1026 Phat trign khai thac than dhu trong da mdng md Rang Ddng Nhung bai hgc kinh nghj|ni^ PHAT TRIEN KHAI THAC THAN DAU TRONG DA MONG M O RANG DONG N H L T N G BAI HOC KINH NGHIEM Nguyen Chu Chuyen, S[.]
1026 Phat trign khai thac than dhu da mdng md Rang Ddng: Nhung bai hgc kinh nghj|ni^ PHAT TRIEN K H A I T H A C T H A N D A U T R O N G D A M O N G M O R A N G D O N G : N H L T N G BAI H O C K I N H N G H I E M Nguyen Chu Chuyen, Shoji Hara, Huynh Thanh Nha Cong ty Ddu Nhdt - Viet Phan Ngge Trung, Le Ngge San Tdng cong ty Ddu Viet Nam TOM TAT Ndm 1994, Cdng ty Ddu Nhdt - Viet (JVPC) tiin hdnh khoan giing thdm dd ddu tiin & md Rgng Ddng thim luc dia Viet Nam Nhirng thung ddu ddu tiin dugc khai thde vdo ngdy 30-8-1998 tir nhimg giing tren gidn cd dinh N-1 Tdng sdn lugmg khai thde ddu tir md Rgng Ddng du dodn se dgt 100 triiu thung ddu vdo giira ndm 2005, hon nira la tu thdn ddu da mdng Tucmg tu cdc md ddu dang khai thde vung nhu Bgch Hd, Rdng, Su Tu Den, ki hogch phdt trien khai thde ddi tugng ndy ddng vai trd hit sue quan trgng qud trinh phdt triin chung cho todn md Ddc tinh ciia thdn ddu dd mdng nirt ne mo Rgng Ddng Id rdng giua hgt (matrix) cua da chira rdt nhd (hdu nhu bdng 0) vd su bdt ddng nhdt cao cua hi thdng khe nut Cdc thdng sd ddc trung cho tinh thdm chira nhu mat do, hudmg, rdng, ddi cua khe nut; rdng vd muc liin thdng giira cdc khu vuc than ddu diu rdt khd xdc dinh mdt cdch chinh xdc Ban thdn ddu v&i dp sudt lom hon dp sudt bdo hda dugc khai thde tir gi&i hgn mdt vung V&i thdnh cdng tdc thdm dd, vung khai thde dugc phdt trien m& rdng vcri viec dua vdo gidn E-1 vd S-1 ndm 2002 Ndm 2004, bom ip nu&c tdng mdng dugc bdt ddu vd nhdn thdy cd su khdc biit vi cdc dge trung khai thac bcrm ip giua cdc viing khdc than ddu Hiin tgi, dp sudt via da thdp hon dp sudt bdo hda, mii da hinh thdnh & phdn trin vd nu&c via cung vol nu&c bom ip phdn bd & phdn sdu bin du&i thdn ddu Bdi viit ndy md td su phdt triin ddi tugng mdng mo Rgng Ddng, dge biit Cdng ty JVPC da dua mdt chiin luge phdt triin linh hogt cho timg giai dagn trin co s& tiip thu nhirng bdi hgc kinh nghiim cdc giai dogn qud khir, hgn chi tdi da nhirng rui qud trinh phdt triin ddi tugng ndy TONG QUAN VE M O RANG DONG Md Rang Ddng nam Id 15-2 thudc bdn triing Cuu Long, them luc dia Viet Nam, each Viing Tau khoang 120km (Hinh 1) Nde cua ddi tugng mdng sau khoang 3000m dudi muc nude bien Ap su4t via ban dau dugc xac dinh khoang 5320psi d sau 3500m dudi muc nude bien, nhiet via khoang tir 120 den 155°C Tuygn tap bao cao HQi nghj KHCN "30 nam DSu Viet Nam: Co' hdi mdi, thach thuc mdi" 1027 Hinh 1: Ban vi tri mo Rang Dong Than dau mdng duge hinh da granitoid nut ne vdi rdng giira hat rat nhd, (gan nhu bang 0) va cac loai khe niit khae chiia hydroeaebon va nude Cac khe niit lien thdng vai tao he thdng khe nurt khdng ddng nhat va vd ciing phiic tap, khae khdng nhimg theo cac vimg ma ca ciing mdt viing Vi vay, thdng sd lien quan tdi dac tinh ciia khdng gian rdng nhu mat do, hudng, rdng, dai cua khe nirt; rdng, tham, v.v rat khd xac dinh mdt each chinh xac Vdi sd lieu thu