Hanyar Girgizar Ƙasa ta CDP a Binciken Hydrocarbon
Binciken hydrocarbon (mai da iskar gas) yana buƙatar cikakken bayani, daidaito, kuma mai faɗi game da taswirar ƙasa. Ɗaya daga cikin hanyoyin ilimin ƙasa mafi rinjaye don wannan dalili shine girgizar ƙasa mai haske, domin yana iya nuna tsarin ƙasa da tsarinta a cikin girma biyu (2D) da girma uku (3D). A cikin girgizar ƙasa mai haske ta zamani, manufar CDP (Matsayin Zurfi na Common) - wanda aka fi sani da CMP (Matsayin Tsakiyar Common) - shine babban tushe a cikin tattara bayanai da sarrafawa don inganta ingancin hotunan ƙasa. Hanyar girgizar ƙasa ta CDP ta tabbatar da tasiri sosai wajen gano tarkuna, taswirar layukan tafki, tantance kauri da ci gaba, da rage rashin tabbas na fassarar.
Ka'idoji na Asali na Tunani Mai Girman Girgizar Ƙasa
Hanyar tunani ta girgizar ƙasa tana aiki bisa ƙa'ida mai sauƙi: tushen makamashi (kamar vibroseis a ƙasa ko bindigar iska a teku) yana fitar da raƙuman girgizar ƙasa zuwa ƙarƙashin ƙasa. Waɗannan raƙuman ruwa suna yaɗuwa ta cikin layukan duwatsu, kuma wasu daga cikin kuzarinsu suna komawa baya lokacin da suka gamu da iyaka tsakanin layukan da ke da bambancin juriyar sauti (samfurin yawan duwatsu da saurin raƙuman ruwa). Ana kama waɗannan raƙuman ruwa da na'urar firikwensin mai karɓa (wani yanki a ƙasa ko hydrophone a teku) kuma ana yin rikodin su azaman sigina akan lokaci. Sannan ana sarrafa waɗannan bayanan da ba a sarrafa ba zuwa ɓangaren girgizar ƙasa wanda ke nuna masu haskaka ƙasa.
Duk da haka, babban ƙalubalen girgizar ƙasa mai haske shine cewa siginar da aka karɓa ba wai kawai tana shafar babban haske ba, har ma da hayaniya, raƙuman ruwa na sama, rarrabuwar kawuna, ninki, bambancin kusa-surface, da tasirin tsarin aunawa. Nan ne hanyar CDP ta zama mahimmanci, domin ta dogara ne akan maimaita ma'auni a wuri ɗaya na ƙarƙashin ƙasa don inganta rabon sigina-zuwa-hayaniya da inganta tantance yanayin haske.
Ma'anar da Ka'idojin Hanyar CDP
Ma'aunin Zurfin Gama-gari (CDP) wata hanya ce ta samowa da sarrafa girgizar ƙasa inda ma'aurata masu karɓar tushe da yawa ke yin rikodin haske daga wuri ɗaya na zurfin ƙasa. A aikace, ana ƙirƙirar tsare-tsaren girgizar ƙasa ta yadda alamomi da yawa ke da tsakiyar tsakiya (CMP), wanda ake ɗauka yana wakiltar kusan yanki ɗaya na tunani don mai nuna haske a kwance ko kuma ɗan karkata. Tarin alamun da aka "taru" a CDP guda ɗaya ana kiransa tarin CDP.
Amfanin tattara bayanai na CDP shine yawan bayanai: ana yin rikodin tunani daga sararin samaniya ɗaya sau da yawa a wurare daban-daban (nisa tsakanin tushen da mai karɓar bayanai). Wannan yawan bayanai yana ba da damar matakai masu mahimmanci kamar nazarin saurin bayanai, gyaran Motsa Jiki na Al'ada (NMO), da kuma tara bayanai. A ƙarshe, tara bayanai da yawa a cikin CDP guda ɗaya yana nuna daidaiton tunani na farko kuma yana rage hayaniyar bazuwar.
