296 '^P <lM"g to hgp cac phuong phap dja chSt - dja chat thuy van - dja vat ly de ...
A P DUNG TO HOfP CAC PHUTONG P H A P DIA C H A T - DIA C H A T THUY V A N - DIA VAT LY DE TIM KIEM NlTdC N G A M 6 NHtTNG
VUNG CO DIEU KIEN DIA C H A T THUY V A N P H L T C TAP
Nguyin Xuan Due, Pham Khanh Hdi, Nguyin Dinh Mudi Vien Ddu Khi Pham Khanh Huy Trudng Dgi hpc Md - Dja chdt
TOM T A T
Td hgp cdc phuang phdp dia chdt - dia chdt thuy vdn - dia vdt ly (DC - DCTV - DVL) md Vien Ddu Khi dp dung di tim kiim nude ngdm a nhirng viing cd diiu kien DCTV phirc tgp vd cue ky phuc tgp da dgt dirac mpt sd kit qud khd quan ddp ung duac nhu cdu
nuac sinh hogt cho cdc dan vi trong Ngdnh (Dung qudt. Qudng Ngdi) vd cdc dia phuang phuc vu ddi sdng ddn sinh (Nguyen Binh, Hd Qudng, tinh Cao Bang). Trong to hgp cdc phucmg phdp ki trin, phuang phdp do sdu phdn cue kich thich (DSPCKT) chiim vai trd
chii dgo. Sau khi do vd xir ly sd lieu DVL theo cdng nghi mdi cd thi dua ra dugc mpt mat cdt Id khoan bao gdm 3 tham sd chinh ciia tdng chua nude Id: vi tri tdng chua H (m), luu lugng tdng chua Q (l/s) vd dp tdng khodng hod M (l/g).
Kit qud tim kiim. thdm dd nude ngdm tgi nhirng viing Vien Ddu Khi da tiin hdnh cho thdy hieu qud cao ciia td hgp phuong phdp ndy.
DAT V A N D E
Thyc tl hien nay d rit nhilu vung va dia ban dan cu, do dieu kien dia hinh, dia mao va khi hau dac thu nen rit khan hiim ngudn nude sinh boat va san xuat. Tuy da cd mgt so don vi chuyen nganh td chuc tim kilm tham dd ngudn nude ngam nhung hieu qua khdng phai luc nao cung dat dugc nhu mong mudn.
Xuit phat tu nhu ciu ndi tai chu ddng tim kiem, tham dd nude ngam phye vu nhu cau san xuat va ddi sdng cho cac don vi trong Nganh Dau khi d cac dia ban khae nhau.
Vien Dau Khi dugc giao nhiem vy su dyng nhan vat lye va thiet bi bien cd de trien khai cdng tac TK - TD nude ngam tai cac dia ban cd dieu kien DCTV khae nhau, trong dd co nhung vung cd dilu kien DCTV rit phue tap (diln hinh la dia ban Dung Quat, Quang Ngai).
Tu ket qua ung dyng td hgp cac phuang phap dia chat - dia chat thuy van - dia vat ly de tim kiem tham dd nude ngim d nhung vung da thyc hien thanh cdng, Vien Dau Khi da due rut, hoan thien duge ve ndi dung co ban cua be phuang phap ke tren.
Ndi dung bao cao nay bao gdm 3 phan chinh:
- Td hgp he phuang phap ap dyng - Ket qua thye te
- Ket luan
Tuygn tap bao eao Hdi nghj KHCN "30 nam D§u khi Viet Nam: Co hdi mdi, thach thde mdi" 297
TO HOfP PHU^ONG P H A P A P DUNG 1. Nguyen tac lua chon
Nhu tren da ndi, nhung khu vyc va dia ban ma Vien Diu Khi da tiln hanh dilu tra nude ngam deu la cac khu vyc cd dieu kien dia chat thuy van phuc tap din cyc ky phuc tap, khd khan (Dung Quat - Quang Ngai, Minh Tam - Cao Bing, v.v...). Kit qua dilu tra CO ban (ban dd DCTV ty le 1/50.000) cua cac don vi chuyen nganh da xac dinh la nhung khu vyc khdng cd tiem nang nude ngam, tham chi nhu d Cao Bing cac don vi tim kilm nude ngam chuyen nganh da tien hanh thi cdng tim kilm md nhd cung cd kit qua rit ban che. Chinh vi vay, de tim ra ngudn nude ngam du de phye vy cho nhu ciu khai thac vdi luu lugng trung binh cho mdi Id khoan khoang lOOm^/ngay dem thi phuong phap ky thuat va khdi lugng cdng viec de ra phai chgn sao cho hgp ly theo nguyen tic tilt kiem, c6 trgng diem va phai tien hanh tung bude.
