Kunzwisisa Kwakakosha Nzira Yekuramba Magineti
Nzira yekudzivirira magnetic resistivity inzira inoshandiswa zvakanyanya mu geophysical yekuongorora mamiriro epasi pevhu pasina chikonzero chekuchera. Nzira iyi inoshanda nekushandisa mhinduro yedombo kana ivhu kusimba remagetsi neminda yemagetsi. Mukuita, nzira iyi inobatsira zvikuru kune zvakasiyana-siyana zvinodiwa, zvakaita sekutsvaga pasi pevhu, kuferefeta zvicherwa, zvidzidzo zvekusvibiswa kwezvakatipoteredza, uye kuona hunhu hweinjiniya hwe geology kumapurojekiti ezvivakwa. Kuti unzwisise nzira iyi zvakanaka, zvakakosha kunzwisisa pfungwa huru dzekudzivirira, hukama huripo pakati pemagetsi emagetsi nezvinhu zviri pasi pevhu, uye kuti kuyerwa kunoitwa sei mumunda.
Pfungwa yeKuramba uye Kutungamira
Kuramba simba kwechinhu kunoratidza kuti simba remagetsi rinotadzisa sei kufamba kwemagetsi. Kuramba simba kwechinhu kunowanzo fananidzirwa ne ρ (rho) uye kune mayuniti e ohm-meters (Ωm). Kuramba simba kwacho kunodzokororwa (σ), izvo zvinoratidza kugona kwechinhu kufambisa magetsi, ne mayuniti e siemens pamita (S/m). Zvichitaurwa zviri nyore, zvinhu zvine simba remagetsi zvinowanzova zvakaoma kufambisa magetsi (semuenzaniso, dombo rakaoma reigneous), nepo zvinhu zvine simba remagetsi zvishoma zvinowanzova nyore kufambisa magetsi (semuenzaniso, ivhu rakazara nemvura ine munyu).
Mumamiriro ezvinhu epasi, resistivity haingoonekwi nerudzi rwedombo chete, asiwo ne porosity, huwandu hwemvura, huwandu hwekuzara, munyu uri mu pore fluid, tembiricha, uye huwandu hwezvicherwa zvinofambisa mvura (zvakadai se graphite kana sulfides). Nekuti zvinhu zvakawanda zvinopesvedzera resistivity values, dudziro yedata inofanira kugara ichitarisa mamiriro epasi enzvimbo.
Nzira Yekutanga Yekudzivirira Magetsi
Izwi rekuti "electromagnetic resistivity" rinowanzo shandiswa kureva matekiniki emagetsi ayo pakupedzisira anovavarira kuderedza kusiyana kwe subsurface resistivity. Nheyo huru ndeiyi: kana electromagnetic field ikachinja nekufamba kwenguva, inokonzera magetsi muvhu (eddy currents). Aya eddy currents anobva agadzira secondary magnetic field iyo inogona kuyerwa nezvishandiso. Nekuti simba re induced current rinoenderana ne conductivity (kana resistivity) ye medium, mhinduro yakanyorwa inogona kushandiswa kufungidzira hunhu hwemagetsi hwe subsurface.
Kusiyana nenzira yeDC resistivity geoelectric, iyo inopinza magetsi zvakananga kuburikidza nema electrodes, nzira ye electromagnetic inoshandisa electromagnetic induction—kazhinji isina kubata zvakananga pasi (kana kuti isina kubata zvakanyanya). Iyi ibhenefiti huru pakuongorora munzvimbo dzine matombo, dzakagadzirwa nematombo, kana nzvimbo uko kuisa ma electrode kwakaoma.
Nheyo yeKugadzirwa kweElectromagnetic
Kupinza simba remagetsi kunobva mumutemo waFaraday, uyo unoti kuchinja simba remagetsi kunoburitsa simba remagetsi (EMF), iro rinozoburitsa simba remagetsi. Muongororo dzeEM, zvishandiso zvinowanzova nechinhu chinotumira simba remagetsi rekutanga. Simba iri rekutanga rinopinda pasi, zvichiita kuti simba remagetsi riumbwe. Simba remagetsi rinobuda rinobva ragadzira simba remagetsi rechipiri rinoonekwa neanogamuchira.
