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Tap chi Khoa hoc va Cong nghe bien T8 (2008) So 3 Tr 18 29 TINH TOAN SU CO T R A N DAU VUNG VEN BIEN BINH THUAN NGUYftN KY PHUNG •", NGUYfeN THI BAY''''̂ ^ Tom tcit Trimg hdi hao,cdc tdc gid trinh hay md[.]
Tap chi Khoa hoc va Cong nghe bien T8 (2008) So Tr 18 - 29 TINH TOAN SU CO T R A N DAU VUNG VEN BIEN BINH THUAN NGUYftN KY PHUNG •", NGUYfeN THI BAY'^^ Tom tcit: Trimg hdi hao,cdc tdc gid trinh hay md liinh hai chieu linh todn km truyen vd phun huy ddu Md Ivnh cd linh tdi qud Irinh loang, hod lan, khuech tdn, phdn huy sinh hgc ciia dau Md hinh diCgc dp dung de linh todn vd md phdng qud trinh lan truyen ddu cho vimg ven hien Binh Thudn I.MdDAU Hien nay, tan suat cua nhQng vu tran dau eang tang lam gia tang sQ quan tam cua toan The gidi Tat ca cac qua trinh khai thac, van chuyen diu, iQu thdng tren sdng, lach, va cac cdng cu iQu trQ dau deu la nhQng ngudn cd nguy cd lam xua't hien tai nan tran dau TQ nam 1988 den nam 1991, cd khoang 28 vu vdi hdn 500,000 lit dau tran da xay (theo NCAA 1992) Td'ng the tich cua nhQng vu tran dau ldn, ngoai trQ vu Kuwait xay d vinh Arabian, cung khoang thdi gian tren la 293,000,000 lit Nam 1991, vu tran dau Kuwait, vinh Arabian thai khoang 143 ty lit hay 37.8 ty gal (theo NOAA, 1992) O Viet Nam cac sQ cd tran dau da xay ra, chu yeu la d khu vt/c ven bien Ddng Nam bg Dac biet viec dau lan suot bai bien mien Trung va Nam bg thdi gian vQa qua la het sQc dang quan tam NhQng lo ngai ve mdi trQdng sinh sau nhffng vu tran dau tren da din den sQ phat trien cua nhieu md hinh toan md phdng qua trinh lan truyen va bien ddi tinh chat: sd phan cua dau tran Mac du cd hdn 50 md hinh lan truyen diu da dQdc phat trien nhieu nam vifa qua, nhQng chi cd mot vai md hinh dQdc phd bien cho de'n NhQng md hinh dQdc sQ dung de' Qng phd xay sit cd, danh gia tac dgng den mdi trffdng, lap ke hoach ffng phd tffc thdi va dao tao cho cdng tac ffng phd Ifiu dai Hdn 25 nam vita qua, cac md hinh tran diu da phat trien tff dang md hinh quy dao chieu ddn gian cho de'n cac md hinh chieu md phdng ca cac qua trinh lan truyen va sff bien ddi tinh chat cua dau tran Trong sud't khoang thdi gian nay, hie\i biet cua 18 chdng ta ve qua trinh chuyen tai va sdphan cua hat dau da phat trien ve can ban Muc dich cua cac md hinh ra't khac Mot vai md hinh dffdc phat trie'n phirc vu dff bao cho cac cbie'n thuat ffng phd tffc thdi, giup ta quyet dinh cho cdng tac ngan chan, kiem soat va lam sach dau Iran sff cd Mdt sd md hinh khac dffdc phat trien vdi muc dich hffdng tdi viec danh gia tac hai lau dai len mdi trffdng Bai bao dffa ke't qua tinh loan sff cdtran dau bang md hinh chieu nhdm tac gia xay dffng va da dffdc ap dung tai so'khu vffc tai vung bien