﻿190 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  tain 
  geology 
  (Krampert, 
  1934; 
  Coffin 
  and 
  DeFord, 
  1934) 
  have 
  sought 
  

   to 
  explain 
  the 
  absence 
  of 
  commercial 
  deposits 
  of 
  oil 
  in 
  certain 
  struc- 
  

   tures 
  otherwise 
  favorable 
  as 
  due 
  to 
  the 
  flushing 
  action 
  of 
  circulating 
  

   water. 
  

  

  Even 
  though 
  visible 
  evidences 
  of 
  the 
  escape 
  of 
  petroleum 
  from 
  under- 
  

   ground 
  reservoirs 
  may 
  not 
  be 
  detected, 
  evidence 
  is 
  accumulating 
  that 
  

   petroleum 
  and 
  petroleum 
  gases 
  penetrate 
  the 
  overlying 
  strata 
  and 
  

   eventually 
  reach 
  the 
  surface 
  in 
  minute 
  quantities. 
  Such 
  microseep- 
  

   ages 
  may 
  be 
  revealed 
  by 
  precise 
  chemical 
  analysis 
  of 
  soils 
  and 
  subsoils, 
  

   and 
  the 
  results 
  of 
  such 
  analyses 
  support 
  the 
  belief 
  that 
  in 
  some 
  degree 
  

   all 
  oil 
  deposits 
  are 
  subject 
  to 
  continuing 
  dispersion 
  (McDermott, 
  

   1940.) 
  

  

  DYNAMICS 
  OF 
  PETROLEUM 
  

  

  Petroleum 
  and 
  natural 
  gas, 
  as 
  they 
  occur 
  in 
  the 
  earth, 
  are 
  confined 
  

   under 
  pressure. 
  Their 
  geologic 
  history 
  is 
  one 
  of 
  motion, 
  and 
  in 
  their 
  

   movement 
  they 
  obey 
  laws 
  of 
  physics 
  related 
  to 
  the 
  flow 
  of 
  liquids 
  and 
  

   gases 
  (Muskat, 
  1937). 
  From 
  the 
  beginning 
  of 
  the 
  oil 
  industry 
  it 
  was 
  

   observed 
  that, 
  when 
  oil 
  and 
  gas 
  sands 
  were 
  penetrated, 
  the 
  fluids 
  which 
  

   they 
  contain 
  were 
  under 
  pressure, 
  the 
  amount 
  of 
  which 
  increased 
  

   normally 
  with 
  depth. 
  This 
  was 
  at 
  first 
  attributed 
  to 
  the 
  weight 
  of 
  the 
  

   overlying 
  rocks 
  and 
  was 
  called 
  "rock 
  pressure." 
  Lesley 
  (1885) 
  showed, 
  

   however, 
  that 
  the 
  pressure 
  of 
  the 
  oil 
  and 
  gas 
  in 
  the 
  reservoir 
  was 
  ap- 
  

   proximately 
  equivalent 
  to 
  the 
  artesian 
  head 
  for 
  the 
  corresponding 
  

   depth, 
  and 
  much 
  less 
  than 
  the 
  pressure 
  which 
  would 
  correspond 
  to 
  the 
  

   weight 
  of 
  the 
  overburden. 
  Nevertheless, 
  the 
  industry 
  continued 
  to 
  use 
  

   the 
  term 
  "rock 
  pressure," 
  and 
  it 
  was 
  not 
  until 
  many 
  years 
  later 
  that 
  

   pressure 
  under 
  which 
  fluids 
  are 
  confined 
  in 
  underground 
  reservoirs 
  

   was 
  termed 
  "reservoir 
  pressure" 
  (Heroy, 
  1928). 
  Reservoirs 
  which 
  

   occur 
  in 
  artesian 
  basins 
  and 
  are 
  controlled 
  by 
  hydrostatic 
  head 
  form 
  

   one 
  group, 
  while 
  those 
  in 
  which 
  the 
  porous 
  bed 
  does 
  not 
  reach 
  the 
  

   surface 
  and 
  consequently 
  is 
  not 
  directly 
  influenced 
  by 
  artesian 
  con- 
  

   ditions 
  form 
  another 
  group. 
  

  

  The 
  outstanding 
  example 
  of 
  a 
  large 
  oil 
  field 
  under 
  artesian 
  control 
  is 
  

   East 
  Texas, 
  in 
  which 
  the 
  reservoir 
  bed 
  is 
  the 
  Woodbine 
  sand. 
  This 
  

   formation 
  outcrops 
  in 
  east-central 
  Texas 
  and, 
  after 
  passing 
  under 
  the 
  

   East 
  Texas 
  syncline, 
  is 
  truncated 
  along 
  the 
  west 
  side 
  of 
  the 
  Sabine 
  

   uplift 
  to 
  form 
  a 
  stratigraphic 
  trap. 
  The 
  original 
  reservoir 
  pressure 
  in 
  

   this 
  field 
  was 
  1,620 
  pounds 
  at 
  3,300 
  feet 
  below 
  sea 
  level, 
  which 
  closely 
  

   approximates 
  the 
  calculated 
  hydrostatic 
  pressure. 
  It 
  is 
  probable 
  that 
  

   the 
  sand 
  is 
  continuously 
  porous 
  from 
  the 
  outcrop 
  to 
  the 
  field 
  and 
  that 
  

   the 
  fluids 
  in 
  it 
  are 
  governed 
  by 
  a 
  common 
  pressure 
  system 
  (Millikan, 
  

   1932, 
  p. 
  902). 
  

  

  Meinzer 
  (1936) 
  has 
  pointed 
  out 
  that, 
  in 
  coastal 
  plain 
  areas, 
  porous 
  

   horizons 
  may 
  have 
  a 
  submarine 
  outcrop 
  and 
  that 
  there 
  may 
  be 
  artesian 
  

  

  