Kugadzira Mepu yeHydrocarbon Uchishandisa Geophysics
Pendauluan
Mahydrocarbon—oiri negasi rechisikigo—anoramba ari iwo manyuko makuru esimba munyika dzakawanda uye zvinhu zvakakosha zveindasitiri yemafuta. Zvisinei, kuwana kuunganidzwa kwemahydrocarbon anobatsira mune zvemari hakugone kuitwa nekufungidzira chete. Matangi ari pasi pevhu, akafukidzwa nematombo akaomarara, uye anopesvedzerwa nenhoroondo refu yezve geology. Nokudaro, kutsvaga kwemazuva ano kunoenderana nenzira dzesainzi dzinogona "kuona" pasi pevhu zvisina kunanga. Apa ndipo panopinda geophysics: nzira dzakasiyana dzekuyera hunhu hwepasi kuti titsanangure chimiro nerudzi rwematombo ari pasi pevhu, zvichibvumira mepu chaiyo uye inoshanda yekutarisira hydrocarbon.
Geophysics haisi yega. Zvakanaka, yakabatana ne geology, geochemistry, uye data retsime. Zvisinei, kubva pakutanga kwekutsvaga kusvika pakugadzira munda, geophysics inowanzova musimboti wekuita sarudzo—kubva pakuona nzvimbo yekuongorora, kuyera misungo, kuona ukobvu hwesediment, kusvika pakutarisa shanduko dzemvura panguva yekugadzirwa.
Pfungwa yeSisitimu yePetroleum uye Zvinangwa zveMepu
Tisati takurukura nezvenzira iyi, zvakakosha kuti tinzwisise zvatiri kuedza kugadzira mapu. Mumasystem epeturu, mahydrocarbon anoumbwa mumatombo anobva, ofamba nenzira dzakatarwa, uye ozoungana mu matombo edziva ine maburi akakwana uye inoyerera zvakanaka. Kuunganidzwa uku kunofanira kufukidzwa nechisimbiso uye kunowanzo kuwanikwa muchimiro chemusungo (semuenzaniso, anticline, fault) kana stratigraphic trap (semuenzaniso, kupwanya, kuunganidza reef).
Basa re geophysics nderekugadzira mepu yezvinhu izvi zvisina kunanga:
1. Geometry yezvivakwa (mapepa, zvikanganiso, madhomu emunyu).
2. Ukobvu uye kupararira kwevhu (sedimentary basin, depocenter).
3. Hunhu hwedombo (lithology, relative porosity, brittle zones).
4. Kuvapo uye rudzi rwemvura (chiratidzo chegasi, mafuta, kana mvura) kuburikidza nemamwe maitiro emuviri.
Panyaya idzi, nzira dzekudengenyeka kwenyika (seismic methods) ndidzo dzinonyanya kushandiswa zvakanyanya nekuda kwesimba radzo repamusoro rekugadzira mamepu ekuvaka nematanho ekuvaka. Zvisinei, dzimwe nzira dzakadai segiravhiti, magineti, magineti, uye kuchekerera matsime dzinobatsirana zvikuru mukuderedza kusanzwisisika.
Nzira yeKutenderera Kwepasi: Mutsipa weKutsvaga
Nheyo Dzekutanga
Nzira yekudengenyeka kwenyika Anoshanda nekutumira simba remafungu (semuenzaniso, kubva kuchinhu chinotenderera pasi kana chipfuti chemhepo chiri mugungwa) pasi pevhu. Mafungu anoonekwa kana kudzorwa paanopfuura nepakati pematombo ane acoustic impedances dzakasiyana. Masensor (geophones kana hydrophones) anonyora nguva yekufamba kwemafungu achidzoka pamusoro.
Kudengenyeka kwenyika kwe2D ne3D
- 2D seismic inogadzira zvikamu zvepasi pevhu zvichienderana nenzira yakatarwa. Yakakodzera zvidzidzo zvedunhu uye mamepu ekutanga ebasin.
- 3D seismic inogadzira huwandu hwedata kuitira kuti dudziro yemaumbirwo ive yakarurama zvikuru, kunyanya kune misungo yakaoma uye kuronga matsime ekuvandudza.
– 4D (nguva-yapera) seismic inoenzanisa ongororo dze3D panguva dzakasiyana kuti iongorore shanduko dzemvura panguva yekugadzira—semuenzaniso, kufamba kwepamberi pemvura kana gasi.
