52 Than dau trong da mdng niii ne - hang hoc mo Bach H5, Dong Nam Rdng va giai phap bcmu
THAN DAU TRONG DA M O N G NUT NE - HANG HOC
M O BACH HO, DONG N A M RONG VA GIAI PHAP B O M EP NUOC N H A M NANG CAO HE SO THU HOI DAU
Tran Le Ddng, Hoang Van Quy. Truang Cdng Tai XNLD Vietsovpetro
TOM TAT
Thdn ddu trong dd mong nut ne - hang hoc mo Bgch Ho, Dong Nam Rong la nhirng thdn ddu ddc biet hiem co tren the gi&i, ddc trung b&i tinh bdt dong nhdt rdt cao, ddc biet ve ddc trung thuy dong lire. Chinh vi vdy, viec dp dung gidi phdp bam ep nu&c nhdm muc dich ndng cao he so thu hoi ddu, doi hoi phdi dirac to chirc het sire phii hop vd khoa hoc.
Trong bdo cdo de cap den ca s& ly thuyet, thuc trgng vd kit qua dp dung gidi phdp tren.
LOI NOI D A U
Mdl trong nhiing dac diem quan trgng nhat ciia bdn trung Cim Eong la tdn tai mdt co che hinh thanh cac than dau Irong da mdng nirt ne - hang hde. Co che nay, theo sd lieu hien tai, khd cd the lim thay d cac be tram tich khae nhu be tram lich Nam Cdn Son, Phii Khanh va Sdng Hdng. Dudi tac ddng ciia lire ldng hgp trong khdi mdng nang md Bach Hd va Ddng Nam Rdng da hinh thanh nhting he thdng pha buy cat cheo nhau, phan bd khdng deu, dac tnmg bdi he thdng nirt ne ldn, vi nut ne va hang hde chang chit. Chinh do cau tnic khdng gian Id hdng nhu vay da khien khdi mdng nang dac trung bdi tinh bat ddng nhat rat cao, dac biet la tinh bat ddng nhat thuy ddng lire hgc. Day la mdt trong nhiing diem dac biet quan trgng. ddi hdi phai thiet lap he thdng bom ep nude rieng biet ddi vdi than dau trong khdi mdng nang md Bach Hd. Ddng Nam Rdng nham duy lri ap suat via va nang cao he sd thu hdi dau.
I. Tinh bat dong nhat thuy dong luc
Tren co sd nghien ciru lai lieu khao sat FMS, FMI d mdt loat giing khoan vao mdng trirdc Kainozoi md Bach Hd nhan thay trong khdi mdng nang tdn tai nhung he thong pha buy cat cheo nhau mdt gdc, chii yeu, tir 40'' den 120", phan bd khdng diu. Vdi do day ttr vai met den 50m. Theo dudng cong tich luy, do day cua cac ddi pha huy tdi 12m cbilm 80%. ldi 20m chiem 90%o. Cd nghia la cac ddi pha buy cd do diiy tren 20m chiim ly le khdng cao. Toan bd he thdng pha buy cat cheo nhau, dac trung bdi he thdng nirt ne Idn, he thdng vi niit ne va he thdng hang hde tao thanh he thdng da chira trong khdi mdng nang.
a. He thong mil ne l&n
Dugc hinh thanh chii yeu bdi cac boat ddng kien lao. bao gdm hai he thdng cac mat nirt ne djnh hudng cat cheo nhau, dac trung bdi kha nang tham thuy ddng lire. Cac ddi nirt ne ldn la cac ddi cho ddng ddng thdi cung la cac khoang tiep nhan nude bom cp khi xudt
Tuyin tap bao cao Hoi nghj KHCN "30 nam Ddu khi Viet Nam: Co hoi mdi, thach thiic mdi" 53
hien mire do chenh ap nhdt dinh. Do tham cua cac ddi pha buy manh, mit ne ldn dao ddng trong pham vi ldn tir vai mD den hang ngan mD.
b. Hi thdng vi nui ne
Dugc hinh thanh bdi cac boat ddng kien tao, co gian maema, v.v..., phat trien dge theo mat cac ddi nirt ne ldn hoae giiia chimg, bat dinh hudng, tao thanh mdt he thdng chira va luu thdng phiic tap. He thdng vi mil ne dac trung bdi kha nang tham mao dan.
c. Hi thdng hang hoc
Phat trien dge theo cac mat nirt ne ldn, md rdng hoae ndi thdng chung, dugc hinh thanh bdi qua trinh boat ddng thuy nhiet dien ra hang chuc trieu nam. He thdng hang bde gdp phan mdt each dang ke cho viec gia tang kha nang chira va tham thuy ddng lire .
d. Khoi dd rdn chac
La khdi da maema nguyen sinh, khdng bj pha buy, khdng cd kha nang tham, chiia chat luu.
