Imiqondo Eyisisekelo Yezibalo Ze-Geophysics
I-Geostatistics iyigatsha lezibalo eziklanyelwe ngqo ukuhlaziya idatha ehlobene nendawo, okungukuthi, idatha enamanani athonywa yindawo. Ku-geophysics, idatha cishe njalo iyindawo: izilinganiso zamandla adonsela phansi, amandla kazibuthe, ukushukuma komhlaba, kanye nokumelana, kanye nedatha ye-geochemical kanye ne-well log, konke kuxhumene nezixhumanisi ezithile. Ngakho-ke, i-geostatistics inikeza isisekelo esibalulekile sokuqonda amaphethini okusatshalaliswa kwamapharamitha angaphansi komhlaba, ukulinganisa amanani ezindaweni ezingalinganiswanga, kanye nokuhlola ukungaqiniseki kokuhumusha. Lesi sihloko sixoxa ngemibono eyisisekelo ye-geostatistics esetshenziswa kakhulu ezimweni ze-geophysical.
Kungani i-Geostatistics ibalulekile ku-Geophysics?
Ucwaningo lwe-Geophysical luhlala lubhekene nemikhawulo yokuthatha amasampula. Akunakwenzeka ukukala wonke amaphuzu ebusweni noma ngaphansi komhlaba ngenxa yezindleko, isikhathi, kanye nemikhawulo yokufinyelela. Ngenxa yalokho, ukuhumusha kwe-geophysical kudinga ukuxutshwa kanye nomodeli. Ukuxutshwa okulula okufana nokulinganisa ibanga eliphambene (IDW) kulula, kodwa kuvame ukunganaki izakhiwo zokuhlobana kwendawo futhi akunikezi silinganiso sokungaqiniseki. I-Geostatistics ibhekana nezidingo ezimbili ezibalulekile: (1) ukusebenzisa amaphethini okuhlobana kwendawo kwedatha ukuze kulinganiswe okungokoqobo, kanye (2) nokuhlinzeka ngohlaka olunobuningi lokungaqiniseki ukuze kunikezwe ulwazi ngezinqumo zokuhlola.
Ekuzijwayezeni kwe-geophysical, i-geostatistics isetshenziselwa ukudala amamephu e-anomaly acwengekile futhi ahambisanayo, ukulingisa izakhiwo zamadwala (i-porosity, i-permeability, ijubane lamagagasi), ukuhlanganiswa kwedatha yemithombo eminingi (isb. i-seismic kanye nemithombo), kanye nokulingisa amamodeli angaphansi komhlaba ngezimo zobungozi.
Idatha Yendawo kanye Nomqondo Wezinsimu Ezingahleliwe
Ingqikithi ye-geostatistics ukubuka izimo ze-geological noma ze-geophysical njengemisebenzi engahleliwe noma amasimu angahleliwe. Lokhu kusho ukuthi amanani epharamitha afana nobuningi, ukuzwela kwamagnetic, noma ijubane P endaweni ngayinye kubhekwa njengokuqashelwa kwenqubo engahleliwe enesakhiwo esithile. Kule ndlela, umgomo wethu akukhona nje "ukudweba imephu," kodwa kunalokho ukulinganisa ukusatshalaliswa kwamanani kanye nokuxhumana phakathi kwezindawo.
Kunezingxenye ezimbili ezibalulekile kumodeli ye-geostatistical: ukuthambekela kanye nokuguquguquka kwendawo. Ukuthambekela kuchaza izinguquko ezinkulu (isb., ukwanda kobuningi kusukela enyakatho kuya eningizimu ngenxa yezinguquko zesifunda se-lithological). Ukuhlukahluka kwendawo kuchaza ukuguquguquka okuncane okuvame ukuhlotshaniswa nokungafani kwamadwala, ukuqhekeka, noma izinguquko ze-facies. Umehluko phakathi kokuthambekela kanye nokuguquguquka kusisiza sikhethe indlela efanele: ukuthi simane sicabangele izimo ezimile, noma ukuthi sifake ngokusobala ukukhukhuleka/ukuthambekela.
Ukuma: Isisekelo Esisetshenziswa Kaningi
Izindlela eziningi ze-geostatistical zakudala zincike ekucabangeni kokuma, okungukuthi, izakhiwo zezibalo zedatha azishintshi ngokushintsha kwendawo. Ifomu elivame kakhulu ukuma kwe-second-order: isilinganiso sihlala njalo, kanti i-covariance incike kuphela ebangeni kanye nesiqondiso sokuhlukana (i-lag), hhayi endaweni ephelele.
