Information method for determination of crude oil type using biomarkers
It is well-known that all types of crude oil produced in different regions have its own set of biomarkers potentially determining this type. In the known system of identification of sources of oil sticks on the basis of biomarkers NORDTEST the methodology based on multilevel approach is proposed. At the first level of this methodology the basic information on hydrocarbons and level of their degradation formed by gas chromatograph is presented. At the second level the gas chromatograph is used in regime of monitoring of selected ions for determination of diagnostic relations for polycyclic aromatic hydrocarbons and several hopans and sterans biomarkers. At the third level the statistic approach on results received in the previous levels is applied. All diagnostic relations with high level of variation are removed from the consideration. The most robust diagnostic relations used for carrying out the correlation analysis to determine the potential source. The suggested information method provides for determination of such aregime for carrying out of measuring experiment on research of biomarker relations upon which the uncertainty of results of experimentsor their informativeness would reach the minimum. Such an attitude to solution of task of determination of oil type is similar in sense with known method based on removal of strongly variable diagnostic relations.  Materials and methods  It was formulated the mathematical task on determination of conditions providing for extremum of functional representing the estimate of information content of resultsof experimental researches of biomarkers relations to solve described problem. Solution of unconditional variation optimization task is carried out using the Euler method.  Results  In comparison with the known method the suggested information method provides for carrying out of series of experiments with increasing number of biomarkers where uponincrease of number of biomarkers their value should be stabilized in the some narrowzone meaning decrease the uncertainty in resulting information used for determination of oil type.  Сonclusions The suggested approach for solution of task on determination of spilled crude oil type using biomarkers make it possible to derive more objective results because it is well-grounded using the theory of information and functional analysis. The all possible subjective errors in estimates generic for known method based on removal of highly variable biomarker relations are lacking in suggested method. The suggested method can lead to increase of effectiveness of practical works on determination of spilled crude oil type using biomarkers.