A computer supported method of exploring and producing a subsurface heterogeneous hydrocarbon source in an area under investigation, based on microbial prospecting, comprising microbial data representing a type and count of a plurality of different microorganisms representative of microbial activity attributable to hydrocarbon microseepage, said method comprising the steps of: i) retrieving, by said computer, of a plurality of geographic locations of an area or play comprising a heterogeneous hydrocarbon source, said microbial data associated with a quantity indicative of subsurface hydrocarbon productivity at a respective location; ii) correlating, by said computer, in a data correlation algorithm, said retrieved microbial data and quantities indicative of hydrocarbon productivity, providing a threshold hydrocarbon productivity quantity and a truncated set of said retrieved microbial data, said set identifying individual types of said microorganisms and corresponding individual weighting factors computed by said data correlation algorithm, for distinguishing prospective hydrocarbon productivity quantities from non-prospective hydrocarbon productivity quantities, iii) retrieving, by said computer, said microbial data of a further geographical location of an area under investigation; iv) calculating, by said computer, an estimated subsurface hydrocarbon productivity quantity for said further geographical location by count weighting retrieved microbial data of said further location for microorganisms identified in said truncated set, applying said individual weighting factors, and v) producing or having produced said hydrocarbon source at said further geographical location if said estimated hydrocarbon productivity quantity compared to said threshold hydrocarbon productivity quantity qualifies as prospective hydrocarbon productivity quantity. i) retrieving, by said computer, of a plurality of geographic locations of an area or play comprising a heterogeneous hydrocarbon source, said microbial data associated with a quantity indicative of subsurface hydrocarbon productivity at a respective location; ii) correlating, by said computer, in a data correlation algorithm, said retrieved microbial data and quantities indicative of hydrocarbon productivity, providing a threshold hydrocarbon productivity quantity and a truncated set of said retrieved microbial data, said set identifying individual types of said microorganisms and corresponding individual weighting factors computed by said data correlation algorithm, for distinguishing prospective hydrocarbon productivity quantities from non-prospective hydrocarbon productivity quantities, iii) retrieving, by said computer, said microbial data of a further geographical location of an area under investigation; iv) calculating, by said computer, an estimated subsurface hydrocarbon productivity quantity for said further geographical location by count weighting retrieved microbial data of said further location for microorganisms identified in said truncated set, applying said individual weighting factors, and v) producing or having produced said hydrocarbon source at said further geographical location if said estimated hydrocarbon productivity quantity compared to said threshold hydrocarbon productivity quantity qualifies as prospective hydrocarbon productivity quantity.