dugc tir sd lugng gieng khoan han che so vdi su phiic tap va bat ddng nhat cao ciia tang mdng, viec sir dung sd lieu khai thac de hieu chinh md hinh dia chat ddng mdt vai trd het siic quan trgng va quyet dinh su cdng cua qua trinh danh gia va tdi uu phat trien md Nude via cd the tich dang ke tdn tai phan dudi than dau da mdng niit ne md Rang Ddng la mdt nhiing dac diem khae biet ndi bat so vdi eae md ldn tuong tu lan can viing nhu md Bach Hd va md Su Tir Den Ranh gidi dau nude ban dau dugc xac dinh d sau tir 3700 - 4000m nhung sau dd lien tuc dang len qua trinh khai thac va bom ep Mac dii khdi lugng nude via khdng du Ion de tiep tuc tri ap suat via nhung lai lam tang nhanh ngap nude cua mdt sd gieng khai thac Dau cua ddi tugng mdng nut ne md Rang Ddng ed he sd - dau va ap suat bao hda cao (1200scf/stb va 4800psi) Do khoang each giira ap suat via ban dau va ap suat bao hda nhd nen chi sau vai thang khai thac mu thii sinh da dugc hinh va tham gia vao ca che khai thac via nhu mdt ngudn nang lugng chinh CAC GIAI DOAN PHAT TRIEN MO VA BAI HOC KINH NGHIEM • • San lugng khai thac dau tir ddi tugng mdng tang len theo timg giai doan (Hinh 2) Dkn viec khai thac dau ciing vdi viec bam ep nude dugc triln khai tren ghn nhu toan 1028 Phat trign khai thde than dau da mdng md Rang Ddng: Nhung b^i hgc kinhjiglufm^ bd dien tich md (Hinh 3, 4) Do cd nhilu thdng sd khd danh gia chinh xac ngay, qua trinh khai thac phat triln ddi tugng chn tiln hanh theo timg bude va trudc trien khai bude tilp theo c§n thilt phai tien hanh nghien cuu xir ly nhiing thdng tin thu dugc tir nhimg bude trudc dd Rang Dong Field Production History Total Basement Reservoir 60000 ; : : 60000 i —•—Daity Oil Prod jt -H-GOR - —— t i Tffl • a -kf—- ; - ^1 iiM || (•'* J 10000 > * 11] Ik s S ^ S Q> a^ o ?; r n~^C) o O S E O i 20000 W'fh p y fli^ 30000 ^ j k i-X 20000 „ , - 40000 30000 A ^ —f~- r 50000 • ^ — C u m Oil Prod 40000 A) ->-Water Cut 50000 t 8 c u o c a d> CO tsi CO o to CM (Nl o o o Q o c CO o 0) CO o c —3 CD CO j j• i* u 10000 k O) 0) •1 ll CO O O ID sc Q o —3 CO CM d> so IS Q CJ> CM to o c -3 CO Hinh 2: Do thi khai thac ddi tirong mong DATE:2005yD3/31 ;umulatTO Oil Produced ( MbbI 8156 16312 Hinh 3: B^n t6ng lirQUg khai thac cua cac gieng doi tirong m6ng den cuoi 3-2005 O Tuygn tap bao cao Hdi nghi KHCN "30 nam D5u Viet Nam: Co' hdi mdi, thach thuc mdi^ 1029 DATE 2005/03/31 Hinh 4: Ban tong luong bom ep cua cac gieng doi tuong mong den cuoi thang 3-2005 1, Giai doan phat trien dau tien (1999) Giai doan phat trien dau tien dugc danh dau bang viec tien hanh khai thae gieng d khu vuc phia Bae (Hinh 5) Y tudng ban dau la xay dung mdt gian khai thac va theo ddi dae trung khai thac d khu vuc cd tinh chat collector tdt (dugc xac nhan bdi cac gieng khoan tham dd RD-IX va 2X) ddng thdi tiep tuc chien luge phat trien danh gia kha nang khai thac thuang mai cae viing khae Trong sd 12 gieng khoan thang dirng/gan thang dung (7 gieng tham dd va gieng khai thac) da khoan trudc dua md vao khai thac chi cd gieng d vimg Bae la cd gia tri thuang mai cdn d cae vimg khae mac