274 Ket qua nghign ciru khi tang ndng d khu virc Thai BinjijJNam^giQJL KET QUA NGHIEN C U U KHI TANG NONG O KHU VU^C THAI BINH NAM DINH • • Le van Dung, Le Dinh Thang Le Nhu Tieu, Do Quang D6i Viin Dd[.]
274 Ket qua nghign ciru tang ndng d khu virc Thai BinjijJNam^giQJL K E T QUA NGHIEN C U U KHI T A N G N O N G O K H U VU^C THAI BINH - N A M D I N H • • Le van Dung, Le Dinh Thang Le Nhu Tieu, Do Quang D6i Viin Ddu Khi TOM TAT Hiin tugng tdng ndng da dugc phdt hiin khoan cho nd thdm dd dia chdn & mien vdng Hd Ndi vdo nhirng nam 1970 O vung Giao Thuy (Nam Dinh), ngu&i ddn dd timg sir dung & tdng ndy dun ndu gia dinh Nhirng ndm gdn day v&i phong trdo nu&c sgch cho ndng thdn UNICEF vien trg thi khoan tim kiim nu&c ngot da dugc tiin hdnh deu khdp & cdc tinh cd nu&c, ddc biet Id & ddng bdng Bde bd vd miin Trung Trong khoan nu&c, mdt sd giing khoan (GK) & Vd Thu, Kien Xuong (Thdi Binh), Giao Thuy (Nam Dinh), Yen Dinh (Thanh Hda), Ly Nhdn (Hd Nam) dd gap Tir phong trdo khoan tim tuphdt nhdn ddn, ddc biet la & Vu Thu ddn din cd chd gdy nin hod hogn nhu&xd Minh Ldng vd Tdng cdng ty Ddu Viet Nam da phdi can thiep de dap tdt V&i hien trgng nhu vdy, eiing v&i yeu cdu cua dia phuong hiin tugng ndng cdn phdi dugc ldm ro di co quy hogch sir dung Bdo cdo tdm luge lgi kit qud nghien cim khdo sdt, ddnh gid so bd ndng ehu yiu Id khu vuc hai tinh Thdi Binh, Nam Dinh md Vien Ddu Khi da tiin hdnh th&i gian qua Trong qud trinh thuc hiin nhiem vu chung tdi da nhgn dugc su giup rdt nhiiu eiia cdc don vi Ngdnh Ddu Vi phia cdc dia phuong chung tdi cung nhan dugc su cdng tdc, giiip chdt che cua cdc s& Cdng nghiep, s& KH-CNMT cdc tinh Thdi Binh, Nam Dinh, Hd Nam, Thanh Hda, Nghe An Chiing tdi xin chdn thdnh cdm on sir giup da qui bdu cua cdc dan vi niu tren KET QUA NGHIEN ClTU Khi tang nong a day duge cho la cac tang nam cac ting tu sau 200 250m tro lai, nghia la khong vugt qua cae lop tram tieh De tu Ve dia tang De tu neu nhu truoc (1965) chi chia lam phan vi la Kiln Xuong va Hai Duong (Golo\emoek, Le Van Chan, v.v.) thi da chia lam phan vi, g6m (tu tren xu6ng): Thai Binh - Hai Hung (Holoxen) va Vmh Phue - Ha Noi - Le Chi (Pleistocen) va theo timg \aing lai tha\- ten ggi theo dia danh viing (Ngo Quang Toaa 1992; Vu Nhat Thang, 1995; v.v.), va dac diem tram tich Moi truong cua cac tap tren ciing dugc nghien cuu kha chi tiet Cac tai lieu va qua khao sat cae GK nong gap a cac tinh Thai Binh, Nam Djnh, v.v cho thay tang nong gap chu ylu tap Ha Noi, Hai Hung, doi co thi nam a tap chua VTnh Phuc va Thai Binh (Hinh 1) De tim hieu hien trang sir dung nong nhan dan, chung toi c6 di khao sat a cac tinh Thai Binh, Nam Dinh, Ha Nam, Ha Noi va mgt so tinh kbac ma chung toi khong de cap den o bao cao Tuygn tap bao cao Hoi nghj KHCN"30 nSm D^u Viet Nam: Co' hdi mdi, thach thiic mdi" 275 Hinh 1: Cot dja tang t6ng hop De tii- khu vyc Thai Binh Tai Thai Binh Da tiln hanh khao sat cac dilm GK co cac