Tuygn tap bao cao Hdi nghj KHCN "30 nam Dau khi Viet Nam Co hdi mdi, thach thiic mdi" 631 TIM KIEM BAY CO YEU TO DIA TANG YEU TO QUAN TRONG TRONG TIM KIEM THAM DO 6 PHIA B A C BE MALAY THO CHU Nguyen[.]
Tuygn tap bao cao Hdi nghj KHCN "30 nam Dau Viet Nam: Co hdi mdi, thach thiic mdi" 631 TIM K I E M BAY CO YEU TO DIA TANG: Y E U T O Q U A N T R O N G T R O N G TIM KIEM T H A M DO PHIA B A C BE M A L A Y - T H O CHU Nguyen Xuan Phong ^ Cdng ty Liin doanh diiu hdnh chung Trw&ng Son JOC TOM TAT Bdi viit phdn dnh cdc hogt ddng thdm dd ddu tgi vimg ria Ddng Bde bi Malay Thd Chu, chu yiu tap trung vdo Id 46/02 phdn bd ngodi khoi Tdy Nam thim luc dia Vid Nam Trong bdi viit ndy thudt ngu: "subtle trap" duge hiiu nhu la cdc dgng bdy gdn Hin v&i yiu td dia tdng That ra, khu vuc nghien ciru, ehi khodng 5% dgng bdy dia tdng thudn dugc biit din Vi vdy, cho din nay, ddi tugng ndy vdn chua la muc tieu chinh edng tde thdm dd muc rid ro cao vd cdng tdc diiu tra cdn nhiiu hgn chi Tuy nhien, tap trung khoan cdc bdy dgng cdu true, mdt sd dgng bdy dia tdng dugc phdt hien mdt cdch tinh c& Phdt hiin ddu tgi cdu tgo Ngoc Hiin ndm 1997 hay Sdng Ddc ndm 2003 la nhung minh chirng cho dgng bdy kit hgp giira cdu true vd dia tdng Cdng tde thdm dd cdn phdi xem xd din dgng bdy ndy Viec nghien cuu dia tdng trdm tieh tir cdc du lieu giing khoan vd cdc bdn dd thudc tinh dia chdn lien quan den phdn bd dia chdt se giup hiiu biit sdu sdc hon vd ddn din cdc phdt hiin m&i gidng nhu Sdng Ddc vd Ngoc Hiin Phuong dn thdm dd bu&c sang mot trang m&i, quan tdm din cdc bdy cd yiu td dia tdng di cd thi gia tdng trir lugng Tuy thuc ti vdn tdn tgi nhiiu rui ro, viec ddi m&i khdi niem vd cdng nghi la cdn thiit di cd thi phdt hiin cung nhu phdt triin ngudn tiim ndng ndy mdt cdch cd hiiu qud GIOI THIEU Co sd ciia nghien ciru dua vao tai lieu ciia 16 46/02, phia Tay Nam ngoai khoi them luc dia Viet Nam Tuy nhien, cac c6ng tac nghien cim d khu vuc lan can, dac biet la viing phat trien chung PM3, dugc sir dung nhu cac phan tich tuong tu cho viing bien phia D6ng Bae cua be Malay - Th6 Chu Theo th6ng ke, bay dja tang thuan chi chiem khoang 5% s6 nhiing phat hien dau cua khu vuc nghien cim Th6ng thudng, chiing phai ket hgp vdi cac yeu t6 cau true nhu nep 16i hoae cau tao dang miii Ljch sir tham ciia khu vuc ciing cho thay dang bay co yeu t6 dja tang dugc phat hien cang nhieu theo thdi gian ciing vdi cac cong tac nghien ciiu va thuc dja Muc dich ciia nghien ciru la c6 gang ket hgp cac tai lieu san co de dua mgt cai nhin khai quat ve dang bay nay, nham giam cac riii ro tham cting nhu img dung khai thac Viec xac djnh cac bay co yeu t6 dja tang yeu cau su ting hgp cac ky thuat tham cung nhu kiln thirc dja chit vl khu vuc nghien ciru Dac biet viec phan tich tuong tu dong vai tro rit quan trgng Do cung la ly tai nghien ciru nay, chiing t6i ap dung cac phuong phap ky thuat da irng dung c6ng d vimg PM3 632 Tim kigm biy cd yeu td dja tang: Yeu td quan trong tim kiem tham dd d phia Biic DIA CHAT KHU VlTC \ Khai quat ve kien tao va dia chat kien triic Vimg nghien ciru nam d phia Bae be Malay - Th6 Chu, la bl co tinh d6i xirng true phan b6 theo hudng Tay Bae - D6ng Nam dai khoang 500km, rong khoang 200km, d trung tam co khoang 8km tram tich De tam Be