Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a Utility Application of prior pending Provisional Application serial No. 60/388,966 filed Jun. 14, 2002 entitled “Method for generating grids to represent fluvial sand bodies”. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The subject matter of the present invention relates to a method and program storage device for generating grids representing the architecture of fluvial reservoirs.  
           [0003]    Shale or other fine grained rock in a reservoir represents a barrier to the flow of oil or gas in the reservoir because the shale or other fine grain rock will inhibit the flow of the oil or gas in the reservoir. On the other hand, sand in a reservoir does not represent a barrier because the sand will not inhibit the flow of the oil or gas in the reservoir. Therefore, in reservoir development, there is a concern regarding the three dimensional distribution in the reservoir of the shale or other fine grained rock because the shale and/or fine grain rock will impede the movement of fluids in the reservoir. As a result, in order to plan development of oil or gas from the reservoir, there is a need to predict the specific locations in the reservoir where the shale and/or fine grain rock exists.  
           [0004]    Accordingly, when modeling a reservoir for development planning, there exists a need to predict the specific locations in the reservoir where the shale or fine grain rock is located.  
         SUMMARY OF THE INVENTION  
         [0005]    A first aspect of the present invention includes a method of generating a plurality of simulation results adapted for display on a display device, comprising the steps of: (a) generating, responsive to a plurality of rock classifications, a plurality of model realizations representing an architecture of a fluvial reservoir; and (b) generating, responsive to the plurality of model realizations representing the architecture of the fluvial reservoir, a plurality of grids, the plurality of grids representing said simulation results adapted for display on the display device.  
           [0006]    Another aspect of the present invention includes a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine, to perform method steps for generating a plurality of simulation results adapted for display on a display device, the method steps comprising: (a) generating, responsive to a plurality of rock classifications, a plurality of model realizations representing an architecture of a fluvial reservoir; and (b) generating, responsive to the plurality of model realizations representing the architecture of the fluvial reservoir, the plurality of grids, the plurality of grids representing said simulation results adapted for display on the display device.  
           [0007]    Another aspect of the present invention includes a system adapted for generating a plurality of simulation results adapted for display on a display device, comprising: apparatus adapted for generating, responsive to a plurality of rock classifications, a plurality of model realizations representing an architecture of a fluvial reservoir; and apparatus adapted for generating, responsive to the plurality of model realizations representing the architecture of the fluvial reservoir, a plurality of grids, the plurality of grids representing said simulation results adapted for display on the display device.  
           [0008]    Another aspect of the present invention includes a method of generating, responsive to a set of predefined channel belt margins, a plurality of model realizations representing an architecture of a fluvial reservoir, the channel belt margins being predefined in response to a set of rock classifications, comprising the steps of: generating a plurality of channel realizations in response to the predefined channel belt margins; rejecting invalid ones of the plurality of channel realizations thereby generating a plurality of valid channel realizations; and gridding tops and bases of the plurality of valid channel realizations, the plurality of model realizations being generated in response to the gridding of the tops and bases of the plurality of valid channel realizations.  
           [0009]    Another aspect of the present invention includes a program storage device readable by a machine tangibly embodying a program of instructions executable by the machine to perform method steps for generating, responsive to a set of predefined channel belt margins, a plurality of model realizations representing an architecture of a fluvial reservoir, the channel belt margins being predefined in response to a set of rock classifications, the method steps comprising: generating a plurality of channel realizations in response to the predefined channel belt margins; rejecting invalid ones of the plurality of channel realizations thereby generating a plurality of valid channel realizations; and gridding tops and bases of the plurality of valid channel realizations.  
           [0010]    Further scope of applicability of the present invention will become apparent from the detailed description presented hereinafter. It should be understood, however, that the detailed description and the specific examples, while representing a preferred embodiment of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become obvious to one skilled in the art from a reading of the following detailed description.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    A full understanding of the present invention will be obtained from the detailed description of the preferred embodiment presented herein below, and the accompanying drawings, which are given by way of illustration only and are not intended to be limitative of the present invention, and wherein:  
         [0012]    [0012]FIGS. 1 and 2 illustrates a workstation or personal computer that stores the ChannelMod software of the present invention which receives rock classifications as input data and generates a computer model representation of grids that represent the architecture of fluvial reservoirs;  
         [0013]    [0013]FIG. 3 illustrates by aerial photograph of a modern river the processes by which ‘fluvial reservoirs’ are formed;  
         [0014]    [0014]FIG. 4 illustrates an example of how the rock classification input data may be derived;  
         [0015]    [0015]FIG. 5 illustrates the concept of two-dimensional (2-D) and three-dimensional (3-D) grids;  
         [0016]    [0016]FIG. 6 illustrates a construction of the FlowGrid software of FIG. 2 including a simulator for generating simulation results and displaying the simulation results on the 3D Viewer;  
         [0017]    [0017]FIG. 7 illustrates an example of a set of simulation results that are generated by the simulator and displayed on the 3D Viewer of FIG. 6;  
         [0018]    [0018]FIG. 8 illustrates an example of the ‘grids representing the architecture of fluvial reservoirs’  22  of FIG. 2 representing the base of a channel belt which are generated as an output by the ChannelMod software of FIG. 2 when the ChannelMod software of the present invention is executed by the workstation processor, the ‘grids’  22  being provided as input data to the FloGrid software  30  via GeoFrame of FIG. 2;  
         [0019]    [0019]FIG. 9 illustrates an example of a three dimensional computer representation of the channel belt of FIG. 8 that is displayed on the 3D Viewer  42  of FIG. 2 and which corresponds to the ‘grids representing the architecture of fluvial reservoirs’  22  of FIG. 2 generated by the workstation computer system of FIG. 1;  
         [0020]    [0020]FIG. 10 illustrates a schematic cross section of the channel belt of FIG. 9.  
