问答题 翻译：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.

问答题 翻译：In addition to being useful as an exploration tool, subsurface maps are a necessary part of any reservoir engineering study; and petroleum engineers, as well as geologists, must be completely familiar with their construction and interpretation.

问答题 翻译：The application of physics to the study of rocks (geophysics)is very important in petroleum geology. In its broadest application geophysics makes a major contribution to understanding the earths crust and, especially through the application of modern plate tectonic(板块构造)theory, the genesis and petroleum potential of sedimentary basins. More specially, physical concepts are required to understand folds（褶皱）, faults（断层）, and diapers（底辟）, and hence their roles in petroleum entrapment.