Page:Popular Science Monthly Volume 90.djvu/110

 Saving Natural Gas with Muddy Water

Why muddy water? Because the mud clogs up the outlets in ^ the gas-bearing sands

���The clay and water are mixed in outside pits and then pumped into the wells. The mud effectually plugs up the gas-bearing sand without interfering with the drilling

IN boring for oil, work is frequently hin- dered by unexpected gas-bearing sands. Huge quantities of valuable gas are thus allowed to escape, because it is oil, not gas, which the workmen are after.

The Government Bureau of Mines, noticing this waste, has recently evolved a method of reducing and practically prevent- ing it, without in any way hindering the work of boring for oil. Thus the gas is conserved for later consumption. Be- sides, it is made far less dangerous for the workmen to operate the drilling machinery.

The method makes use of so simple a remedy as muddy water — a material some- times dignified by the technical name of "mud-laden fluid." It is based on the principle that a drill-bit on the end of a long cable can go up and down in fairly fluid water almost as readily as it can in a dry hole and hit the bottom of the hole just as hard. The muddy water in the well opposes the outflow of gas. Why muddy water? Because water has a ten- dency to become muddy by loosening

��material from the sides of the hole, causing cav- ing and unending diffi- culties. If the water is already muddy, the solid material carried in sus- pension soaks into the gas-bearing sands as they are encountered, effect- ually plugging them up, at the same tim.e permit- ting the drill to work on the bottom of the hole. It is little hindered by the presence of the water. If the gas pressure is great, the well can be nearly filled with the muddy water, the weight of the resultant liquid column being sufficient in most cases to stop any outflow of gas bubbles, thus reinforcing the ef- forts of the mud which has soaked into the gas- eous sands.

The mud-laden fluid is usually made up of about twenty per cent clay and the rest water. Sticky clays, such as gumbo, are most effective. The clay and the water are mixed in outside pits and then pumped into the well. The precise methods by which the pumping is done depend upon various factors, such as whether the well is already blowing gas or not, whether the well is deep enough so that a water column is sufficient to hold back the gas pressure without external aid, and similar considerations. In each case simple expedients are used, the desired end being to get the muddy water into the hole with as little danger of asphyxiating the workmen as possible and with as little loss of the gas as may be. A well once sealed up with muddy water in this fashion may be opened at any later time simply by pumping out the water. The gas pres- sure will at once overcome any opposition of the mud soaked into the sands.

Thus the owner of the well may keep the gas bottled up in its natural reservoir until such time as he may find use for it.

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