         [0021]    [0021]FIG. 11 illustrates a more detailed construction representing a workflow of the ChannelMod software stored in the memory of the computer system shown in FIG. 1;  
         [0022]    [0022]FIG. 12 illustrates the input parameters that can be controlled in the ChannelMod software;  
         [0023]    [0023]FIG. 13 illustrates the definition of base channel radius and channel width and the manner in which channel radius varies between successive meander loops;  
         [0024]    [0024]FIG. 14 illustrates the control exerted on channel direction by the Wiggle Factor;  
         [0025]    [0025]FIG. 15 illustrates the process whereby successive channel units stack to form a channel belt;  
         [0026]    [0026]FIG. 16 which includes FIGS. 16A, 16B, and  16 C illustrates three model realizations generated by the ChannelMod software;  
         [0027]    [0027]FIG. 17 illustrates the process applied to ensure that all input data are honored in the minimum number of realizations;  
         [0028]    [0028]FIG. 18, which includes FIGS. 18A and 18B, and FIG. 19, which includes FIGS. 19A and 19B, illustrate the method embodied in the ChannelMod software for testing the validity of each model realization;  
         [0029]    [0029]FIG. 20, which includes FIGS. 20A and 20B, and FIG. 21, which includes FIGS. 21A and 21B, illustrate the grids generated by the ChannelMod software;  
         [0030]    [0030]FIG. 22 illustrates the process of simulating channel scouring by surface truncation in Framework 3D software  29  of FIG. 2;  
         [0031]    [0031]FIG. 23 illustrates the different rock volumes that can be calculated using the ChannelMod software; and  
         [0032]    [0032]FIGS. 24 through 45 are referenced in the ‘Detailed Description of the Invention’ section of this specification, wherein:  
         [0033]    [0033]FIG. 24 illustrates an Aerial view of a modern channel belt;  
         [0034]    [0034]FIG. 25 illustrates a Conceptual model of a channel belt, as applied in ChannelMod;  
         [0035]    [0035]FIG. 26 illustrates Control on amount of base level rise;  
         [0036]    [0036]FIG. 27 illustrates a Schematic representation showing the logic of simulating successive channel units to fit wells with progressively shallower channel unit bases;  
         [0037]    [0037]FIG. 28 illustrates a definition in terms of circles;  
         [0038]    [0038]FIG. 29 illustrates a depiction of the ChannelModeling process;  
         [0039]    [0039]FIG. 30 illustrates a Chart depicting a Point Bar sheet showing one simulation of the channel course and point bar locations;  
         [0040]    [0040]FIG. 31 illustrates a CPS-3 base map showing channel belt margins in purple, wells within channels in white and wells outside channels as red circles;  
         [0041]    [0041]FIG. 32 illustrates an Input Polyline worksheet;  
         [0042]    [0042]FIG. 33 illustrates an Input Parameters worksheet;  
         [0043]    [0043]FIG. 34 illustrates a Test-Point Bar worksheet;  
         [0044]    [0044]FIG. 35 illustrates a first part of macro “Export2” in workbook Export.xls;  
         [0045]    [0045]FIG. 36 illustrates a First dialogue box to appear after macro “Export2” has created text files Book1.txt to Book40.txt;  
         [0046]    [0046]FIG. 37 illustrates a third dialogue box to appear after macro “Export2” has created text files Book1.txt to Book40.txt.  
         [0047]    [0047]FIG. 38 illustrates a Dialogue box that appears when macro “Export2” has finished running;  
         [0048]    [0048]FIG. 39 illustrates a First part of macro “FRAMEWORK” in the CPS directory;  
         [0049]    [0049]FIG. 40 illustrates a Map of channels and point bars generated in CPS-3 by macro “Map”;  
         [0050]    [0050]FIG. 41 illustrates a Model Editor window showing how polygon (yellow) can be defined for adding a value of −1 to all grid values within the polygon;  
         [0051]    [0051]FIG. 42 illustrates Structure contours on base of channel belt;  
         [0052]    [0052]FIG. 43 illustrates the First part of macro “VOLUMETRICS” in the CPS directory;  
         [0053]    [0053]FIG. 44 illustrates the First part of macro “Vol_Import” in workbook ChannelMod*.xls; and  
         [0054]    [0054]FIG. 45 illustrates a Workbook Vol_Table, generated by macro “Vol_Import”.  
     
    
     DESCRIPTION OF THE INVENTION  
       [0055]    As rivers meander across a floodplain, they deposit sediments on the inside bank of each meander loop. The resulting accumulation of sand or gravel, together with minor proportions of mud, is known as a “point bar”. As the meandering process continues, the meander loops move in a downstream direction, such that sediment is continually eroded from the upstream edge of each point bar and deposited at the downstream edge. This process continues until the river changes course upstream, at which point the channel is abandoned. The abandoned meander loops then become “oxbow lakes” that eventually fill with mud. At some later time, an active river channel might return to the area as a result of further changes in course; this new channel will tend to erode away all or part of the earlier-formed point bars and channel mud fills. However, continuing subsidence will reduce the severity of this erosion. The end result of a long period of river flow is the deposition of a “channel belt” containing a complex spatial distribution of partly preserved point bars, channel mud fills and the predominantly muddy sediments of the floodplain.  
         [0056]    After burial under a sediment overburden, channel belts can become filled with oil or gas to become “fluvial reservoirs” in oil or gas fields. In such reservoirs, the point bars provide storage capacity for the oil or gas and also a conduit for fluid movement, while the channel mud fills, now lithified to shale, act as barriers to the movement of oil or gas.  
         [0057]    Since fluvial reservoirs do not comprise or include uniform slabs of sand, there exists in each such reservoir a plurality of curvilinear lines of shale (the channel mud fills) that can badly affect the production of oil or gas from the reservoir. The ‘method and program storage device’ of the present invention ‘for generating grids representing the architecture of fluvial reservoirs’ will predict the specific locations in the oil or gas reservoir where the plurality of curvilinear lines of mud will exist. These locations of the curvilinear channel mud fills in the reservoir will be displayed on a ‘computer representation of the reservoir’ which is generated as an output display by the present invention. The aforementioned ‘computer representation of the reservoir’ is actually a model of the ‘heterogeneity’ of the oil or gas reservoir.  