Tren co sd tiem lye cdng nghe va kinh nghiem tim kiem nude ngam hien cd, Vien Dau Khi xac dinh lay cac phuang phap do DVL (trong dd phuang phap do sau phan cue kich thich la chu dao) la phuang phap tim kiem chinh tren co sd khao sat DC - DVL, khoan tim kiem va cac dang cdng tac khae.
TRINH Tir TIEN H A N H
1. Thu thap tai lieu
Myc dich cua bude nay nham xac dinh dugc khdi lugng cdng tac dieu tra tiep theo.
2. Khao sat tdng hop DC - DCTV - DVL de chon vi tri bd tri tuyen do DVL
Tren co sd phan tich dae diem cau true binh thai - dia mao - tan kien tao vung nghien cuu, can xac dinh dugc:
- Dy kien so bd chieu day ldp phu hoae tram tich bd rdi. Chieu sau gap da gde.
- Dy kien so bd phuang phat trien chu dao cua cau true tang da gdc.
- Dy kien dugc tinh lien tuc, chieu sau, the nam va sy phan bd cua cac tang chua va each nude.
- Cac yeu td anh hudng den qua trinh thu va thai nude.
- Dy kien cac thdng sd DCTV can tinh toan cung nhu tinh chat vat ly, thanh phan hoa hgc cua nude ngam.
Cdng tac khao sat tdng hgp khdng nhat thiet phai tien hanh ehi tiet nhu cdng tac lap ban dd DCTV ty le ldn ma chi tap trung vao eae dae trung cy the de bd tri tuyen do DVL chi tiet.
Tren co sd khao sat tdng hgp se dua ra so dd bd tri tuyin do, dilm do DVL theo cac phuong phap khae nhau.
3. Do va xu- ly sd lieu dja vat ly
Cdng nghe do va xu ly sd lieu DVL dl tim kilm nude ngim chu ylu dya vao 3 phuong phap:
298 Ap dung td hgp cac phuong phap dja chat - dja chit thiiy van - dja vat ly dg ...
- Phuong phap tu
- Phuong phap mat eat ddi xung
- Phuang phap do sau phan cyc kich thich (PCKT)
Trong dd phuong phap do sau PCKT la phuong phap chu dao. Sau khi do va su dung ky nang xu ly cac sd lieu chung tdi cd the khang dinh tai vi tri dd cd bay khdng c6 ting chua nude ngam va se dua ra mdt mat cat DC - DCTV Id khoan theo tai lieu DVL vdi 3 tham sd chinh la: vi tri tang chua nude H(m), luu lugng nude Q(l/s) va do tdng khoang hoa M(g/1)
a. Phuang phdp tir
Phuang phap tu AT ed tinh dinh hudng ban dau. Tren mdi ddi cau true da dugc xac dinh se bd tri cac tuyen do tu AT. Sd lugng tuyen do phy thude vao dien phan bd ciia cau true dy kien. Bude dich chuyen d = 5m. Buc tranh trudng tu AT trong mdi vung thudng rat khae nhau. Neu phat hien ed ddi cac di thudng tu AT vdi dac trung dieh dae, nhay bae va nhat la cae di thudng am tuong ddi thi day chinh la cac dau hieu cho thay sy cd mat cua cae tiep xuc kien tao, ddi dap vd va cae dut gay.
b. Phuang phdp mat cdt ddi xung dan (MCDXD)
Phuang phap nay dugc do tren co sd ket qua cua phuang phap tu AT. Cac tuyen do tap trung vao vung da cd di thudng tu AT cd dac trung dich dac va gia tri am tuong ddi.
Cach do nhu sau: Qua hai dien cue phat AB phdng ddng dien cd cudng do I xuong dat, qua hai dien cyc thu MN thu dugc the AV. Gia tri dien trd suat bieu kien (p^) dugc tinh theo cdng thue:
P.. = ' ^ x — (1) (k: He sd thilt bj)
Dieu luu y la can dac biet tap trung vao cac ddi cd gia tri di thudng dien trd suat (DTS) thip nam trung vdi cac di thudng AT. Thyc tl cho thiy tai cae dilm do DVL da khoan cho ket qua tdt deu cd gia tri tai AT am trung vdi cac dilm cd gia tri DTS thip cua phuong phap MCDXD.
