Casingdị mkpa na akụrụngwa na-egwupụta mmanụ, na akụrụngwa ya bụ isi gụnyere ọkpọkọ, ọkpọkọ isi na casing, akwa ọkpọkọ na ịkụnye obere ọkpọkọ nchara na ihe ndị ọzọ.

A na-eji ihe mkpuchi ahụ na-akwado mgbidi mmanụ na gas nke ọkpọkọ, iji jide n'aka na ịkụ ala na imecha usoro nke ọrụ nkịtị nke olulu mmiri.Dabere na mkpọpu mmiri ọ bụla omimi na geological ọnọdụ, iji ọtụtụ n'ígwé nke casing.Casing cimenting na-agbadata mgbe ejiri ya na tubing, ọkpọkọ ọkpọ dị iche iche, enweghị ike iji ya mee ihe ọzọ, ihe na-eri otu oge.Ya mere, ngụkọta oriri nke casing bụ 70% nke mmanụ olulu mmiri.Enwere ike kewaa casing dị ka ojiji: catheter, casing elu, casing na casing mmepụta.Casing bụ ọkpọkọ nwere dayameta buru ibu, kpọọ olulu mmanụ na gas, ma ọ bụ mmetụta mgbidi nke ọma.A na-etinye ihe mkpuchi ahụ n'ime oghere olulu mmiri ahụ, a na-edozi ya na simenti iji gbochie nguzobe na olulu mmiri na-adaba n'olulu mmiri na iji hụ na a na-ekesa apịtị a na-egwupụta ihe na ebe a na-egwupụta ihe.

A na-ejikarị casing eme ihe maka ịkụnye olulu mmiri n'oge a na-egwupụta ihe na mgbe emechara mgbidi nkwado iji hụ na omume nke usoro ịkụ ihe na ịmecha olulu mmiri mgbe a na-arụ ọrụ mmanụ mgbe niile.A na-ejikarị OCTG eme ihe maka igwu mmiri nke ọma mmanụ na gas na njem mmanụ na gas.Ọ na-agụnye ọkpọkọ ọkpọ mmanụ, mkpuchi mmanụ, tubing mgbapụta.A na-ejikarị ọkpọkọ mkpọ mmanụ na-ejikọta olu olu na-egwupụta ihe na ịgafe ike mkpọpu mmiri.A na-ejikarị casing eme ihe maka igwu mmiri na imecha mgbidi ziri ezi nke nkwado ahụ, iji hụ na omume na ịmecha usoro nhazi ahụ mgbe arụ ọrụ nkịtị nke olulu mmiri gasịrị.Ịgbapụta olulu mmiri na ala nke tubing ga-abụkarị mmanụ, gas na-ebuga n'ala.Ihe mkpuchi bụ idobe olulu mmiri na-agba ọsọ ndụ.Dị ka ọnọdụ dị iche iche geological, n'okpuruala mgbagwoju ọnọdụ nrụgide, ịdọrọ, ịpị, na-ehulata, torsional nrụgide na-eme na ngwakọta mmetụta nke tube, nke casing onwe ya, àgwà nke elu chọrọ.Ozugbo casing n'onwe ya mebiri emebi n'ihi ihe ụfọdụ, nwere ike iduga n'olulu mmiri mmepụta dum, ma ọ bụ ọbụna kpochapụ.