         [0058]    Referring to FIG. 1, a workstation or other computer system, which stores the ChannelMod software of the present invention for generating grids representing the architecture of fluvial reservoirs, is illustrated. In FIG. 1, a computer system  10  includes a processor  12  operatively connected to a system bus, a recorder or display device  14  operatively connected to the system bus, and a memory  16  operatively connected to the system bus.  
         [0059]    Referring to FIG. 2, the memory  16  is adapted to store a ‘ChannelMod’ software  18  in accordance with the present invention. The ‘ChannelMod’ software  18  is initially stored on a CD-Rom or other program storage device, the ‘ChannelMod’ software  18  being loaded from the CD-Rom into the memory  16  of the computer system  10  for storage therein. The computer system  10  may be a personal computer (PC), a workstation, or a mainframe. Examples of possible workstations include a Silicon Graphics Indigo 2 workstation or a Sun SPARC workstation or a Sun ULTRA workstation or a Sun BLADE workstation. The memory  16  is a computer readable medium or a program storage device which is readable by a machine, such as the processor  12 . The processor  12  may be, for example, a microprocessor, microcontroller, or a mainframe or workstation processor. The memory  16 , which stores the ChannelMod software  18 , may be, for example, a hard disk, ROM, CD-ROM, DRAM, or other RAM, flash memory, magnetic storage, optical storage, registers, or other volatile and/or non-volatile memory.  
         [0060]    In FIGS. 1 and 2, the computer system  10  receives, as input data, a plurality of wireline logs which further include a plurality of rock classifications  20 , to be described with greater detail below with reference to FIG. 4. When the processor  12  executes the ChannelMod software  18  stored in the memory  16  of the workstation  10 , a plurality of ‘grids’  22  are generated as output data (see FIG. 2), the ‘grids’  22  of FIG. 2 representing a ‘plurality of model realizations which further represent the architecture of a fluvial reservoir’. The concept of ‘grids’ will be discussed in greater detail below with reference to FIG. 5. A computer model representation of the grids  22  is ultimately displayed on a 3D Viewer  42 .  
         [0061]    In FIG. 2, the memory  16  of the computer system  10  is illustrated. The memory  16  stores the ChannelMod software  18  adapted for generating the ‘grids representing the architecture of fluvial reservoirs’  22  (hereinafter called ‘grids  22 ’) in response to the rock classifications  20 , the ‘grids  22 ’ of FIG. 2 further representing a ‘plurality of model realizations which further represent the architecture of a fluvial reservoir’. The GeoFrame software  24  includes a CPS software  26 , a Framework 3D software  29 , a Property 3D software  28 , and a Master Database  27 . The grids  22  are provided to the ‘Framework 3D’  29  and ‘Property3D’  28  software in GeoFrame  24 . The CPS software  26  is operatively connected to the ChannelMod software  18  via line  19  in FIG. 2. The output of the Property3D software  28  is operatively connected to a FloGrid software  30 , and the output of the FloGrid software  30  is operatively connected to the 3D Viewer  42  via a simulator  40 .  
         [0062]    Seven separate blocks of software are illustrated in FIG. 2: (1) ‘GeoFrame’  24 , (2) ‘CPS’  26 , (3) ‘Framework3D’  29 , (4) ‘Property3D’  28 , (5) ‘FloGrid’  30 , (6) ChannelMod  18  and (7) the simulator  40 . Each of these seven blocks of software are owned by Schlumberger Technology Corporation of Houston, Tex. The ‘FloGrid’ software  30  is disclosed and claimed in U.S. Pat. No. 6,106,561 to Farmer, the disclosure of which is incorporated by reference into the specification of this application.  
         [0063]    In FIG. 2, the grids  22  of FIG. 2, generated as an output by the ChannelMod software  18  of the present invention in response to the rock classifications  20 , are used by the ‘Framework3D’  29  and ‘Property3D’  28  portion of ‘GeoFrame’  24  for subsequent use by the ‘FloGrid’  30  software. The ‘Framework 3D’  29  software is used to truncate grids  22  as a means of simulating channel erosion, while the ‘Property 3D’  28  software is used to generate 3-D grids to embody the reservoir architecture represented by the grids  22  of FIG. 2. When the FloGrid software  30  receives the grids  22  from the GeoFrame software  24 , a ‘simulation grid output’ is generated by the FloGrid software  30 . A simulator  40  receives that ‘simulation grid output’, and, responsive thereto, the simulator  40  generates a plurality of ‘simulation results’ which are displayed on a 3D Viewer  42 . These concepts are discussed in greater detail in U.S. Pat. No. 6,106,561 to Farmer and hereinbelow with reference to FIGS. 7 and 8 of the drawings.  
         [0064]    Referring to FIG. 3, an aerial photo of a channel belt or fluvial reservoir is illustrated. Recall from FIG. 2 that a plurality of grids  22  representing the architecture of a ‘fluvial reservoir’ are generated by the ChannelMod software  18 . FIG. 3 illustrates an example of an aerial photograph of a modern river. In FIG. 3, sands consisting mainly of sand are deposited in the point bar  31 . Following channel abandonment, the channel  32  will become filled with mud  35 . If the river channel of FIG. 3 subsequently forms a part of an oilfield reservoir, the channel mud fill  35  will represent a barrier to the subsequent flow of oil or gas from that oilfield reservoir.  
         [0065]    Referring to FIG. 4, a more detailed description of the rock classifications  20 , being provided as input data to the workstation or computer system of FIG. 1, is illustrated. Wireline log responses  33  are interpreted in terms of the depositional environment in which the sediments causing the responses were laid down. A indicator log  34  is then constructed to represent the interpreted depositional environment; the different values assigned to this log  34  thus represent a rock classification scheme  20 . In FIG. 4 three such facies or rock classifications  20  are shown: channel  35 , splay  36  and floodplain  37 . In this example, no channel fill shale is interpreted. The ‘rock classification’  20  in FIG. 4 is provided as input data to the computer system  10  of FIG. 1 which stores the ChannelMod software  18  of the present invention in the memory  16 . As an alternative approach, the rock classification generation software as described in prior pending U.S patent application Ser. No. 10/338,380 filed Jan. 8, 2003, entitled “Rock Classification Method and Apparatus”, may be used. The disclosure of the latter is incorporated by reference into the specification of this application.  