huyen VQ Thu, Kiln Xuong, Tiln Hai ciing cac can bg cua So Cong nghiep Thai Binh Cac xa da tiln hanh khao sat gdm: Tan Hoa, Minh Lang, Xuan Hoa, Viet Hung, D6ng Thanh, Song An, Vu Tiln, Vu Hgi, Vu An, v.v cac dilm khao sat diu co \hy mau nuoc dl phan tich Qua tat ca cac diem khao sat thay rang: a tinh Thai Binh, viec sir dung nong nhan dan chu ylu d hai huyen Vu Thu va Kiln Xuong (Bang 1) Nhilu nhat la a Vu Thu, tap trung theo khu vuc kep giii:a song Hdng va sdng Tra Ly Da sd cae giing khoan 276 Kgt qua nghign ciiu ting nong d khu vuc Thai Binh - Nam^jnh^ dIu khoan nam 1999 - 2000 va cac Id khoan thudng duge khoan sau din 46 - 50m Do sau bilu hien manh thudng tir 10 - 12m trd xudng nhu d xa Minh Khai, Viet Hiing Da sd cd bilu hien tir 27 - 30m, ap suat ldn nhat dugc khoang 2,5 - 3,Oat, nhung sau mdt thai gian sir dung ap suat giam rat nhanh (Hinh 2) I Hinh 2:Gilng khoan nha anh Pham Van Toi ff Tan Hoa, Vu Thu, Thai Binh dung cho bep voi voi ga chay cao 0,8m (dnh chup ngdy 22-7-2000) 277 Tuygn tap bao cao Hdi nghj KHCN"30 nam Phu Viet Nam: Co hdi mdi, thach thiic mdi' Bang 1: ThSng ke cac ho khoan giing de khai thac dot cua tinh Thai Binh (do S& Cdng nghiep cung cdp) TT A Ho va ten chu ho Ngdy Ngdy dua Chieu S6 khoan vdo sir sdu voi giing dung (m) ddt 10/4/2000 11/4/2000 52 ho ThdnXom So ho Ghi chii diing Huyen Vu Thu' Xd Minli Ldng Nguyen The Tiem 10 Xung quanh siii 70m Nguyen HOu Thu 12 1/1999 3/1999 80 dat gap da ldp cung, soi da Le van Chuan 10 5/4/2000 10/4/2000 45 1 Xung sui Xung Ho^ng van Khanh 10 25/3/2000 26/3/2000 50 1 2,5kg Vfl van Nam 10 1/4/1999 10/4/1999 50 1 Vu van Son 15 1/4/2000 3/4/2000 45 1 Pham van Thanh 15 2/4/2000 3/4/2000 45 1 Pham van Due 10 - - - - - 15/2/2000 16/2/2000 25 20/3/2000 21/3/2000 20 2/3/2000 50 Xd Xuan Hod Tran Thj Ly Tran Van TTnh Xom 2, Thanh Ban X62, Thanh Ban Xd Tdn Hod 24/12/199 Phan van Tdi Xom Phan Gia Mong Xom i 26/2/2000 6/3/2000 50 Hoang van Han Xom 4/11/2000 6/11/2000 50 11/1999 11/1999 20 1 12/1999 12/1999 40 i 12/1999 12/1999 45 1 11/1999 11/1999 40 1 Til tran Vii Tliir Nguyin Ngoc Son Dang van Thuy Pham Hdng Thai Ba Hoa (Nhuong) To Minh Tan Td Am Binh Td Am Binh To Tan Minh quanh Da hgt quanh sui, ap Kit qua nghien ciiu thng ndng d khu vuc Thai BinhjJ^^iani Oinh 278 Bang (tiep): Thing ke cac ho khoan gieng de khai thac dot ciia tinh Thai Binh (do S& Cdng nghiep cung cdp) TT Ho va ten chu hd ThdnXdm Ngdy Ngdy dua Chieu So khoan vdo su sdu vdi gieng dung (m) ddt Sdhd Ghi chii diing Xd Vii Tien Hoang Xuan Dung Ngoc Tien 5/9/1999 5/9/1999 30 1 Tran Xuan Le Ngoc Tien 10/9/1999 10/9/1999 30 Tran Xuan Tiem Quan Tien 12/9/1999 12/9/1999 30 1 Tran Xuan Khue Quan Tien 14/9/1999 14/9/1999 30 Tran Dinh Nuoi Quan Tien 16/9/1999 16/9/1999 30 5/2/2000 10/2/2000 30 1 8/3/1999 5/5/1999 30 1 8/4/1999 18/4/1999 40 1 5/1999 5/1999 32 1 Xd Viet Hiing Tran Khae Dy Dinh van Tinh Tran Van Gia Pham Quang Hop Xdml, Phii Loc Xom 2, Phu