CHALLENGEConfidently calculate bitumen volume in place for the vuggy, heterogeneous Grosmont dolomite as the basis for estimating oil reserves.

SOLUTIONRun Litho Scanner* high-definition spectroscopy service to measure elemental concentrations for determining total organic carbon (TOC) that is independent of formation water salinity.

RESULTSAccurately determined the Grosmont bitumen saturation based on the TOC content as confirmed by laboratory core measurements.

Hydrocarbon saturation in a complex formationThe highly heterogeneous mineralogy and porosity of the Grosmont Formation in Alberta, Canada, make it difficult to accurately determine the TOC content for estimating the bitumen volume. Conventional approaches based on resistivity logging or carbon-to-oxygen ratios introduce many uncertainties arising from the Grosmont’s highly variable lithology and the effects of enhanced oil recovery on the formation water salinity and resistivity.

CASE STUDY

Formation Evaluation

Resistivity-Independent Spectroscopy Determines Total Organic Carbon for Accurate Bitumen VolumeLitho Scanner high-definition spectroscopy service quantifies key elements for determining TOC of highly heterogeneous Grosmont dolomite

The accuracy of the dry-weight element logs measured by Litho Scanner high-definition spectroscopy service and the resulting TOC (far-right track) is confirmed by the results of core analysis.

Gamma Ray

0 gAPI 150

Ca

0 0.5

Core Ca

0 0.5

Dept

h, m

X25

X50

Mg

0 0.2

Core Mg

0 0.2

Al

0 0.2

Core Al

0 0.2

Si

0 0.5

Core Si

0 0.5

Fe

0 0.2

Core Fe

0 0.2

Mn

0 0.05

Core Mn

0 0.05

S

0 0.25

Core S

0 0.25

TOC

0 0.2

Core TOC

0 % 0.24

CASE STUDY: Accurate TOC determined by Litho Scanner service, Alberta, Canada

www.slb.com/ls

Formation mineralogy, TOC, and hydrocarbon saturation based on Litho Scanner service measurements also compare well with results from core.

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Gamma Ray

0 gAPI 150

Cumulative Weight Percent

0 1

Clay

Quartz-Feldspar-Mica

Clay

Core

0 Weight Percent 1

Quartz-Feldspar-Mica

Core

0 Weight Percent 1

Hydrocarbon Saturation Limestone

0 1

Dept

h, m

X25

X50

Calcite

Dolomite

TOC

Core

0 % 0.2Core Oil Saturation

0 % 0.24

Core Oil Saturation

0 % 1

Calcite

Core

0 Weight Percent 1

Dolomite

Core

0 Weight Percent 1

Accurate measurement of elements for TOC determinationLitho Scanner high-definition spectroscopy service employs both inelastic and capture gamma ray spectroscopy to quantify elemental weight fractions. The direct measurement of formation carbon coupled with an assess-ment of inorganic carbon from the mineralogy results in a robust, accurate TOC determina-tion that is independent of formation water salinity and does not require core calibration or previous knowledge of the kerogen type or maturity.

Quantified bitumen volumeThe accuracy of the bitumen volume based on the TOC determined with Litho Scanner service is confirmed by comparison with core measurements. The measured dry-weight elements and the resulting mineralogy, TOC, and hydrocarbon saturation from Litho Scanner service measurements are in excellent agreement with core measurements. Litho Scanner service is also quite timely, not requiring sampling operations and then the wait for results from laboratory core analysis.