﻿PETROLEUM 
  GEOLOGY 
  — 
  HEROY 
  175 
  

  

  6,000 
  pounds 
  per 
  square 
  inch. 
  When 
  pressures 
  of 
  that 
  magnitude 
  

   occur 
  in 
  combination 
  with 
  temperatures 
  of 
  300° 
  F., 
  their 
  potency 
  

   to 
  effect 
  chemical 
  changes 
  must 
  be 
  great. 
  

  

  Recent 
  unconsolidated 
  sediments 
  contain 
  large 
  amounts 
  of 
  water. 
  

   As 
  compaction 
  progresses, 
  fluids 
  in 
  the 
  strata 
  which 
  are 
  being 
  com- 
  

   pressed 
  are 
  forced 
  from 
  them. 
  While 
  this 
  movement 
  may 
  be 
  of 
  

   great 
  importance 
  in 
  connection 
  with 
  the 
  migration 
  of 
  petroleum 
  

   (Athy, 
  1930b), 
  it 
  may 
  also 
  be 
  a 
  significant 
  factor 
  in 
  the 
  chemi- 
  

   cal 
  reactions 
  which 
  produce 
  petroleum 
  by 
  facilitating 
  m®lecular 
  

   rearrangement. 
  

  

  AGGREGATION 
  

  

  The 
  work 
  of 
  Trask 
  and 
  others 
  has 
  indicated 
  that 
  there 
  is 
  great 
  varia- 
  

   tion 
  in 
  richness 
  of 
  organic 
  content 
  between 
  types 
  of 
  sediments 
  and 
  be- 
  

   tween 
  beds 
  in 
  the 
  same 
  geologic 
  section. 
  Vertical 
  variation 
  in 
  organic 
  

   content 
  is 
  generally 
  greater 
  than 
  horizontal 
  variation. 
  But, 
  after 
  full 
  

   allowance 
  has 
  been 
  made 
  for 
  such 
  differences, 
  the 
  fact 
  remains 
  that 
  

   organic 
  matter 
  is 
  quite 
  universally 
  distributed 
  throughout 
  sediments 
  of 
  

   marine 
  origin. 
  The 
  sediments 
  which 
  are 
  usually 
  richest 
  in 
  organic 
  

   matter 
  are 
  fine-textured 
  shales, 
  and 
  the 
  organic 
  matter 
  is 
  minutely 
  

   disseminated 
  through 
  them. 
  The 
  pore 
  spaces 
  of 
  such 
  sediments 
  are 
  of 
  

   capillary 
  dimensions, 
  and 
  older 
  sediments 
  of 
  this 
  character 
  are 
  highly 
  

   impervious 
  to 
  the 
  movement 
  of 
  fluids. 
  When 
  first 
  deposited, 
  such 
  sedi- 
  

   ments 
  were 
  clays 
  and 
  silts 
  with 
  large 
  volumes 
  of 
  interstitial 
  water 
  

   (Trask, 
  1932, 
  p. 
  77; 
  Twenhofel, 
  1932, 
  p. 
  258). 
  

  

  It 
  is 
  in 
  such 
  an 
  environment 
  that 
  the 
  solid 
  organic 
  matter 
  laid 
  down 
  

   with 
  the 
  sediments 
  has 
  been 
  transformed 
  into 
  other 
  compounds 
  which 
  

   are 
  capable 
  of 
  being 
  transported 
  by 
  water. 
  If 
  the 
  organic 
  matter 
  were 
  

   water-soluble 
  its 
  movement 
  through 
  capillary 
  spaces 
  would 
  occur 
  more 
  

   readily 
  than 
  if 
  it 
  were 
  in 
  the 
  form 
  of 
  minute 
  globules 
  of 
  hydrocarbons 
  

   insoluble 
  in 
  water. 
  It 
  is 
  conceivable 
  that 
  the 
  solid 
  organic 
  matter 
  

   which 
  is 
  later 
  to 
  become 
  petroleum 
  has 
  at 
  first 
  been 
  converted 
  into 
  

   water-soluble 
  or 
  water-miscible 
  intermediate 
  compounds 
  and 
  that 
  it 
  

   was 
  in 
  some 
  such 
  state 
  when 
  it 
  first 
  left 
  the 
  place 
  of 
  original 
  deposition. 
  

   In 
  that 
  case 
  the 
  further 
  chemical 
  change 
  of 
  such 
  intermediate 
  com- 
  

   pounds 
  to 
  petroleum 
  might 
  occur 
  after 
  the 
  organic 
  matter 
  had 
  been 
  

   removed 
  from 
  the 
  point 
  of 
  original 
  deposition 
  and 
  had, 
  in 
  the 
  course 
  

   of 
  its 
  movement, 
  come 
  into 
  contact 
  with 
  solutions 
  or 
  forces 
  which 
  had 
  

   caused 
  further 
  reactions 
  to 
  produce 
  the 
  hydrocarbons 
  which 
  collec- 
  

   tively 
  form 
  petroleum 
  and 
  natural 
  gas. 
  No 
  experimental 
  work 
  with 
  

   which 
  the 
  writer 
  is 
  conversant 
  clarifies 
  this 
  problem. 
  

  

  WTiatever 
  the 
  precise 
  process 
  of 
  chemical 
  change 
  may 
  have 
  been, 
  it 
  

   seems 
  necessary 
  to 
  postulate 
  that 
  somewhere 
  in 
  the 
  very 
  early 
  history 
  

   of 
  petroleum 
  there 
  must 
  have 
  been 
  an 
  aggregation 
  of 
  finely 
  divided 
  

  

  