Len dang ke, yeu Khdng dung LOG Xdm 5, Phii Loc Xom 1, Tan Phong Xd Song An Nguyen Ba Can Bae An 20/3/2000 21/3/2000 45 4 Nguyen Van Sau - 1/2000 1/2000 45 10 Do The Thuc - 1/2000 1/2000 45 10 Tran Van Nhu - 3/2000 3/2000 45 Tran Van Son - 12/1999 12/1999 45 32 16 Nguyen Ngoc Hai - 1/2000 1/2000 45 Phan Duy Tiic - 2/2000 2/2000 45 14 Tran Van Thong - 3/2000 3/2000 45 Xd Minli Khai Pham Van Ha Xom 14 1999 40 2 NguyenVan Luan 14 1999 40 3 *> J Pham Van Khang 17 9/1999 24 Tran Van Hanh 17 7/1999 40 Tran Van Ngu 17 7/1999 40 khdng Hong Tuygn tap bao cao Hdi nghj KHCN"30 nam Phu Viet Nam: Co hdi mdi, thach thuc mdi" 279 Cach khai thac thd so, hieu suk sir dung thap, gay d nhiem mdi trudng Theo ket qua phan tich cac miu cua Vien Diu Khi, thi d day cd chua H2S vdi ham lugng < Ippm Khi H2S vdi ham lugng khdng true tiep anh hudng den tinh mang ngudi, nhung ve lau dai cung anh hudng den sire khoe Tinh trang sir dung la don gian ehi diing dng nhua dan vao vdi bep cd van khoa ddng md Bep thi tu thiet ke thudng la mdt dng sat dat dudi bep kieng hoae giiaa hdn gach Sir dung nhu the ddt khdng bet rat lang phi (Hinh 3) Hinh 3: Bep ga nha ong Pham Cao K, Dong Thanh, ^ Vu Thu" mo* het ngon lu'a cao gan Im (dnh chup 22-7-2000 trdi vd 14-1-2002phdi) Tai Nam Dinh • • Chu yeu la cac xa d huyen Giao Thuy, dien tich kep giiia sdng So va sdng Hdng Chung tdi da tien hanh khao sat eae diem dan dang sir dung d cae xa Giao Long, Giao Nhan, Bach Long, Giao Hai, Giao Lac, Giao An, Giao Thien mdt sd hd dan khoan nude va gap da sir dung tir lau, ke ca sir dung tir cac gieng khoan thu nd dia chan tir nhiang nam 1970, nhu vay da qua 20 - 30 nam, van cdn diing nhu nha dng Thang (Giao An), nha dng Doan (Giao Thien) Do sau cd ve phia cira Ba Lat chi tir 15 - 20m Cach thiire sir dung hien rat don so, khdng ed van ddng, khdng diing thi chi chan mdt hdn gach tren mieng GK (Hinh 2), vay lang phi rat nhieu Quy trinh khoan, chdng dng, phin Igc, each truyen dan va sir dung d day deu het sue don gian, khdng dugc nhu d Thai Binh THU THAP, LAY MAU THtTC DIA Trong qua trinh di khao sat thuc dia chung tdi da \hy miu va nude tai nhiing GK ma nhan dan dang sir dung Tai Thai Binh da lay miu (6 d Vu Thu, d Kiln Xuong) va miu nude (5 d Vu Thu, d Kiln Xuong) 280 Kgt qua nghign ciiu tSng nong d khu vuc ThaiBmhj-JNani_Dinh^ Tgi Nam Dinh da lay mau va miu nude d cac dilm thudc xa Giao Long, Giao Nhan, Bach Long, Giao Hai, Giao Thien thudc huyen Giao Thuy Phan tieh mau duge tien hanh tai Phdng Dia hoa, Vien D I U Khi sau mdi dgt khao sat thuc dia KET QUA PHAN TICH MAU (Bang 2) Kit qua phan tieh cac mau d Thai Binh, Nam Dinh eho thiy phan ldn phin la CH4 chiim 93 - 97%, sau dd la nito cbilm tir - 5%, CO2 tir 0,4 - 2,5% edn lai la mdt sd phan khae Rieng cac mau d Via Tien, Vii Hdi, Tan Hoa, Minh Lang cd them phan nang tir C2 - C4 nhung chiem ty le khdng dang ke Vi vay ed the ndi, da phat hien la khd tieu bieu va CH4 