Roj Lub Tebchaws Tubular Khoom (OCTG) cov kav dej ua haujlwm hauv qee qhov kev xav tau tshaj plaws hauv ntiaj teb. Txhim kho ntau txhiab meters hauv qab av, lawv raug kev kub ntxhov sab hauv, sab nraud tsim kev ntxhov siab, kub gradients, thiab corrosive kua uas muaj carbon dioxide los yog hydrogen sulfide. Raws li cov xwm txheej no, kev xaiv cov qib carbon steel tsis yog qhov kev txiav txim siab niaj hnub siv tab sis qhov kev txiav txim siab engineering uas cuam tshuam ncaj qha rau kev ncaj ncees, kev nyab xeeb ntawm kev ua haujlwm, thiab kev siv lub neej.
Cov pa roj carbon steel tseem yog cov khoom tseem ceeb rau cov kav dej OCTG vim nws muab qhov sib npaug ntawm cov khoom siv dag zog, kev tsim khoom, thiab kev lag luam. Thaum alloyed thiab corrosion-cov ntaub ntawv resistant yog siv nyob rau hauv tshwj xeeb qhov dej, feem ntau ntawm lub ntiaj teb no drilling ua hauj lwm cia siab rau standardized carbon steel qib raws li API 5CT. Kev nkag siab txog cov qib no yuav tsum tau tshuaj xyuas tsis yog lawv cov qib zog nkaus xwb tab sis kuj yog lawv cov qauv tsim metallurgical thiab kev txwv kev pabcuam.
Nkag siab Carbon Steel hauv OCTG Cov Ntsiab Lus
Chemical Composition Control
Cov pa roj carbon steel siv hauv OCTG daim ntawv thov feem ntau muaj cov tshuaj tswj cov pa roj carbon, manganese, silicon, thiab cov kab sib xyaw ua ke. Cov ntsiab lus carbon yog ua tib zoo sib npaug. Cov pa roj carbon ntau ua kom lub zog tab sis txo cov ductility thiab weldability, thaum cov pa roj carbon qis dua txhim kho toughness tab sis txwv cov txiaj ntsig tau los ntawm lub zog. Manganese txhim kho hardenability thiab tensile zog, thiab microalloying ntsiab yuav muab ntxiv rau refine grain qauv.
Rau cov qib txheem xws li J55 thiab K55, chemistry yog qhov yooj yim thiab ua kom zoo rau nruab nrab - qhov tob tob. Raws li lub zog xav tau nce qib hauv qib zoo li N80 lossis P110, kev tswj hwm nruj dua ntawm kev sib xyaw thiab kev kho cua sov yog qhov tseem ceeb los tiv thaiv brittleness thiab xyuas kom meej cov khoom siv sib xws raws li cov yeeb nkab lub cev thiab cov xov sib txuas.
Kev kho cua sov thiab Microstructure
Kev kho cua sov ua lub luag haujlwm txiav txim siab hauv kev txhais cov khoom siv kho tshuab OCTG. Cov qib qis dua tuaj yeem ua tau zoo los tsim cov ferrite zoo ib yam -pearlite microstructure. Cov qib siab dua feem ntau dhau mus quenching thiab tempering, uas hloov cov hlau mus rau hauv cov qauv tempered martensitic nrog cov txiaj ntsig zoo dua.
Qhov kev sib tw hauv OCTG ntau lawm yog ua tiav lub zog siab thaum tswj kom muaj kev cuam tshuam txaus, tshwj xeeb tshaj yog nyob rau hauv qis - qhov kub thiab txias. Kev kho cua sov tsis zoo tuaj yeem ua rau muaj kev nyuaj siab ntau dhau, ua rau muaj kev cuam tshuam rau sulfide kev nyuaj siab tawg hauv qhov dej qaub. Yog li ntawd, metallurgical tswj yog ib qho tseem ceeb raws li nominal qib xaiv.
Common Carbon Steel Qib thiab lawv daim ntawv thov
API system categorizes OCTG carbon steel qib feem ntau los ntawm qhov tsawg kawg nkaus yield zog. Txawm li cas los xij, kev xaiv cov tswv yim yog nyob ntawm qhov tob, siab, qhov kub thiab txias, thiab cov dej chemistry es tsis yog lub zog ib leeg.
Cov lus hauv qab no qhia txog feem ntau siv cov qib carbon steel rau casing thiab tubing.
| API Qib | Yam tsawg kawg nkaus tawm lub zog (MPa) | Hom Qhov tob tob | Thaum tshav kub kub kho mob | General Application |
|---|---|---|---|---|
| J55 | 379 | ntiav | Li qub | Nto thiab conductor casing |
| K55 | 379 | Nyias mus rau nruab nrab | Li qub | General - lub hom phiaj casing |
| N80 | 552 | Nruab nrab | Normalized los yog Q&T | Intermediate casing |
| L80 | 552 | Nruab nrab mus tob | Quenched & Tempered | Qab zib kev pabcuam ib puag ncig |
| C90 | 620 | Sib sib zog nqus | Quenched & Tempered | Lub qhov dej siab dua |
| P110 | 758 | Sib sib zog nqus thiab siab -siab | Quenched & Tempered | Kev tsim cov casing hauv HP qhov dej |
J55 thiab K55 yog dav siv nyob rau hauv qis - ib puag ncig siab uas cov qauv kev txhawb nqa yog lub luag haujlwm tseem ceeb. N80 sawv cev rau theem tseem ceeb hauv lub zog thiab feem ntau siv rau cov hlua nruab nrab. L80, txawm hais tias zoo sib xws hauv lub zog rau N80, tshwj xeeb yog tsim los nrog cov kev txwv hardness los txhim kho kev tiv thaiv rau hydrogen sulfide-induced cracking.