Ku-geophysics, lokhu kucabanga akulona iqiniso ngaso sonke isikhathi ngoba izimo ze-geological zivame ukushintsha kancane kancane. Kodwa-ke, ezikalini ezithile (isibonelo, ngaphakathi kwesizinda esisodwa se-lithological), ukucabanga kokuma ngokuvamile kunengqondo impela. Uma idatha ikhombisa ukuthambekela okunamandla, ukuchithwa kwe-trend kuvame ukwenziwa noma kusetshenziswa indlela ehlukile, njenge-universal kriging, evumela ukuthambekela.
I-Variogram: Inhliziyo Yezibalo Zendawo
Umqondo odumile kakhulu ku-geostatistics yi-variogram (noma i-semivariogram). I-variogram ibonisa ukuthi ukufana kwamanani edatha kushintsha kanjani ngebanga. Ngokwemvelo, amaphuzu amabili asondelene avame ukuba namanani afanayo, kuyilapho amaphuzu aqhelelene kakhulu evame ukuba namanani ahlukene. I-variogram ilinganisa lesi simiso.
I-semivariogram ye-empirical ngokuvamile ibalwa yi:
\[
\gamma(h)=\frac{1}{2N(h)}\sum_{i=1}^{N(h)}[Z(x_i)-Z(x_i+h)]^2
\]
lapho \(h\) kuyi-lag (ibanga kanye nesiqondiso), \(N(h)\) inani lama-data pair kuleyo lag, kanye \(Z(x)\) inani ledatha.
Amapharamitha amathathu abalulekile e-variogram:
1. I-Nugget: inani le-semivariogram ekubambezelekeni okusondela ku-zero. Ama-Nuggets abonisa iphutha lokulinganisa, umsindo, noma ukungafani esikalini esincane kunebanga lokuhlola.
2. I-Sill: inani le-semivariogram uma lifika endaweni ephakeme. Lokhu kuhlobene nokwehluka okuphelele kwedatha kuleso sizinda.
3. Ububanzi: ibanga lapho i-variogram isondela khona esikhaleni. Ngaphansi kobubanzi, idatha isahlobene; ngaphezu kobubanzi, ubudlelwano bubuthakathaka/bulahlekile.
Ama-Variogram angabonisa futhi i-anisotropy, okuwubudlelwano obuhlukahluka kuye ngokuthi isiqondiso sithini. Ku-geophysics, i-anisotropy ivame ukuvela ezakhiweni ze-geological ezifana nombhede, amaphutha, noma indlela yokugeleza kwe-sediment. I-variogram eqondisayo isiza ekunqumeni izinkomba zokuqhubeka okukhulu nokuncane, okubalulekile ekuboniseni amadamu noma ekuchazeni isakhiwo.
Amamodeli e-Variogram: Kusukela Emisebenzini Engokomfanekiso Kuya Eyezibalo
Ama-variogram e-empirical avame ukuba nomsindo futhi awahlangabezani njalo nezidingo zezibalo zokusetshenziswa ku-kriging. Ngakho-ke, adinga ukufakwa imodeli yethiyori efana nalokhu:
– Okuyindilinga
- Ukubonisa
– IsiGaussian
– I-Matérn (eguquguqukayo kakhudlwana, kodwa eyinkimbinkimbi kakhudlwana)
Ukukhethwa kwamamodeli kuqondiswa ukuma kwe-variogram ye-empirical kanye nokuqonda kwe-geological. Isibonelo, amamodeli e-Gaussian avame ukukhiqiza izinguquko ezibushelelezi kakhulu emabangeni amafushane, afanelekela imingcele eqhubekayo kakhulu. Amamodeli e-Exponential aqinile emabangeni amafushane, afanelekela izimo ezinezinguquko ezisheshayo.
I-Kriging: Isilinganiso Esifanele Esisekelwe Ku-Variogram
I-Kriging iyindlela yokuhlanganisa i-geostatistical esebenzisa i-variogram ukuhlinzeka ngesilinganiso esihle kakhulu se-linear unbiased estimator (BLUE). Ngokungafani nezindlela zokuhlanganisa eziqondile, i-kriging:
1. Cabanga ngebanga kanye nokuhambisana kwendawo.
2. Ikhiqiza imephu yokulinganisa kanye nemephu yokuguquguquka kwe-kriging (ukungaqiniseki).
Izinhlobo ezivamile ze-kriging:
– I-Simple Kriging (SK): isilinganiso siyaziwa futhi asiguquguquki.
– I-Kriging Ejwayelekile (Kulungile): isilinganiso asaziwa kodwa kucatshangwa ukuthi sihlala njalo endaweni yakini.
– I-Universal Kriging (UK): ifaka phakathi i-trend/drift (isb. umsebenzi we-polynomial maqondana nezixhumanisi).
– Ukuhlanganisa: ukusebenzisa iziguquguquko zesibili (isb. ukulinganisa i-porosity ngosizo lwe-seismic impedance).
– Inkomba ye-Kriging: yedatha yezigaba/yemicimbi (isb. amathuba e-lithology ethile).
