Oil-Well Cementing in Deep Wells

Although oil-well cementing has not been carried on at depths in excess of 10,000 feet, temperatures, pressures and volumes are three big questions always present in the minds of men absorbed in deep well cementing. Each discovery, each problem and each conversation leads back to mixing speeds, pumping pressures and rapid handling of large volumes of fluids. Cementing equipment has been developed to move over most difficult roads under its own power and, upon short, notice, to continuously and thoroughly mix and pump cement slurry into a well at a wide range of mixing speeds, instantly selective, according to requirements in the well. These requirements have inspired the development of a simple, rugged and very flexible mixer which, in standard size, weighs less than 150 lbs. but has greater mixing capacity than the daily output of an ordinarysize cement manufacturing plant. Where very fast mixing speeds are required, either a battery of two or more of the standard-size mixers are used or one or more of a special-size mixer, larger than the standard-size and employing two or more sack-cutting tables. The size of the mixers are consistent with portability and convenience to the men who feed the cement. It is a simple matter to hook up a battery of two or more mixers to continuously and properly mix a thousand sacks of cement every few minutes. Such speed of mixing cement is one of the favourable factors in the long chain of mechanical details in successful completion of deep wells. Such high-speed mixing, however, is just part of a cementing system of co-ordinated units and operating procedure in which the other parts must keep pace. It will be attempted herein to describe some important mechanical and physical factors, new developments and operating methods used in cementing modern deep wells. CEMENTING EQUIPMENT. Considering the mechanical cementing equipment which operates at the surface, it is desirable that such equipment be capable of moving under its own power over oilfield roads, and very flexible over a wide range of cement mixing speeds, high pump pressures and large volumes. Performance of a cementing unit while moving over bad roads is facilitated by the equipment being mounted on a motor truck in which either the front wheels, rear wheels, or all four wheels can be selectively used for driving purposes. If either the front or rear wheels become stuck, the power can be applied to, the free wheels for pulling or pushing. With the addition of a winch, the unit can independently surmount many obstacles. The pumping system in surface cementing equipment may be classified as either steam or gasoline-motor driven.