Binh Thuan II CO sd KHOA HOC vA THlJC TE THIET LAP MO HINH Thffc te dat van de cin giai quyet la: ne'u dau bi tran thi nd se lan truyen nhff the nao de cd phffdng thffc ddi phd kip thdi va hffu hieu Va hdn nffa, cac dff bcio khoa hgc ve hien tffdng se gdp phan khdng nhd cho cdng tac quy hoach va bao ve mdi trffdng Dd'i tffdng cua cac nghien cffu trien khai md ta phan la qui luat lan truyen dau sff cdtran dau tren vQng bien Binh Thuan Muc tieu cudi cung can dat dffdc la giai quyet va'n de dff bao vet dau loang vung ven bien Binh Thuan Trong phan , ehung t'di md ta phffdng phap va dffa md binh toan nham dff bao hien tffdng lan truyen dau sit cd vung xay difng dif an d Binh Thuan StJ" lan truyen dau tren bien la qua trinh phffc tap Dieu kien vat ly cir the nhff : dffdng bd, long dan, gio', ddng chay, thuy trieu, lffdng dau tran, vi tri tran dau va loai dau tran la cac ye'u to'quyet dinh sff lan truyen vet dau Nhiem vii dat la: • Chgn md hinh toan va phffdng phap giai cd chat lffdng tffdng thich vdi chat lffdng cd sd dff lieu thffc te hien cd, cac tien bg nghien cffu cd ban da dat dffdc ffng vdi Ccic phffdng tien tinh toan hien • So heu nhap cho md hinh dff bao phai tffdng ffng vdi kha nang hien cua cac he thd'ng cac dich vu nganh Khi tffdng thuy van va theo dung chuan mffc cua Viet Nam de dam bao tinh tht/c thi Md hinh lan truyen dau: bao gdm cac mddun chinh la md hinh thiiy Iffc va md hinh khuyech tan 19 HI MO HINH THUY LUC Cac phffdng trlnh cd ban: du dl du dx du dy ' fir+v' (h-^s)C' r, p(h + s) dv dv dv , ds fir -^• v' - + !/ — -i-v — -\- fii + g — -i-^v dl dx dy dy (h + s)C' p(h + s) (h + s )u + + dt ds dx dx (j^ (2) (h + s )v = Q dy C3) Trong do: u,v: van tdc ddng chay theo phffdng x, y [m/s], t: thdi gian [s] f: thamsdCoriolis [1/s ],f= 6:>sin^ ; ^ :vT dia ly; co :van tdc quay cua trai dat [rad/s] g: gia tdc trgng trffdng [iii/s^]; s: dao dgng mitc nffdc [m]; b: sau [m| Xx, Ty: ffng suat tie'p tuye'n gid theo phffdng x, y.[N/iii ] r^ = Co * /9„ *\W\ * IF.; r,, = C^, * p„ * \w\* W^.; C,o - (0.075 + 0.065 * W) * 10"' W : van tdc gid [m/s]; p„ =1.3 [kg/m'']; Wx : van tdc gid theo phffdng x; Wy: van td'c gid theo phffdng y Digu kien ban diu cua bai toan: thdi diem ban dau t=0 :V=0, U=0, s =0 Di§u kien bien bai toan: a Dieu kien bien ran Tai bien ran: Un = vdi u,, - phan van td'c phap tuye'n b Dien kien bien long - Tinh toan ddng chay trieu: dieu kien tai bien long cho dffdi dang dao dgng mffc nffdc trieu - Tinh toan ddng chay gid: cho trffdng van td'c gid thffc 20 Vd dong chdy tong hc/p Id dong chdy bao gom dong clidy gio vd ddng chdy trien Thuat toan giai He phffdng trinh tren dffdc giai bang phffdng phap sai phan luan hffdng O nffa bffdc thdi gian dau tien hanh sai phan an cac bie'n