chinh la phan quan trgng nhat cua cac nay, quyet dinh cae thdng sd vat ly ciia nhu ty trgng, nhiet tri, BTU, v.v Ngoai ra, phan Id cdn cd nito, carbonic va mdt lugng rat nhd vai ppm ciia hydrosunphua, mercaptan Khdng phat hien thay heli, hydro va oxitcarbon r f Chi phat hien thay am (hydrocabon tir C2 trd len) vdi mdt lugng rat nhd so vdi metan tu d Tan Hoa, Minh Lang (Vu Thu - Thai Binh) Tat ca phat hien deu nhe hon Tien Hai va nhe hon khdng Hinh 4: Bep ga nha ong Tran Van H., Giao Long - Giao Thuy dimg tu 1976 den (thoi diim Kh.S) dong mff "van" bSng hon gach tren mieng gieng 28: Tuygn tap bao cao Hoi nghj KHCN"30 nam Phu Viet Nam: Co hdi mdi, thach thiic mdi' Bang 2: Tong hop ket qua phan tich mau tang nong So thu tu / 3* 4* 5* Ky hieu mau Khi ndng chung K6 KH-YD-3 KH-VT-3 KH-VT-4 Loai mau Khi tu d cac Khi mo Khi tu Khi tu Khi tu Vi tri lay mau diem 16 dan dang Tien Hai C Dinh Tien Vu Tien Vu Hoi su dung Thai Binh Thanh Hoa Va Thu VuThu Diem Diem Diem >jJu7ijJwJti-i.^«J>^' ] o h ro ^ '^ Caf AViff •a^ng Mi c y - ' T ••.•••'•: CJL* i>Ov Cili '5^5 5-^0 -ac—Si:—tar-W(r-"-3Ei—ap—-fetf~-*s- 5-30 PSttHattin mm-giiia 44 - 100 O ,'0 sut Ml &*! vet) PIKtieo 40 - 300 ã(4Kô>flK(iMHiaMKMpi'iÊaBb rv nw! VQ una ntHm^ (liosi Hinh 5: Mo hinh tang chua chan khf nong Hinh: 19 Tuygn tap bao cao Hdi nghj KHCN"30 nam Phu Viet Nam: Co- hdi mdi, thach thiic mdi" 283 Tang chu-a Cd tang ehua ehinh thudc tang De tir d ddng bang Bae bd: - Tang chua thu nhat thudc he tang Thai Binh (a, amQ,v'"^/'Z?/.2) - Tang chua thu thudc he tang Hai Hung (a, amQiv'/?/?/) - Tang chira thii thudc he tang Le Chi, Ha Ndi va VTnh Phuc dudi Tang chan Cd tang chan chinh: - Tap set Vinh Phuc: La tap set bien tien, phat trien kha manh d ddng bang Bae bd, vdi ten ggi la set Vinh Phuc (mQi,i'vp2), day cd thi la tang chan tdt, ed chilu day trung binh cd 12 - 15m, day nhat 30m - Tap set, bdt nde he tang Hai Hung Ngoai cdn tang chan dia phuong thuoc phu he thng Thai Binh QUY LUAT PHAN BO KHI TRONG TRAM TICH DE Tif Khi tir cac ldp than Tien Hung, Phu Cir (hoae cd thi tir cac md khi) da di chuyin len tren theo chieu thang dirng, hoae theo cae dut gay, theo via cam ddc sau dgt van ddng kiln tao cudi Miocen vugt qua tang VTnh Bao, v.v va se tich tu lai d cac tang chira ndng 1, 2,3 Tiiy thudc vao dac diem dia chat timg viing ma ta cd the gap dugc ndng d tang chira thir nhat khoang chieu sau 10 - 30m hoae ndng hon thudc he tang Thai Binh hay tang chira thu khoang sau tir 25 - 50m thudc he tang Hai Hung, va tang chira thii khoang chieu sau tir 45 - 90m thude he tang Ha Ndi, Le Chi Mac dii vay, ddi chieu vdi tinh hinh thue te cho thay khdng phai cir bat gap tang chira tren d noi nao cung deu cd khi, cu the khao sat d cac xa cho thay chi each hoae Om la da khdng gap nira, nhu vay kha nang chi tieh tu rieng biet, khdng trai tren mdt dien tich rdng Dieu dd ciang phii hgp vdi dac diem dja chat De tir la ddng bang tam giac