Hunhu hweKutenderera Kwepasi uye Zviratidzo zveHydrocarbon
Kuwedzera kune ma "map reflectors", indasitiri iyi inoshandisa ma "seismic attributes" kuti iwane rumwe ruzivo, rwakadai se "amplitude", "frequency", "coherence", uye "curvature". Dzimwe pfungwa huru:
– Nzvimbo yakajeka: amplitude yakakwira iyo dzimwe nguva inoratidza gasi, kunyanya munzvimbo dzakati.
– Nzvimbo yakati sandara: kuratidzwa kwakati sandara kunogona kuratidza kusangana kwemvura (semuenzaniso gasi-mvura).
– AVO (Amplitude Versus Offset): kuchinja kwehukuru maererano nedaro renzvimbo inobva panobva chiedza kunogona kubatsira kusiyanisa lithology nerudzi rwemvura.
- Kuchinja kweSeismic: kushandura data reSeismic kuita mamodheru ezvivakwa zvematombo akadai se acoustic impedance ayo ari nyore kubatanidzwa nedata rewell.
Zvisinei, zviratidzo zvekudengenyeka kwenyika hazvisi zvega nguva dzose. Mavara akajeka, semuenzaniso, anogona kuoneka nekuda kwekuchinja kwema lithological, kwete mahydrocarbon. Saka, kubatanidzwa nedzimwe nzira dze geophysical uye data retsime kwakakosha.
Nzira Yekukwevera Simba: Kunzwisisa Mabheseni Nezvivako Zvikuru
Nzira yekukwevera pasi inoyera misiyano midiki mukumhanya kwesimba regiravhiti nekuda kwekusiyana kwehuwandu hwematombo. Panyaya yemahydrocarbon, simba regiravhiti rinobatsira zvikuru kune:
– Kugadzira madhaka emvura: marara anowanzo kuve akareruka kupfuura kristalline basement, saka madhaka akakora anogona kuonekwa sekusarongeka kwesimba remuchadenga.
– Tsvaga zvivakwa zvemunzvimbo: semuenzaniso madhomu emunyu, nzvimbo dzakakwirira dzepasi pevhu, kana miganhu yebheseni.
Zvakanakira simba regiravhiti ndezvekuti rinofukidza zvinhu zvakawanda uye mutengo wakaderera kana tichienzanisa ne3D seismic, zvichiita kuti ive yakakodzera pakugadzira mapu ekutanga. Zvakashata zvayo zvinosanganisira resolution yakaderera yekumira uye yekumativi, uye dudziro yayo haisi yega (multiple density models inogona kugadzira anomalies dzakafanana).
Nzira yeMagineti: Kuziva Nzira dzeBasement neStructure
Ongororo yemagineti kuyera kusiyana kwesimba remagineti rePasi iyo inokonzerwa nezvicherwa zvemagineti (semuenzaniso magnetite) mumatombo. Mukutsvaga mahydrocarbon, minda yemagineti inowanzoshandiswa pa:
– Kugadzira mepu yehudzamu nechimiro chepasi pevhu (bed rock).
- Kuziva zvikanganiso zvemunzvimbo uye mitsara inodzora kuumbwa kwenzvimbo uye nzira dzekutama.
– Nzvimbo dzekuongorora: mabheseni akakora e sedimentary anowanzova nemhinduro yakasiyana yemagineti pane nzvimbo dziri pasi pevhu.
Magneti anoshanda zvikuru pakuongorora kwenzvimbo uye anokurumidza kushanda (kusanganisira emumhepo). Zvisinei, haaone zvakananga matangi ehydrocarbon; basa rawo nderekutarisa magariro enzvimbo.
Nzira yeElectromagnetic (EM): Inonzwa Mvura
Nzira dzemagetsi dzinoshandisa musiyano uripo mukudzivirira kwemagetsi pasi pevhu. Mahydrocarbon anowanzo dzivirira kupfuura mvura ine munyu, saka EM inogona kubatsira kuratidza kuvapo kwemvura, kunyanya munzvimbo dzegungwa.
Imwe nzira inozivikanwa ndeye offshore CSEM (Controlled-Source Electromagnetic). Iyi nzira inotumira masaini eEM kubva kunobva kunodhonzwa uye inorekodha mhinduro parinogamuchira pasi pegungwa. CSEM inowanzoshandiswa sekuwedzera kune ongororo dzekudengenyeka kwenyika dze:
- Inoderedza njodzi yekuboorera matombo anotaridzika zvakanaka asi achizopedzisira ava nemvura.
- Kuona nzvimbo dzinodzivirira mvura dzinoenderana nemahydrocarbon, kunyanya mumadhamu ejecha.
Zvipingamupinyi zveEM zvinosanganisira resolution isina kukwira sekudengenyeka kwenyika uye kunzwa kune mamwe mamiriro e geological (semuenzaniso anisotropy, shallow resistive layers) izvo zvinogona kukanganisa dudziro.