theo phffdng x, va giai hien cho cac bien theo phffdng y De'n nffa bffdc thdi gian sau thi lam ngffdc lai, nghTa la sai phan an cac bien theo phffdng y va giai hien cho cac bie'n theo phffdng x IV MO HINH LAN TRUYEN DAU Phu'dng trinh mo phdng quy luat lan truy§n diu: dC dC dC , d'c , d'c ^, Q — + u — + v— = k^—- + k^,—y + F[+^ dl dx dy ' dx' - dy' ' ' , (4) V • • ' " - ''-''-' Trong dd : u,v : phan van td'c theo true x, tine y [m/s] C : ham lffdng dau [kg/m" ]; Kx,Ky; he so khuyech tan rd'i ngang [m^/s] F c : cac phin tham gia lam thay ddi ndng chat nhff bdc hdi, lang dgng, phan huy Q : ngudn thai [kg/s]; V : the tich dau [m''] Didu kien ban dau:, C(x,y,0)=C„(x,y) Dieu kien bien: Dieu kien bien cho phffdng trinh (4) rang buoc nhff sau: a) Tren cac diem bien ran: — =0 d n ' • • ••••• • • " ' : • • • • ' " ' • • ' • b) Tren cac diem bien Idng: • C=Cs(t) nffdc chay vao mien tinh, t>0, Cs la nong dau ldp mat tren bien long • ^— = nffdc chay khdi mien tinh ,t>0, dn 21 Xem xet ve'phai Fe cua phffdng trinh (4) Ggi Q la tdng the tich dau tran Q dffdc tach lam N phan tff the tich Q,, thff tif tran vung tinh khoang thdi gian T Ngoai qua trinh tai va tan xa, sdphan cua mdi phan tff dau cdn phu thugc vao cac qua trinh nhff: cdng suat tran dau tff ngudn ra, sff loang dau, sff bdc hdi, sff nhu tffdng, sff phan sinh -hoa, sff lang dgng, sff tffdng tac vdi bd sdng Fc la dai lffdng dffdc hinh tac dgng ddng thdi cua cac qua trinh dd mot ddn vi thdi gian Qua trinh loang dau vd cung phffc tap Nhieu hieu ffng vat ly, hoa hgc va cd hgc dffdc tham so hoa qua cac cdng thffc thffc nghiem Hau bet cac qua trinh tffdng tac giffa cac hat dau vdi mdi trQdng deu din de'n sQ suy giam ham iQdng dau nQdc sau nd tran , trff qua trinh nhu tffdng diu Tuy nhien viec xae dinh chinh xae sff suy giam la mot van d6 rat khd Dieu cdn cd nghia la, bd qua cac tffdng tac nay, ke't qua dif bao theo md hinh tren se cho chQng ta bffc tranh lan truyen dau xa'u nha't Dd'i vdi bai toan ve quan ly mdi trffdng, day la mot kich ban dt/ bao rat can thie't vi ehung ta can mot he so an toan cao cho van de bao ve mdi trffdng ., Ta tie'p tuc sff dung sd tinh d phin tinh ddng chay vdi each bd' tri u,v, e nhff cO va nong C dffdc dat trung vdi cac nut chan (i,j) Sff dung sd an luan hffdng de' giai Cd soT diJ lieu nhap De thffc hien mot dt/ bao sff lan truyen dau , md binh ddi hdi ngffdi dung nhap cac dff lieu ve dau tran va dieu kien mdi trQdng dau tran va cac dQ bao sau dd Dd'i vdi mdi diem dau tran, cin nhap vao cac so lieu nhQ sau: - Vi tri xay sff cd tran dau; - Thdi gian keo theo sff cd tran dau; - Thdi diem bat diu tran; - So lffdng dau tran sdng; - Ty trgng dau gd'c; - Do nhdt dau gd'c; 22 ,, - Nhiet sdi dau gd'c; ' - Ty so'phan tff lffdng