dii tim thay cd dau nhung chua khang dinh dugc gia tri thuang mai Vi vay, giai doan nay, cac gieng duge khai thac d viing Bae mdng theo che giam ap tu nhien va cac thdng sd thuy ddng cua cac gieng dugc theo ddi chat che dae biet mdi cd gieng mdi dua vao khai thac Trong qua trinh khai thac d vimg Bae, ap suat cua mdt gieng d trung tam giam rat nhanh Dieu ehirng td trii lugng dau xung quanh khu vue gieng la nhd mac dii he sd san pham cua gieng tuong ddi cao Mdt gieng khae d ria phia Tay giam ap cham, ap suat via dugc tri d mire cao nhung ngap nude sdm va gia tang nhanh tir nam 1999 Nguyen nhan d day la cd mdt lugng nude via kha ldn xam nhap tir ria phia Tay ciia viing Bae mdng qua vi tri gilng Phat trign khai thac than dau da mdng md Rang Odng: Nhung bai hoc kinh nghiem 1030 Hinh 5: Ban cau true doi tu'ong mong mo Rang Dong Sau day la mdt sd bai hgc kinh nghiem giai doan dau phat trien md: Tinh chat ididng ddng nhat tdn tai t ^ g mdng ca vimg khai thac phia Bae Mu hinh ap suat bao hda cao va sau dd mii boat ddng nhu mdt CO che nang lugng via chinh Nude via xam nhap tir ria phia Tay cua vimg Bae mdng - Dieu chinh su thay ddi ranh gidi dau nude va ranh gidi dau la cdng viec rat quan trgng tuang lai Giai doan tham va phat triin vung S/C va E (2000 - 2003) a Nhwng thdnh cong cong tdc khoan thdm Tir nam 2000 den 2001, bdn gilng tham dd dugc khoan tir gian tam S-1 va C-1 Cac gieng khoan se dugc chuyin sang khai thac nlu qua trinh thir cho kit qua trir lugng dau va he sd san pham du ldn Vi tri cua cac gieng khoan tham dd dugc lira chgn can than bang viec phan tich lai tai lieu dia chan Tat ca cac gieng deu dugc khoan gan nhu ngang de mdt gilng cd thi gap dugc tdi da cac ddi nut ne Quy dao gilng khoan dugc thiet ke tuang ddi sau dl tranh mia xam nhap sdm khai thac va huong gilng khoan gan nhu vudng gdc vdi hudng cua khe nirt de cd the gap nhieu ddi nirt ne chira dau Qua trinh thir via eiing dugc thuc hien tuang ddi dai hem nham cd dii thdng tin cSn thilt cho tinh toan xac dinh trO lugng d§u thuang mai Viec lap dat gian khai thac S-1 dugc quylt dinh nhanh chdng sau phan tich sd lieu thir gieng va tinh toan tru lugng theo phuang phap can bang vat eh§t cho ket qua kha tdt j;uygn tap bao cao Hdi nghj KHCN "30 nam Dau Viet Nam: Co- hdi mdi, thach thuc mdi^' 1031 Ddi vdi gian khai thac E-1 ma chu ylu khai thac tir tang san phim Mioeen dudi, cac gieng khoan ngang vao mdng ciing cho ket qua hua hen Tiep theo sau dd mdt sd gieng khoan ngang tham dd/khai thae khae tir gian S-1 va E-1 ciang ed ket qua tdt Mdt sd gilng khoan tham dd khae tir gian tam C-1 eiing cdng va dan den quyet dinh nhanh chdng la se lap dat gian khai thac C-1 nam 2005 b Su" lien thong Idiong dang ke giira cac vung than dau Su phirc tap cua he thdng khe nirt mdng md Rang Ddng rat phiic tap nhung da dan dan dugc lam rd thdng qua sd lieu ap suat via Trudc E-1, S-1, C-1 dugc dua vao khai thac, ap suat cua eae gilng khu vuc giam it nhieu khae so vdi ap suat ban diu va eho thiy cd su lien thdng thuy lue tir viing bae mdng tdi S-1 (Hinh 6) Tuy nhien, miic lien thdng tir viing