The flow path of petroleum in underground reservoirs is monitored by injecting a stable free radical, or spin label, into the reservoir as a tracer which becomes detectable in a sample taken from a producing well. Detection of the spin label is by electron spin resonance (ESR) spectroscopy. Spin label tracers are, on the average, detectable at dilutions 1 million times lower than is possible with standard chemical tracing methods.
A method for tagging an oil so that subsequently it may be identified as to source by incorporating into the oil as a tracer material an oil-soluble or oil-dispersible Group VIB, Group VIIB or lanthanum series rare earth metal salt of a fatty acid. The so-tagged oil may be utilized in any desired manner. Thereafter, an oil suspected to contain at least a portion of the so-tagged oil is analyzed for the presence of the added metal moiety. The method is especially useful in tracing a complex oleaginous and petroliferous material so that it may be recovered and identified following a theft or spill or to trace the flow of such oil injected through a subterranean reservoir.
A method for determining the reservoir properties of a solid carbonaceous subterranean formation is disclosed. The method uses field data obtained from an injection/flow-back test, which utilizes a gaseous desorbing fluid, in conjunction with reservoir modeling techniques to determine the reservoir quality and the enhanced methane recovery characteristics of the formation.
A method for determining the concentration of a brine tolerant sulfonate surfactant in a complex mixture containing, in addition to said brine tolerant sulfonate surfactant, lignosulfonates, crude oil, salts, and water and, optionally, petroleum sulfonates and alcohols, that comprises incorporating into the brine tolerant sulfonate surfactant molecule a small amount of deuterium prior to addition to the complex mixture and determining the concentration of the brine tolerant sulfonate surfactant by measuring its infrared absorption at 2150 cm.sup.-1.
A method for tagging an oil so that subsequently it may be identified as to source by incorporating into the oil as a tracer material a minor amount of certain halohydrocarbons or halocarbons, utilizing the so-tagged oil in any desired manner wherein control of the oil is at least temporarily lost, and thereafter analyzing an oil suspected to contain at least a portion of the so-tagged oil for the presence of the tracer material by gas chromatography, using a pulsed election capture detector.
A method for quantitative monitoring of a gas injected into a reservoir and likely to react chemically with the injection medium includes injecting into a reservoir a mixture of the potentially reactive gas to be quantified with a low proportion of a tracer gas whose chemical inertness is total, and in determining the variation with time of the initial proportion of reactive gas that may have disappeared through conversion, by measuring the concentration variation of the tracer gas in the mixture. The tracer gas is preferably selected from the rare gas family and from isotopes thereof, unlikely to be contaminated by contact of the mixture with the injection medium, and which have physical properties such as solubility in water or diffusion coefficients as close as possible to the gas injected. The method is applicable to monitoring of the evolution and conversion of a reactive gas such as carbon dioxide or methane, injected into an underground reservoir for example.