phin diu bdc hdi va khdng bd'c hdi; - Sffc eang mat ngoai dau gd'c; - Ty le phan bdc hdi cffc dai; - Chu ky ban phan buy sinh-hoa; ; - Dia hinh vung nghien cffu; - Kich thffdc mang Iffdi phii nut; - Cd sd dff lieu ve trieu; gid Va mot sdcac thdng so khac, vi dir: he sdphan tan, he so'nham, V LfNG DUNG MO HINH CHO KHU VUCVEN BIEN BINH THUAN : Md binh tinh dffdc ap dung cho vung ven bien khu vffc VTnh Tan, ndi dff kie'n xay dffng nha may nhiet dien (hinh 1) Cac dac diem tu'dng thuy van vimg VTnh Tan Vi tri chffa cd day du cac dff lieu Hai dffdng hoc Dac i trffng thuy trieu khu vffc nha i T' r •- may bi anh hffdng trffc tie'p bdi nhffng ddt thuy trieu d khu vffc - '} ( \'^; i Tai day cd nhffng ddt ban nhat ' , trieu va nhffng nhat trieu vdi ^ nhffng ddt sdng Idn nhat len < f ^ JIT ""eii01BmiNMTA.-H, den khoang 2.00m Nhat trieu ^iflf^io xay khoang 18-20 mdi thang, nd xay thffdng xuyen (TUY PHOfiri hdn ban nhat trieu Mffc nffdc k , trieu cao nhat tif 1,5-2 m va thap nhat la 0,5 m ' Hinh Vj tri vimg tinh 23 Mffc nffdc trieu cao nhat dffdc xae dinh dffa vao nhffng phan tich tff tram quan trac thuy van Binh Thuan - Ninh Thuan va nhffng dff heu thffc te cua tram dao Phu Quy, Nha Trang va Ba Ria- Vung Tau va theo dd mffc thuy trieu dffdc dffa dffdi day: Mffc nffdc trieu cao nhat: + 1.05m Mffc nffdc trieu thap nha't: -1.40in Mffc nffdc trieu trung binh(P=50%):+0.10m Khu vffc cung thQdng hay gap nhQng cdn Id'c xoay va nhffng ap thap nhiet ddi Dffdi tac dgng cua nhffng cdn gid va nhffng cdn sdng dang len bien gay nhffng cdn bao Sdng cung cd the lam cho vd de, gay lu kit va mang de'n nhffng thiet hai cho dan dia phffdng Lffdi tinh va cac thong so'dau vao Lffdi tinh dffdc chia 652 d theo phffdng x, va 395 theo phffdng y Bffdc tinh theo khdng gian Ar = ls.y = 30m Gid Ddng Bac va Tay Nam la trudng gid chinh duge dua vao md hinh tinh He so phan buy dffdc lay bang 0.5 10 "^ /giay, he so rd'i ngang dffdc lay bang 10m"^/giay Gia sff cd tau chd dau xay st.f cd'va bi chay lffdng dau DO la 500 tan Lffdng dau chay vdng gid Chung ta se xem xet qua trinh lan truyen dau xay nhff the nao Dia hinh vung tinh dffdc trinh bay nhff hinh Day la dia hinh da dff kie'n nao vet de dan tau chd than vao *i 910000 912000 914000 916000 918000 920000 922000 924000 926000 928000 ITinh Ban dd dia hinh khu vffc tinh loan (khi da cd cdng trinh eang) 24 Hinh 3: Ban dd 3D dia hinh day khu vffc nghien cffu nao vet va cd eang, nhin Iff phia Nam le Ke't qua va nhan xet: ' a Trong triCbng hcfp gio miia Dong Bac: Do bai bao bi gidi 12=6000 -H ban ehung tdi khdng di ,^54000 sau phan tich che' 1252000 ddng chay d clay ma tap trung di sau vao qua ^^^°°°° ,- ,' - trinh lan truyen chat d 1248000 nhiem cd sff cd 124600( Tren hinh 5, 6, 7, 8, 9, 