Xuat phat tir nhirng dac diem cau tnic tren, da mdng niit ne - hang bde cd mirc bat ddng nhat kha cao ve tinh chat thuy ddng luc. Cac ddi pha huy d mirc do kbac nhau, cd kha nang luu thdng trong toan bd khdi nang. Trong qua trinh bom ep nude, gieng chi nhan theo timg khoang nhat djnh phu thudc vao su cd mat cua cac ddi pha buy manh. Dau trong he thdng vi nirt ne khdng the bj day ra neu nhu tdc do cua nuac bam ep vugt tren tdc do mao dan. Neu tdc do djch chuyen ciia nude bam ep Idn cd the mdt lugng dau kha Idn van cd the d lai trong cac hang hde, niit ne cd do tham thap ban.
2. He so thu hoi dau trong da mong niit ne - hang hoc
He sd thu hdi dau (THD) thuc chat la tich cua hai he sd day dau va he sd bao triim.
Do dac diem bat ddng nhat thuy ddng lire kha cao nen he sd day dau va he sd bao triim trong da chira nirt ne - hang hde cting cd tinh bat ddng kha ldn.
Vdi md hinh da chiia neu tren, he sd day dau (HSDD) ddi vdi timg khdi mdng dugc tinh theo cdng thirc:
Kdd = Kmakr. a makr+ Kmikr.a mikr
Trong dd Kmakr va a makr, Kmikr va CT mikr la HSDD va ty phan cua niit ne ldn (nirt ne thuy ddng luc), nut ne nhd (nirt ne mao dan) tuong ung.
Ket qua tinh toan ddi vdi khdi mdng nang md Bach Hd cho thay HSDD dao ddng tir 0,100 den 0,680 cd xu the giam dan theo chieu sau, trung binh 0,549 vdi he sd dau du 0,384. Theo bilu dd phan bd HSDD trung binh cd thi dat tdi 0,570.
Nhu vay, HSDD phu thudc kha nhieu vao ty phan cua niit ne thuy ddng lire va nirt ne mao dan. Vdi muc dich nang cao he sd thu hdi dau, qua trinh bom ep nude can phai dugc tien hanh sao cho cac nirt ne thuy ddng luc va mao dan dugc huy ddng cao nhat vao qua trinh day dau. Thuc te cho thay ngay ca khdng it nirt ne thuy ddng lire cting khdng dugc Idi cudn vao qua trinh day dau bang nude bom ep.
Ket qua thi nghiem cua tac gia Pham Anh Tudn cho thdy HSDD cdn phu thudc vao hudng day ciia nude. Tir dudi len -0,89, ngang -0,71 va tren xudng -0,67.
54 Than dau trong da mong niit ne - hang hoc md Bach Ho. Dong Nam Rong va giai phap bonUj-^
Viec tinh toan he sd quel hay he sd bao triim. dac biet ddi vdi da mdng nirt ne \ a hang hde cd mirc do bat ddng nhat cao. la mdt van de bet sire khd khan \ a phirc tap. Tren co' so nghien cim he sd quet (he sd bao triim) ddi vdi than dau trong ky Phan mudn md Mangobek - Voznhenko Aliurtovcki (Lien Xd cii) [1] cho thay neu ta bom ep vao ddi chi cd nude du. vi du 0,15, thi he sd quel (HSQ) khdng vugt qua 0.50. Va nguge lai. neu ta bom ep viio ddi ngap nude 100%. hay chi cdn ddu du 0,384 thi HSQ dat ldi tir 0.75 din 0.85.
3. Cac bien phap nang eao HSDD va HSQ trong qua trinh bom ep nuoc
Cac bien phap nang cao HSDD va HSQ thuc chat la cac giai phap dam bao mirc do dich chuyen dn dinh cho qua trinh dich chuyen mat tiep xiic dau nude. Khi qua trinh day dau bang nude khdng dugc dn dinh se xuat hien hien tugng kich ddng ranh gidi phan tach pha, rieng ddi vdi da nirt ne, tao thanh ludi nude xam nhap thang vao gieng khoan khai thac. Do dn dinh dich chuyen RGDN phu thudc vao kha nang tham ciia da chira, do chenh ap va mirc do chenh lech gitra do nhdt va mat do cua dau va nude bom ep. Mirc do khai thac va bom ep cang nhieu khien mirc chenh ap gitra cac gieng khai thac va bom ep cang ldn dan den xac suat tao ra ludi nude cang cao. Tieu chuan quan trgng quyet djnh sir djch chuyen dn djnh ciia mat RGDN la gradient thuy ddng luc csi = — ( 1 '.1—^) ludn phai nhd hon hoae bang
^ l^,dKi
gradient trgng lire csi = y„ -yj • Trong dd /SF, H - do chenh ap va do sau tir mat bom ep tdi mat thu hdi dau; K^, K,„ \x^, p,„ y^, y„- do tham, do nhdt va mat do ciia dau, nude tuong img.
