Abstract: A method of evaluating a geological formation (20) of non-homogeneous porosity and permeability, particularly in exploration for hydrocarbon fluids, comprising the steps of: (a) inserting a formation evaluation tool (30) into a borehole (10) to a location (10a) within the geological formation (20); (b) setting the formation evaluation tool (30) into position isolating interval(s) of the borehole (10) with a packer arrangement (50) forming portion of the formation evaluation tool (30), for sample evaluation for said interval(s); (c) extracting representative samples of formation fluid from the location within the geological formation (20) for evaluation under downhole conditions using sampling means (32a, 52b, 54b) operative to extract formation fluid samples over a range of porosity and permeability encountered within the geological formation (20); and (d) analysing the formation fluid samples and measuring formation (20) permeability.

Abstract: A method for analyzing properties of fluids contained in a geological formation including the steps of lowering a tool containing a chromatograph down to a location within the geological formation; setting the tool into position; extracting a sample of formation fluid from the location within the geological formation under controlled conditions and directing it into the chromatograph; and analyzing the composition of the formation fluid sample located downhole. The formation fluid sample is delivered to the chromatograph with or without admixture with a solvent. A sampling tool for use in the method forms another aspect of the invention.

Abstract: A method for analyzing properties of fluids contained in a geological formation including the steps of lowering a tool containing a chromatograph down to a location within the geological formation; setting the tool into position; extracting a sample of formation fluid from the location within the geological formation under controlled conditions and directing it into the chromatograph; and analyzing the composition of the formation fluid sample located downhole. The formation fluid sample is delivered to the chromatograph with or without admixture with a solvent. A sampling tool for use in the method forms another aspect of the invention.