Applications of Streaming Potential Transient Tests to Electrokinetic Characterization of Oil Reservoirs

Alkafeef, Saad F.; Al-Ajmi, Nab Mahdi; Alajmi, Abdullah F.

doi:10.2118/105372-ms

Cited by 5 publications

(1 citation statement)

References 18 publications

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“…Electrokinetics is the general term associated with the relative motion between charged solid/liquid interfaces, which has proven to provide direct information on oil reservoir characterizations [4][5][6][7][8]. There are various electrokinetic techniques, all yielding, in principle, the same information.…”

Section: Introductionmentioning

confidence: 99%

The electrical conductivity and surface conduction of consolidated rock cores

Alkafeef

Alajmi

2007

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

The electrical conductivity and surface conduction of consolidated rock cores

Alkafeef

Alajmi

2007

Journal of Colloid and Interface Science

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On the Relationship between Electrokinetics and Reservoir Rock Physical Properties

Alkafeef¹,

Zaid²,

Alajmi

2009

SPE Middle East Oil and Gas Show and Conference

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Numerous investigations have been made of the relationship between formation resistivity factor and porosity of reservoir rocks. One of the most widely used expressions is the familiar Archie equation. This paper presents an investigation of the relationship between electrokinetics and reservoir rock formation conductivity factor and porosity. Electrokinetics is the general term associated with the relative motion between charged solid/liquid interfaces, and has proven to provide direct information on oil reservoir characterizations. The movement of liquid through the capillaries carries a net charge (mobile part of the Electrical Double Layer) and it gives rise to streaming current, consequently, a potential difference (streaming potential). This investigation leads to the determination of formation conductivity factor from the total electric conductivity of reservoir rocks. This was achieved from the estimation of the ratio of the pores' area cross section 'A' to its length 'L' by coupling streaming current and streaming potential measurements. The validity of calculated formation conductivity factor from this analysis is established by the use of sandstone data with various porosities. The results are in good agreement with the Humble expression for porosity-formation resistivity factor relationship. These results could prove to be valuable in determining formation conductivity factor from simple and quick measurements of streaming current and streaming potential. The factor can then be used to estimate water saturation in the normal manner. Introduction Numerous electrical properties of reservoir rocks are currently being investigated and utilized to determine the reservoir parameters. Porosity and permeability of reservoir rocks are very important parameters, but their estimation from well logs is not straight forward and is often cumbersome and difficult. Correlation between porosity and permeability for a rock type is a basic procedure applied in core data interpretation. However, this correlation may not always be satisfactory because of pore heterogenenety and pore geometry. Correlations between two flow properties, namely, electrical current flow and fluid flow have been investigated by number of workers (Brouers 1986), (Banavar 1987), (Wong 1988), (Avellaneda 1991), (Kostek 1992), and (Schwartz 1993). The fluid flow property is represented by permeability, and the current flow property is represented by electrical conductivity, which is the reciprocal of resistivity. Both properties are functions of porosity and pore interconnections. The latters are represented by a factor known as the formation factor, F, normally defined as the ratio of the conductivity of the fluid and of the apparent conductivity of the inhomogeneous sample 100% saturated by the same fluid. The formation resistivity factor, F, is a well known parameter in electric investigations, which is used for petrophysical evaluation of reservoirs. It is a function of several physical parameters and lithological attributes, including electric resistivities of formation and pore fluid; temperature, viscosity, and degree of saturation of pore fluid; type amount of clays; intricate geometry of pores and pore channels (represented by tortuosity); size, shape, and system of pores (represented by porosity) formation's ability to transmit pore fluid (represented by permeability) (Salem 2001). It is also a function of degree of cementation, consolidation, and compaction of sediments (Salem 1994; Salem and Chilingarian 1999).

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Laboratory Measurements and Numerical Modeling of Streaming Potential for Downhole Monitoring in Intelligent Wells

et al. 2011

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Summary Downhole monitoring of streaming potential, using electrodes mounted on the outside of insulated casing, is a promising new technology for monitoring water encroachment toward an intelligent well. However, there are still significant uncertainties associated with the interpretation of the measurements, particularly concerning the streaming potential coupling coefficient. This is a key petrophysical property that dictates the magnitude of the streaming potential for a given fluid potential. We present the first measured values of streaming potential coupling coefficient in sandstones saturated with natural and artificial brines relevant to oilfield conditions at higher-than-seawater salinity. We find that the coupling coefficient in quartz-rich sandstones is independent of sample type and brine composition as long as surface electrical conductivity is small. The coupling coefficient is small in magnitude, but still measurable, even when the brine salinity approaches the saturated concentration limit. Consistent results are obtained from two independent experimental setups, using specially designed electrodes and paired pumping experiments to eliminate spurious electrical potentials. We apply the new experimental data in a numerical model to predict the streaming potential signal that would be measured at a well during production. The results suggest that measured signals should be resolvable above background noise in most hydrocarbon reservoirs. Furthermore, water encroaching on a well could be monitored while it is several tens to hundreds of meters away. This contrasts with most other downhole monitoring techniques, which sample only the region immediately adjacent to the wellbore. Our results raise the novel prospect of an oil field in which the wells can detect the approach of water and can respond appropriately.

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Applications of Streaming Potential Transient Tests to Electrokinetic Characterization of Oil Reservoirs

Cited by 5 publications

References 18 publications

The electrical conductivity and surface conduction of consolidated rock cores

The electrical conductivity and surface conduction of consolidated rock cores

On the Relationship between Electrokinetics and Reservoir Rock Physical Properties

Laboratory Measurements and Numerical Modeling of Streaming Potential for Downhole Monitoring in Intelligent Wells

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