bic mdng tdi S1/C-l yeu hon tdi E-1 Dieu chung td rang cd tdn tai mdt ranh gidi khdng hoan toan phan each giiia E-1 va S-l/Cl ciing nhu giiia viing Bae mdng va viing E-1 Bottom Hole Final Shul-ln Pressure Rang Dong Basement Reservoir 5,500 Date Hinh 6: Xu hu'ong giam ap suat cua cac gieng mong theo cac vung Ap suat d khu vue vimg gieng S-03P/S-05P khdng giam, giii nguyen ap suit via ban diu chiing td cd ranh gidi phan each hoan toan khdng thim giiia viing gilng S-03P/S-05P va cac khu vue dang khai thac khae Ngoai ra, cdn nghien cuu khae ciing khing dinh su tdn tai ciia ranh gidi khdng thim la dimg: Mdt la kit qua phan tich dia hda cho thiy phin diu d gieng S-03P/S-05P khae biet so vdi cae gilng d nhirng khu vuc khae Hai la cd su khae biet vl phin thach hgc qua viec phan tich mim khoan d S-03P/S-05P va cac gilng khae Quan sat thu giao thoa da cho thiy tinh bit ding huong rit cao d khu vuc S-1 va ddng nhat hon d khu vuc E-1 va vimg Bic mdng Vi du, gilng S-O IP va S-04P Hinh cho thay sir lien thdng thuy lire rit nhanh dd giiia gilng S-01P/S-04P va S-02P khdng thay su lien thdng thuy luc nao va vay ddng chit ldng viing chi di 1032 Phat trign khai thac than dau da mdng md Rang Ddng: Nhung bai hgc kinh nghif m chuyin theo hudng Bic - Nam Mat khae, nhiing gilng khai thae d viing BSc cd sir lien thdng thuy lire rit nhanh chiing td rang he thdng nirt ne phat triln manh theo nhieu hudng Su giam ap suit nhanh d khu vuc S-1 cho thay tni lugng diu khu vuc anh hudmg ciia gilng khdng ldn mac dii gieng ed he sd san pham cao Hinh thi hien sir quan he giiia xu hudng giam ap suit va phin khai khae tir trii lugng diu ban diu (theo kit qua thir via) cua timg gieng trudc bom ep nude Dudng liln net va dudng nhilu cham la nhiing dudng tinh toan ly thuyit xu hudmg giam ap suat theo cac gia tri GOR khae va tni lugng dau ban dau khdng ddi Theo ly thuyet, muc suy giam ap suit se nhd hon sau mii thii sinh hinh Tuy nhien, thuc te d phin ldn cae gilng ap suat deu giam it hon so vdi tinh toan Dieu chimg td viing lam viee cua gilng dugc md rdng (cd sir gia tang tni lugmg dau so vdi tinh toan ban dau) khai thac bang che giam ap tu nhien 30% 40% 70% % of production to Initially observed OIP Hinh 7: Sy giam ap suat via so voi % he so thu hoi dau ban dau Md hinh sd eho ddi tugng mdng hien dugc xay dung dua tren nhiing phat hien neu tren Md hinh da phan nao md phdng dugc dac tinh bat dang hudmg va su xam nhap/di chuyen cua chat luu giiia cac khu vuc than dau va vi vay ddng thai ap suat ciia cac gieng theo md hinh da kha phii hgp vdi thuc te Sau day la mdt sd bai hgc kinh nghiem nit tir giai doan khai thac nay: Cae gieng khoan ngang rat cd hieu qua than dau mdng md Rang Ddng Cac khu vuc cd xu hudng giam ap suat khae Ranh gidi dau va dau nude khae theo timg khu vuc Cd sir lien thdng thuy lire md nhung rat khae va manh hay ylu tiiy theo khu vuc Tuygn tap bao cao HQi nghi K H C N "30 nam Phu k h i Viet N a m : CQ- hdi m d i , thach thiic m d i " - 1033 He thdng nirt ne phat triln rit tdt d viing Bic, d vimg S-1 kem hon va bat dang hudng cao hom Tdn tai