Cae vi tri nay se dugc bd tri do sau phan cyc kich thich (PCKT) la phuang phap Igc cudi cung de ehi ra vi tri nao tdn tai ting chua nude, vi tri nao ehi la ddi dap vd, dut gay khdng chua nude.
c. Phuang phdp do saupltan cue liich thich (DSPCKT)
Phuang phap do sau phan cyc kich thich (DSPCKT) dugc coi la phuang phap chii dao gdm cd 4 dien cue AMNB. Qua hai dien eye phat AB phdng ddng dien cd cudng do 1 xuong dat. Qua hai dien eye thu MN thu dugc thi AVQ va cung tinh ra dugc gia tri DTS bieu kien nhu d (1). Tuy nhien, sau khi ngit ddng, the cdn du van cdn tdn tai trong mdt khoang thdi gian nhit dinh, ta thu dugc cac tbI phan cyc d cae thdi diem khae nhau AV,, AV2, AV3, v.v... Tu dd cd thi tinh ra cac dai lugng do phan cyc:
Tuygn tap bao cao Hdi nghj KHCN "30 nam Dau khi Viet Nam: Co hgi mdi, thach thuc mdi' 299
Av^
AVr, ; Hi
Av,
A V r ; n, Av Av„ ^ (%) (2)
trong dd: r||, r|2, ... r],: Do phan cyc tai thdi diem thu 1, thu 2. ... thu i
Nhu vay, do sau PCKT cd 2 tham sd co ban la p^ va r|i^. Ben canh dd, do sau PCKT cdn cd khoang 20 tham sd nhu G (do set), S, (thdi gian the phan cyc suy giam xudng cdn mdt nua), Zf (dai lugng dac trung cho do phan cyc va thdi gian suy giam), Z (do suy giam the phan cyc), v.v... Cac dai lugng nay dugc dung de phan tich dinh tinh, dinh lugng tu\' theo myc dich cu the. Viec phan tich djnh tinh cac dudng cong do sau PCKT trong viec tim kiem nude ngam chu yeu tap trung vao 4 tham sd chinh la St, Zr, G va Z.
S, (cd thu nguyen thdi gian) la thdi diem the PCKT giam xudng cdn mdt nua so vdi the sau khi ngat ddng. St cd the tinh toan bang bieu dd hoae dge tryc tiep tren may. Nhu vay, sau khi do sau, ngoai dudng eong p^ va rl^^ ta edn cd dudng cong St. Chi vi tri nao dudng cong St cd gia tri cyc tieu, tuc la cd dau hieu cua tang ehua nude mdi dugc quan tam.
De khang dinh vi tri eo tdn tai tang chua nude, cd ngudn cap can phai tinh Z, cung CO cyc tieu tai vi tri cyc tieu cua St.
Zf = 0,75. St. t l , (3)
Trong dd: r|i: la do phan cyc tai thdi diem dau tien.
Phan tich dinh lugng dudng cong do sau PCKT duge tien hanh tren may dien toan.
4. Phan tich djnh liroTig dudng cong do sau PCKT a. Xdc djnh dp set G
G la ty le phin tram ham lugng hat cd kich thudc < 0,05mm tdn tai trong mdt ldp dia dien nao dd. Vdi vung da gdc, G duge tinh theo cdng thuc thyc nghiem nhu sau:
Ln G = - 21,95 - 0,03 - 14,1A - 0,024A* + 1,58A^ + 0,791np +
53,Iln(A+1,93)+ 0,691n(A* +1,85) (4) trong do: p: dien trd suat ldp dia dien
A = Til - ri2 (do phan cyc tuong ddi): Hieu sd do phan cyc tai hai thdi diem nhit dinh va duge lya chgn tuy theo tac gia. Tai Dung Quat dd la thdi diem
180ms va 320ms.
