Putting in Rods.—The next operation is to put in the pump plunger and pump rods. The first stand of sucker rods is con nected to the pump parts consisting of standing-valve, garbut rod, steel-plunger and top-valve.
This length is then put in the hole. Other joints are screwed on until the plunger and valves touch the bottom of the tubing.
The polished rod connects the sucker rods and the lifting power. The iron-pump rods or sucker rods are VI or in. in diameter. These rods come in 30-ft. lengths joined by box and pin couplings. Three or four such rods may be welded together to form one long rod. They are attached at the bottom to the top valve of the pump, and are fastened to the walking beam or jack by a connecting rod called the polished rod.
A special box with threads for a sucker-rod pin on one end and threads for the polished rod on the other is screwed upon the top sucker rod and the polished rod is screwed into this. The well is now ready to put on the beam.
The walking beam is set on the wrist pin which is adjusted for the stroke desired. The beam carries a pair of reins sus pended from the slot in the end of the beam much as the temper screw is suspended.
These reins carry a yoke which fits under a clamp held by U-bolts to the polished rod. When the clamps are fastened the stroke is adjusted after several trials. The adjustment is so timed that the top valve or plunger has the proper stroke and does not touch the lower valve. This can be assured by allowing for the same when the polishing rod is screwed on, and the foot or standing valve is seated. This seating is done in the case of the California wells, by letting the weight of the rods force down the standing valve. In the Eastern fields the valve is seated in the foot of the pump cylinder when put in the well or, in a few cases, is dropped in the tubing. This latter course is followed when the hole is full of fluid.
The well is now on the beam and ready to start pumping. The engine is started and in 15 to 30 min. of pumping is pushing out the oil.
Handling of Mid-Continent and Eastern Wells.—The finishing
of wells in areas of hard rock is quite different from those of Cali fornia or the Louisiana and south Texas areas. In the hard-rock areas it is customary to drill a well into the oil sand as far as the driller considers prudent, to avoid water.
The perforated oil string as known in California is not used. The hole around the sand is left open (not cased). The last string of casing is set just above the oil sand. The hole is then shot.
Shooting Oil Wells.—The shooting of oil sands is a subject about which little is known. It is recognized that shooting hard sands or limestones generally increases the production if the well is producing, or in many cases where only a showing of oil occurred it has caused the bringing in of big wells.
Many operators can tell stories of wells that showed scarcely a rainbow of oil, which when shot, made big wells.
In shooting wells the oil operators determine from the character of the sand how much nitroglycerin to use. There is no set rule for the amount; experience is the only real gauge. Coarse, porous sandstones or conglomerate do not need shooting, nor do soft flowing sands. Hard, fine-grained sandstones, and porous limestones must be shot.
Shooting accomplishes several things: (a) Breaks up the sand causing channels to form.
(b) Allows connection with fracture zones or joint planes.
(c) Makes a larger collecting area.
(d) Creates more seepage space in the hole.
Liquid nitroglycerin and solid gelatin have both been used successfully.
Liquid nitroglycerin is more generally used than solid gel atin. The difficulty with solid gelatin has been in obtaining proper detonators. The Allison detonator, however, has been very successful in California. There is no doubt at all but that a general use of solid gelatin would be safer if it were employed as efficiently as the liquid form. Nitroglycerin is made by stirring glycerin oil into a mixture of nitric and sulphuric acids.
The operator usually informs the torpedo or shooting company what is needed in the way of a shot, and the "shooters" do the rest.