De dam bao mirc do dn dinh djch chuyen mat RGDN can thiet phai ban che gradient thuy ddng lire sao cho chiing ludn nhd hon gradient trgng lire O]. Do do nhdt ciia dau via than dau trong da mdng md Bach Hd gan bang 2 lan do nhdt ciia nude bom ep nen trong trudng hgp dd tham tuong ddi —- <0,52 mat RGDN ludn dich chuyen dn dinh vdi moi mirc chenh ap K thay ddi. Rieng ddi than dau trong da mdng md Ddng Nam Rdng. nai dau via cd do nhdt tdi 1.6 -^ 2,2Cp gap 6 lan do nhdt cua nude bom ep nen dii cd dieu chinh ap suat bom xudng kha thap van khdng dam bao do dn djnh dich chuyen mat ranh gidi dau nude.
Ddi vdi ddi pha buy- cd —-= 0,75, do chenh ap an toan la do chenh ap cd gia tri nhd K K^i
uP ' ' ' • AT*
ban hoae bang 10 —^ . Mudn cho a2 nhd can thiet phai dieu chinh — hay ap suat bom hoae
^,„ H phai dieu chinh gia lang ty sd —'-^^-^ hay giam ty sd linh ddng —^^-^. Ddi vdi timg than dau
K
va cu the ban la timg khoang bom ep cu the ty sd do tham tuong ddi —- la cd dinh nen ty sd dd nhdt -^ cd y nehla dac biet quan trong, cd the mdt each chii quan dieu chinh duoc nhdm nana cao he sd da>' dau va he sd bao trtim. Ty sd — cang nhd. trong dieu kien ty sd dd thdm pha nhat djnh thi gradient thiiy ddng lire cang nhd. Ddi vdi than dau trong mdng md Bach Hd
Tuygn tap bao cao Hoi nghj KHCN "30 nam Dau khi Viet Nam: Co hoi mdi, thach thiic mdi" 55 ty sd —^ = 0.52 nhung ty sd nay chi dat khoang 0,17 ddi vdi than dau Irons mdns khu \uc Ddng Nam Rdng. Day la mdt diem dac biet quan trgng, ddi hdi phai cd nhung giai phap nhat dinh nham tang ty sd tren bang each tang do nhdt ciia nude bom ep. Mudn dat dugc hieu qua bom ep nude nhu ddi vdi than dau trong mdng md Bach Hd, do nhdt ciia nude bom ep cdn dugc nang cao it nhat gap 3 lan.
.40 J-
Hinh 1: Xac djnh cac thong so boin ep toi ban nhdm nang cao he so ddy dau bdng bom ep nuoc; A - Doi voi mong mo Bach Ho; B - Doi voi mong mo Dong Nam Rong (1 - Dai xudi hien ludi mrirc; 2 - Dai dich chuyin 6n dinh trong diiu kien chenh dp c6 djnh;
3 - Dai dam bao dich chuyen on dinh).
56 Than dau trong da mdng niii ne - hang hoc md Bach H5, Dong Nam Rong va giai phap boTt^^
Tren co sd nhtrng luan diem tren, vdi muc dich nang cao he sd thu hdi dau, chiing tdi cd the di den nhiing ket luan chinh sau day ve giai phap bam ep nude:
• Vdfi muc dich nang cao he sd bao triim cac khoang bam ep nuac chi dugc bd tri a nai da ngap nude, duai mat RGDN he sd bao trum cd the dat tai 0,85 -^ 0,90.
• Qua trinh day dau bang nuac xay ra tir duai len la qua trinh cd he sd day dau cao nhdt (0,89).
• Ddi vai tirng gieng khoan cu the trong mgt than dau cd do nhdt nhat dinh ap suat bam phai dugc dieu chinh sao cho phii hgp vai do sau bam va do tham cao nhat ciia da trong khoang tiep nhan (02 < CT]).
• Trong dieu kien khd cd the tim dugc che do bam phii hgp vai yeu cau CT2 ^ ^\
can thiet phai ap dung che do bam ep theo chu ky nham dam bao gradient thuy ddng lire cij dao dgng xung quanh gradient trgng lire CTI.