Malay - TbI Chu nam ngi mang Sunda la ket qua cua sir va cham mang An - Uc va Au - A each khoang 46 trieu nam Sir va cham day cac kh6i vo ciia Sunda theo hudng D6ng Nam doc theo cac he th6ng diit gay trugt sau ldn nhu S6ng H6ng, Wang Chao, Ba Chiia (Hinh 1) Cac be d vinh Thai Lan la ket qua cua sir tach gian theo hudng xien cheo vdi cac he th6ng dirt gay trugt ngang Do do, chiing dugc xem nhu la cac b6n triing trugt ngang Trong be Malay - Th6 Chu la ket qua ciia su dich chuyen irng suat ldn doc theo he th6ng dirt gay Ba Chiia (Hinh 2) Diit gay trugt ngang theo hudng Tay Bae keo dai ve phia D6ng Nam va dong vai tro nhu mgt dirt gay true mong dge theo chieu dai ciia be Malay - Th6 Chu Kieu trugt ngang phai ciia bl Malay - Th6 Chu hinh he th6ng dirt gay lien hgp theo hudng B I C - Nam va Tay Bae - D6ng Nam Nhu tren da de cap, d phia B I C bl Malay - Thd Chu, he thing dirt gay trugt ngang hudng Tay Bae - D6ng Nam dong vai trd dirt gay bao kit hgp vdi he th6ng dirt gay trugt nghieng hudng Bae - Nam TRUONG SON 3zm«» «I.!I.'LI.IJJ:H,I.'UJWT Hinh 1: Cac yeu to kien tao Ljch su kien tao ciia khu vuc dac trung bdi pha (Hinh 2): Tuygn tap bao cao Hdi nghj KHCN "30 nam Dau Viet Nam: Co" hdi mdi, thach thiic mdi" 633 • Pha 1: Tach gian theo hudng D6ng - Tay keo dai tir Eocen (?) din culi Oligocen vdi sir trugt phai dge theo he thing dirt gay Ba Chiia, hinh cac ban dja hao hudng Bae - Nam • Pha 2: Tilp theo sau la giai doan tach gian nhanh di kem vdi xoay, trugt nghieng va lun thu dgng tir Miocen sdm den giua • Pha 3: Xay nen ep vao culi Miocen gitra gay nghjeh dao kien tao va b6c mon mgt s6 dja hao Pha kh6ng quan sat ro d phfa Bae be Malay - Th6 Chu, nhien bat chinh hgp culi Miocen giiia (MMU) dugc vach d s6 tuyen dja chan • Pha 4: Mgt giai doan lun thu dong keo dai bat dau tir Miocen muon den hien tai Xay sir tai boat dgng cac he th6ng dirt gay D6ng Bae - Tay Nam hinh trudc do, kh6ng dang ke nhung cd anh hudng ldn den cac yeu td kien true cac cau tao ciia khu vuc nghien ciiu TRUONG SON tEmsmmm Hinh 2: Cau true va tien hoa Bae be Malay - Tho Chu Dja tang va su- bien hoa bl Co yeu t6 co ban tac dgng len su hinh cac tap dja tang ciia be Malay - Th6 Chu mat vT m6 (theo kh6ng gian va thdi gian), d6 la tien hoa kien tao ciia b6n va d quy md nh6 hon la cac chu ky len xu6ng cua muc nude bien U'ng vdi cac pha kien tao, dja ting cung chia cac giai doan tuong umg (Hinh va 3) 634 Tim kigm bay co ygu to dja thng: Y gu td quan trong tim kilm tham dd d phia Bae TRUONG SON Hinh 3: Cot dia tang tong hgp - Giai doan tao rift (tir 32 den 23 trieu nam), hinh cac h6 nude nggt hoae nude Ig sau, phan lap, m6i trudng thieu oxy Cac h6 chira cac ldp set giau vat chat hiiu CO, dugc biet nhu da me sinh dau d phan ldn cac tich tu dau khu vuc D6ng Nam A - Giai doan sut lun nhiet sau rift (tir 23 den 12 trieu nam), la giai doan tram tich phii len be Dang luu y la cac tap than, dugc xem nhu la co sd cho cac da me sinh khu vuc Con cac tap cat ket m6i trudng s6ng ngoi chau th6 la da chira chfnh khu vuc - Giai doan tai hoat dong kien tao (tir 12 den 10 trieu nam), xay ngin ngiii vdi sir nang len va bao mon d MMU Giai doan it anh hudng tdi phia BIC be Malay Thi Chu - Giai doan hoi phuc hoat dong sut liin (tir 10 trieu nam din