42 BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
The two greatest wastes connected with oil-well drilling are caused 
by the harmful infiltration of water from water-bearing strata and 
the uncontrolled escape of natural gas encountered in the course of 
drilling. Water is a formidable enemy to oil extraction; as the posi- 
tion of the oil depends, in part, upon a nice equilibrium between oil 
and water, the undue influx of water into the drill hole means a 
reduced recovery of oil, if not a total loss of the well ; and not only 
may a single well be completely ruined by inadequate protection 
against water, but what is more grave a whole field of operations 
ma}^ thereby be spoiled. The damage done in the past by water is 
immeasurable and largely irretrievable, but the danger from water 
may be controlled by means of a method of cementation already em- 
ployed with success in California and Texas, whereby a water-tight 
band of cement is forced into the space between the well casing and 
the water-bearing stratum. 
Many wells in sinking penetrate gas-bearing formations, and in 
such instances it has usually been customary to suspend operations 
while the gas escaped into the air, so that the pressure might be re- 
lieved against which continued drilling was difficult or impossible. 
The actual waste of gas due to this circumstance has been first and 
last enormous, amounting to billions, if not trillions, of cubic feet, 
with a fuel equivalent of millions of tons of coal; indeed, it would 
be safe to say that over half of the natural gas developed to date has 
been made no use of whatever . 1 But this physical waste, great as it 
has been, is of small consequence as compared with the waste of the 
energy represented by the gas-pressure, the dissipation of which 
leads to a reduced and more difficult recovery of the oil. The gas, 
therefore, is not only substance but energy, and represents a force 
which must be conserved for the sake of later gaining a proper pe- 
troleum yield. It is rather interesting that the waste of oil and gas 
involved in the premature production of gas may be prevented by 
comparatively simple means; namely, by drilling in a medium of 
mud-laden fluid which serves to encrust the critical parts of the 
drill-hole, sealing off the formations so that there is no improper 
escape of gas and preserving the conduit intact down to the produc- 
tive stratum . 2 3 
After the oil is struck, there are many methods for controlling the 
output so as to avoid the waste incidental to much of the current 
practice. The flow may be controlled by rather elaborate mechanical 
1 See R. S. Blatchley, Waste of Oil and Gas in the Mid-Continent Fields : Technical 
Paper 45, Bureau of Mines, 1913. 
J. O. Lewis and W. F. McMurray, The Use of Mud-Laden Fluid in Oil and Gas Wells : 
Bulletin 134, Bureau of Mines, 1916. 
3 This process is described in detail in Bulletin 134, Bureau of Mines, 1916. There 
are numerous details of drilling practice which are subject to improvement, but these 
need not be gone into here. 