Ku-geophysics esetshenzisiwe, i-kriging evamile ivame ukuba yisinqumo sokuqala esinamandla ngoba iyaguquguquka futhi ayidingi ukucabanga ngesilinganiso somhlaba wonke esaziwayo.
Ukulingisa Kwesimo Sezwe: Okungaphezu Kwemephu Nje
I-Interpolation ikhiqiza imodeli eyodwa "engcono kakhulu", kodwa indawo engaphansi komhlaba ayiqiniseki neze. Ukuhlola ubungozi nokudala izimo, kusetshenziswa ukulingisa kwe-geostatistical, okufana nalokhu:
– Ukulingisa kwe-Gaussian okulandelanayo (SGS) kweziguquguquko eziqhubekayo.
– Ukulingisa Izinkomba Ezilandelanayo (SIS) kweziguquguquko zezigaba.
– Izibalo zamaphuzu amaningi zamaphethini ayinkimbinkimbi ejiyoloji asekelwe ezithombeni zokuqeqesha.
Ukulingisa kukhiqiza ukuqashelwa okuningi okuhambisana nedatha kanye ne-variogram, okusivumela ukubala amazinga okunokwenzeka, ama-quantile, kanye namathuba. Esimweni se-geophysical, ukulingisa kubalulekile ekuhleleni ukubhola, ukuhlola ukungaqiniseki kwevolumu, kanye nokuhlanganiswa nokumodela kokugeleza.
Ukuqinisekiswa Kwemodeli: Ukuqinisekiswa Okuphambene Nokuxilongwa
Izibalo ezinhle ze-geostatistics azigcini ekudaleni ama-variogram kanye ne-kriging. Ukuhlolwa kudingeka kwenziwe, isibonelo:
– Ukuqinisekiswa kwe-cross-validation kwe-Leave-one-out: iphuzu ngalinye libikezelwa kusetshenziswa amanye amaphuzu, bese liqhathaniswa nenani langempela.
– Ukuhlaziywa kwensalela: ukuthi izinsalela zisatshalaliswa ngokungahleliwe, ukuthi kukhona yini ukucwasa okuhlelekile.
– Ukuhlolwa kokwehluka kwe-Kriging: ukuthi ukungaqiniseki kunengqondo yini (kuphezulu ezindaweni ezingenayo idatha, kuphansi ezindaweni ezinedatha eningi).
Ukuqinisekisa kusiza ekunqumeni ukuthi i-variogram "ibushelelezi kakhulu," ububanzi bude/bufushane kakhulu, noma kukhona i-anisotropy engakabanjwa.
Izinselele Ezivamile Ezisetshenzisweni Ze-Geophysical Geostatistical
Ezinye izinselele ezivame ukuvela:
1. Umsindo kanye nokungabi yi-Gaussian: Idatha ye-Geophysical ivame ukuqukatha izinto ezingaphandle kanye nokusatshalaliswa okungejwayelekile. Ukuguqulwa (isb., amaphuzu ajwayelekile) ngezinye izikhathi kuyadingeka.
2. Ukusampula okungalingani: indlela yokulinganisa (indlela) ibangela ukuthi idatha ibe minyene kolunye uhlangothi futhi ibe yincane kolunye uhlangothi.
3. Ukungaguquguquki: izinguquko ku-lithology noma isakhiwo sesifunda ziveza ukuthambekela okunamandla.
4. Ukuhlanganiswa kwezinga eliningi: ukuzamazama komhlaba kukhulu kodwa isixazululo sihlukile kudatha yomthombo enemininingwane eminingi.
Ukunqoba lezi zinselele kudinga inhlanganisela yokuqonda izibalo kanye nokuqonda kwe-geological/geophysical.
I-Penutup
Imiqondo eyisisekelo ye-geostatistics—i-stationarity, i-variogram, i-kriging, kanye ne-simulation—inikeza uhlaka olunamandla lokucubungula idatha ye-geophysical esekelwe endaweni. Nge-variogram, simaka isakhiwo sokuhlobana kwendawo; nge-kriging, sithola izilinganiso ezifanele kanye nokungaqiniseki kwazo; futhi ngokulingisa, sakha izimo eziningi ezibonisa ngokungokoqobo ukungaqiniseki okungaphansi komhlaba. Ekugcineni, i-geostatistics akuyona nje indlela yokwenza imephu, kodwa indlela yokulinganisa yokwenza izinqumo zokuhlola kanye nokuhumusha kwe-geophysical ezinolwazi oluthe xaxa.
Uma ufisa, ngingangeza nezibonelo zesimo sohlelo lokusebenza (isb. imephu ye-magnetic anomaly noma ukulinganiswa kwejubane le-seismic), noma ngifake ukuhamba komsebenzi okusebenzayo kusukela ekubalweni kwe-variogram kuya ku-kriging kusofthiwe ethile.
