20 BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
The marked difference between the open flow of a gas well and the 
actual flow that may be obtained under routine operating conditions 
is emphasized in the next section. 
MISLEADING WELL CAPACITY. 
The natural gas well capacities that are given to the public are 
always the open flow capacity; that is, the capacity of the well in 
24 hours when discharging freely into the atmosphere with no back 
pressure at all. This is misleading, and comes far from representing 
the true service capacity or true gas delivery capacity under routine 
operating conditions, of any gas well, because : 
1. The first open flow measurements, which are usually the ones 
advertised in the newspapers, are nearly always made by the drillers, 
who do not have the facilities or skill to make an accurate test, and 
the errors are invariably on the side of a capacity larger than the 
actual facts. The volume is determined immediately after the well 
comes in, and is therefore larger than it would be several days after- 
ward, on account of the fact that the well has not been drawn upon. 
2. In routine operations of natural gas wells it is not possible to 
keep a well in service 24 hours, day in and day out. For various 
operating reasons, such as repairs, salt-water troubles, etc., it is 
necessary to rest wells at intervals. For this reason, the actual 
operating period of a well will be, on an average, very much less 
than 24 hours a day. 
3. It is not feasible to maintain atmospheric pressure conditions 
in the pipes into which the wells discharge, but, on the contrary, the 
pressures are very much higher than atmospheric pressure. For 
this reason, the wells must discharge against considerable back pres- 
sure, thus retarding the amount of gas that will go out. 
4. Based on actual operating tests, it has been determined that 
25 per cent of the open flow capacity is about all that can be delivered 
from the average natural gas well. It must also be borne in mind 
that the open flow capacity will constantly decrease, with the removal 
of gas from the well. 
5. As the rock pressure declines it will be necessary to install 
compressing stations in order to transmit the gas into and through 
the main transmission line. 
6. After the compression station has been installed, the further 
inevitable decline in rock pressure will lower the capacity of such 
station, as shown on page 29. 
MIGRATORY AND FUGITIVE NATURE OF NATURAL GAS. 
Natural gas has no fixed position under any particular portion of 
the earth’s surface. On account of its inherent tendency to expand it 
has the power, as it were, of self transmission and is capable of flow- 
