Page 168 - Reservoir Formation Damage
P. 168

150   Reservoir Formation Damage


















                           Figure  8-4.  Particles  approaching  a  pore  throat.



               and

                  k, = 0 otherwise                                        (8-16)

                   represents  the  critical  time  when  the  pore  throats  are  first  jammed
                t cr
               by  particles.
                  This  time  is  similar  to  the  screen-factor.  Himes  et  al.  (1991)  define
               the  screen-factor  as:
                  A  screen-factor  value  is  the  time  for  a  given  volume  of  a  solution
                  to  pass  through  a  network  of  five  lOO-U.S.-mesh  screens  stacked
                  together  and normalized  to  the  time  taken for  the carrier  fluid  alone
                  (usually  water).  A  higher  screen-factor  value  means  less  mobility
                  and  poor  injectivity. A value  of  one  indicates  equal  mobility  to  the
                  carrier  fluid.

               |3 is  the  pore  throat  to  particle  diameter  ration  given  by  (see Figure  S-4):

                                                                           (8-17)
                  P = D t/D p

               and  P cr  is the  critical  value below  which pore  throat  blocking  can  occur.
                  One  of the  factors affecting  the particle  migration through a pore  throat
               is  the  particle  size  relative  to  the  pore  throat  size.  The  hydraulic  tube
               diameter  is  given  by  the  Carman-Kozeny  equation:



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