         [0066]    Referring to FIG. 5, a more detailed discussion of the ‘grids’ in block  22  of FIG. 2 (i.e., grids  22 ) is set forth in the following paragraph with reference to FIG. 5. In FIG. 5, 2-D grids represent the upper  51  and lower  52  bounding surfaces of a point bar. Such 2-D grids are generated by the ChannelMod software  18  (see ‘grids representing architecture of fluvial reservoirs’  22  in FIG. 2). However, the FloGrid software  30  of FIG. 2 operates on grid representations of rock volumes rather than surfaces. Thus, the point bar of FIG. 5 must be represented as a 3D grid  53  of FIG. 5. This conversion is carried out by ‘Property 3D’ software  28  (FIG. 2).  
         [0067]    Referring to FIG. 6, a more detailed construction of the FloGrid software  30  is illustrated. The FloGrid software  30  is operatively connected to the simulator  40 , the simulator  40  being operatively connected to the 3D Viewer  42 . In FIG. 5, the FloGrid software  30  receives ‘horizon data, fault data, and geo-cellular models’  50 ; however, the FloGrid software  30  also receives the grids  22  of FIG. 2. The FlowGrid software  30  includes the following blocks: a reservoir data store which receives the ‘horizon data, fault data, and geo-cellular models’  50 , a structural framework, an upgridder, a property modeler, structured and unstructured gridders, either of which can receive the grids  22  of FIG. 2, and an upscaler. Each of these blocks of the FloGrid software  30  in FIG. 6 are described in detail in U.S. Pat. No. 6,106,561 to Farmer, the disclosure of which has already been incorporated by reference into the specification of this application. In FIG. 6, the upscaler of the FloGrid software  30  will generate a ‘simulation grid output’ and the ‘unstructured gridder’ of the FloGrid software  30  will also generate a ‘simulation grid output’. In response to both ‘simulation grid outputs’, the simulator  40  will generate a plurality of ‘simulation results’ which will be displayed on the 3D Viewer  42 .  
         [0068]    Referring to FIG. 7, an example of the ‘simulation results’ generated by the simulator  40  and displayed on the 3D Viewer  42  of FIG. 6 is illustrated.  
         [0069]    Referring to FIG. 8, recall from FIGS. 1 and 2 that the ChannelMod software  18  will generate the ‘grids’  22 , representing the ‘architecture of fluvial reservoirs’ when the processor  12  executes the ChannelMod software  18  stored in the memory  16  in response to the rock classifications  20 . FIG. 8 illustrates an example of the ‘grids’  22  of FIG. 2 which represents a ‘plurality of model realizations representing an architecture of a fluvial reservoir’ generated by the ChannelMod software  18  of FIG. 2. FIG. 8 comprises a plurality of grid cells. Each grid cell will be assigned a color depending on the numerical property assigned to that grid cell. As a result, FIG. 8, which represents depth to the base of a channel belt, includes a plurality of colors corresponding, respectively, to the plurality of grid cells which comprise the channel belt of FIG. 8.  
         [0070]    Referring to FIG. 9, when the ChannelMod software  18  is executed by the processor  12  of the computer system  10  of FIG. 1, a ‘final output display’ is displayed on the 3D Viewer  42 , and that ‘final output display’ is illustrated in FIG. 9. FIG. 9 illustrates a three dimensional ‘computer model representation’ of the channel belt aerial photo of FIG. 3, FIG. 9 representing a plurality of grids, the plurality of grids being adapted for display on a display device, such as the 3D Viewer  42 . FIG. 9 appears on the 3D Viewer  42  and it corresponds to the ‘grids’  22  in FIGS. 2 and 8 that are generated by the ChannelMod software  18  representing the ‘architecture of fluvial reservoirs’. In FIG. 9, an illustration  42  which is displayed on the 3D Viewer  42  of FIG. 2 includes a channel belt  52 . The channel belt  52  includes a first element  52   a  representing sand through which oil or gas can flow and a second element  52   b  representing shale, through which oil or gas cannot flow. The impervious rock of the second element  52   b  represents a barrier because oil or gas cannot flow through the barrier. As a result, the oil or gas cannot flow directly from a first element  52   a,  through a second element  52   b,  and back into another first element  52   a  because the impervious rock of the second element  52   b  represents a barrier through which oil or gas cannot flow. As a result, the illustration  42  of FIG. 9 is a ‘computer model representation’ of the internal architecture of a fluvial reservoir. Consequently, the illustration  42  in FIG. 9 is a visualization of the ultimate grid output generated in response to the execution of the ChannelMod software  18  by the processor  12  of computer system  10 . The illustration  42  of FIG. 9 is displayed on the 3D Viewer  42 .  
         [0071]    Referring to FIG. 10, a cross section of the channel belt  52  of FIG. 9 is illustrated. In FIG. 10, several layers of the reservoir or channel belt  52  of FIG. 9 are illustrated in cross section. Note a plurality of the first elements  52   a  in a plurality of layers of the channel belt  52  which represent the sand through which the oil and/or gas can flow and further note a plurality of the second elements  52   b  in another plurality of layers of the channel belt  52  which represents the shale or other impervious rock through which the oil and/or gas cannot flow.  
         [0072]    Referring to FIGS. 11 through 23, a workflow, for which the ChannelMod software  18  stored in the memory  16  of the computer system  10  of FIG. 1 is designed, is illustrated in FIG. 11. In FIG. 11, that workflow includes the following steps: (1) Define channel belt margins and digitize  18   a,  (2) Set other input parameters  18   b,  (3) Generate multiple channel realizations  18   c,  (4) Reject invalid realizations  18   d,  (5) Grid tops and bases of channel units  18   e,  (6) Simulate scour by surface truncation  18   f,  (7) Export ‘final 2D grids’  18   g,  where the ‘final 2D grids’ represent the grids  22  of FIG. 2, the grids  22  further representing the ‘plurality of model realizations representing the architecture of a fluvial reservoir’, (8) Convert grids to 3D  18   h,  (9) Export final 3D grids to FloGrid  18   i,  and (10) Volumetrics  18   j  and  18   k.  Each of these steps will be discussed in detail below. Steps  18   b  to  18   f  inclusive, and  18   j,  are performed by the ChannelMod software  18  of FIG. 2.  
