         [0067]    Other advantages are improvements in initial production per hectare and efficiency of hydrocarbon recovery. 
         [0068]    In the current invention, the cost, waste and other non-preferables, associated with a stimulated wellbore are eliminated when incorporating a passive wellbore as described herein, while benefiting from the result of the proximate stimulated wellbore. 
         [0069]    The current invention, when used with markers or tracers, in particular gamma emitting tracers, and wellbore imaging logs allows for the mapping and localization of fractures in the formation, which allow for optimization of wellbore location for overall increase in hydrocarbon production, as well as fracture treatment design optimization.  FIG. 6  depicts tracers migrating to a proximate well via fractures from a distant well. 
         [0070]    The use of a passive well, of the current invention seems to run contrary to conventional thinking in that a non-stimulated wellbore may capture hydrocarbons from a fracture proximate a stimulated wellbore. It is generally accepted in the industry that a wellbore must be hydraulically fracture stimulated directly to produce hydrocarbons. 
         [0071]    The following data provides the use of the current invention in identifying and mapping the location of hydrocarbon reservoirs in the formation. 
         [0072]    The wellbores in the map view of  FIG. 7  are each 400 metres apart. 
         [0073]    Wellbore b-18-I was stimulated via hydraulic fracturing with gamma emitting particles (Iridium isotope) pumped with the fracturing fluid. 
         [0074]    Wellbore b-A18-I was stimulated via hydraulic fracturing with gamma emitting particles (Scandium isotope) pumped with the fracturing fluid. 
         [0075]    Non-fractured wellbores b-B 18-I and b-C18-I were hit by fractures created in stimulated wellbores b-A18-I and b-18-I. 
         [0076]    This was confirmed by the detection of gamma emitting isotopes in non-stimulated wellbores b-B18-I and b-C18-I, originally contained in the hydraulic fracturing fluids used in hydraulic fracturing of wellbores b-18-I and b-A18-I. 
         [0077]    The arrows indicate the location where the Scandium from the hydraulic fracturing fluid used in stimulating b-A18-I, and Iridium from the hydraulic fracturing fluid used in stimulating b-18-I hit non-stimulated (capture) wellbores b-C18-I and b-B18-I. b-C18-I is 400 m from b-A18-I and 800 m from b-18-I. b-B 18-I is 400 m from b-18-I and 800 m from b-Al 8-I. 
         [0078]    As many changes can be made to the preferred embodiment of the invention without departing from the scope thereof; it is intended that all matter contained herein be considered illustrative of the invention and not in a limiting sense.