A* = A/p(; (do phan cyc tdng hgp)
Nhu vay, vdi bit ky mdt ldp dia dien nao cung tinh ra dugc G. Qua thyc nghiem cd the dung G de xac dinh tang chua nude theo Bang 1 dudi day:
Bang 1 Dp set a (%)
0,5-3 3 - 8 10-20 30-70
>70
Ddi tugng Ddi dap vd khong chua nude Ddi dap vd, cat, cuoi, soi chua nude Bun nhao
Set. phien set Da goc dn dinh
300 Ap dung td hgp cac phuong phap dja chat - dja chat thiiy van - dja vat ly de
b. Du bdo dp tdng khodng hod cua nude duai ddt
Do tdng khoang hoa (M) cua nude dudi dat dugc tinh theo cdng thuc thyc nghiem nhu sau:
Ln(M + 0,7) = 4 + 0,5p - 0,55A* + 0,02p^ + 0,03A*^ + 0,0004G^ - 0,91np + 0,31 InA (5) c. Du bdo luu lugng nude qua Id khoan (Q) trong tdng chira nuac
Viec tinh Q theo thu nguyen lit/giay (l/s) dugc thyc hien theo cdng thuc thyc nghiem nhu sau:
Ln(Q + 1,75) = aH + bln(Z + 0,17) (6) trong dd: H: Chieu day tang ehua nude
a,b: Cac he so dae trung cho thanh phin thach hgc cua tang chua nude
C> tren Z dugc dua ra nhu mdt dai lugng ed dinh nhung thyc te viec xac dinh Z cho mdt tang chua nude la ket qua cua viec giai bai toan ma tran sd vdi cac dieu kien bien chat che nhim tinh tdi cac dilu kien DCTV nhu he sd tham, he sd nha nude, do rdng, v.v...
Lim lugng Q toan vung dugc tam tinh tren co sd sd lieu Q cua tung vi tri do sau PCKT.
d Thiit bi
Hien Vien Diu Khi su dyng may do dia vat ly SYSCAL-R2 cua Phap la bd may chuyen dyng cua Phap de tim kiem nude ngam.
KET QuA A P D U N G
1. Tai Quang Ngai
Ket qua ap dyng dau tien cua td hgp phuang phap neu tren eua Vien Dau Khi la d Dung Quat, Quang Ngai. Khu vyc nay chu yeu bao gdm dien phan bd cua da phun trao bazan, da granit ran chac khdng dap vd. Theo tai lieu dieu tra co ban cua Lien doan DCTV-DCCT mien Trung cho thay tiem nang nude ngam rat ban che. De chu ddng ngudn nude cho san xuat va sinh boat cho nha may lge dau Dung Quat ndi rieng va nhan dan trong vung ndi chung, Tdng cdng ty Dau khi Viet Nam da bude dau dau tu tim kiem nude ngam tai chd bang cdng nghe va thiet bi hien cd. Trong sd 3 Id khoan da thi cdng theo tai lieu do va xu ly theo td hgp phuang phap ap dung ke tren thi cd 2 Id khoan dat ket qua tot (Bang 2):
Bang 2: So sanh tai lieu DVL va tai lieu khoan bom DCTV tai Quang Ngai Diem do
PCKT
D63, cgc 69, tuyen 7 D93.cgcl5,t52
Chieu ddy Q (m) theo DVL/theo
khoan
2,0m/1,2m 2,5 m/2,0 m
Ddi dap va ddy (m) theo DVL/theo khoan
27-75m/16-35m 10-65/22,6-67 m
Liru lugng nude (m /ng.d) theo
DVL/Khoan
2-3 /3,09 3,36/3,28 l/s
Tdng khodng (g/l) theo DVL/theo
khoan 0,64-0,81/0,09-
0,35 0,70/0,107g/l
Tuygn tap bao cao Hgi nghj KHCN "30 nam D^u khi Viet Nam: Cff hdi mdi, thach thde mdi" 301
Rieng lo khoan 3-VDK (Dung Quit) do do va xu ly theo PCKT tren da granit khdng nut ne thieu thdng sd dau vao nen chu yeu dya theo tai lieu do tu mat dat va cung cho kit qua rat tdt vdi cac thdng sd co ban sau: luu lugng Q = 2,241/s; tdng khoang hoa M = 0.36g/l.
Ca 3 Id khoan tai khu vyc dieu tra deu ed chat lugng nude rit tdt, dat va vugt tieu chuin cho phep theo TCVN. Rieng Id khoan sd 2 (LK VDKII) theo so sanh nude dat tieu chuan nude khoang thien nhien ddng chai, Vien Diu Khi da cd dl an thim dinh ty my trinh Tdng edng ty Diu khi Viet Nam cho phep tiln hanh Dy an khai thae va kinh doanh nude khoang thien nhien ddng chai lay ngudn nude tai Id khoan nay.
2. Tai Cao Bang
Cung nhu cac vung khae, dai lugng duge chu y diu tien la do set G.