Samun Bayanan Girgizar Ƙasa tare da Tsarin CDP
A cikin binciken girgizar ƙasa ta 2D, ana sanya maɓuɓɓuka a takamaiman wurare a kan hanyar, yayin da ake tura masu karɓa a cikin jeri tare da tazara ta yau da kullun. Duk lokacin da aka harba tushen, masu karɓa da yawa suna yin rikodin siginar, suna ƙirƙirar "taro guda ɗaya na harbi." Ta hanyar motsa tushen a hankali tare da hanyar (juyawa tare), nau'ikan masu karɓar tushe daban-daban za su samar da tsakiyar wuri ɗaya, don haka suna kafa isasshen murfin CDP.
A cikin girgizar ƙasa ta 3D, manufar iri ɗaya ce amma an faɗaɗa ta zuwa saman abubuwa masu girma biyu (a layi da layi ɗaya). An tsara tushen bayanai da masu karɓa a cikin tsarin grid don kowane kwandon CDP (wanda galibi ake kira kwandon CMP) ya ƙunshi wasu alamomi tare da azimuths da offsets daban-daban. Babban ɗaukar hoto - wanda aka bayyana a matsayin naɗewa - yana da amfani don inganta ingancin bayanai, rage tasirin hayaniya, da kuma ƙara amincin halayen girgizar ƙasa.
Wasu sigogin saye da ke shafar ingancin CDP sun haɗa da:
1. Tazarar CDP (girman kwandon shara): girman kwandon shara wanda ya yi girma sosai zai iya ɓoye cikakkun bayanai game da tsarin, yayin da ƙarami sosai zai iya rage ninki a kowanne kwandon shara.
2. Rufin ninkawa: girman ninkawa, gabaɗaya sakamakon tarin ya fi kyau (har zuwa wani iyaka).
3. Matsakaicin rage gudu: ana buƙata don nazarin saurin gudu da AVO (Amplitude Versus Offset), amma yawan rage gudu na iya ƙara karkacewa da hayaniya.
4. Rarraba Azimuth (3D): yana da mahimmanci don ɗaukar hotunan gine-gine masu rikitarwa kamar kurakurai da gishi.
Matakan Sarrafa Bayanan CDP
Tsarin aikin girgizar ƙasa na tushen CDP yawanci ya ƙunshi waɗannan manyan matakai.
1. Rarraba zuwa CDP Gather
Ana sake tsara bayanan farko a cikin nau'in tattarawar harbi zuwa tarin CDP. Tare da wannan rarrabuwa, kowane CDP yana ɗauke da alamun da ke rikodin haske daga wuri ɗaya na ƙarƙashin ƙasa (da kyau).
2. Gyaran Tsaye da Gyaran Kusa da Sama
A ƙasa, layukan da ke kusa da saman sau da yawa suna haifar da jinkiri daban-daban na lokaci. Gyaran tsaye yana nufin daidaita ma'aunin lokaci ta yadda tunani daga sararin sama ɗaya ya daidaita a kan alamun da ke cikin tarin CDP.
3. Binciken Sauri
Gudun raƙuman girgizar ƙasa a cikin dutsen yana ƙayyade siffar motsi a cikin tarin CDP. Ana yin nazarin saurin ta amfani da kamanni ko haɗin kai don nemo saurin da ke samar da mafi kyawun daidaiton tunani. Wannan saurin yana da mahimmanci ga gyara da ƙaura na NMO.
4. Gyaran NMO (Motsawa ta Al'ada)
Saboda masu karɓar suna da bambance-bambancen da suka bambanta, lokacin tafiyar nuna haske zai fi tsayi a manyan canje-canje. Gyaran NMO yana kawar da wannan bambancin lokaci, wanda ke haifar da tunani a layi ɗaya. Nasarar NMO ta dogara sosai akan saurin da ya dace.