chau thd vdi cac tao tram tich sdng, ngdi, hd, dam lay, cira sdng va bien ven bd vdi cac than cat nhd DANH GIA SO BO TIEM NANG VA PHAN VUNG TRIEN VONG Dua tren sd lieu tai cae diem ndng dan dang sir dung, ddi chieu vdi chieu sau d cac GK ma dan dang lay de sir dung nhdm khao sat da ve so dd cac tap chira nam phu he Hai Hung (Hhl) va Thai Binh (TbI, Tb2) cho khu vue la Vii Thu, Giao Thuy noi ngudi dan dang sir dung nhieu nhat, de danh gia so bd trti lugng tiem nang Tir cac dti" lieu thuc te, qua phan tieh cac dilu kien dia chat, dia tang cd the so bd phan viing trien vgng nhu sau (Hinh 6) Viing trien vong thu* nhat La khu vuc nhu Vii Thu, Giao Thuy: v l mat phan trani tich cung nhu dia hinh ta thay cac tinh ven biin ddng bang Bae bd, khu vuc dge triln sdng la nhirng noi cd kha nang tich tu ndng Kit qua nghign 284 CUTJ thng nong o khu vuc Thai Binhj-j^an^j^!"*^ v l mat kiln tao: nam tren dai nang Khoai Chau - Tiln Hai Kiln Xuang \ a la noi kep gitra cac dirt gay sau, cd nhieu boat ddng dirt gay kl ca diit gay tan kien tao, cac ldp tram tieh bi nang vat dan ke ap vao cac trhm tich De tir, ddng thdi cd the pha buy cac tich tu cd dan den tai dich chmen theo cac dirt gay va tich tu d nhirng tang ndng v l mat sinh thi day la nhirng viing nam gan nhung noi cd ngudn sinh tdt Hinh 6: Ban phan vimg trien vong nong ff viing dong bang Bae bo Viing trien vong thu- hai La nhiing khu virc cdn lai nam kep giira dirt gay Hung Yen va VTnh Ninh keo dai ve phia Ha Ndi md rdng ve phia Tay Nam Viing trien vong thu- ba La viing trien vgng kem, bao gdm nhiing viing cd than biin Holoxen KET LUAN Tir CO sd tdng hgp, phan tieh da xac dinh nhimg tang chiia chan De tir lien quan den ndng dd la cac tang chira 1, thudc he dia tang Thai Binh, Hai Hung va Ha Ndi ciing Le Chi, dd tAng chira dugc coi la tang chira chinh Mac dii vay ddi Tuygn tap bao cao Hdi nghj KHCN"30 nam Phu Viet Nam: Co hdi mdi, thach thiic mdi" 285 chilu vdi tinh hinh thuc tl cho thay khdng phai cir bat gap tang chiia tren d noi nao eiing deu cd khi, cu thi khao sat d cac xa cho thay chi each hoae lOm la da khdng gap nira va nhu vay kha nang chi tich tu rieng biet, khdng trai tren mdt dien tich rdng Dieu dd ciing phii hgp vdi dac diem dia chat De tir la ddng bang tam giac chau thd vdi cac tao tram tich sdng, ngdi, hd, dam lay, cira sdng va bien ven bd vdi cac than cat nhd Khi cd the duge tich tu d nhiing than cat kieu ldng sdng, cira sdng hoae cac cdn cat ven bd va phan bd nhieu d cac vimg thudc khu vue luu cua cac ddng sdng Tinh trang sir dung ba ndng dan la rat y, khdng theo mdt quy dinh nao ca, cd bep chi la mdt cai Id dun xong day gach len tren, vi vay rat lang phi va nhat chi cd d Thai Binh nhan dan da khoan cd chdng dng, dan qua binh tach don gian cd van, theo dudng dan vao bep tu tao cae ket qua phan tich mau lay duge cho thay phan ndng ehu ylu la CH4 tdi > 95% va mdt sd phan khae Day la loai sach cd thi sir dung