QEMSCAN® WellSite™

Unprecedented cuttings analysis in a field-tested solution for the well site

www.fei-natural-resources.com

Particles to Cuttings | Cuttings to Lithologies | Lithologies to Properties | Properties to Logs

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Advanced MudloggingQEMSCAN® WellSite™ is a solution facilitating advanced mudlogging

services during remote on- and off-shore drilling operations.

Mudlogging commonly complements down-hole (in-situ) logging

using remote sensing technologies known as wireline or logging-

while-drilling (LWD). Rock cuttings, returned to the surface through

the circulating drilling mud, represent the tangible evidence

of the subsurface geology, and therefore a description and/or

analysis of cuttings is a cost effective method to obtaining valuable

complementary data on the stratigraphy of the drilled sequence.

Optical description of cuttings is a common activity of mudlogging

services; however, the process of optical cuttings description is manual,

labor-intensive and qualitative, as echoed by well-site geologists:

”we always ask for an experienced mudlogger, but never get one”.

QEMSCAN WellSite was developed with 2 objectives in mind:

•Provideasolutionforautomatedandquantitativecuttings

descriptions, providing more accurate and detailed information

than manual and qualitative methods.

•Provideasamplepreparationandanalysisworkflowtodeliver

quantitative cuttings descriptions in near real-time at the well

site, ready for seamless integration with logging data provided by

integrated and independent service providers, particularly LWD

and wireline.

Whereas many emerging advanced mudlogging technologies are

primarily bulk cuttings analysis methods, QEMSCAN WellSite is

essentially an imaging technique providing petrographic images

of individual particles in a mud sample. QEMSCAN WellSite uses

this feature to digitally screen particles in a mud sample in order

to separate cuttings particles from other particles such as cavings,

swarfordrillingadditives.Aunique4-stepdataanalysisworkflow

deconvolutes a bulk sample into cuttings properties on a lithology

basis, providing superior confidence in rock properties obtained from

cuttings.

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Cuttings PetrographyQEMSCAN WellSite is actually an automated petrography solution

developed since the late eighties primarily for the mining industry.

QEMSCAN enables access to two primary components of petrography

analysis: mineralogy and texture (i.e. microstructure). The primary

output of QEMSCAN WellSite is 2D numerical mineral and texture

maps of cuttings. These maps form the basis of subsequent image

and chemical analysis on a cutting-by-cutting basis. The visual nature

of the color-coded petrographic images make QEMSCAN WellSite

data readily accessible to a wide range of professionals at the rig (both

geologists and petrophysicists).

SystemBased on a product platform consisting of a compact, rugged and

mobile Scanning Electron Microscope (SEM), energy dispersive

spectrometers (EDS) and QEMSCAN Automated Petrography

measurement and analysis routines, QEMSCAN WellSite has been

designed for, and tested at, remote on- and off-shore well-site

Schematic of the sample measurement process. The electron beam is scanned across the sample surface; at each measurement point (also called a pixel) the BSE and x-ray signals are used for mineral identification by analyzing the EDX spectrum for chemical composition and subsequent classification based on known mineral chemical compositions.

locations. The physical dimensions easily permit placement in 30

foot or larger mudlogging units, or even smaller <20 foot units when

dedicated to the QEMSCAN WellSite solution.

One analogy – familiar to geologists – to how QEMSCAN WellSite

works is point counting. The system counts points (“pixels” in the

numerical mineral map) at a rate of 100–200 measurements per

second over a pre-determined grid. Typical measurement times of

approximately 30 minutes per cuttings sample can be achieved, with

a total number of points up to 400,000 measured. At each point,

the system determines the mineralogy from backscattered electron

intensity (indicative of mineral density), and elemental chemistry

(secondary X-rays generated as the electron beam interacts with

the mineral), using QEMSCAN’s Species Identification Protocol (SIP)

developed over decades for reliable mineral classification in the mining

industry. Once analyzed, cuttings descriptions can be made based on

a unique rock particle-by-particle basis, as opposed to other cuttings

analysis techniques such as LIBS, XRF or XRD, which are bulk methods.

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Optimized Sample Preparation WorkflowSamples for QEMSCAN WellSite are presented in the form of 30 mm

diameter resin blocks containing an average of 1,000–2,000 cuttings

particles/block, depending on the average size of the cuttings. The

samplepreparationworkflowinvolves:mixingcuttingparticles

with resin, curing the resin block, cutting and cross-sectioning the

block with a diamond saw, and finally coating the sample surface

with a conductive carbon film. Each device used in the sample

preparation process has a small enough footprint to be placed on

desktops typically found in a mudlogging unit. An additional benefit

of the sample preparation process is that the resulting resin blocks

improve handling and archiving, making cuttings readily available

for complementary analysis at a later stage at a central storage or

laboratory facility.

Near Real-time Data AcquisitionThe development phase of QEMSCAN WellSite included two extensive

field tests: in the highlands of Papua New Guinea, and off-shore Qatar,

aimed primarily at testing the feasibility and value of near real-time

data acquisition. Whereas time-to-data and throughput may vary

significantly as a function of primary data required, these field tests

yielded near real-time results.

From the time cuttings are collected at the shaker station, cleaned

and dried, it takes less than 30 minutes to prepare a resin block for

analysis. Samples are typically loaded in the system in batches of 6,

with measurement times of around 30 minutes per sample. The initial

data, therefore, are available one hour after collection of cuttings from

the first sampling horizon.

Experience from the first two field tests has demonstrated that up

to 35 cuttings samples can be measured in a 24 hour interval, with

an average of 22 samples if interruptions in the drilling process are

included. Sample preparation efficiency can exceed sample analysis

as demonstrated by one trial where 55 samples were prepared in a

24 hour period. At high drilling rates typically > 100 foot per hour, a

backlog of samples may accumulate; however, during both field tests,

drilling downtime due to e.g. cementation runs, allowed operators to

catch up on the backlog.

(Left) Wet cuttings sample, direct from a shale shaker, with resin impregnated block of same sample, for comparison.(Right) Multiple cuttings samples, prepared, labelled and laid out in stratigraphic order.

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Three MapViews showing a cuttings sample before digital or contextual screening (left), after digital screening to remove drilling mud particles (middle), and after contextual screening to remove cavings, swarf and drilling additives (right).

Particles to CuttingsOnce the numerical mineral maps have been acquired by the system,

image analysis allows for digital screening to remove particles

below a size attributed to drilling mud – typically < 63 micrometers.

Subsequent contextual screening removes particles attributed to

caving, swarf and drilling additives, each identified on the basis of

textural and/or compositional properties that differentiate them from

genuine cuttings.

Relevant parameters derived from this screening include cuttings

versus drilling additives ratio (measure of percentage returns), or

cuttings size and shape (measure on drilling performance and stress

fields).

Cuttings to LithologiesThe nature of cuttings collection at a constant sampling (i.e. depth)

interval ensures that multiple rock types (lithologies) are likely to be

represented within a single sampling interval. While bulk cuttings

analysis techniques cannot take this lithology variation into account,

QEMSCAN WellSite separates the cuttings into lithology classes, using

mineralogy and texture-based lithology classification rulesets.

While QEMSCAN WellSite comes pre-configured with standard

lithology rulesets, these can be customized at the well site prior to

cuttings collection, or applied retrospectively during or after the

drilling activities, on- or off-site.Schematic diagram illustrating that a cuttings sample may contain multiple lithologies.

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Lithology to PropertiesThe next level of analysis is the determination of specific lithology

properties, such as:

•modalmineralogy

•claytyping(glauconite/micas,radioactiveclays,swellingclays)

•K-feldsparabundance

•quartzgrainsize

•calculatedmatrixdensity(inferred)

•tracemineralogysuchaspyriteorapatite

•calculatedmatrixelementalchemistry(inferred)

•organicparticleabundancecommonlyencounteredingasandoil

shale plays

A variety of preconfigured reports are available for reporting each of

the above properties for any given batch of depth intervals. Additional

report templates can easily be created and retained for future use.

Lithology classes from a siliciclastic reservoir sequence.

Property sheet for lithology class ‘calc-cmt-si’ (calcareous cemented silt) based on combined cuttings. This cuttings class comprises siltstone cuttings cemented by calcite.

calc-cmt-crs-qtz ark-crs-qtz cl-crs-qtz crs-qtz calc-cmt-si cl-si si calc-cl cl cmt uclass

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Properties to LogsFinally, each of these properties can be easily exported for

incorporation into 3rd party logging software, such as ODM™, for

subsequent interpretation by petrophysicists or reservoir evaluation

specialists. Results from the two field tests demonstrate excellent

consistency between the conventional mudlog cuttings descriptions

and those obtained by QEMSCAN WellSite on the one side, but on the

other side superior resolution and detail of mineralogy and texture,

from which specific properties such as cuttings / additives ratio,

lithology, clay type, or calculated matrix density can be derived with

significant confidence.

Retrospective Data InterrogationAnother key feature of QEMSCAN WellSite solution is that all of the

raw data is retained in datastores (databases) that can be revisited

retrospectively with the help of off-line software on workstations at

oil and gas company operational centers. As insights into formation

evaluation continue to develop, it is anticipated that these quantitative

cuttings databases will carry significant value over time

for historical interrogation studies.

Collaborative DevelopmentQEMSCAN WellSite requirements have been gathered in close

collaboration with many major oil and gas companies and service

providers, whose input is greatly acknowledged. Furthermore, field

tests have been conducted in Papua New Guinea in close collaboration

with Halliburton (Houston, Texas) and OilSearch (Sydney, Australia),

and off-shore Qatar. Further development and testing is ongoing with

independent surface logging company GEOLOG at its R&D facilities in

Milan, Italy.

For a full description of the field tests, we refer to application

notes available upon request and for download on

www.fei-natural-resources.com/wellsite.

Integrated ODM™ log juxtaposing QEMSCAN® data with selected down-hole data.

FEI CompanyFEI is a leading developer and manufacturer of electron and ion beam

microscopes, headquartered in Oregon, USA, and is listed on the

New York NASDAQ Stock Market. The Natural Resources business unit

is dedicated to the development, marketing, sales and support of

technology solutions for the mining, oil & gas, and geosciences sectors.

Demonstration facilities are available in Australia, The Netherlands

and USA.

For more information please visit: www.fei-natural-resources.com

World HeadquartersPhone: +1.503.726.7500

FEI Europe Phone: +31.40.23.56000

FEI Japan Phone: +81.3.3740.0970

FEI Asia Phone: +65.6272.0050

FEI Australia Phone: +61.7.3512.9100

© 2011. We are constantly improving the performance of our products, so all specifications are subject to change without notice.QEMSCAN, WellSite and the FEI logo are trademarks of FEI Company, and FEI is a registered trademark of FEI Company. All other trademarks belong to their respective owners. BR00?? ??-2011

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