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  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  Permian 
  of 
  the 
  Yates 
  and 
  Hobbs 
  pools 
  have 
  apparently 
  not 
  been 
  

   affected 
  by 
  fracturing. 
  In 
  contrast, 
  the 
  movement 
  of 
  oil 
  in 
  the 
  

   Panuco 
  field 
  in 
  Mexico 
  is 
  largely 
  due 
  to 
  fracturing 
  and 
  faulting 
  

   (Muir, 
  1934), 
  and 
  Lees 
  (1933) 
  considers 
  that 
  the 
  permeability 
  of 
  the 
  

   Asmari 
  limestone 
  in 
  the 
  Iranian 
  fields 
  is 
  primarily 
  due 
  to 
  fault 
  cracks. 
  

   Limestones 
  such 
  as 
  the 
  Asmari 
  and 
  the 
  El 
  Abra 
  have 
  enormous 
  per- 
  

   meability 
  over 
  wide 
  areas. 
  

  

  DISTANCE 
  OF 
  LATERAL 
  MIGRATION 
  

  

  One 
  of 
  the 
  most 
  debated 
  topics 
  in 
  petroleum 
  geology 
  is 
  the 
  extent 
  

   to 
  which 
  petroleum 
  has 
  migrated 
  from 
  one 
  area 
  to 
  another; 
  some 
  

   consider 
  that 
  such 
  movement 
  has 
  been 
  restricted 
  to 
  comparatively 
  

   short 
  distances 
  (Clark, 
  1934; 
  McCoy 
  and 
  Keyte, 
  1934), 
  while 
  others 
  

   contend 
  that 
  it 
  may 
  have 
  traveled 
  for 
  "tens 
  or 
  even 
  hundreds 
  of 
  

   miles" 
  (Rich, 
  1931). 
  

  

  The 
  basic 
  factors 
  which 
  determine 
  the 
  distance 
  of 
  lateral 
  migration 
  of 
  

   oil 
  and 
  gas 
  are 
  the 
  extent, 
  permeability, 
  and 
  continuity 
  of 
  the 
  carrier 
  

   beds. 
  In 
  the 
  hypothetical 
  case 
  of 
  a 
  carrier 
  bed 
  of 
  high 
  and 
  uniform 
  

   permeability 
  and 
  of 
  regional 
  extent 
  it 
  is 
  evident 
  that, 
  under 
  conditions 
  

   of 
  differential 
  pressure, 
  fluids 
  should 
  be 
  able 
  to 
  move 
  through 
  it 
  for 
  

   long 
  distances. 
  But 
  conditions 
  of 
  sedimentation 
  which 
  even 
  approach 
  

   such 
  uniformity 
  are 
  exceptional; 
  lateral 
  variation 
  is 
  the 
  normal 
  

   condition. 
  

  

  The 
  simplest 
  case 
  is 
  that 
  of 
  a 
  lenticular 
  sand 
  enclosed 
  within 
  shales 
  

   and 
  having 
  an 
  areal 
  extent 
  of 
  a 
  few 
  square 
  miles. 
  In 
  such 
  a 
  carrier 
  

   bed 
  the 
  movement 
  of 
  fluids 
  is 
  not 
  caused 
  by 
  artesian 
  pressure 
  but 
  by 
  

   forces 
  of 
  more 
  limited 
  scope 
  ; 
  it 
  occurs 
  most 
  readily 
  while 
  the 
  sediments 
  

   are 
  in 
  process 
  of 
  compaction 
  and 
  while 
  the 
  shales 
  are 
  sufficiently 
  per- 
  

   vious 
  to 
  permit 
  substantial 
  movement 
  across 
  bedding 
  planes. 
  During 
  

   this 
  interval 
  the 
  sand 
  would 
  have 
  received 
  from 
  the 
  source 
  beds 
  adja- 
  

   cent 
  to 
  or 
  near 
  it 
  its 
  quota 
  of 
  oil 
  and 
  gas. 
  It 
  is 
  difficult 
  to 
  see 
  how, 
  

   later, 
  after 
  compaction 
  and 
  lithification 
  are 
  essentially 
  completed, 
  

   much 
  migration 
  beyond 
  the 
  limits 
  of 
  the 
  sand 
  would 
  normally 
  occur. 
  

   Any 
  further 
  movement 
  of 
  fluids 
  in 
  a 
  carrier 
  bed 
  of 
  such 
  limited 
  extent 
  

   would 
  result 
  from 
  the 
  deformation 
  of 
  the 
  sedimentary 
  basin, 
  produc- 
  

   ing 
  tilting, 
  faulting, 
  and 
  folding. 
  Cementation 
  in 
  sands 
  and 
  lime- 
  

   stones 
  would 
  limit 
  lateral 
  migration 
  by 
  creating 
  restrictions 
  on 
  

   movement 
  comparable 
  to 
  lensing. 
  

  

  On 
  the 
  other 
  extreme 
  are 
  carriers 
  such 
  as 
  the 
  Woodbine 
  and 
  the 
  Da- 
  

   kota 
  in 
  which 
  artesian 
  conditions 
  are 
  known 
  to 
  occur 
  over 
  many 
  thou- 
  

   sands 
  of 
  square 
  miles. 
  Drilling, 
  both 
  for 
  water 
  and 
  for 
  oil, 
  have 
  dem- 
  

   onstrated 
  that 
  through 
  basins 
  such 
  as 
  East 
  Texas, 
  the 
  artesian 
  pressure 
  

   system 
  is 
  essentially 
  continuous 
  even 
  though 
  there 
  may 
  be 
  local 
  varia- 
  

   tions 
  in 
  permeability. 
  It 
  is 
  again 
  difficult 
  to 
  explain 
  how 
  such 
  an 
  

  

  