Pore length scales and pore surface relaxivities of sandstone were studied on a 2 MHz Rock Core Analyzer in this work. To determine the pore length scales of rock cores, high eigenmodes of diffusion equation were detected with optimized encoding periods in the presence of internal magnetic fields Bin. The results were confirmed by a 64 MHz NMR system. Furthermore, this methodology was combined ...

Reactive iron (Fe) oxides and sheet silicatebound Fe in reservoir rocks may affect the subsurface storage of CO2 through several processes by changing the capacity to buffer the acidification by CO2 and the permeability of the reservoir rock: (1) the reduction of threevalent Fe in anoxic environments can lead to an increase in pH, (2) under sulphidic conditions, Fe may drive sulphur cycling and...

Rock selection in modeling and simulation studies is usually based on two techniques; routinely defined rock types and those defined by special core analysis (SCAL). The challenge in utilizing these two techniques is that they are frequently assumed to be the same, but in practice, static rock-types (routinely defined) are not always representative of dynamic rock-types (SCAL defined) in the re...

We discuss petrophysical analysis of wireline logs, methods for formation evaluation and issues in evaluating tight sandstone formations. The main concerns of log interpretation in tight gas sandstones include porosity interpretation, understanding the effect of clay on the log responses, accurate computation of water saturation, and permeability determination (Kukal et al., 1985). Moreover, va...

A capillary pressure function is proposed for interpreting core-scale flow experiments. This function has been found suitable for a wide range of rock/fluid systems with different pore geometry and wettability characteristics. The petrophysical controls are reflected in the asymptotic values relating to irreducible saturation, and threshold capillary pressure, and in the shape parameters relati...

We investigate the acoustic and mechanical properties of a reservoir sandstone saturated by two immiscible hydrocarbon fluids, under different saturations and pressure conditions. The modeling of static and dynamic deformation processes in porous rocks saturated by immiscible fluids depends on many parameters such as, for instance, porosity, permeability, pore fluid, fluid saturation, fluid pre...

Figure 1. Model of P-wave velocity (above) and density (below) verses gas saturation for a sandstone reservoir with a porosity of 25%. The velocity was modelled using Gassmann’s equation (1951) with the Reuss average moduli of the fluids. For a gas saturated reservoir, a decrease in gas saturation causes a negligible change in the P-wave velocity for saturations above 20% and more significant c...

Abstract As more engineering projects and activities are taking place on around weak rocks, it is becoming important to study characterize them. Since regular practices of rock mechanical testing not effective for special laboratory tests measurements were performed the Alkharj Saudi sandstone which a clastic dominantly sandy limestone sandstone. Test results presented in this paper. Porosity, ...

A study of the diagenetic evolution of sandstones from Panyu low-uplift in the Pearl River Mouth Basin was carried out to unravel the controls on shelf margin sandstone reservoir quality. The reservoir rocks, Oligocene volcanic clastic sandstones of the Zhuhai Formation, have a burial depth of 2765 to 3440 m. 70 samples were studied using the granulometric analyses, X-ray diffraction (XRD) anal...

The porosity exposed in a series of petrographic thin sections from a sub-arkosic sandstone reservoir of the Alwyn area (North Sea) is described by 5 morphological porous descriptors, Pore-Types, obtained by quantitative image analysis procedures and pattern recognition algorithms developed by Ehrlich et al. (1991a). By combining Pore-Type data with capillary pressure curves, we obtain prelimin...