PRODUCTION.
Flowing Wells. Flowing wells are encountered in nearly every oil field of importance and are often of such violence as completely to destroy the rig and damage the casing in the well. The gas pressure throws the sand out with a force so great that it often cuts through heavy steel plates in a few hours, while the rig timbers fall rapidly before the blast. Such wells as the Dos Bocas in Mexico, the Lucas at Spindle Top, the Lake View in California, and the great Baku gusher in Russia Produced thousands of tons of oil and sand before they ceased flowing, the first tearing a great hole in the surface of the ground before it subsided. Where a heavy flow is unexpected, and no prepara tions for capping have been made, to gain control is exceedingly difficult, often impossible. When a stream of oil is shooting into the air, there is naturally a heavy loss, especially of the lighter oils. To prevent this, boiler shells placed upon skids, or heavy timbers reinforced with steel plates on exposed surfaces are drawn over the hole at the derrick floor and prevented from being thrown off by wire slings anchored to the derrick sills. The oil is caught in earthen sumps excavated near the derrick, and, when the flow has abated somewhat, efforts are usually made to get the well under control. The Lake View gusher was controlled by placing a levee around the derrick 12 to 15 ft. higher than the mouth of the well. The oil, accumulating inside the embankment, acted as a cushion and prevented the flow from shooting into the air (Fig. Most operators do not believe in checking the flow entirely, for this might result in choking the underground oil-channels, thus ruining the well, the idea being, rather, to attach a heavy gate or blow-out preventer to the top column of the oil-string with a tee above the gate, if one be used, and the oil conveyed through a lead-line to proper storage. Extensions of all turns in the lead-line should be made with a nipple and cap to allow the oil to cushion, thus saving the fittings from cutting out by sand.
Should the flow be expected, the gate or other safety appliance may be installed in advance of the time of bringing in the well, when considerable loss of oil can be avoided. The pressure is
often so great, however, that the heaviest fittings do not stand (Fig. 135). In this case the well is temporarily capped with timbers or a steel shell until such time as' it can be properly controlled. It is usual, in high-pressure districts, to fill in around the outer casing with concrete to a depth f 15 or 20 ft. and securely anchor the strings of casing to the concrete block and to each other by means of casing-clamps and bolts, thus prevent ing any damage to the casing. Wells maintaining pressure as high as 1000 lbs. are safely handled in this way. Although running the oil into earthen sumps causes considerable loss through seepage and evaporation, it is not always possible to do otherwise until the flow has abated. A large percentage of the oil from gushers is generally lost in this way, particularly so if the oil is of a high gravity. When the flow is going above the derrick, it is often possible to place heavy timbers across the second or third girts from the floor, which act as buffers and prevent loss. Occasionally a flowing well takes fire, and when the well is not capped it is often a difficult matter to extinguish the blaze. If a sufficient number of boilers is available nearby, the use of steam is often successful in snuffing out the fire. Chemicals such as sodium bicarbonate and sulphuric acid are also successful at times if used in large quantities. Another method is to tunnel 8 or 10 ft. under the surface to the casing at which point it can be dynamited or squeezed together with jacks. The oil in this case runs out through the tunnel, lessening the flow on top, so that the flame can be extinguished by an application of steam. Danger from fire cannot be overestimated, for fire means loss of property and often of life before being extinguished. Every precaution should be taken to guard against fire around oil-well derricks and tanks (Fig: 136). When a well is flowing and not under control, the neighboring boilers should be shut down and spectators kept at a safe distance. It is a good idea to com pletely fence the gusher and to install the boilers at a safe distance and at a point where the wind does not usually pass the derrick first.