• Ddi vdi than dau trong mdng khu virc Dong Nam Rdng nai dau via cd do nhdt gap tai 6 lan do nhdt ciia nude bam ep, mudn viec bam ep cd hieu qua bugc phai cd giai phap nang cao do nhdt cua nuac bam ep, tdi thieu dat tai 0,9Cp.
4. Danh gia hieu qua ap dung giai phap bom ep niro'c doi voi than dau trong da mong niit ne - hang hoc mo Bach Ho va Dong Nam Rong
a. Mo Bgch Ho
Tir thang 6-1993 gieng 421 la gieng khoan dau tien dugc dua vao bam ep. O giai doan khai thac theo che do tu nhien, cir khai thac 1 trieu tan dau thi ap suat via giam di khoang 6,7atm. Do tac ddng tich cue cua qua trinh bam ep ap suat via dau dn dinh bat dau tir khi san lugng cdng ddn dat tdi 23 trieu tan. Cho tdi thdi diem san lugng cdng ddn dat
115 trieu tan, so vdi thdi diem 23 trieu tan, ap suat via trung binh ehi suy giam 19atm.
Nhu vay, rd rang viec born ep nude da thuc sir duy tri dugc nang lugng ciia via khien san lugng cao nhat dat ciia than dau dat tdi 12 trieu tdn/nam. Tuy nhien, qua trinh bom ep dugc dieu chinh lien tuc tir luu lugng bom, ap suat bom va do sau bom. Khdi lugng bom d do sau tren - 3850m giam ddn tir 5,04%o (1993 - 1995) din 1,72% (1996 - 2000) va 0,81% (2001 - 2005). 6 do sau 3850 - 4200m khdi lugng bom cting giam di rd ret tir 71,94%) (1993 - 1995) xudng 41,63%) (1996 - 2000) va 30,05%) (2001 - 2005). Trong khi dd khdi lugng bam ep d do sau duai 4200m dugc tang len rd ret tir 23,02% (1993 -1995) len 56,65% (1996 - 2000) va 68,68% (2001 - 2005).
Cho den het nam 2004 san lugng tich ddn dat 124 trieu tan dau vdi khdi lugng nude dugc bom la hon 157 trieu m^, he sd thu hdi la 0,277. Neu khdng bam ep nude san lugng tich ddn chi dat khoang 62 trieu tan vdi he sd thu hdi dau 0,138. So sanh con sd d hai che do tren da cho ta thay hieu qua ciia viec bom ep nude ddi vdi than dau trong mdng nirt ne va hang hde md Bach Hd.
b. Md Dong Nam Rong
Md dugc dua vao khai thac tti nam 1996, din nam 2000, sau khi thu hdi 1,3 trieu tan ddu, viec bom ep nude dugc bdt ddu. Din hit nam 2004, cd 4 gieng khoan bom ep vdi khdi
Tuyin tap bao cao Hoi nghj KHCN "30 nam Ddu khi Viet Nam: Co hoi mdi, thach thiic mdi" 5^
lugng 2500m^ du bii san lugng khai thac 1700 tan/ngay dem. Nang lugng via dang cd xu hudng dn djnh. Tuy nhien, do do nhdt ciia dau via qua ldn (1,7 ^ 2,2Cp) so vdi nude bom (0,3 ICp) nen cdn thilt phai xir ly nham gia tang do nhdt ciia nude bom ep, it nhat 3 lan.
Do do nhdt ciia dau qua ldn so vdi do nude bam ep nen xay ra hien tugng:
- Do tiep nhan kem
- He sd day dau thap khien nude cd kha nang xe dau, theo mach pha buy ldn, tiln thang vao gieng khai thac.
Tdm lai, giai phap bam ep nude la giai phap dugc ap dung kha hieu qua, dac biet ddi vdi than dau trong da mdng nirt ne va hang hoc md Bach Hd. Do dac tinh thdm chira va thuy ddng lire ciia chiing cd nhieu kbac biet so vdi da cd do rdng giiia hat nen he thdng bom ep can phai dugc xem xet va bd tri phu hgp, dac biet do nhdt ciia ddu va do thdm cua cac ddi pha buy la hai yeu td kha quan trgng quyet dinh dieu chinh che do bom ep nude cho timg gieng.
TAI LIEU THAM KHAO
1. N.P. Lebedinhes, 1997. Nghien ciru vd khai thde mo ddu trong dd chira nut ne. Moskva
"Nauka".
2. Tran Le Ddng, Hoang Van Quy, Phiing DSe Hai, 1997. Ddc diim phdn bd khong gian 16 hong vd mo hinh dd chua trong mong mo Bgch Ho. Tap chi Dau khi, Sd 2-1997.
