Abstract
Permeability is one of the most important property for reservoir characterization, and its prediction has been one of the fundamental challenges specially for a complex formation such as carbonate, due to this complexity, log analysis cannot be accurate enough if it’s not supported by core data, which is critically important for formation evaluation. In this paper, permeability is estimated by making both core and log analysis for five exploration wells of Yammama formation, Nasiriyah oil field. The available well logging recorders were interpreted using Interactive Petrophysics software (IP) which used to determine lithology, and the petrophysical properties. Nuclear Magnetic Resonance (NMR) Measurements is used for laboratory tests, which provide an accurate, porosity and permeability measurements. The results show that the main lithology in the reservoir is limestone, in which average permeability of the potential reservoir units’ values tend to range from 0.064275 in zone YA to 20.74 in zone YB3, and averaged porosity values tend to range from 0.059 in zone YA to 0.155 in zoneYB3. Zone YB3 is found to be the best zone in the Yammama formation according to its good petrophysical properties. The correlation of core-log for permeability and porosity produce an acceptable R^2 equal to 0.618, 0.585 respectively
Highlights
Permeability is a porous medium property that tests the formation's capacity and ability to transmit fluids
Well log analysis has been made for the five wells, formation evaluation needed a lot of tests, laboratory experiments, and correlations, combined with log interpretation, Petrophysical properties were calculated to make a clearer picture of the two methods of calculation and the difference between them, and to evaluate the reservoir zones, the work flow diagram is shown in Figure (6)
Environmental corrections have been made for available logs of the five wells using Schlumberger environmental correction charts 2005, which are provided with Interactive Petrophysics software (IP) software, corrections have been produced per 0.25 m of depth in order to avoid inaccurate log interpretation performance
Summary
Permeability is a porous medium property that tests the formation's capacity and ability to transmit fluids. Permeability determination in Carbonate reservoirs is a very complicated matter, since they are characterized by the extreme heterogeneity of permeability and porosity, often, multiple challenges present in the representation of these properties due to the heterogeneity attributed of texture, vugs, diagenesis, and multiple types of fractures. This complexity was the key driver for selecting the required measurements to make an appropriate characterization of the reservoirs. Log analysis with the combination of routine core data and well test data, have made some significant advancements in characterization the study formation [2]. LithoMetrixTM and GIT systems software were used to run rock core analysis on standard NMR equipment, it performs routine measurements such as T1 and T2based pore size distributions, porosity, permeability and fluid mobility calculations such as Free Fluid Index (FFI), Bound Volume Irreducible (BVI) and Clay Bound Water (CBW) [3]
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