Articulo de la revista WorldOil 0413-XRF

8/10/2019 Articulo de la revista WorldOil 0413-XRF

1/6World Oil / APRIL 2013163

Application of cuttings gas/oil analysis, rapid XRF and

high-resolution photography to reservoir evaluation

SPECIAL SECTION:GEOLOGICAL & GEOPHYSICAL TECHNOLOGY

Rock and fluid analyses

are essential for prediction

and characterization of

produced hydrocarbons andfor understanding reservoir

architecture. A new approach

for archived drill cuttings,

or cores of any age, allows

evaluation of small rock

samples and associated

trapped fluid with a single,

semi-automated workflow.

DON HALL, MIKE STERNER and ROHITSHUKLA, Fluid Inclusion Technologies, Inc.

Exploraion and exploiaion of in-creasingly complex reservoirs, along

wih echnical challenges associaed wihopimizing horizonal wells ino igh orunconvenional pay secions, benefisfrom new approaches involving addi-ional daa colleced in a cos- and ime-

effecive manner. This aricle describesone such mehodology applicable osamples ha are hisorically viewed asconaining limied value, namely, unpre-served cuings. During his procedure,he rock is firs phoographed under

visible and UV ligh, hen crushed andanalyzed for included hydrocarbon andnon-hydrocarbon species wih a sen-siive mass specromery sysem, andfinally probed for is elemenal compo-siion wih a cusomized X-ray fluores-cence (XRF) analyzer.

A key aspec of he process is ha allanalyses are conduced on he same 1-gmrock sample wih an auomaed sysem,

hus preserving inerrelaionships amongrock ype, fluid ype and rock chemisry.Auomaion and rapid analyical cyclesallow collecion of large daa ses, and en-courage analysis of enire wellbores fromfirs reurns o TD. Individually, he ech-niques are useful. Togeher hey provideunique insighs ino conrols on hydrocar-

bon, reservoir and pay disribuion, repre-sen an addiional ool for well placemen,and allow organized archival of rock ype,fluid and rock chemisry informaion hais easily rerieved and sudied in he con-

ex of fuure wells, even in he absence ofhe original rock maerial.

TECHNIQUES

Photography. Washed and driedsamples are phoographed in whie lighand under broadband UV exciaion wiha special, high-resoluion imaging sysemo produce a sraigraphic caalog of everysample submied for analysis. Ideally, his

would represen all samples colleced suchha a complee record of he peneraedsecion is available for subsequen sudy.

Grain-scale deails of porosiy, rock ypeand exure can be idenified. UV imagesindicae specific mineral fluorescence hacan be correlaed wih cemen or rock ypesha are hard o disinguish under whieligh. Also, kerogen fluorescence is observ-able and can be relaed o hermal mauriy

when appropriae macerals are idenified.Rock fluorescence is unlikely o represenresidual oil (unlike similar procedures con-duced wih fresh samples a he well sie),

because he samples have been washed anddried and may have been sored.

Images are sored and can be reviewedwih a special viewer (see secion below).These archived phoographs are easier omanage han he samples hemselves, arepreserved for fuure use even when origi-nal samples have been los, disposed of ordepleed, and allow geologiss o sudyrocks a heir desks wihou relying onsample descripions or lower qualiy im-ages from wellsies. These images alsocan be made available o well sie person-nel on subsequen wells o aid in sample

descripion and recogniion of key srai-graphic markers.Trapped fluid analysis. Peroleum

migraion, reservoir charging, and localgeneraion of hydrocarbons from mauresource rocks leave race evidence as fluidinclusions: micron o sub-micron sizedsealed fluid-filled caviies in diageneiccemens and healed microfracures.1Fluid inclusions are no idenified dur-ing convenional show analysis and arecommonly presen even in he absenceof hese classical shows. In addiion o

migraed fluids, Adsorbed or free-phasevolailes wihin convered kerogen nano-

An ultra-high-resolution photographicprofile of the borehole lithology recordedfrom drill chip cuttings.

Originally appeared inWorld Oil

APRIL 2013 issue, pgs 163-168. Posted with permission.