ddng xam nhap/di chuyin cua chat luu giiia cac khu vuc md va su md rdng viing lam viec ciia cac gieng khai thac theo thdi gian d che giam ap tu nhien NHtTNG THACH THlTC TRONG VIEC GIA TANG HE SO THU HOI D A U (2004) Trong qua trinh khai thac bang giam ap tu nhien, ban dau dau dugc thay the mdt each hieu qua bdi mil d phan tren eua than dau Tuy nhien, sau khi da xam nhap vao gieng, viee tri ap suat via bang bom ep nude can phai thuc hien, mdt mat de dieu chinh ranh gidi dau eho dugc giii ludn d tren khoang lam viec cua gieng khai thac, mat khae de tri nang lugng via Mac dii bom ep nude, san lugng khai thac nude cua mdt sd gieng va mdt sd viing cua md cd the gia tang nhanh Nam 2004, bom ep nude duge trien khai than trgng d khu vue S-1 va N-1 Mdt sd gilng bom ep khoan ngang ban dau d N-1 khdng cdng quy dao gieng qua sau, khdng gap cac khe nirt lien thdng vdi cac gieng lam viee khu vuc Nhting gieng bom ep d S-1 mac dii ciing dugc khoan sau nhung lai cd tiep nhan rat tdt va lien thdng true tiep, rat nhanh den cac gieng khai thac Tuy nhien, trii lugng dau khu vuc lien thdng giira gieng bom ep va gieng khai thac nhd han rat nhieu so vdi du tinh va miic bat ding hudng cao khu vuc nay, nude da xam nhap vao cac gieng khai thac sdm hon du kien Qua ket qua phan tieh ban diu ve bom ep nude nam 2004, Cdng ty JVPC nhan thay rang can phai ed chien luge khai thac/bom ep khae cho timg vimg cua than dau Hinh cho thay birc tranh toan canh ve co che thu hdi diu bang che khai thac sir dung ddng thdi nang lugng mii nhan tao va nude day Nhung ciing can luu y rang, mat gieng khoan, sau cua cac gieng khai thac (gitra ranh gidi diu va ranh gidi diu nude) va gieng bom ep, ap suat via can tri, v.v can phai duge thiet ke hgp ly, tdi uu tiiy theo dac diem ciia timg vimg rieng biet End of Natural Depletion Water Injection ^ ^ + Aquifer -p-f-Bottom Water ; + Aquifer Water njecfion ^CITBottom Water Water is injected > to keep GOC above producers by maintaining reservoir pressure > to sweep oil to producers Hinh 8: Che dp khai thac co ban o' doi tu-ong mong mo Rang Dong •Shallow oil was swept by gas v^Gas cap reached some producers 1034 Phat trign khai thac than dau da mdng md Rang Dong: Nhung b^i hgc kinh ngjij|ni Trong nam 2005, cd gieng bom ep dang hoat ddng gdm gilng d viing Bic va gilng d khu vuc S-1 Dae biet sd cd hai gilng bom ep dugc chuyin ddi tir gieng khai thae 100% nude dang boat ddng rat hieu qua Khi gian C-1 dua vao khai thae - du tinh vao khoang gitia nam 2005, chiln luge bom ep/khai thae toan md se dugc xem xet lai dua tren ket qua nghien eiiu bo sung tir cac gieng bom ep/khai thac Chien luge bom ep/khai thac cho timg khu vuc eiing ludn can cd sir dilu chinh hgp ly tren co sd cac thdng tin khai thac/bom ep, dae biet la tir nhumg thdng tin khae biet vdi tinh toan du bao Vi vay, Cdng ty TVPC se tilp tuc tri ap dung chien luge khai thac/bom ep linh ddng tren ca sd giam sat chat che cac thdng so khai thac/ bom ep de dat hieu qua eao nhat KET LUAN Su linh ddng chien luge phat trien md la can thiet ddi vdi md cd tinh bat ddng nhat cao Phat