COMPLETION OF WELLS a well is "brought-in" and classed as a producer, the well is put in shape for production. Gas wells require that a string of tubing be set, in most cases its bottom being above the sand with a packer to prevent the entrance of all foreign material in the well. The size of the tubing depends on the size of the wells; very small ones need only r-inch tubing, the most common size in use being the 2-inch, and for large wells 3- and 4-inch tubings are used. In case of gusher wells, it is impossible to lower a string of tubing and such wells arc shut in the casing, and when they decline, tubing may then be inserted. In some instances it is possible to pull the casing, leaving only the tubing in the hole. Gas wells should be equipped with at least two gates, one for shutting off the well from the line, the other used for blowing and gauging purposes. (Fig.
16) If for some reason or other a well is" making " water it is necessary to elimi nate it to prevent it from ruining the well. Such water is removed by allowing the well to blow open, the sudden release of the pressure bringing the water with it. At the time of blow ing wells the pressure should be taken as well as the general behavior of the well noted. Many wells need agitating before the water may be lifted; this is clone simply by lowering a weight on a line, which will agitate and flow the water. Quite often the sudden release of large pressure will freeze up gas wells; in such cases the volume and pressure arc lower than usual; it is only necessary to shut the well in and it will thaw itself out in a short time. In many instances a gas well may salt up and this condition seems to occur mostly in sands that do not carry water, or very little of it. This may possibly be due to the fact that the original connate water having been lost, some of its contents may have been deposited in the sand, which when brought into action by the movement of gas may entirely clog the pore spaces. Many wells are entirely lost, ruined by salting.
All gas wells should be equipped with drips, the purpose of which is to catch water or oil and prevent it from getting into the lines. Drips generally consist of a few joints of larger sized casing placed on the line at the mouth of the well, the direction of the gas flow being changed, thus causing the dropping of foreign elements in the drip. (Fig. 117.) The chemical analysis of all waters encountered during the drilling of the wells may be used in determining the probable source of water with the gas.
Meters are placed between the wells and the gathering pipe lines to show the amount of gas the well is able to deliver against the pressure carried on the line. Meters are often omitted by gas companies who drill their own wells and carry the gas through their own pipe lines, if the lease calls for a certain specified sum as well rental to the property owner. If the lease specifies a certain percentage of the gas as a royalty, then the volume obtained is measured.
Oil wells need entirely different methods of handling, and unless a gusher well is completed, all wells require a cleaning out process after the shot to remove all the accumulated debris. After cleaning out, the well Is tubed similarly to gas wells, only packers arc often omitted if the well is to be pumped, as any water that may find its way down into the sand through the hole will be pumped out with the oil. It is customary to drill a pocket below the pay, in which sediments may accumulate, especially those caused by shooting. The lower joints of the tubing are perforated, allowing the entrance of oil into it, through which the oil is pumped by means of valves in a working-barrel, raised and lowered by sucker rods which are attached to a power at the surface. In instances where the bottom of the last string of casing is a considerable distance above the sand a sufficient number of joints of casings are inserted that fit inside the long string casing, and reach from the bottom of it to the sand, this extra lower string of casing being known as the liner, and its object is to protect the walls of the hole between the last casing point and the sand.
In a shallow field the different wells are pumped with one power in common for many wells, the sucker rods in the wells are and allowed to drop back by their own weight; they are attached to pumping jacks (Fig. rib) which impart the motion to the sucker rods from the power with which it is con nected with shackle-rods. Very deep wells require a separate pumping power for each well, for which the original drilling power may be used, or a gas engine installed. If sufficient amount of gas is present with the oil it may be separated from the oil by means of a gas trap installed at the receiving tank, and the gas used for fuel on the lease or elsewhere.
Considerable difficulty is offered by the formation of paraffin in the well, which will clog up the pores of the sand as well as obstruct the passage of oil in the tubing. The common practice is to pull out the rods and properly clean them as well as the hole. If the original derrick has been dismantled, as in the case of most moderate depth fields, a portable cleaning-out outfit is used, which may readily be set up over a well, and the neces sary pulling done by a team of horses.
As a well is being pumped the oil is carried through one or more lead lines to the receiving tank. It is customary to use two sets of tanks, the first to collect the oil, water and whatever sediments may be brought up by the pump (flow tanks) (Fig. 119); the sediments and water are drawn of through drain holes located near the bottom of the tank, and the oil is run into another tank (receiving tank). The oil on a large lease is collected at several places and from the various points brought by gravity to the main tank, from which the purchasing company runs the oil into their pipe lines, after having drawn off the water and sediments and gauging the amount of oil thus stored.