         [0073]    Define Channel Belt Margins and Digitize, step  18   a  of FIG. 11  
         [0074]    In FIG. 2, it is necessary to set up a framework in GeoFrame  24 , since the Master Database  27  resides in GeoFrame  24 . Using the data residing in GeoFrame  24 , and, in particular, the rock classifications  20  of FIGS. 1 and 2, we can define the ‘limits of the channel belt’, such as the channel belt  52  in FIG. 9 (see also FIG. 31). In FIG. 2, those ‘limits’, as defined in GeoFrame  24 , are then provided by the GeoFrame software  24  to the ChannelMod software  18  via line  17  in FIG. 2.  
         [0075]    Set Other Input Parameters, step  18   b  of FIG. 11  
         [0076]    In FIGS. 11, 12,  13 ,  14 , and  15 , the output from Channel Mod software  18  in FIG. 2 depends not only on the ‘rock classifications’ input data  20  of FIG. 2 and the ‘limits of the channel belt’ from step  18   a  but also on the settings assigned to a number of input parameters. The parameters that can be altered by the user are shown in FIG. 12. Those parameters may be classified into three groups  54 ,  55  and  56  in FIG. 12. First are the parameters that control the size and shape of the individual meander loops as shown in  54  of FIG. 13. The software incorporates a random number generator  54   a  in FIG. 13 to allow generation of a plurality of loop sizes. Second are the parameters that influence extent to which the course of the modeled channel varies, or “wiggles”, as shown in  55  of FIG. 14. Another random number generator  55   a  in FIG. 14 is incorporated to allow generation of a plurality of channel courses within the constraint provided by the wiggle factor  55   b  in FIG. 14. Third are the parameters that control the vertical thickness of the channel belt and its component channel units, as illustrated in  56  of FIG. 15. Note that the thickness of each channel unit  56   a,    56   b  and  56   c  in FIG. 15 represents its original deposited thickness, such that the sum of thicknesses of individual channel units can exceed the thickness of the channel belt, as is the case in  56  of FIG. 15. In such cases, part of all or some of the units is removed by simulated erosion to ensure that the sum of the final thicknesses of the channel units  56   c,    56   d  and  56   e  in FIG. 15 is equal to the thickness of the channel belt.  
         [0077]    Generate Multiple Channel Realizations, step  18   c  of FIG. 11  
         [0078]    In FIGS. 11, 16A,  16 B,  16 C, and  17 , when the ‘limits of the channel belt’ are provided to the ChannelMod software  18  from step  18   a,  the ChannelMod software  18  will then generate a plurality of channels (first one channel then another channel). As a result, when the ChannelMod software  18  generates the plurality of channels, a ‘plurality of statistical realizations’  57   a,    57   b  and  57   c  in FIGS. 16A, 16B, and  16 C, are created corresponding, respectively, to the plurality of channels. FIGS.  16 A- 16 C depict one of the well data points as being a “conditioning well”  57   d.  This well is selected on the ‘Input Parameters’ worksheet of ChannelMod software  18 ; the program then ensures that all realizations are ‘conditioned’ by, or honor, that data point. Thus the ‘conditioned well’  57   d  is known from ‘Rock Classifications’  20  to contain a point bar in the channel unit being modeled for FIGS. 16A through 16C. However it will not necessarily be possible to honor all the other wells using one specific well for conditioning. In such cases, other wells need to be selected for conditioning. The logical process for doing this is shown in FIG. 17. Channel units are modeled one at a time. After selecting the first channel unit  66 , one well  67  is selected as the conditioning well. Multiple realizations  68  are then run; invalid realizations are rejected  69  and grids are saved for each valid realization  70 . This continues until no improvement in the degree of fit to the input data is possible. At that point, a different well is selected for conditioning  71  unless all the wells in the channel unit have been honored in at least one realization  72 . The process is then repeated using a series of new conditioning wells until all the wells have been honored. Once that has happened, the process is repeated for the next channel unit  73 .  
         [0079]    Reject Invalid Realizations step  18   d  of FIG. 11  
         [0080]    In FIGS.  11 ,  18 A- 18 B, and  19 A- 19 B, the following paragraph describes the process whereby invalid realizations are rejected, as shown in step  69  of FIG. 17. If a particular statistical realization indicates that there is a sand body in a particular well and it is known that shale (and not sand) exists in that particular well, that particular statistical realization must be rejected. Thus, for example, Channel unit 1  58   a  in FIGS. 18A and 18B can occur in Well 4  58   b  but not Wells 1, 2 and 3  58   c.  Similarly, Channel unit 2  59   a  in FIGS. 19A and 19B can occur in Wells 3  59   c  and 4  59   b  but not in Wells 1 and 2  59   d.  The ‘plurality of statistical realizations’ is continuously tested in this manner via a do-loop  18   d   1  in FIG. 11. The do-loop  18   d   1  in FIG. 11 ensures that the multiple channel realizations of step  18   c  are continuously generated and that the generated multiple channel realizations are continuously tested in the ‘reject invalid realizations’ step  18   d  of FIG. 1. Testing is carried out using the spreadsheet  60  in FIGS. 19A and 19B. As a result, a plurality of ‘valid channel realizations’ are generated by the ChannelMod software  18  of FIG. 11.  
         [0081]    Grid Tops and Bases of Channel Units, step  18   e  of FIG. 11  
         [0082]    In FIGS. 11, 17,  20 A- 20 B, and  21 A- 21 B, for every valid realization generated by ChannelMod software  18 , grids representing the tops and bases of the modeled channel units are saved as indicated at  70  in FIG. 17. Examples of the resulting 2-D grids are shown in FIGS.  20 A- 20 B and  21 A- 21 B. The numbers in red correspond to the value of the grid at the grid nodes represented by black crosses. Note that the grids are indeterminate outside the area occupied by the channel unit being modeled.  