5. Tarawa
Da zarar an daidaita haske, ana tattara alamun da ke cikin tarin CDP (an tara su). Tarawa yana inganta rabon sigina zuwa hayaniya saboda siginar haske mai haɗin gwiwa tana ƙarfafa juna, yayin da hayaniya bazuwar ke shafar juna. Sakamakon shine alamar "taro" guda ɗaya ga kowane CDP, wanda ya fi tsabta kuma ya fi sauƙin fassarawa.
6. Hijira
Hijira tana motsa kuzarin haske zuwa matsayin da ya dace na lissafi, musamman ga masu nuna haske masu karkata, masu matsala, da kuma masu nuna haske. Ba tare da ƙaura ba, sassan girgizar ƙasa na iya ɓatar da masu nuna haske. Ana iya yin ƙaura a cikin yankin lokaci ko zurfin, kuma ingancinsa ya dogara da samfurin saurin gudu.
Fa'idodin Hanyar CDP don Binciken Hydrocarbon
Hanyar girgizar ƙasa ta CDP tana da babban tasiri ga binciken hydrocarbon saboda:
1. Inganta ingancin hotunan ƙasa
Tare da tattarawa, manyan abubuwan da aka yi nazari a kansu suna bayyana sosai don haka za a iya tsara taswirar da aka yi niyya akai-akai.
2. Yana tallafawa taswirar tsarin tarko
Ana iya gano alamun da suka yi kama da na baya, kurakurai, juyawa, da tsarin stratigraphic bayan ƙaura bisa ga saurin gudu da aka samu daga CDP.
3. Inganta ingancin fassarar stratigraphic
Ci gaba da haskakawa, ƙarewar layuka (onlap, downlap, truncation), da kuma yanayin laka suna taimakawa wajen fahimtar tsarin man fetur.
4. Yana shimfida hanya don ƙarin bincike (AVO da sifofi)
Bayanan tattara bayanai na CDP kafin lokaci suna ba da damar nazarin AVO don nuna ruwa, da kuma juyewar impedance don siffanta tafki.
5. Ingancin yanke shawara kan haƙa rami
Ƙarin ingantaccen tsari da zurfin bayanai yana rage haɗarin wurin rijiyar kuma yana taimakawa wajen kimanta yawan rijiyar.
Iyakoki da Kalubale
Duk da fa'idodinsa, hanyar CDP tana da iyakoki. Zato na "ma'aunin tunani iri ɗaya" ya fi dacewa ga masu haskakawa a kwance da kuma kafofin watsa labarai masu sauƙi. A cikin tsare-tsare masu rikitarwa - misali, yankunan da ke da tsayin gangara, kurakurai masu tsauri, ko saurin canzawa a gefe - tarin CDP na iya ƙunsar kuzari daga wurare daban-daban na tunani (motsi mara ƙarfi), yana sa NMO da tara ƙasa da mafi kyau. Bugu da ƙari, abubuwa da yawa da hayaniya masu haɗawa na iya bayyana ko da lokacin da aka yi tara. Saboda haka, ana buƙatar ƙarin sarrafawa kamar demultiple, gyaran anisotropy, da ƙaura kafin tara a wasu lokuta.
Penutup
Hanyar girgizar ƙasa ta CDP muhimmin ginshiƙi ne na zamani na nazarin girgizar ƙasa don binciken hydrocarbon. Ta hanyar amfani da ma'auni akai-akai a wuri ɗaya na ƙarƙashin ƙasa, CDP yana ba da damar ingantaccen nazarin gudu, gyara motsi, tara bayanai don inganta rabon sigina zuwa hayaniya, da ƙaura, wanda ke haifar da daidaiton matsayin mai haskakawa. Sakamakon ƙarshe shine mafi kaifi da aminci don gano tarkuna, taswirar tafkuna, da rage haɗarin bincike. Yayin da fasahar siyan 3D, sarrafa lissafi, da hanyoyin fassara bisa ga halaye ke ci gaba, hanyar CDP ta kasance mai dacewa a matsayin tushe don cire bayanan ƙasa yadda ya kamata daga bayanan girgizar ƙasa.