Mugamuchiri anogona kuyera amplitude yemunda, phase (phase shift pakati pemasignals ekutanga neechipiri), kana zvese zviri zviviri. Ruzivo urwu rweamplitude nephase zvinozogadziriswa kuita ma parameter akadai se aspire conductivity kana aspire resistivity. Aya ma values anodaidzwa kuti "apparent" nekuti anomiririra integrated averages mu subsurface volume, achikanganiswa nekudzika kwekupinda kwesignal, pane pure value pane imwe point.
Kudzika kweKupinda uye Kudzika kweGanda
Imwe pfungwa inokosha mukushandisa ma electromagnetic methods ndeye kudzika kwekupinda kwechiratidzo, kunowanzonzi "kudzika kweganda." Kudzika kweganda ndiko kudzika kwehunhu uko amplitude ye electromagnetic wave inodzikira zvakanyanya (kazhinji kusvika pa37% yehukoshi hwayo hwekutanga). Kudzika kweganda kunokanganiswa nekuramba kwechinhu, frequency yechiratidzo, uye magnetic permeability.
Panyaya yehunhu, mafrequency akaderera anowanzo pinda zvakadzika, nepo mafrequency akakwirira achinyanya kunzwa ma layer asina kudzika. Saizvozvowo, medium inodzivisa zvakanyanya inobvumira kupinda kwakadzama kupfuura medium inofambisa mvura. Nokudaro, kusarudza mafrequency muongororo dzeEM inzira yakakosha yekuona kuti zvinangwa—zvakadai sema aquifers, nzvimbo dzakaoma, kana mineral bodies—zvinogona kuonekwa pakadzika kwakakodzera.
Mhando Dzakajairika dzeNzira dzeMagetsi
Kune mhuri dzakasiyana dzenzira dzemagetsi dzinoshandiswa mukuongorora kwekudzivirira pasi pevhu:
1. Frequency Domain Electromagnetic (FDEM)
Nzira iyi inoshandisa zviratidzo zve sinusoidal pane imwe kana kupfuura frequency. Zvishandiso zveFDEM zvinowanzo shandiswa pakuongorora nekukurumidza mafambiro emhepo asina kudzika, semuenzaniso, muzvidzidzo zvekusvibiswa, mapu evhu, kana ongororo dzekurima. Data reFDEM rinowanzo sanganisira zvikamu zvemukati nezvikamu zvina zvine chekuita nemafambiro emhepo uye magineti enzvimbo yacho.
2. Nguva yeMagetsi eMagineti (TDEM)
Nzira iyi inoshandisa pulse yemagetsi kuenda kutransmitter uye yobva yaona kuora kwemunda wechipiri mushure mekunge transmitter yadzimwa. Ruzivo rwenguva yekuora runoenderana nekugoverwa kweresistivity nekudzika. TDEM yakakodzera pakutsvaga kwakadzama kupfuura FDEM, senge kutsvaga pasi pevhu rakadzika kana kuferefeta kwegeothermal.
3. Magnetotelluric (MT)
MT inoshandisa manyuko echisikigo ekushanduka kwesimba remagetsi kubva mumhepo uye kudyidzana kwezuva nenyika. Nzira iyi ine simba pakudzidza chimiro cheganda rePasi pakadzika kwazvo, zvichiita kuti rishandiswe kakawanda mukutsvaga kwegeothermal uye muzvidzidzo zve tectonic. Kuchinja kwema frequency echisikigo kunobvumira kugadziriswa kubva pakadzika kusvika pakadzika zvakanyanya.
Kunyangwe nzira nhatu idzi dzichisiyana maererano nekwadzinobva uye nzira dzekuyera, chinangwa chikuru chakafanana: kuwana modhi yekudzivirira pasi pevhu.
