58 
BULLETIN 102, UNITED STATES NATIONAL MUSEUM. 
the offset well burden, as well as the large number that were drilled 
on the demands of the lessors. 
Reason for drilling: Number of wells. 
To save lease 96 
Offset 68 
For oil 74 
For gas 52 
Wildcat 4 
Requirements of lease 5 
Demand of lessors 130 
Total 429 
GAS LEAKAGE. 
The difficulty in keeping gas joints tight is not ordinarily appre- 
ciated and results in an enormous waste from defective joints and 
minute openings in gas-cariying equipment. The laws controlling 
gas leakage may be stated as follows : 
1. The relative leakage tendencies of any two fluids under the same 
conditions are practically inversely proportional to the square roots 
of their respective densities. Natural gas has a density of practically 
0.64. With regard to air, the relative leakage of air and natural gas 
will vary as the square root of 1 and square root of 0.8 or as 1 is to 
0.8. That is, the leakage tendency of natural gas will be l-^-0.8=1.25 
times that of air under similar conditions. Water has a density 
819.5 times heavier than that of air; hence leakage tendency of 
natural gas in comparison to that of water at the same pressure is 
much greater than that of water. This accounts for the universal 
difficulty in keeping gas confined without leakage. 
2. The quantity of leakage through a given opening will vary di- 
rectly as the square root of the differential pressure. 
3. Amount of leakage is independent of the quantity or velocity 
of gas passing through the main. In other words, the pressure re- 
maining the same, the leakage will be just as much during the period 
of low gas consumption as during the period of high gas consumption. 
A typical gas main joint coupling, as shown on page 59, has four 
surfaces adjacent to the rubber and the metal where leakage may be 
possible. On a 16-inch main each coupler presents about 17 linear 
feet of such potential leakage surface. The magnitude of this in a 
large system is evident when we consider that about 270 couplers 
will be required to the mile, thus making 270X17=4,590 feet of pos- 
sible leakage surface to the mile of a 16-inch gas main. 
Welded gas mains are coming into use, but the welded process 
can not be used except on new work or in such main line installations 
where the entire line can be shut down and drained of all gas before 
the welding operation is attempted. 