         [0083]    Simulate Scour by Surface Truncation, step  18   f  of FIG. 11  
         [0084]    In FIGS. 11 and 22, at this point, it is necessary to simulate an occurrence, called ‘scouring’, whereby one channel will cut into another channel; that is, a later generated channel will erode away another previously generated channel. The Framework3D software  29 , part of GeoFrame  24 , will simulate the ‘scouring’ by surface truncation as illustrated in FIG. 22. Three simulations, of Channel Units  61   a,    61   b  and  61   c  of FIG. 22, are submitted to surface truncation in the Framework3D software  29  to produce 2-D grids representing the configuration  62  in FIG. 22.  
         [0085]    Export Final 2D Grids, step  18   g  of FIG. 11  
         [0086]    When the ‘scouring’ is completed, the ‘two-dimensional (2-D) grids of the original and eroded top and base surfaces of these channels’ are transferred to the ‘Property3D’ software  28  of FIG. 2. The aforementioned ‘two-dimensional (2-D) grids of the original and eroded top and base surfaces of these channels’ represent the ‘plurality of model realizations representing the architecture of a fluvial reservoir’.  
         [0087]    Convert Grids to 3D, step  18   h  of FIG. 11  
         [0088]    Export Final 3D Grids to FloGrid, step  18   i  of FIG. 11  
         [0089]    Volumetrics, steps  18   j  and  18   k  of FIG. 11  
         [0090]    In FIGS. 11 and 23, the ‘two-dimensional (2D) grids of the original and eroded top and base surfaces of these channels’ can now be converted to three dimensions (3-D) using the ‘Property3D’ software  28  and transferred to FloGrid  30  in RESCUE file format. The Volumetrics can be accomplished either in either step  18   j  using ‘CPS’  26 , or in step  18   k  using ‘Property3D’  28 . Referring to FIG. 23, step  18   j  is part of ChannelMod software  18  and allows calculation of total channel belt volume  63 , channel unit volume  64 , sand volume  65   a,  and shale volume  65   b.    
       Detailed Description of the Invention  
       [0091]    The following ‘Detailed Description of the Invention’ represents a functional specification associated with the ChannelMod software  18  shown in FIG. 2 of the drawings.  
         [0092]    Refer now to FIGS. 24 through 45.  
       1. Introduction  
       [0093]    The objectives of this document are to:  
         [0094]    1. Record the philosophy and mathematical basis of the ChannelMod algorithm;  
         [0095]    2. Provide guidance as to how the algorithm should be used.  
         [0096]    ChannelMod was developed to provide a means of modeling fluvial reservoirs that would be complementary to FluvSim, the currently available method in GeoFrame. This was deemed necessary for two reasons:  
         [0097]    a. Because FluvSim does not allow generation of realistic models representing the shale plugs that commonly form important barriers within fluvial reservoirs  
         [0098]    b. Because FluvSim does not provide grids that represent the bounding surfaces of the sand bodies; such grids are required under circumstances in which a deterministic reservoir model is to be simulated in Eclipse.  
         [0099]    ChannelMod is designed to be used with GeoFrame. The grids are generated in CPS-3 so that they can be exported directly into FlowGrid. However, owing to lack of access to the GeoFrame code, the channel simulation itself is done in an Excel 2000 workbook. Ultimately it would probably be advisable to incorporate the Excel logic into GeoFrame code so that simulation and mapping can be done in a single environment. The next section of the report discusses the workflow under which information moves from Excel to GeoFrame and back to Excel.  
         [0100]    Following the workflow discussion, the report describes in detail the structure and content of the Excel workbook containing the simulation algorithm. After this description, instructions are provided for applying ChannelMod.  
       2. Workflow  
       [0101]    ChannelMod generates grids that represent the tops and bottoms of point bars and channel fills within a multi-storey channel belt that is a product of deposition from successive channel systems. The channel belt associated with a modern river is illustrated in FIG. 24, which shows how abandoned channel fills are partially preserved between point bar deposits.  
         [0102]    A key requirement of the method is to generate grids that represent the channel fills, which commonly comprise mud and thus act as important barriers to fluid flow within reservoirs.  
         [0103]    The ChannelMod system comprises 2 Excel workbooks and 4 CPS-3 macros:  
         [0104]    ChannelMod*.xls  
         [0105]    Export.xls  
         [0106]    FRAME WORK.mac  
         [0107]    VOLUMETRICS.mac  
         [0108]    VOLUMETRICS_AOI.mac  
         [0109]    Map.mac  
         [0110]    The workflow is shown in FIG. 11. It is assumed that all the well and seismic data that will provide constraint to the ChannelModel are contained within an existing GeoFrame project. The process begins with definition of the margins of the channel belt within GeoFrame. These margins are digitized and exported to the Excel workbook ChannelMod*.xls, in which the simulation is performed. After simulation, the resulting polygon and data files representing the modeled point bars and channel fills are exported to GeoFrame where CPS-3 is used to truncate each storey base and point bar top by successively younger storeys of the channel belt. Volumetrics can be calculated at this point. The final step is to convert the 2-D grids from CPS-3 into 3-D grids within Property3D.  
       3. The ChannelMod Simulation Algorithm  
       [0111]    The algorithm is designed to model a channel and its associated point bars for all the storeys in a multi-storey channel belt. It is assumed that the channel belt is represented in all the wells penetrating it by a single interval comprising point bar sandstones or channel-fill shales. The base of this interval is set relative to the top, such that the depth of the base corresponds to the thickness of the channel belt (FIG. 25). This interval is divided into successive storeys, such that the relative depths of each successive storey represent the amount of rise in base level (FIG. 26). The interval of rock deposited before erosion to generate a storey is termed a “channel unit” (FIG. 27).  
         [0112]    Each channel unit is modeled separately by one or more simulations. Simulation is repeated until all the wells representing a point bar or channel for the channel unit in question have been correctly located within point bars or channels (FIG. 27). For each simulation, one well is set as a data point to which the simulation is conditioned. The same well can be used in any number of simulations. In addition the algorithm determines how many of the other wells are correctly located.  