tdt lam nhien lieu, v.v Khi lai tap trung chii yeu d vimg ddng bang, dien phan bd rdng va neu duge khai thac tdt thi nhieu ngudi ed the sir dung dugc Neu cd chii truong cho dan sir dung, can cd quy trinh, quy pham va hudng dan cho dan biet de bao dam sir dung an toan va phdng chdng chay nd Chieu sau den tich tu thudng tap trung vao khoang: 10 den 50m, va tir 45 din 90m (viing cd than biin chi sau tir - 10m) Day la nhiing tich tu dang tui nhd, khdng phai la ddi tugng khai thae thu gom cdng nghiep, chi phuc vu dugc eho nhu cau dan sinh vdi quy md nhd TAI LIEU THAM KHAO B.A Demidov, Nguyen Xuan Dan, 1975 Ddc diim phdn bd cabuahydro phdn tdn & phdn tren d&i trdm tich vung triing Hd Ndi vd tim kiim cdc via ddu Tap san Dia chat Dau khi, Sd Golovenok, Le Van Chan, 1965 Thgch hoc mien vong Hd Ndi Lien doan 36 Hoang Ngge Ky, 1976 Trdm tieh nhdn sinh vd sir hinh thdnh ddng bdng Bde bd Tap chi Dja chat, Sd 126, thang - Hoang Ngge Ky, Le Van Cu, Nguyen Ngge Men Quaternary geology in North Vietnam Progress in Quaternary Geology of East and Southeast Asia, CCOP/TP 18 Hoang van Soan, Dang Ngge Bich, 1972 Vdi net vi ddt vung X, N, H Tap san Dia chat Dau khi, Sd Kisliakov, 1970 Bdo cdo cdu triic dia chdt vd triin vgng ddu miin vdng Hd Ndi Luu trii tai Thu vien Vien Dau Khi Le Trgng Can, 1983 Cdc dut gdy vd vai trd cua chung su hinh thdnh binh cdu tgo vd quy lugt phdn bd caebuahydro a miin vong Hd Ndi Bao eao D I tai 22-0101-04 Luu trtr tai Thu vien Vien Dau Khi Lai Dire Hiing, 1996 Kit qud lap bdn dd dia chdt thuy vdn vitng Thdi Binh, ty li 1/50.000 Lien doan Dia chat thuy van 286 Kgt qua nghien ciiu thng nong d khu vuc Thai Binh - Nam_Pjnh^ Le Hung, 1998 Tiim ndng sinh thdnh hydrocarbon cua than vd set than trdm tich De tam phdn Tdy vd Tdy Bde be Sdng Hdng Luu trtr tai Thu vien Vien Dau Khi 10 Martin Schoeli, 1983 Genetic charaterization of natural gases AAPG Bull., Vol 67, November I.Nguyen Tien Bao, 1972 Vi suxuat hien cabuahydro ndng (CnH2n+2) trdm tich chira than vung Hdn Gai, Cdm Phd Tap san Dia chat Dau khi, Sd 12 Phan Huy Quynh, 1973 Trdm tich Di tu vung triing Hd Ndi Tap san Dia chat Dau khi, S d i 13.Pham Van Hiing, Nguyin Dich Dy, Le Van Vd, 1998 Thuyet minh bdo cdo dia chdt ddng bdng Bde bd, ty li 1/200.000 Ha Ndi 14 Tran Ngge Toan, 1999 Vi metan cd ngudn gde than dd Tap chi Dau So ... a Vu Thu, tap trung theo khu vuc kep giii:a song Hdng va sdng Tra Ly Da sd cae giing khoan 276 Kgt qua nghign ciiu ting nong d khu vuc Thai Binh - Nam^ jnh^ dIu khoan nam 1999 - 2000 va cac Id... day la nhirng viing nam gan nhung noi cd ngudn sinh tdt Hinh 6: Ban phan vimg trien vong nong ff viing dong bang Bae bo Viing trien vong thu- hai La nhiing khu virc cdn lai nam kep giira dirt... voi voi ga chay cao 0,8m (dnh chup ngdy 22-7-2000) 277 Tuygn tap bao cao Hdi nghj KHCN"30 nam Phu Viet Nam: Co hdi mdi, thach thiic mdi'' Bang 1: ThSng ke cac ho khoan giing de khai thac dot cua