P110 yog ib qho ntawm cov qib siab tshaj plaws - cov pa roj carbon steel qib hauv kev siv. Nws ua kom qhov tob tob tob thiab siab dua - kev tswj kom muaj zog tab sis yuav tsum muaj kev tswj xyuas kom tsis txhob muaj qhov tsis zoo los yog kev sib txuas tsis muaj zog.
Mechanical Property Relationships
Thaum lub zog tawm los yog qhov tseem ceeb ntawm kev faib tawm, kev ua haujlwm OCTG nyob ntawm ntau yam ntsuas. Lub zog tensile txiav txim siab qhov kawg ntawm lub peev xwm, elongation qhia txog ductility, thiab kev cuam tshuam toughness ntsuas tsis kam mus rau tam sim ntawd tawg.
Cov lus hauv qab no qhia txog cov cuab yeej cuab tam ib txwm muaj rau cov qib xaiv.
| Qib | Yield Strength Range (MPa) | Tensile zog (MPa) | Tsawg kawg Elongation (%) | Ntsiab Performance Focus |
|---|---|---|---|---|
| J55 | 379–552 | Ntau dua lossis sib npaug li 517 | 19 | Cov qauv kev ntseeg tau |
| N80 | 552–758 | Ntau dua lossis sib npaug rau 689 | 18 | Sib npaug zog |
| L80 | 552–655 | Ntau dua lossis sib npaug rau 655 | 18 | Kev tiv thaiv tawg |
| P110 | 758–965 | Ntau dua lossis sib npaug rau 862 | 17 | Siab siab kam rau ua |
Raws li cov txiaj ntsig muaj zog nce ntxiv, elongation feem ntau txo qis me ntsis, cuam tshuam kev lag luam - tawm ntawm lub zog thiab ductility. Cov kws kho tsheb yuav tsum ntsuas qhov nyiaj tshuav no ua tib zoo, tshwj xeeb tshaj yog nyob rau hauv qhov dej uas muaj kev thauj mus los lossis kev caij tsheb kauj vab.
Environmental and Operational Constraints
Cov qib carbon steel siv nyob rau hauv OCTG yuav tsum sib haum rau ib puag ncig raug mob. Hauv cov dej qab zib qhov twg hydrogen sulfide concentration yog qhov tsis txaus ntseeg, cov qib txheem xws li N80 lossis P110 feem ntau txaus. Txawm li cas los xij, nyob rau hauv cov kev pabcuam qaub uas muaj H₂S, cov kev txwv hardness ua qhov tseem ceeb los tiv thaiv sulfide kev ntxhov siab tawg. Cov qib zoo li L80 tau tsim tshwj xeeb rau cov xwm txheej zoo li no, nrog rau qhov siab tshaj plaws hardness thresholds tau teev tseg hauv cov qauv.
Qhov kub thiab txias kuj cuam tshuam rau kev coj tus cwj pwm. Cov qhov dej sib sib zog nqus tuaj yeem muaj qhov siab hauv qab - qhov kub thiab txias uas txo cov khoom muaj zog. Hloov chaw, qhov chaw txias txias ua rau muaj kev pheej hmoo ntawm pob txha tawg. Kev ntsuam xyuas cuam tshuam ntawm qhov ntsuas kub kom ntseeg tau tias muaj kev puas tsuaj txaus.
Ntxiv nrog rau cov xwm txheej downhole, kev sib txuas tsim muaj feem cuam tshuam rau qib kev xaiv. Siab - cov ntaub ntawv muaj zog yuav tsum tau hwm cov xov xov sib txuas kom muaj kev sib koom ua ke nyob rau hauv axial nro thiab sab hauv siab.
Kev txiav txim siab txog nyiaj txiag thiab lub neej
Txawm hais tias qib siab dua muaj lub zog zoo dua, lawv kuj nce kev yuav khoom thiab ua cov nqi. Tshaj - specifications tuaj yeem ua rau kev siv nyiaj tsis tsim nyog, thaum nyob rau hauv - kev qhia tshwj xeeb ua rau muaj qhov ua tsis tiav thiab kev kho kom zoo. Yog li, kev xaiv qib OCTG yog ib qho kev ua kom zoo tshaj plaws uas sib npaug ntawm kev nyab xeeb nrog kev lag luam.
Kev txheeb xyuas tus nqi ntawm lub neej feem ntau suav nrog cov khoom xws li kev tiv thaiv corrosion, kev cia siab tias yuav siv sijhawm ntev, thiab muaj peev xwm ua haujlwm. Nyob rau hauv lub sijhawm ntev - qhov dej ntau lawm, xaiv cov qib nrog kev txhim kho kom ruaj khov tuaj yeem txo cov nqi khiav lag luam tag nrho txawm tias pib nqis peev ntau dua.
Xaus
Cov qib carbon steel siv hauv cov kav dej OCTG yog cov kev daws teeb meem tsim los rau cov chaw tshwj xeeb downhole es tsis yog pawg zog yooj yim. Los ntawm J55 hauv kev siv cov qauv ntiav mus rau P110 hauv qhov sib sib zog nqus siab - cov qhov dej siab, txhua qib qhia txog kev tswj hwm kev sib xyaw ntawm cov tshuaj muaj pes tsawg leeg, kev kho cua sov, thiab kev ua haujlwm txhua yam. Kev nkag siab zoo ntawm cov khoom muaj zog, tawv, kev tiv thaiv ib puag ncig, thiab kev ua haujlwm xav tau ua kom cov kav dej OCTG ua tiav lawv lub luag haujlwm tseem ceeb: tswj kom muaj kev ncaj ncees zoo thiab ua tau zoo thoob plaws hauv lub neej drilling thiab ntau lawm.