         [0113]    The algorithm resides within Excel workbook ChannelMod*.xls, which contains 9 worksheets. The purpose of each of these is discussed below.  
         [0114]    3.1. Input Polyline sheet  
         [0115]    The purpose of this sheet is to interpolate X,Y values for the channel belt margins imported from GeoFrame. Up to 28 points can be imported; from these the worksheet interpolates 2 Y values (representing the margins of the channel belt) for each of 121 X values.  
         [0116]    3.2. Input Parameters sheet  
         [0117]    All the input parameters are specified in this sheet. Point bars and channel fills are assumed to be bounded by a combination of circle segments and circle chords, as shown in FIG. 28.  
         [0118]    Variation is allowed in the radius of each successive bounding circle by random proportions of a maximum percentage of a defined base radius. Variation in channel width is similarly defined. The extent to which the channel bends back on itself is controlled by means of a parameter termed “Wiggle Control”, which can comprise any number greater than or equal to 0.5. The larger the number, the closer will be the center of each circle to the center of the channel belt.  
         [0119]    Other parameters defined in this sheet are the thicknesses of the channel belt and the channel belt storeys and the depths to the top and base of the story being modeled. The sheet also specifies the locations of all the wells that provide constraint on the location of the channel belt, channels and point bars, and the location of the particular well to which the model is being conditioned.  
         [0120]    3.3. Calculation—Point Bar sheet  
         [0121]    The simulated channel path is constrained to stay almost entirely within the defined channel belt by ensuring that the maximum and minimum Y values of each circle are respectively less than and greater than the maximum and minimum Y values of the channel belt margin at a certain search distance from the center of the previous circle, as illustrated in FIG. 29. The search distance is set at the sum of the radii of the circle in question and the previous circle.  
         [0122]    The worksheet generates a channel containing 21 loops based on 21 circles placed as shown in FIG. 29. Each re-calculation of the sheet generates a new simulation, or realization. In each case, the conditioning well specified in the Input Parameters sheet falls within the point bar of Circle 1. The worksheet also determines whether each of the other wells specified in the Input Parameters sheet falls inside or outside a point bar.  
         [0123]    3.4. Calculation—Channel sheet  
         [0124]    This sheet differs from the Calculation—Point Bar sheet only in forcing the conditioning well to fall within a channel, and in determining whether each of the other wells falls inside or outside a channel.  
         [0125]    3.5. Chart—Point Bar sheet  
         [0126]    This chart shows a map of the channel and point bar boundaries for the simulation that was last performed, together with the boundaries of the channel belt and the locations of the conditioning well and all other control points (FIG. 30).  
         [0127]    3.6. Test—Point Bar sheet  
         [0128]    This sheet indicates how many of the wells are modeled correctly, in simulations conditioned to a well inside a point bar, as falling inside or outside a point bar or channel. It also allows the top and base of each successive story to be recorded.  
         [0129]    3.7. Test—Channel sheet  
         [0130]    This sheet is similar to the Test—Point Bar sheet except that it indicates results for simulations conditioned to a well inside a channel.  
         [0131]    3.8. Output Polygons  
         [0132]    This sheet contains the X,Y coordinates of the polygons that bound all the point bars and channel fills of the realization that was last performed. Successive realizations may be exported to a single workbook (Export.xls) using a macro entitled “Export” within ChannelMod*.xls.  
         [0133]    3.9. Output Data  
         [0134]    This sheet contains Z values corresponding to the top and base of the storey for all of the points specified in the Output Polygons sheet. These values are exported at the same time as the polygons when the “Export” macro is run.  
       4. Instructions for Use  
       [0135]    4.1. In GeoFrame CPS-3  
         [0136]    4.1.1. Digitize channel belt margins as polyline (FIG. 31).  
         [0137]    4.1.2. Export as ASCII file.  
         [0138]    4.2. In Excel  
         [0139]    4.2.1. Copy workbooks ChannelMod*.xls and Export.xls into project directory.  
         [0140]    4.2.2. Open Export.xls and delete all worksheets except Sheet 1, which should be blank.  
         [0141]    4.2.3. Open ChannelMod*.xls.  
         [0142]    4.2.4. Open ASCII file created in step 4.1.2 and copy to “Input Polyline” sheet of ChannelMod*.xls (FIG. 32).  
         [0143]    4.2.5. Set input parameters on “Input Parameters” sheet of ChannelMod*xls, including the depth to the top of the storey to be modeled (FIG. 33).  
         [0144]    4.2.6. Input well locations and depths to channel belt base, relative to the top of the channel belt in each well, to “Input Parameters” sheet and sort the wells in order of decreasing channel belt thickness (FIG. 33).  
         [0145]    4.2.7. Insert the value 1 in columns B and E of the “Test—Point Bar” or “Test—Channel” sheet for each well located in a point bar or channel for the storey being modeled (FIG. 34). Start with a storey corresponding to the thickest channel belt.  
         [0146]    4.2.8. Copy the X,Y coordinates of the well selected for conditioning into cells B14 and B15 of the “Input Parameters” sheet (FIG. 33).  
         [0147]    4.2.9. Set workbook to Manual calculation without “Recalculate before Save”.  
         [0148]    4.2.10. From the “Test—Point Bar” or “Test—Channel” sheet, run macro “ChkFirstUntil” to run first simulation. This will generate a realization having the correct number of wells located outside point bars and channels (FIG. 34).  
         [0149]    4.2.11. Check to see how many wells are correctly located within a point bar or channel (FIG. 34). For each correct well, set the base and top of the appropriate storey to the depths specified in the “Input Parameters” sheet. Run macro “Export” in ChannelMod*.xls to copy output polygons and data to new worksheets in Export.xls.  
         [0150]    4.2.12. If the first simulation does not correctly locate all the wells for the storey being modeled in point bars or channels, run macro “ChkFirstUntil” repeatedly until that condition is met. Run macro “Export” in ChannelMod*.xls.  
         [0151]    4.2.13. Repeat Steps 4.2.8 to 4.2.13, working down the list of wells in point bars or channels until each well has been modeled within a channel in at least one realization. The conditioning option can be used for any well that is difficult to fit. In each case, any number of wells with deeper storey bases than in the well in question can be located within the same channel as the latter well (FIG. 27).  
