Electrical Properties

Capillary Pressure

Relative Permeability

Wettability

Sor, Swir and Srg

Whole Core Analysis

Sonic Velocity

Cap rock Analysis

Pore volume compressibility

NMR Core Spectrometer

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Capillary pressure
Sample pore size distribution capilary pressure and saturation relationship

The ability of a formation to retain water (Swir) is an important reservoir property and is a function of rock texture, wettability, fluid properties, IFT, density and formation saturation history.

Capillary pressure is measured on core plugs and can be used to:
· Evaluate reservoir rock quality, pore throat size distributions and wetting characteristics;
· Predict fluid saturations in the reservoir vs. height;
· Estimate the thickness of the transition zone;
· Quantify sealing capacity of overlying rock.

The three measurement techniques available to determine capillary pressure characteristics are:

Air-mercury capillary pressure
Mercury intrusions and extrusion curves from 0 up to 60,000 psi injection pressure can be obtained by using an automated Autopore III 9420. It can be used on cuttings and 1" x 1" core plugs. This analysis gives capillary pressure data, pore throat accessibility, and pore level heterogeneity in a short time frame. In combination with petrography, this information can be used to investigate a caprock for its sealing capacity (seal capacity studies). Other parameters derived from mercury injection are theoretical permeability, reservoir grade and mercury entrapment.
Capillary pressure by porous plate
Authigenic clay by SEMThis method is used to determine capillary pressure curves and saturation relationships on cylindrical rock samples of either 1" or 1.5" diameter at ambient conditions or confining pressures up to 10,000 psi. The maximum Pc that can be applied is about 20 bar (gas-water system). Usually sample permeability has to be > 1 mD for a successful drainage of the rock fluid.
Automated Ultra-Centrifuge
Capillary presure and saturation determination

Two Beckman ultra-centrifuges, fully automated with video data collection systems, were available for determination of capillary pressure and wetting characteristics (gas-water, oil-brine, imbibition/drainage). Ultra-centrifuges allow capillary pressure-saturation characterization of low permeability rocks.
In October 2009, our capacity for centrifuge work was increased by 50% with the addition of a new state-of-the-art Ultra Rock Core Centrifuge (URC – 628). This was acquired due to increasing workload (hence reducing lead-times) and up-grade our capability by being able to perform tests at confinement. The ability to run tests at confinement firstly increases the simulation to be closer to the true reservoir conditions and secondly allows the use of fragile samples as the confining pressure effectively increases the samples resistance to the stress exerted by the centripetal forces.
All our systems can accommodate samples of 1" or 1.5" diameter and can run at reservoir conditions. The average saturations obtained from the centrifuge can be calculated to inlet-face saturations using different available solutions.
For wettability restoration, core samples are first saturated with SFW, then, using the centrifuges, spun with oil to Swir. This enables the subsequent wettability restoration in ageing cells prior to testing. Typically, combined Amott-USBM tests can then be performed to obtain the wettability indices of the rock under study.

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