Kunyora Matanda Emvura muGeophysical: Kugadzirisa uye Kuvimbisa
Kana tsime racherwa, kucherwa kwematombo emugodhi kunova sosi chaiyo yeruzivo rwepasi pevhu kuti riongororwe mudura. Mamwe magwaro akakosha:
– Gamma ray: inosiyanisa shale nejecha/carbonate.
– Kuramba: inoona nzvimbo dzehydrocarbon (dzinodzivisa zvakanyanya) uye inofungidzira kuwanda kwemvura.
- Sonic uye density logs: inobatsira kuverenga porosity uye kubatanidza data rekutenderera kwenyika kuburikidza nekushandura kwenguva yakareba.
– Neutron log: inonzwa hydrogen, inobatsira pakupinza maburi uye kuziva gasi pasi pemamwe mamiriro ezvinhu.
Ruzivo rwetsime rwakakosha pakushandura dudziro yekudengenyeka kwenyika kubva pa "chimiro" kuenda pa "dombo nemvura." Pasina kuyera tsime, kuyera geophysical kwaizova kufungidzira.
Kufamba Kwemamepu Ehydrocarbon Akabatanidzwa
Mukuongorora, kugadzira mamepu ehydrocarbon kunowanzo tevera nzira inotevera:
1. Zvidzidzo zvemunzvimbo: kuunganidzwa kwe geology, data regiravhiti-magnetic, uye 2D seismic to map basin uye pfungwa dzemitambo.
2. Tsananguro yetarisiro: kududzirwa kwekudengenyeka kwenyika kwezvisungo zvemaumbirwo/matanho, ongororo yehunhu, uye kufungidzira njodzi.
3. Ongororo yakawedzerwa: 3D seismic uye/kana CSEM yekuwedzera chivimbo.
4. Kuboorera pakutsvaga: kusimbiswa kwemuenzaniso uye kuunganidzwa kwedata guru.
5. Kugadzirwa: 3D yakadzama seismic, time-lapse (4D) kana zvichidikanwa, modeling reservoir, uye kugadzirisa kugadzirwa.
Chinangwa chikuru ndechekugadzira mamepu ekuvaka (semuenzaniso, mamepu ekudzikira kwedhamu/kumusoro), mamepu eukobvu (isopachs), uye mamepu enzvimbo dzedhamu (porosity, impedance, relative saturation) akavimbika zvakakwana kutsigira sarudzo dzekudyara mari uye dzekuchera.
Matambudziko neZviri Kuitika Pari Zvino
Kugadzira mamepu ehydrocarbon kwagara kuchisangana nematambudziko: ruzha rwedata, kuomarara kwenzvimbo (subsalt, hollow carbonates, thrust belts), uye kusanzwisisika kwedudziro. Parizvino, mafambiro eindasitiri ari ku:
– Kugadziriswa kwepasi pemvura kwakadzama (semuenzaniso, kufungidzira pasi pemunyu).
- Full Waveform Inversion (FWI) yemhando dzespeed dzakadzama.
- Kudzidzira kwemuchina wekuisa muzvikamu zvemafacies uye kubvisa hunhu, ukuwo uchichengetedza kudzora kwakasimba kwejeologi.
- Kubatanidzwa kwezvingangoitika kuti pave nekusava nechokwadi, pane kungogadzira mepu imwe chete "ingangoitika".
Mhedziso
Kugadzira mapuroteni ehydrocarbon epasi pevhu inzira yakazara inosanganisa nzira dzakawanda dzekududzira chimiro chepasi pevhu, lithology, uye mvura. Seismic ndiyo chishandiso chikuru nekuda kwesimba rayo repamusoro, nepo simba regiravhiti nemagineti zvichiwedzera kunzwisisa kwenzvimbo, EM inowedzera kunzwa kwekudzivirira kwemvura, uye kunyorwa kwenzvimbo dzemvura kunoita kuti pave nekuongororwa kwakananga uye kusimbiswa. Nekubatanidzwa kwedata nekududzirwa kwakarongeka, geophysics inogona kuderedza njodzi yekutsvaga, kuwedzera kubudirira kwekuchera, uye kugadzirisa kukura kwemunda wehydrocarbon.
Kana muchida, ndinogona kugadzirisa chinyorwa ichi kuti chienderane nemamiriro ezvinhu chaiwo (semuenzaniso, Indonesia iri pamhenderekedzo yegungwa, mvura yakadzika iri pamhenderekedzo yegungwa, kana kutarisa pa3D/AVO seismic) uye kuwedzera bibliography nemifananidzo yezvirongwa.
