56 BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
well that it is to offset. Thus one well may be an offset to two or 
more contiguous wells. In other cases the shape of the tract will 
determine the position of the offset well. The primary feature to be 
borne in mind is that the offset well is drilled for purposes of pro- 
tection, and that this is more important than hard and fast rules 
regarding exact location. The adventitious origin, migratory habits, 
and fugitive tendencies of natural gas, as well as the nature of the 
sand and the topography of the country, are - also factors that must 
be considered. 
DRILLING OFFSET WELLS MAY MAKE EXISTING WELLS COMMERCIALLY WORTHLESS. 
In gas territory the lessee may sink many wells and find gas in them all, but 
he can utilize only such of them as have a volume and pressure sufficient to 
enable him to transport the gas through his line and deliver it to the pur- 
chaser. If no one of them has the requisite pressure, then no one of them can 
be utilized ; the gas must be wasted, the cost of the wells will be lost, and the 
lessor entitled to no royalty. What is the proper way to operate a gas lease 
is therefore a question beset with some, difficulty. Its settlement requires 
some general knowledge of the business and some knowledge of the local field. 
The lessee may have a good well, from which he can utilize the gas with 
profit. He may put down another on the same farm and thereby so reduce the 
pressure in the first as wholly to destroy its value, without getting a sufficient 
pressure at the second to enable him to utilize that. The gas, if coming from 
one well, would be of great value. Divided in such manner that the whole 
volume and pressure at each is below the necessary standard, the whole is lost. 1 
WHY OFFSET WELLS ARE FREQUENTLY DRY. 
It is a matter of common observation in natural gas mining tbat 
offset well locations are frequently dry holes. This is because most 
natural gas pools are not strictly continuous, but are made up of 
many small local pools, frequently surrounded in whole or in part 
by a gas rock of low porosity. For this reason, if a producing well 
has been drilled into one of these small local gas pools, there is a 
large chance that the offset well location may go beyond the limits of 
the pool, and therefore be a dry hole. 
WHY OFFSET WELLS ARE FREQUENTLY OF LOW CAPACITY. 
The fact that offset natural gas wells are frequently of lower 
capacity than the wells that they offset may be accounted for as 
follows : 
If the offset well is drilled at the extreme edge of a small local pool 
its capacity would naturally be smaller than the original well drilled 
more nearly in the center of the pool. Furthermore, when the first 
well is drilled into the pool the rush of gas from the then high rock 
1 Pennsylvania Supreme Court. McKniglit versus Manufacturers Natural Gas Co. (146 
Pa. St., p. 185). 