nay), chii ylu la cac trim tich bien a Don vi dia tdng Cac don vj dja tang tram tich ciia khu vuc sir dung theo phan chia ciia Esso (EPMI), danh dau theo mau tu tir A tdi M tuong img cac nhom dja tang tir tre tdi gia, va mli tap nho ben dugc danh sl theo thir tu ldn din (Hinh 3) Cu the tir cd cho den nhu sau: - Tuong irng vdi giai doan va 2, la giai doan khdi dau cho su lap day bl la cac nhom dia ting tir M din L co tuli tir Oligocen sdm tdi thai ky diu cua Tuygn tap bao cao Hdi nghj KHCN "30 nam Dau Viet Nam: Co hoi mdi, thach thuc mdi" 6^5^ Miocen Trim tich giai doan chii ylu la tram tich m6i trudng luc dja va dim h i Tilp theo sau tir I din H tu6i tir Miocen sdm tdi thdi k}- dau ciia Miocen giiia, hinh cac trim tich sau tao rift Tuong irng vdi thdi diem gitra nhom dia ting H, tin tai mot giai doan bien thoai manh, theo sau la chu ky biin tiln din Miocen gitra la luc hinh tap F Den tap E tu6i gan cu6i Miocen giiia, lai chiem uu the bdi cac chu ky bien thoai Sau lai ph6 bien cac dieu kien bien tien su6t giai doan cu6i ciing ciia Miocen giua, tapD - Tuong img vdi giai doan va la mgt bat chinh hgp MMU d cu6i thdi ky hinh tap D, su6t giai doan nay, chu ky bien tien lu6n tiep dien tdi tap B va A tu6i Miocen mugn va Pleistocen b Sir phdt triin cdc tw&ng dia tdng Khu vuc nghien ciiu kh6ng co nhieu tai lieu ve dja tang tu6i trudc Oligocen Mgt vai gieng khoan tdi tang va du doan gap phai da simg bien chat, quartzit bien chat, tram tich bien chat tudi Creta (?) Cac da quartzit bien chat dugc quan sat thay tren mat cat dja chan vdi cac phan xa manh, gan phang, kh6ng c6 cac cau triic ngi tai Cdn da phien sirng dudng nhu xuat hien vdi cac tang don nghieng nam ben dudi bat chinh hgp goc ciia m6ng tu6i trudc Oligocen vdi mgt giai doan dai nang len va bao mon Cac tang da luc nguyen mau trudc rift tu6i Paleogen sdm chem vao gitra, ben dudi la cac da sirng, da quartzit bien chat nam kh6ng chinh hgp va ben tren la cac da tram tich tu6i sau Oligocen Dac trung dja chan ciia tap la cac phan b6 dang ldp co le co tu6i Eocen (?) Bieu hien dau quan sat dugc mong trudc De tam, thudng chi gap khoan di qua ddi dirt gay Vi vay, thien ve kha nang bieu hien dau tir ddi dirt gay noi no dong vai tro nhu dudng dan hydrocarbon Ben tren mat bat chinh hgp trudc Oligocen la cac tang tram tich c6 nhat lap day cac dja hao thuoc nhom tir O tdi L tu6i tir Eocen muon tdi Oligocen sdm (theo Hutchison, 1996) Suit giai doan khdi thiiy cua tach gian va tao rift nay, tram tich chii yeu la trim tich vun tudng boi tich aluvi lap day cac dja hao va phii dja hinh mgt s6 noi, tai lieu dja chan cho thiy tang tram tich day den vai km (theo Hutchison, 1996) Sau do, ma t6c sut liin tang len, tao kh6ng gian lang dgng ldn hon su cap lieu ciia tram tich, cac h6 phat trien d cac phu be noi co cau true khep kin va lugng mua d6i dao (kha ph6 bien d khu vuc nhiet ddi ciia Sunda) Tram tich dam h6 lang dgng cac ldp set day co kha nang sinh dau d day h6 va cac tudng h6 di kem nhu turbidit h6, chau th6 ven h6, tudng ven h6 Phan tren la ldp tram tfeh tap K dai dien cho ddi chuyen tiep tir d6ng tao rift sang giai doan dau ciia pha liin vong Tap dugc phii bdi mot tap set h6 phan b6 rgng mang tinh khu vuc "K shale" Giai doan ke tiep dien nguge lai sir cap