| 摘要 |
In order to provide a reliable test for the presence of native hydrocarbons down a borehole during drilling with an oil-base drilling mud, a sample of the rock cuttings brought up from the vicinity of the drill bit by the circulating mud flow is collected, the sample or a fluid prepared from the sample is then placed in a spectrometer and is excited with electromagnetic radiation of one or more wavelengths. The radiation absorbed and/or emitted by the excited sample or sample preparation is sensed, and a plot is produced of the excitation and/or emission wavelengths against intensity, or in certain circumstances of the emission wavelengths against the excitation wavelengths. It can then be determined from the characteristic profile so obtained whether the hydrocarbon content of the sample incorporates only the oil base of the drilling mud or a combination of this oil-base and native hydrocarbons. |
