Spatial distribution of petrophysical properties on the basis of laboratory results, well logging and seismic data

The Miocene formation in the Polish Carpathian Foredeep is still the subject of prospecting works due to many gas fields discovered there in the long period from the 19th century up to now [1]. The Sarmatian sandy-shaly thin-bedded formation in gas fields from this region was selected for tests of proposed methodology as rocks being potential hydrocarbon and water reservoirs. Mutual relationships between rock properties determined using methods based on different physical phenomena and measured in various scale (micro- in laboratory, mezzoand macro- in situ) were the basis for petrophysical three- dimensional analysis. Rock models – important for proper petrophysical parameters determination – were the result of modeling of mineral composition, volume and type of media filling pore space (combining data from various sources and of different scale). Input parameters for simulations were obtained from laboratory measurements on rock plugs and comprehensive interpretation of well logging. The X-ray computed microtomography (μCT) is a new non-destructive technique for visualization of three dimensional rock structures basing on variations in Xrays absorption. Prototype μCT equipment (IFJ PAN) provided structural data of fine spatial resolution (about 4 μm). Basing on μCT data simulations of the fluid dynamics in the void space of porous media was carried out. The Lattice Boltzmann method was used in order to predict the hydraulic permeability of the media. Mercury porosimetry provided us with data on the volume of porous space and its geometry (distribution of predominating pore diameters and specific surface of porous space). Nuclear Magnetic Resonance laboratory spectroscopy delivered information on total porosity with division into clay bound water, capillary water and movable water or hydrocarbons. Mineralogical investigations (roentgen analysis) and results of well logging interpretation were the basis for construction of the mineral composition of rock formation. The spatial distribution of petrophysical properties was realised on the basis of combination of seismic attributes calculated in the vicinity of wells with attributes calculated in the same way as seismic ones for the acoustic full wavetrains. Reservoir and elastic properties were included in properties distribution calculations to gain information on the fluid flow ability of the rock.