10 lan Iffdt bieu dien vet loang dau (ndng do, g/lil) theo thdi V= 135 (m/s) Hinh Phan bd ddng chay sau 12 gid tinh, gid Ddng Bac gian • San xay siCcol2 gi&: ndng ldn nha't dat 0.5 g/1 Ban kinh d nhiem de'n ndng 0.1 g/1 khoang 500ni Dffdi anh hffdng ciia gid mua Ddng Bac nen ddng chay se chay theo hQdng lech vdi hQdng Tay Nam ve ben phai khoang 15-25 do, keo theo vet dau cQng cd hQdng lan truyen la hQdng Tay Nam (Hinh 6,7,8) 25 • Sau xdy siico24gi&: ndng d nhidm ldn nhat cdn 0.2 g/1, luc ban kinh d nhilm de'n ndng 0.05 g/1 khoang 1000m HQdng lan truyen da chuyen hQdng Nam • Sau xdy sii co 36 giif: ndng ldn nhai dat 0.12 g/1 VQng d nhidm de'n mffc 0.02 g/1 kha ldn HQdng lan truyen chuyen sang hQdng Tay - Tay Nam • Sau xdy sii co 48 gib: nong d nhiem cite dai cdn 0.09 g/1 Tam d nhiim dich chuye'n mot it sang phia Tay Vung bi d nhiem tie'p luc md rgng Ban kinh vQng d nhidni len de'n 2kin Vet dau bat dau keo dai Iheo hQdng Tay Nam • Sau xdy sit co60 gib: ndng ldn nhat cdn 0.07 g/1 Tam d nhiem dich chuyen kha chain theo hQdng Tay Nam, each vi Iri ban diu khoang 1km • Sau xdy sii co 72 gib: ndng d nhiem la 0.06 g/1 Vung d nhiem tie'p luc md rgng ve phia Tay Nam 0' 9)0000 912000 9].100O 9)6000 9)S00O 920000 922000 924000 926(ND0 910000 9)2000 9)4000 9)6000 9)6000 920000 922000 924000 926000 928000 Hinh 5: Phan bd ndng vet dau loang (g/1) sau 12h xay sQ cd Hinh 6: Phan bd ndng vet diu loang (g/1) sau 24h xay sQ cd g o 06 03 ™0 02 0' 910000 912OO0 91-1000 916000 918000 920000 922000 924000 926000 928000 n Hinh 7: Phan bdndng ve'l dau loang (g/1) sau 36h xay sff cd 26 910000 912000 91-1000 916000 918000 920000 922000 92^000 926000 926000 Hinh 8: Phan bdndng ve't dau loang (g/1) sau 48h xay sff cd Nhff vay, trffdng bdp cd gid mua Ddng Bac, vet diu se lan truyen theo hffdng Tay Nam Vung eang vi cd xay ke chd'ng sdng va vi ke d phia Bac nhd hcfn so vdi ke d phia Nam cho nen vet diu se Irffdl ngdai vung eang, khdng anh hffdng nhieu de'n cha't lffdng nffdc khu vffc eang Tuy nhien sau 72 gid, dffdng kinh vet dau loang tffdng dd'i ldn, rgng hdn 5km, do can cd phffdng an ffng phd kip thdi de' giam thiei hai cho mdi trffdng 910000 912000 91-1000 916000 91 920000 922000 92-1000 926000 928000 910000 ETinh 9: Phan bd nong vet dau loang (g/1) sau 6()h xay sff cd' 912000 914000 916000 918000 920000 922000 924000 926000 928000 HTinh 10: Phan bd ndng ve't dau loang (g/1) sau 72h xay sff cd' b Trong trii'bng h(fp gid ntiia Tdy Nam: Tff binh 12 -17 la ndng vet loang dau theo thdi gian theo Ihu' Iff tff sau 12 gid de'n 72 gid • Sau xay sff co '^''°°° ^, 12 gid, ndng d nhiem ldn 1254000 nhat dat 0.5 g/1 Vet dau da 1252000 lan kha xa theo hffdng Ddng vdi khoang each 2km -; '''°°°° • Sau 24 gicf, ndng ^248ooo r'•: