WIRELINE AND PERFORATING SERVICES

Laminated Reservoir Analysis (LARA™)

Many highly-laminated reservoirs have been missed inexisting wells due to the coarse vertical resolution of olderlogging tools and the inadequate analysis techniques oftraditional interpretation programs. To better detect andstudy thin-bed reservoirs, it has been necessary to developnew logging tools, postprocessing techniques, and dataanalysis methods.

High-resolution shale indicators allow separation of thesand and shale components, but still require thin-bedresolution of true formation resistivity and porosity.The measurements produced by high-resolution shaleindicators are used with those from conventional orresolution-enhanced porosity logging tools to improve thesaturation analysis of the laminated reservoir. This is thebasis of LARA™.

To determine shale volume, the high-resolution shale devicedata is first integrated to the vertical resolution of theporosity device. Then two medium-resolution shale volumesare calculated-one from the integrated high-resolution dataand one from the porosity data. Device-specific shaleparameters are automatically adjusted until the two volumesare equal. Then LARA calculates the conventional total andeffective porosities. It also determines the mode of claydistribution, i.e., dispersed or laminated.

The high-resolution shale volumes are then used with theknown shale resistivity to generate high-resolution resistivityexpressions that involve shale and non-shale volumes andresistivities. These expressions are integrated to the verticalresolution of the resistivity device. The integrated resistivityis equated to the measured resistivity, and the resultingequation solved to give the non-shale resistivity, which isessentially a shale-corrected true formation resistivity (Rt).

Finally, the calculated effective porosity and true formationresistivity are used in a modified Waxman-Smits equation tocalculate Sw .

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HALLIBURTON

As can be seen in the LARA interpretation above, thinly laminatedhydrocarbon bearing zones above the main clean sand pay zones wouldhave been overlooked with conventional log analysis. In this case highresolution data from the EMI Image tool was integrated into the LARAanalysis. Note the gas effect Density-Neutron x-over in the clean sands andlack of x-over in the thinly laminated zone above the clean sand zone.

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LARA Features

The use of a high-resolution shale indicator in LARAgenerally yields significantly more accurate analysis inlaminated reservoirs than standard shaly sand models.

LARA Benefits

LARA offers the following benefits:

• Resolving gross shale volume % to high-resolutionlaminated and dispersed clay content

• Helps with the reliable quantitative interpretation ofthinly laminated reservoirs

• Helps identify potential hydrocarbon production oftenmissed by conventional analysis

HALLIBURTON

Laminated Reservoir Analysis (LARA™)

Inputs

Outputs

In addition to the minimun of a GR, resistivity and porosity measurement, one or more of the following thin-bed shale indicatorinputs is required for LARA: SED™, Pe (unfiltered), Microresistivity (ML, MSFL™), CAST™, EMI™, EVR-GRThe best high-resolution shale indicators are six-arm dipmeter or EMI, but alternatives include all of the above. LARA programrequires only a single porosity device but yields better results when more than one is used.

Sw, Sxo, VSH, φeff, Lithology Hydrocarbon weight (oil, gas), Permeability