         [0152]    4.2.14. Delete text files Book1.txt to Book40.txt in destination directory.  
         [0153]    4.2.15. Edit macro “Export2” in Export.xls to ensure that correct destination directory is specified (FIG. 35). Then run macro “Export2” to copy all output polygons and data to text files Book1.txt to Book40.txt. Files in excess of number of channels modeled will automatically be assigned the same polygons as the first ChannelModeled, and data values of zero so that they do not truncate older surfaces. After starting the macro, click on the icon for Export.xls. When the macro has finished creating files Book1.txt to Book40.txt, a dialogue box will come up (FIG. 36); the answer to this question is “No”, for the first and all subsequent boxes asking the same question. The box will come up twice, and then another box will appear, to which the answer is “Yes” (FIG. 37). A long series of boxes will then appear, to which the answers are alternately “No” (for FIG. 36 type) and “Yes” (for FIG. 37 type). Finally, the box shown in FIG. 38 will appear; the “End” button should be pressed.  
         [0154]    4.3. In GeoFrame CPS-3  
         [0155]    4.3.1. Select modeling and display environment that will areally encompass all channel realizations.  
         [0156]    4.3.2. Digitize area of interest (e.g. lease area) as a sub-area of the project area if desired.  
         [0157]    4.3.3. Copy macro files FRAMEWORK.mac, VOLUMETRICS.mac, VOLUMETRICS_AOI.mac and Map.mac to the CPS directory.  
         [0158]    4.3.4. Edit macro “FRAMEWORK” to ensure that correct source directory is specified for importing text files Book1.txt to Book40.txt (FIG. 39). Run macro “FRAMEWORK” to generate truncated and gridded surfaces.  
         [0159]    4.3.5. If desired, run macro “Map” to generate map of channels (FIG. 40).  
         [0160]    4.3.6. Open Model Editor and load surface D1_base_merged_trunc, making the contour maximum and the contour interval both greater than the maximum thickness of the channel belt.  
         [0161]    4.3.7. In Model Editor, create a closed polygon corresponding to the channel belt margins (FIG. 41).  
         [0162]    4.3.8. Add −1 to all grid values inside the polygon and set all grid values outside the polygon to NULL. Save the resulting surface as CB_base.  
         [0163]    4.3.9. Close Model Editor.  
         [0164]    4.3.10. Back in the Main Module of CPS-3, perform Single Surface Logical Operation (B=b, if A=a, otherwise B=A) to substitute the minimum base storey depth for the −1 grid node values in surface CB_base (use the name CB_base as output).  
         [0165]    4.3.11. Perform Multiple Surfaces Logical Operation (C=MAX(A,B) If A or B is NULL, then C=NULL) to create a corrected Base Channel Belt surface from surfaces CB_base and D1_base_merged_trunc (use name CB_base as output).  
         [0166]    4.3.12. If desired, use Display functions in CPS-3 Main Module to generate a map of the base of the channel belt (FIG. 42).  
         [0167]    4.3.13. Perform another Single Surface Logical Operation (B=b, if A=a, otherwise B=A) to substitute zero values for the NULL grid node values in surface CB_base (use the name CB_base as output).  
         [0168]    4.3.14. Copy D20_top as CB_top.  
         [0169]    4.3.15. Transfer the grids for CB_base and CB_Top to GeoFrame, remembering to set attributes with named surfaces.  
         [0170]    4.3.16. In Framework3D, create a structural framework from CB_Top and CB_Base.  
         [0171]    4.3.17. Volumetrics can be calculated in CPS-3 using macros as described in the following steps, or they can be derived in Property3D using Grid Operations.  
         [0172]    4.3.18. Edit Macros “VOLUMETRICS” and “VOLUMETRICS_AOI” to ensure that the correct destination directory is specified for the volumetric output (FIG. 43).  
         [0173]    4.3.19. Run Macro “VOLUMETRICS” to generate text file of results for entire channel belt (rjames.vlm) after deleting all data from previous runs in rjames.vlm.  
         [0174]    4.3.20. Run Macro “VOLUMETRICS_AOI” to generate text file of results for channel belt within the area of interest (rjames.vlm) after deleting all data from previous runs in rjames.vlm.  
         [0175]    4.4. In GeoFrame Property3D  
         [0176]    4.4.1. Create a structural model from the above structural framework  
         [0177]    4.4.2. Use Direct Assignment in Property Population Manager to create 3-D grids corresponding to the CPS grids for channel fills (i.e. same value throughout columns at each X,Y location). Name them D1_CF_Top, D1_Base, etc.  
         [0178]    4.4.3. Multiply the ZAverage grid by −1 to convert it to a depth grid  
         [0179]    4.4.4. Use Blank Maximum and Blank Minimum in Grid Operations to create depth grids that have non-null values only between top and base of each channel. Name them D1_CF_Top_Depth, D1_Base_Depth, etc.  
         [0180]    4.4.5. Use Direct Assignment in Property Population Manager to overwrite non-null depth values with value 1. Name the grids D1_CF_Flag, etc. The value 1 will represent channel fills.  
         [0181]    4.4.6. Use Direct Assignment in Property Population Manager to overwrite null depth values with value 0. Overwrite the D*_CF_Flag grids. The value 0 will represent point bars.  
         [0182]    4.4.7. Add all of the D*_CF_Flag grids together to create a composite flag grid (e.g. CB_CF_Flag).  
         [0183]    4.4.8. Correct for any edge effects by using Direct Assignment in Property Population Manager to overwrite all Flag values greater than 1 with the value 1. Overwrite the CB_Flag grid.  
         [0184]    4.5. In Excel  
         [0185]    4.5.1. In ChannelMod*.xls, edit macro “Vol_Import” to ensure that correct source directory is specified (FIG. 44).  
         [0186]    4.5.2. In ChannelMod*.xls, run macro “Vol_Import” to create workbook Vol_Table.xls (FIG. 45).  
         [0187]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Technology Category: g