trien md theo nguyen tac md rgng timg buoc pham vi khai thac (phat trien cac giai doan) la rat hieu qua nham giam thieu nii ro dau tu ldm vao viing cd trii lugng thap Su linh ddng thiet ke gian khai thac la can thiet vi sd lugng gieng khoan se tang trii lugng dau ban dau tang theo kit qua gilng tham dd - Viec lap dat gian tam de khoan cac gieng tham dd d cac viing ed trti lugng diu nhd nham lam giam chi phi va thdi gian Cac gilng se dugc dua vao khai thac sau gian khai thac cd dinh dugc lip dat - Viee chuyen ddi gilng khai thac gilng bom ep va nguge lai la phuong an can thiet ma ranh gidi diu nude thay ddi theo thdi gian Cac thilt bi khai thac can phai thiet ke phii hgp va nen cd du tinh truoc cho su ehuyin doi Nhimg so lieu ban diu thu duge qua trinh khai thae o ehi giam ap tu nhien cho chiing ta rat nhieu thdng tin vl md - Giai do^n khai thac d chi giam ap tu nhien rit quan trgng dl danh gia tru Iugng diu lien thdng va mirc lien thdng thuy luc giiia cac khu vuc md Tiiy thudc vao mirc lien thdng eua he thdng khe nut viing khai thae vdi ben ngoai, ddng chit luu xam nhap cd thi xuit hien sau ap suit giam va trii lugng diu lien thdng cd thi gia tang d nhimg giai doan khai thac tilp sau - Phan tich su giam ap suit qua trinh thir gilng cd thi xac dinh dugc trir lugng dau thuong mai tdi thilu dl nhanh tiln hanh lip dat gian nhim tang tde khai thac 3.Cac gilng khoan ngang rit cd hieu qua khai thae than diu mdng nirt ne - Gieng khoan ngang cd thi gap nhilu ddi mit ne chiia diu Dac biet khu vuc ma nhiing ddi nut ne cd trti lugng dau thip khdng dii bien luan cho mdt gilng khoan rieng vi gia Gieng khoan ngang rat hieu qua viec dieu chinh khai thac nhiing than diu ed mil d tren va viing nude via d dudi j^tQJnJap bao c^o Hdi nghj KHCN "30 nam Dau Viet Nam: Co' hdi mdi, thach thuc mdi" 1035 Chiln luge bom ep nude theo timg viing linh ddng la rit ein thilt Ranh gidi diu nude, ap suat via va miic xam nhap eua nude via d timg viing la khae Hieu qua cua bom ep nude phu thudc vao nhieu thdng sd eua via nhu mat khe mit, tinh ding hudmg, su lien thdng thuy lire via, v.v ma cac thdng sd thay ddi theo timg viing Chien luge bom ep nude eho timg vimg can linh ddng va thay ddi dua tren sd lieu cap nhat eua cac gieng TAI LIEU THAM KHAO Dake L.P., 1994 The pactice of reservoir engineering Elsevier Science Saidi A.M., 1987 Reservoir engineering of fractured reservoirs Edition Presse Aguilera R., 1980 Naturally fractured reservoirs PennWell Publishing Company ... sau vai thang khai thac mu thii sinh da dugc hinh va tham gia vao ca che khai thac via nhu mdt ngudn nang lugng chinh CAC GIAI DOAN PHAT TRIEN MO VA BAI HOC KINH NGHIEM • • San lugng khai thac dau... doan (Hinh 2) Dkn viec khai thac dau ciing vdi viec bam ep nude dugc triln khai tren ghn nhu toan 1028 Phat trign khai thde than dau da mdng md Rang Ddng: Nhung b^i hgc kinhjiglufm^ bd dien tich... trien danh gia kha nang khai thac thuang mai cae viing khae Trong sd 12 gieng khoan thang dirng/gan thang dung (7 gieng tham dd va gieng khai thac) da khoan trudc dua md vao khai thac chi cd gieng