2/6164 APRIL 2013 / WorldOil.com

GEOLOGICAL & GEOPHYSICAL TECHNOLOGY

pores can comprise an appreciable com-ponen of rapped fluid in maure, organ-ic-rich rocks.2Desrucive bulk analysisof rapped organic and inorganic fluidsis accomplished via he Fluid InclusionSraigraphy (FIS) echnique.3 Samplesare crushed in a vacuum sysem, and

liberaed fluids are analyzed via direcquadrapole mass specromery for C1-C13 peroleum species, and inorganic

volailes (e.g., CO2, H2S, He). Mass spec-ra and deph profiles of criical species

provide a full wellbore profile of rappedfluids ha documen rapped peroleumdisribuion wihin he sraigraphic sec-ion, he chemisry of migraed or locallygeneraed peroleum, he locaion andeffeciveness of seals and evidence ofproximal charged reservoirs ha may no

have been peneraed by he borehole.The laer applicaion relies on enrap-men of waer-soluble organic speciessuch as aceic acid and benzene. Thesecompounds are concenraed in waer-

bearing inervals wihin kilomeers ofperoleum reservoirs, and produce dif-fusion halos cenered on hese deposis.4

Wihin unconvenional reservoirs, FIScan infer swee spos, calculae likely pro-duced-fluid characerisics and help dis-inguish poor compleions from poorly

placed laerals. FIS provides a conveniengeochemical screening ool for follow-upperographic and microhermomeric

work. These echniques help idenify spe-cific hydrocarbon charge evens, quan-iaive API graviies, sauraion sae ofhydrocarbon fluid, and saliniies for logcalculaions of waer sauraion.5

Elemental analysis. XRF of rock ma-erial has been shown o have a number ofinvaluable applicaions o peroleum ex-ploraion, wih more recen focus owardunconvenional sysems.6,7XRF analyzers

deermine he chemisry of a sample bymeasuring he specrum of he characer-isic fluorescence X-rays emied by hedifferen elemens in he sample when iis illuminaed by X-rays of sufficien en-ergy. The daa provide informaion hacan be relaed o rock and cemen ype

via compuer programs,8 alhough quan-iaive analysis also benefis from spoanalyses via addiional echniques (e.g.,

XRD, QEMSCAN).9Hisorically, chemi-cal sraigraphy via XRF and ICP-MS has

been used o correlae monoonous srai-graphic inervals wih unclear or variablelaeral exen and hickness, paricularly inhe absence of sufficien biosraigraphic orlihosraigraphic markers. Trends in ele-men abundance and raios have also beenused o infer deposiional environmen,anoxic evens conducive o preservaion oforganic maer, ransgressive vs. regressivecycles and sedimen provenance. Empiricalcorrelaions can provide semi-quaniaiveindicaions of TOC, and elemenal sum-maions have been proposed as a means

of quickly deermining relaive brileness.The laer is relevan o compleions. Oncedelineaed from verical peneraions, keychemosraigraphic markers can be used oseer he wellbore in real ime,10or, in hecase of he presen mehod, rerospecivelydeermine or confirm he wellbore pah.

Viewer. The resuls of hese hree sepsare loaded ino a viewer ha allows heuser o rapidly assess relaionships amonghe various image and chemical daa ses,Fig. 1.Alhough no a daa analysis ool inhe sric sense, he sofware has virually

no learning curve and is uniquely suiedo his specific daase. LAS files and san-

Fig. 1.Static image from an interactive software program that allows mud gascompositions, rock and fluid chemical data, electric logs and rock images to be viewedand manipulated.

Fig. 2.Selected XRF and FIS data from a horizontal well within Cardium sandstone. Datadocument a sweet spot which was found to have highest initial production.


3/6World Oil / APRIL 2013165


dard image files are creaed as well, whichare compaible wih virually all oher in-dusry programs.

EXAMPLES

Figure 2shows seleced XRF and FISdaa from a horizonal well wihin Car-

dium sandsone. The wellbore encoun-ered an unexpeced faul, and drilledou of secion ino he overlying shale inhe lower par of he well. The ransiionfrom sandsone o shale and back againis clearly idenified in he XRF daa as anincrease in Al and K (dominanly relaedo clay minerals in his case), and a con-comian decrease in Si (reflecing lower

bulk quarz percenage). A simple crossplo of Al vs. Si defines he basic rockypes here. However, of greaer ineresis he relaionship beween Fe, Ca, Si and

FIS peroleum indicaions (represenedby C1 and C7). The highlighed inervalis characerized by increased Fe and Ca,decreased Si and increased ligh oil in-dicaions in FIS daa. Perographic workindicaes ha he zone conains increased

visible porosiy relaed o he presence ofsiderie cemen. High visible peroleuminclusion abundance is consisen wihhigh peroleum sauraion, in his case42 graviy undersauraed ligh oil (de-rived from fluid inclusion perographyand microhermomery). This zone wasesed independenly and found o be he

bes producing inerval in he wellbore.If laerally coninuous, i may represen aarge for fuure wells in he area. FIS ace-ic acid anomalies are presen hroughouhe well, consisen wih he presence ofpeneraed liquid peroleum charge wihprobable elevaed waer sauraion.

Figure 3illusraes FIS, XRF and com-pressed image daa from a verical well,along wih hree zones ha will be dis-cussed in more deail. The upper zone is

siliciclasic dominaed wih hin carbon-ae-enriched inervals, some of which havedisincive UV fluorescence. Two Fe-Sanomalies correlae wih wha appear o

be hin red beds or exposure surfaces, asimages indicae he presence of hemaie-sained rock. Covariance of Ca and Sr isnoed in carbonae bearing beds, and, inhis well, disinguishes limesone from do-lomie. Thin, dry o we gas FIS anomaliescorrespond o hese carbonae-enrichedinervals, and indicae peroleum migra-ion hrough hese zones. Overall, how-

ever, he upper secion appears o have lim-ied peroleum prospeciviy, conains no

Fig. 3.FIS, XRF and image data from a vertical well i llustrating three zones.

2,000

3,000

4,000

5,000

6,000

7,000

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9,000

0

60

,000

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,000

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,000

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,000

Si

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8,

000

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,000

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,000

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,000

Al

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,000

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,000

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,000

K

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,000

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,000

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,000

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,000

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S

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,000

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,000

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,000

Ca

0

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Sr

0

262

,5000

525

,0000

7875

,000

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,500

,000

CO2

0

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,000

1,

000

,000

1,5

00

,000

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000

,000

CH4

0

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,000

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,000

90

,000

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,000

Parafins 57

0

1,2

50

2,

500

3,7

50

5,

000

AlkNaphtha

Si Al K Fe S C4 C7C1Ca Sr CO2

XRFa)

b)

c)

FIS

Zone 1

2,000

3,000

4,000

5,000

6,000

7,000

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0

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,000

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,000

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,000

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,000

Si

0

8,0

00

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,000

24

,000

32

,000

Al

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00

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,000

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,000

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,000

K

0

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,000

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,000

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,000

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,000

Fe

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00

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,000

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,000

Ca

0

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300

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600

Sr

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262

,5000

525

,0000

7875

,000

10

,500

,000

CO2

0

500

,000

1,0

00

,000

1,

500

,000

2,0

00

,000

CH4

0

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,000

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,000

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,000

120

,000

Parafins 57

0

1,2

50

2,5

00

3,7

50

5,0

00

AlkNaphtha


XRF FIS

Zone 2

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

0

60

,000

120

,000

180

,000

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,000

Si

0

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00

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,000

24

,000

32

,000

Al

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00

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,000

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,000

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0

25

,000

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,000

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,000

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,000

Fe

0

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00

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00

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00

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00

S

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,000

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,000

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,000

360

,000

Ca

0

150

300

450

600

Sr

0

262

,5000

5

25

,0000

7875

,000

10,5

00

,000

CO2

0

500

,000

1,0

00

,000

1,5

00

,000

2,0

00

,000

CH4

0

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,000

60

,000

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,000

120

,000

Parafins 57

0

1,2

50

2,5

00

3,7

50

5,0

00

AlkNaphtha


XRF FIS

Zone 3


4/6166 APRIL 2013 / WorldOil.com


proximiy o pay indicaions and reporedno significan drilling shows. Shallow CO2is inerpreed o be bacerial in origin andis inerpreed o have been formed by bac-erial sulfae reducion in he presence of

verically seeping ligh hermogenic hydro-carbons. These FIS microseeps are saisi-cally correlaed o deeper liquids poenialin many insances, and here are consisen

wih FIS and mud gas indicaions of pen-eraed liquid peroleum deeper in he well.

The middle of he well is carbonae-dominaed wih lile or no covariance ofCa and Sr. The zone is dolomiic, and re-cords UV fluorescence. FIS hydrocarbonindicaions increase, wih he bulk rappedphase varying in characer from dry gas ooil. Thin, dry gas zones and decoupled C1and C7 behavior imply a leas wo dis-inc charges, consisen wih perographic

work described below. FIS CO2 responseis elevaed hrough his zone, bu does nocovary wih hydrocarbons; hus, a separaesource (probably diageneic) is suggesed.FIS daa sugges he upper and lower hirds

of his secion have beer prospeciviy,and perographic analysis documens hepresence of liquid peroleum inclusionsin high abundance wihin hese high FISresponse zones. High peroleum inclu-sion abundance implies high oil sauraionor paleo-sauraion. Moderae o upper-moderae graviy (~30 o low 40 graviy),undersauraed oils are inferred from fluidinclusion relaionships, consisen wihproduced fluids in he area. A dual porosiysysem is indicaed, wih inergranular andfracure porosiy being significan.

The lower secion conains mixed silici-clasics and carbonaes wih some covari-

Fig. 4.Correlation of elemental sulfur response with gamma ray response suggestsvariation in source potential, and correlates with visual organic matter in images andthin section.

5,750

6,250

6,750

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0 100 200 300 400 500 600 700Gamma

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0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000

Sulfur

Source rock

Mature oil-proneorganic matter

Fig. 5.Cross plot of Zr and Si illustratingthe difference between biogenic silica(chert in this case) and terrestrial derivedsilica (quartz associated with sandstoneand siltstone). Sample point colors aregrouped according for formation.

Biogenicsilica

Terre

strial

Si-Zrt

rend

-100

0

0 100 200

Zr

300 400 500

100

200

SI,10A

3

300

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500

Visit Us at: NAPE EastBooth #122; GeoConventionBooth #1004;

AAPGBooth #2033; SPWLA Booth #500

PetroFectafrom Fluid Inclusion Technologiesis a unique approach combining XRF (PDQ-XRF), Trapped Fluid Analysis (FIS), and

High Resolution Photography (RockEye) of the entire wellbore from well cuttings or core samplesof any age. All analyses are conducted on the same 1 gram sample (up to 575 samples per well)

with an analytical cycle of four days. Data provided on a DVD with previewer software.

Information about PetroFectaand the umbrella of FIT services,

call 918.461.8984or visit www.fittulsa.com


5/6


ance of Ca and Sr consisen wih a mixedlimesone and dolomie inerval. Elemen-al sulfur response correlaes wih he gam-ma ray curve in his zone and hroughouhis well, Fig. 4,and likely reflecs sourcepoenial.11 Maure oil-prone kerogen isidenified in hin secion. A fla o negaive

Si/Zr profile hrough he upper porion ofhis secion is consisen wih biogenic sili-ca, Fig. 5,in conras o he generally posi-ive relaionship obained in siliciclasics,12and phosphorus anomalies are consisen

wih he presence of apaie in hin secion,a near-shore deposiional environmen

wih relaively low sedimenaion raes andelevaed surface produciviy.

The mos promising zone, based onFIS response, is a abou 9,000 f, corre-sponding o a fracured chery carbonae,

which also displayed significan mud gas

anomalies while drilling. CO2 covarieswih hydrocarbons, and was also recordedin he mud gas, suggesing ha some CO2

will be presen in he produced pero-leum. The source of CO2and inermiensulfur species is hough o be relaed ohermochemical sulfae reducion a highemperaure. As i is unlikely ha maxi-mum burial emperaure a his deph ex-ceeded he hreshold for local TSR (abou130oC), influx of maure gas from deeperin he basin is suggesed. This is consis-en wih he presence of discree dry gasphase in he FIS daa. High visible liquidperoleum inclusion abundance is docu-mened here, and suggess high sauraionof ligh oil and gas-condensae in frac-ured chery carbonae.

There is evidence from fluid inclusiondaa ha he reservoir conains boh gasand condensae or ligh oil. Lower inclusionabundance and presence of ar-like dead oildeeper in he secion represens residualoil. Some of his dead hydrocarbon mayhave been sourced via gas-deasphalening

during emplacemen of he previously

menioned dry, maure gas from deph.Composiional calculaions of he bulkFIS volailes in his lower inerval sugges aslighly ligher bulk peroleum phase in hedeeper zone as compared o he lower sec-ion of he middle inerval described above.

CONCLUSIONSThe combinaion of phoography,rapped fluid chemisry and bulk rockelemenal analysis has been shown oprovide valuable and oherwise unobain-able informaion wih broad applicaion,including presen and pas peroleumdisribuion, source and chemisry, rockand cemen ype, chemical sraigraphyand mineralogical rends necessary for logcalculaions, deposiional environmenand likely source rock poenial, and rockproperies relevan o compleion. Daa

are all colleced on a single approximaely1-gm aliquo of washed and dried rockmaerial, wih an analyical cycle of fourdays. Approximaely 600 samples per wellcan be analyzed. Daa can be used o helpundersand peroleum sysems in conven-ional and unconvenional reservoirs, andopimize wellbores and compleions.

REFERENCES

1. Hall, D. L., Fluid Inclusions in Peroleum Sysems: ACompendium of Influenial Papers, AAPG GetingSared Series, vol. 15, 2008.

2. Kausik, R., C. C. Minh, L. Zielinski, B. Vissapragada,

R. Akkur , Y. Song, C. Liu, S. Jones and E. Blair, Char-acerizaion of Gas Dynamics in Kerogen Nanoporesby NMR, SPE, Denver, 2011.

3. Hall, D. L., W. Shenwu, S. M. Serner and P. D. Wag-ner, Using fluid inclusions o ex plore for oil and gas,Harts Petroleum Engineer International, pp. 2934,1997.

4. Burel l, S. G., and V. T. Jones, Benzene conen ofsubsurface brines can indicae proximiy of oil, gas,Oil and Gas Journal, June 3, pp. 5963, 1996.

5. Munz, I. A., Peroleum inclusions in sedimenary ba-sins: sysemaic analyical mehods and applicaions,Lihos, vol. 55, pp. 195212, 2001.

6. Hildred, G. V., and C. R. Rice, Using high resoluionchemosraigraphy o deermine well-bore pahways inmulilaeral drilling campaigns: an example from heHorn River Formaion, Briish Columbia, Canada,

Geoconvenion 2012: Vision, pp. 14, 2012.7. Racliffe, K. T., A. M. Wrigh and K. Schmid, Appli-

caion of inorganic whole-rock geochemisry o shaleresource plays: an example from he Eagle Ford ShaleFormaion, Texas, Te Sedimentary Record, vol. 10, no.2, pp. 49, 2012.

8. Cohen, D., and C. R. Ward, SEDNORM a programo calculae a normaive mineralogy for sedimenaryrocks based on chemical analyses,Computers &Geosciences, vol. 17, no. 9, pp. 12351253, 1991.

9. Bucher, A. R., Geting he mos ou of dich cutings:Find ou how a new echnology is revoluionizing he

way we can auomaically quanify mineralogy, exureand lihoype on a cuting-by-cuting basis, PeroleumExploraion Sociey of Ausralia, PESA NSW, Sydney,Ausralia, Sep. 12, 2008.

10. Marsala, A. F., A. M. Loermans, S. Shen, C. Scheibeand R. Zereik , Real-ime mineralogy, lihology andchemosraigraphy while dril ling, using porableenergy-dispersive X-ray fluorescence,Saudi AramcoJournal of echnology, Summer issue, p. 1824, 2011.

11. Berner, R. A ., Sedimenary pyrie formaion: anupdae, Geochimica et CosmochmicaAca, vol. 48, pp.605615, 1984.

12. Wrigh, A. M., D. R. Spain and K. T. Racliffe, Applica-ion of inorganic whole rock geochemisry o shaleresource plays, CSUG/SPE Paper 137946, Calgary,2010.

DON HALL received BS (1982)and MS (1985) degrees in

geology from the University of

California at Riverside, and a

PhD (1989) in geology from

Virginia Tech. He joined AmocoProduction Research in 1990 as

a research scientist, where he worked on

development and implementation of novel fluid

inclusion instrumentation and techniques. Heleft Amoco in 1997 and co-founded Fluid

Inclusion Technologies, Inc.

MIKE STERNERhas a BS in

chemistry from the University

of Michigan and a PhD in

geology from Virginia Tech.

After post-doctoral researchpositions in Germany and at

U.C. Berkley, he joined Pacific

Northwest Laboratory where he was involved inthermodynamic modeling of electrolyte

solutions. Mike co-founded Fluid Inclusion

Technologies, Inc.

ROHIT SHUKLAreceived his

Bachelors in MechanicalEngineering from the University

of Mumbai in May 2005, and his

Masters in Mechanical

Engineering from the Oklahoma

State University in December2007. He started working at FIT in March 2008.

Article copyright 2013 by Gulf Publishing Company. All rights reserved. Printed in U.S.A.

Not to be distributed in electronic or printed form, or posted on a website, without express written permission of copyright holder.


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Articulo de la revista WorldOil 0413-XRF