lieu ciia tram tfeh bat dau vugt qua kh6ng gian lang dgng (do sut liin) Cac h i dugc lip diy va trd nen nho, n6ng din Cac h i CO the t6n tai sau tach gian da ngimg bin giai doan sau rift phan each dia 636 Tim kigm biy cd yeu to dja ting: Ygu td quan trong tim kilm tham dd d phia^ac^^^ hinh, nhung sau no se dugc lap day hoan toan va biin mit bdi cac trim tich tuong s6ng ngoi va chau tho Cac tram tfeh s6ng ngoi tap J la dai dien cho giai doan diu ciia sir sut lun nhiet sau tao rift Cac tram tich chu yeu hinh m6i trudng d phin tren ciia d6ng bang ven bien (UCP), chii yeu la cac tram tich luc dja nhu cat kit xen kep set ket mau d6, rat it than va set giau vat chat hiiu co Cang ve phia Bae va phia Tay, tram tich tap cang CO anh hudng bdi s6ng O pha cu6i cua sir sut lun nhiet sau tao rift, be mat dja hinh kha bang phang, ca viing bien ciia rift ciing da dugc phii kin Luc cac tram tich gan bd bat dau phat trien vdi cac tudng thay d6i, phu thuge vao sir nang len hay xu6ng ciia muc nude bien Tap I den E dac trung bdi cac tram tich hat mjn Theo tirng giai doan muc nude bien cao hay thap, cac tap cat chiia thay d6i hudng phan b6, hinh thai kh6ng gian chieu Than va set giau vat chat htru co gap nhieu cac dja tang I va H va la mgt cac tang sinh chu yeu d khu virc Danh dau giai doan I, la sir kien muc nude bien xu6ng thap sau bj gian doan bdi mgt qua trinh bien tien toan dien tir H den D Bat chinh hgp MMU tuong iing vdi tang C, phii len tren no la he tang B va A Hai he tang hinh giai doan bien tien, chiing kha day, lai chu yeu la set ddng vai tro tang chan noc khu vuc c Hi thdng ddu (TTmh 4) Be Malay - Th6 Chu dugc xac djnh co hai he thong chinh: • Hi thdng Oligocen/Miocen: he th6ng co da me la kerogen loai I tu6i Oligocen, chii yeu la da phien set dam h6 d6ng tao rift (Loai sinh dau cd chay cao la ket qua ciia cac vat lieu ngu6n g6c thuc vat d6 vao h6 Da chira chinh la cac tap cat ket s6ng tu6i Miocen sdm va giua hinh giai doan dau cua qua trinh sut vdng nhiet (nhom dja tang J, I, H) Chiing dugc chan bdi cac tang tram tich hat mjn xen giiia cac he tang • Hi thdng Miocen/Mioeen: da me chu yeu la cac tang set than giau vat chat hiru co tu6i Miocen sdm va gitra Loai da me dac trung sinh va khi/condensat (kerogen loai III) Da chira va chan ciing nhu he thdng tren, rieng da chira tudng s6ng ngoi va chau th6 phan b6 xen lan vdi da sinh Mot s6 nghien ciru cho thay dau khu vuc co trudng tuong irng 0,8%VRE vitrinite, tuong duong khoang 2800m sau tinh theo dja nhiet trung binh Do do, co the ket luan rang hau het da me phan bd khu vuc nghien ciru chua du trudng de co thi sinh hydrocarbon Cac nghien ciru dja hoa cho thay, cac phat hien dau khf khu vuc co ngu6n g6c djch chuyen tir viing sau hon phia trung tam b6n Va tang J vdi ty le cat cao, lai nam gan tang sinh ddng vai tro la tang dan ly tudng Tuyin tap bao cao Hdi nghj KHCN "30 nam Dau Viet Nam: Co hdi mdi, thach thiic mdi" 637 TRUONG SON 15 «| '.'H.,JJ:H,!'!,lj v - m / j TU6IO!ACHAT^ 'o (tr nam) MIOXEN OLIGOXEN PLIO veUTdCUA HT D A U KHi OASINH L/P D D§E[^EE GDI I I I I I [ DA CHliA OA C H A N D A LC^P P H U T R ^ N HiNH T H A N H BAY W>-^^ ^^'^'' ^v^ c^""' ^c^ =,\^'^ 0^ _^ BAO QUAN CHU THiCH L: h^ ^6ng Il6n quan a4n 06 sinh tifdng h6 C: h$ thSng Il6n quan