Laboratory investigation of wettability and hysteresis effects on resistivity index and capillary pressure characteristics

Moss, Adam Keith; Jing, Xudong; Archer, J. S.

doi:10.1016/s0920-4105(99)00045-5

Cited by 38 publications

(11 citation statements)

References 13 publications

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“…Typically, its value is around 2 in water-wet formations and it is assumed constant for clean, sandy like formations (Archie, 1942;Mavko et al, 1998). Lewis et al (1988), Longeron et al (1989a, b), Donaldson and Siddiqui (1989), and Moss et al (2000) found that the saturation exponent n increases to values as high as ten in oil wet formations. Furthermore, Diederix (1982), Anderson (1986), Longeron et al (1989a, b), and Worthington and Pallat (1992) found that the saturation exponent is not always constant over the whole saturation range in disagreement with the early work by Archie (1942).…”

Section: Petrophysical Parametersmentioning

confidence: 99%

Irreducible Water Saturation from Capillary Pressure and Electrical Resistivity Measurements

Attia

Fratta

Bassiouni

2008

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Estimation de la saturation irréductible en eau à partir de la pression capillaire et des mesures de la résistivité électrique -Cet article présente les résultats de mesures de la pression capillaire et de la résistance électrique de trois types de roches : le sable argileux (Berea), le quartz et le calcaire. Nous rapportons également des données expérimentales pour l'indice de résistivité, le facteur de formation, la tortuosité, la pression capillaire et les exposants de saturation en eau de ces roches dans le système air/saumure. Les données de résistivité électrique sont évaluées par la loi d'Archie modifiée. Les résultats des mesures de la pression capillaire et de la résistivité électrique en fonction de la saturation en saumure montrent l'existence de deux saturations irréductibles en eau correspondant à deux phénomènes physiques différents. Les deux valeurs des saturations irréductibles forment des limites hautes et basses qui peuvent être utilisées pour estimer la capacité de la production d'un milieu poreux. L'analyse détaillée des données a aussi montré un changement de valeur de l'exposant de saturation. Ce changement pourrait également être observé à la saturation irréductible en saumure obtenu lors des mesures de pression capillaire. Abstract -Irreducible Water Saturation from Capillary Pressure and Electrical Resistivity

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Section: Petrophysical Parametersmentioning

confidence: 99%

Irreducible Water Saturation from Capillary Pressure and Electrical Resistivity Measurements

Attia

Fratta

Bassiouni

2008

Oil & Gas Science and Technology - Rev. IFP

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“…The saturation exponent is around 1.6 for the "equilibrium" displacement, but we see that the resistivity index tends to curve toward the saturation axis. This kind of "non-Archie" behavior is experimentally observed (Worthington and Pallatt 1992;Moss et al 1999), and can be explained by the increasing amount of electric current in the water layers as S w decreases. If water is only residing in water layers, and the connectivity of the layers is preserved, the resistivity index yields I R = 1/S w .…”

Section: Fig 10mentioning

confidence: 73%

“…Some experiments show hysteresis in the resistivity index between drainage and imbibition cycles in water-wet sandstones (Longeron et al 1989;Knight 1991). However, some authors also report no significant hysteresis (Moss et al 1999;Han et al 2007). The shape of the curve for the "equilibrium" imbibition is bending slightly upward, while for FSI and FI the curve is bending downward.…”

Section: Fig 10mentioning

confidence: 99%

A Dynamic Network Model for Two-Phase Flow in Porous Media

Tørå

Øren²,

Hansen

2011

Transp Porous Med

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We present a dynamic model of immiscible two-phase flow in a network representation of a porous medium. The model is based on the governing equations describing two-phase flow in porous media, and can handle both drainage, imbibition, and steady-state displacement. Dynamic wetting layers in corners of the pore space are incorporated, with focus on modeling resistivity measurements on saturated rocks at different capillary numbers. The flow simulations are performed on a realistic network of a sandpack which is perfectly water-wet. Our numerical results show saturation profiles for imbibition in agreement with experiments. For free spontaneous imbibition we find that the imbibition rate follows the Washburn relation, i.e., the water saturation increases proportionally to the square root of time. We also reproduce rate effects in the resistivity index for drainage and imbibition.