Matanho eOngororo: Kuwana Dudziro
Ongororo dzekudzivirira simba remagetsi (electromagnetic resistivity surveys) dzinowanzo sanganisira matanho akati wandei. Chekutanga kuronga: kuona zvinangwa, kudzika kwechinangwa, uye mamiriro emunda, pamwe nekusarudza nzira dzakakodzera uye magadzirirwo emidziyo. Chechipiri kutora data mumunda uchishandisa poindi chaiyo kana nzira yekufamba. Padanho iri, kudzora mhando kwakakosha, sekudzokorodza kuyerwa, kuona kusagadzikana kwetsika (tambo dzemagetsi, fenzi, mapaipi esimbi), uye kugadzirisa nzvimbo.
Danho rinotevera kugadzirisa data, iro rinosanganisira kubvisa ruzha, kugadzirisa kusvetuka, kushandurwa kwedata kuita pseudo-parameters, uye kugadzira chikamu chimwe chete kana mepu. Zvadaro, inversion inoitwa kushandura data rekuyera kuita subsurface resistivity model inoenderana nedata. Inversion inowanzo gadzira 1D (vertical), 2D (cross-sectional), kana 3D (volume) model, zvichienderana nehuwandu hwepasi uye kuoma kwechinangwa.
Dudziro yekupedzisira haifanirwe kumira yoga. Muenzaniso wekudzivirira hunhu hwezvinhu uchava nemusoro zvakanyanya kana ukasanganiswa nedata rinotsigira senge surface geology, drill data, geochemical measurements, kana dzimwe nzira dze geophysical (semuenzaniso, seismic kana gravity). Kudzivirira kwakakwirira kunogona kuratidza dombo rakaoma rakaoma, asi kunogonawo kuratidza jecha rakaoma; kudzivirira kwakaderera kunogona kuratidza ivhu, mvura ine munyu, kana mineralization chaiyo. Mamiriro e geology anosarudza zvazvinoreva zvechokwadi.
Zvakanakira uye Zvisina Kukwana
Zvakanakira nzira ye electromagnetic resistivity zvinosanganisira kumhanya kwekuongorora, kugona kushanda pasina kubatana kwe electrode, uye kunzwa kwakanaka kune shanduko mu conductivity inokonzerwa nemvura kana zvicherwa zvinofambisa mhepo. Nzira iyi inoshandawo pakugadzira mapu enzvimbo dzakakura.
Zvisinei, pane zvipingamupinyi zvinofanira kunzwisiswa. Chekutanga, data reEM rinogona kukanganiswa nezvivakwa zvevanhu zvakaita semagetsi, njanji, mota, uye zvivakwa zvesimbi. Chechipiri, kududzira kunogona kusanzwisisika kana kusingatsigirwi neruzivo rwezve geology. Chechitatu, mumidziyo inofambisa mhepo zvakanyanya, kudzika kwekupinda kwakaganhurirwa, zvichiita kuti zvinangwa zvakadzika zviome kuona. Naizvozvo, kusarudza nzira, dhizaini yekuongorora, uye kubatanidzwa kwedata ndizvo zvakakosha kuti ubudirire.
Penutup
Kunzwisisa kwakakosha kwenzira dzekudzivirira electromagnetic kunobva mupfungwa dzekudzivirira electromagnetic induction. Nekuona mhinduro yemumunda wechipiri nekuda kwemagetsi anokonzerwa nemagetsi ari pasi pevhu, tinogona kufungidzira kusiyana kwekudzivirira kune chekuita ne lithology, huwandu hwemvura, uye chimiro che geological. Nzira dzakasiyana-siyana - FDEM, TDEM, uye MT - dzinopa kuchinjika kubva pakuferefeta kudiki kusvika kwakadzama. Pasinei nematambudziko akadai seruzha rwetsika uye kusanzwisisika kwekududzira, nzira idzi dzinoramba dziri maturusi akakosha mukushandiswa kwe geophysics nekuda kwekugona kwadzo kuyera pasi pevhu nekukurumidza, kwete kuparadza, uye neruzivo. Kana dzakagadzirwa zvakanaka uye dzichitsanangurwa, nzira dzekudzivirira electromagnetic dzinogona kupa mipiro yakakosha mukutsvaga zviwanikwa, kuderedza zvakatipoteredza, uye kuronga budiriro.
