翻譯：A portion of the sample is used to determine the gravity of the oil expressed in AIP unit the lighter the oil, the higher the API gravity .In most cases the price paid for the coude is determined in prat by the API gravity, hence ,the importance of careful gravity determination in each instance.

翻譯：In these early days, as lamp oil, was the important product and the main objects of refining was to extract as much of it as possible from the crude. Lubricants and some fuel oil were also sold, but gasoline was burnt off as unwanted and bitumen was also largely useless.

翻譯：The total quantity of petroleum now thought to exist on Earth is about 14 trillion gallons. In weight that is only one-ninth as much as the total existing quantity of coal and ,at the present moment, petroleum is being used up much more quickly. At the present rate of used, the worlds supply of petroleum may last for only thirty years or so.

翻譯：The primary limitations for gas lift operations are the lack of formation gas of an outside source of gas, wide well spacing, and available space for compressors on off-shore plat forms. Generally, gas lift is not applicable to single-well installations and widely spaced wells that are not suited for a centrally located power system.

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