Method for determining the absorption cross section of small fluid samples

A method for estimating, independent of diffusion effects, the absorption cross section for a small quantity water sample, comprising:

• measuring the absorption cross section including diffusion effects for each of a series of small water samples of various, known salinity;
• calculating the corresponding actual absorption cross section independent of diffusion effects for each of said series of samples;
• developing a continuous functional relationship between said series of measured absorption cross sections and said true absorption cross sections;
• measuring the absorption cross section for a small water sample of unknown characteristic;
• equating said measured absorption cross section of said unknown sample to said measured absorption cross section of said series of known samples;
• and
• estimating the absorption cross section, independent of diffusion effects, for said unknown sample from said functional relationship of said series of measured absorption cross sections and said true absorption cross section.

A radioactivity method for evaluating the true absorption cross section for a small sample of formation water, comprising:

• irradiating a series of samples of known absorption cross section values with neutrons;
• detecting the radiations caused by said irradiating;
• generating from said detected radiations a series of absorption cross section measurements functionally related to said known absorption cross section values;
• irradiating a sample of formation water with neutrons;
• detecting the radiations caused by irradiating said formation water sample;
• generating an absorption cross section measurement for said formation water sample;
• and
• estimating the true absorption cross section for said formation water sample by correlation to said functional relationship generated from said series of known samples.