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“…[33][34][35][36] The plugs have all been cleaned to reach a water-wet state, and use of refined oil was chosen to avoid aging effects. However, cleaning of lowpermeability samples is difficult to achieve, and some clays may have a particular affinity with oil.…”

Section: Discussionmentioning

confidence: 99%

Effect of Pore-Lining Chlorite on Petrophysical Properties of Low-Resistivity Sandstone Reservoirs

Durand¹,

Brosse²,

Cérepi

2001

SPE Reservoir Evaluation &Amp; Engineering

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Chlorite-bearing sandstones usually give low resistivity signals and are thus erroneously identified as nonpay zones, even if they exhibit good preserved porosities at depth. The purpose of this paper is to provide petrophysical and mineralogical laboratory measurements that help improve the log interpretation of these sandstones.The main results were obtained from a selection of reservoir cores. For sandstones having an amount of chlorite between 3 and 11 wt%, they show that the cementation index and saturation exponents (m and n) have values lower than 2, with n frequently around 1.5. These low values have been checked carefully to avoid experimental artifacts. Cationic Exchange Capacities (CEC) and Specific Surface Areas (SSA) both have low values, as expected from the clay structure. The distribution of pore throats is bi-or trimodal, with a large contribution of microporosity.The interpretation suggested by these results is that the amount and distribution of microporosity associated with pore-lining clay is the key to the chlorite sandstone electrical behavior. The values of CEC or SSA are too low to fully explain the low values of the saturation index n.Use of these low values in log interpretation has the effect of increasing the interpreted oil in place. Advantages of a multidisciplinary approach for better evaluation of such complex argillaceous sandstone reservoirs is highlighted.Concentration of clay fraction, to better characterize the clay nature, polytype, and crystallinity, was performed by sedimentation after similar cleaning. The SSA and CEC were also determined on these fractions. Fig. 1. Experiments were run in a sophisticated Hassler cell (Ergotech), allowing measurements in 2-or 4-electrode mode (with the two current electrodes at each end of the plug) on the water inlet/outlet tubes, and up to six potential electrodes every 1.25 cm along the length of the plug. No ceramic or porous plates were used. This cell was located in an oven, with a temperature regulated at 22±0.1°C. Experimental Setting. F and IR Determination. The experimental setting is shown inResistance measurements were acquired on a PC every 15 minutes on each slice (i.e., interval between the potential electrodes) of the sample, both in 2-and in 4-electrode settings, without any manipulation of the sample during the entire experiment. These records allowed us to identify possible contact problems, to check the homogeneity of the electrical values along the samples, and ensure that a plateau was reached in the electrical values.Electrical measurements were performed with a HewlettPackard 4263B impedance meter. The conditions were 1V, 1kHz. The phase angle was negligible at this frequency.For the F experiments, the brine salinities were increased from 20 to 200 g/L NaCl.The brine used for all the IR experiments was 96 g/L NaCl. The reason for this was that the field salinities are very high in all cases-sometimes at the limit of NaCl solubility at reservoir temperature, and thus impossible to reproduce at room temperature. The ...

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Laboratory investigation of wettability and hysteresis effects on resistivity index and capillary pressure characteristics

Cited by 38 publications

References 13 publications

Irreducible Water Saturation from Capillary Pressure and Electrical Resistivity Measurements

Irreducible Water Saturation from Capillary Pressure and Electrical Resistivity Measurements

A Dynamic Network Model for Two-Phase Flow in Porous Media

Effect of Pore-Lining Chlorite on Petrophysical Properties of Low-Resistivity Sandstone Reservoirs

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