翻譯：Nearly three-fifths of all known petroleum reserves on Earth is to be found in the territory of the various Arabic-speaking countries. Kuwait , for instance , which is a small nation at the head of the Persian Gulf , with an area only three-fourths that of Massachusetts and a population of about half a million , posseses about one-fifth of all the known petroleum reserves in the world.

翻譯：Practically every rig uses internal-combustion engines as its prime power source, or its prime mover.

翻譯：The fluids of a petroleum reservoir are generally gas, oil, and water in varying proportions. Each phase can differ widely in composition and properties. Gas and oil, either as separate fluids or in mixtures, change their state or phase as reservoir pressure changes.

翻譯：A porous medium has a permeability of one darcy when a single phase fluid of one centipoise viscosity that completely fills the voids of the medium, will flow through it under conditions of viscous flow at a rate of one cubic centimeter per second per square centimeter cross sectional area under a pressure or equivalent hydraulic gradient of one atmosphere per centimeter.

翻譯：the fluid must be identified by direct measurement of certain properties. These measurements involve securing samples of the fluids from the field. The simplest procedure is to make measurements of the properties of the produced fluids. The API gravity of stock-tank oil and the producing gas-oil ratio are routinely determined. The gas-oil ratio is ordinarily the ratio of volume, in standard cubic feet, of gas from the separator to the volume of stock tank oil both measured over the same time interval. If good field practice is followed, the gravity of the separator gas is determined. These data, together with estimates or observations of the reservoir pressure and temperature, can be used to estimate the properties of the reservoir fluids. Such estimates may be of limited accuracy.