Page 238 - The Geological Interpretation of Well Logs
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-  THE  GEOLOGICAL  INTERPRETATION  OF  WELL  LOGS  ~


             DELTAIC-FLUVIAL  ENVIRONMENTS

                  A.  CHANNEL-POINT  BAR                      8.  DELTA  BORDER  PROGRADATION
                     alluvial  or  fluvial
                                  grain  size




               25m




                                          erosion

                         GR  or  SP



               MARINE  ENVIRONMENTS

                  C.  TRANSGRESSIVE  MARINE  SHELF
                                  grain  size



                         GR  or  SP
               25m








               DEEP  SEA  ENVIRONMENTS

            PROXIMAL                                                                        DISTAL
              E.  SLOPE  CHANNEL   F.  INNER  FAN    G.  MIDDLE  FAN    H.  SUPRA-FAN     1,  BASIN
                                    CHANNEL            CHANNEL             DEPOSITIONAL    PLAIN
                                                                           LOBES
             26m                                                                  9.8








                 GR  or  SP        GR  or  SP

        Figure  14.5  Facies  indications  from  gamma  ray  (or  SP)  log  shapes.  These  are  idealized  examples  both  of  log  shape  and
        sedimentologic  facies,  (Modified  from  Serra,  1972;  Parker,  1977;  Galloway  and  Hobday,  1983).


        in  grain  size,  rather  than  the  direct  change  in  grain   Visher,  1968;  Doveton,  1986;  Finley  and  Tyler,  1986;
       size  itself.  However,  the  principles  are  similar  (Figure   Cant,  1992).  Once  an  interval  is  reliably  identified,  then
        14.5).                                            the  variations  in  log  shape  within  that  interval  give  an
         Once  established,  the  log  shape  system  can  be  used   indication  of  facies  variations  and  hence,  an  indication
        in  a  number  of  ways.  Maps  made  of  the  geographical   of  palacogeography  (Figure  14.6).  More  recently,  log
       distribution  of  log  shapes,  are  effectively  both  facies   shapes  have  been  used  as  a  too!  for  sequence  stratigraphy
        distribution  and  palaeogeographic  maps  (Saitta  and   (Van  Wagoner  er  al.,  1990),  with  variations  in  log  shape

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