Tai diem 99B, tuyen 8B cd 3 ldp dia dien dygc chu y dd la: ldp nim tren cung cd G = 8%, tiep den la 2 ldp cd G = 4,3% va 5,2%. Ldp diu tien gin vdi ldp phu De tu, ldp thu 2 va thu 3 gan vdi da vdi dap vd. Ca 2 ldp ghep chung thanh mdt ldp cd G = 4,8%).
Gia tri G tuang ddi thap ed nghia do rdng P ldn va it nhieu co anh budng tdi muc do phong phu nude cua tang chua nude.
Tai diem 8, tuyen 17 tu tren xudng dudi cd lien tiep 3 ldp cung cd gia tri G = 7,1%.
Chung tdi xep chung vao mdt ldp da vdi dap vd chua nude. Mac du each dilm 99B, tuyin 8B khoang 300m, nhung dya vao cac dac trung DVL chung tdi khing djnh d day ldp phu khdng dang ke.
Tai diem 25, tuyen 15 tu tren xudng dudi cd 3 ldp cd gia tri G tuong ung la 8%, 7,5% va 7,9%. Ldp tren cung duge gan vao ldp phu De tu theo cac dac trung DVL: hai ldp cdn lai dugc gan vdi da vdi dap vd chua nude vdi gia tri G = 7,7%. Mdt dieu de nhan thay la gia tri G kha ldn dan tdi do rdng P nhd va dieu nay anh hudng tdi muc do chua nu- dc cua ddi dap vd nay (Hinh 1, 2, 3).
Cdng nghe DVL neu tren chung tdi da ap dyng cd hieu qua d nhieu noi. Dieu can luu y la chung tdi da dung tdi 7 tham sd de xac dinh vi tri tang chua nude, trong do dang luu y nhat la do set G. Chi noi nao cd do set G dao ddng trong khoang 3 - 8% mdi dugc coi la tang cd kha nang chua nude. Vdi gia tri nay cd the phan biet ty my ddi da goc, bun, bun nhao va nhat la ddi dap vd khdng chua nude
Bang 3: So sanh tai lieu DVL va tai lieu khoan bom DCTV tai Cao Bang (xa Minh Tam - Cao Bang)
Diem do sau 99B T8B
8T17 25T15
Ldp phu (m) DVL
10 Rat mong
8
Khoan 9
1,2 8,7
Doi dap vd chtra nirdc (m) DVL
80 78,8 81,3
Khoan 85 80 80
Liru liro-ng (I/s) DVL
3-6 3-6 2-3
Bam 1.83*
2,0'
i,r
Do tong khoang hoa (g/l)
DVL 0.2 0,2 0,2
Phdn lich hod 0,25 0,25 0,25 Ghi chii: *: Sd lieu bom trong giai doan kilm chung vdi dudng kinh dng 91mm
302 Ap dung td hgp cac phuong phap dja chat - dja chat thiiy van - dja vat ly de
5(10 400
300 200
50 40 30
G= 4,3%
G=8,0% G= S.2% G= 70%
II ; o 3 0 411 5(1 10(1 2 0 0 3110 4110 5 0 0 1 0 0 0
Hinh 1: Bieu d6 tinh do set G tai diem do sau 99B tuyen SB
500 400
300 200
50 40 30
G= 7,1%
G=7,1%G=7,1% G= 75%
A /f /h
4 5 10 20 30 40 50 100 200 300 400 500 1000
Hinh 2: Bilu do tinh d6 set G tai diem do sau 8 tuyen 17
Tuygn tap bao cao Hgi nghj KHCN "30 nam D^u khi Vift Nam: Cff hdi mdi, thach thde mdi' 303
500 400
300 200
30 20
- -t- 4- -
-X G= 8,0% G= 7,5%G= 7,9% G=71%
0 30 40 5(1 100 200 300 400 500 1000
Hinh 3: Bieu do tinh do set G tai diem do sau 25 tuyen 15
KET L U A N
1. Viec ap dyng td hgp cdng nghe dja chat - dia chat thuy van - dia vat ly de tim kiem nude ngam d vung trung du va mien nui la nhung vung cd dieu kien DCTV phuc tap cua Vien Dau Khi da dat dugc nhimg kit qua kha quan. Hien Vien Diu Khi da hoan thien cong nghe nay va giu bi quyet cdng nghe.
2. Viec do ve va phan tich, tdng hgp tai lieu la mdt qua trinh cd lien quan chat che vdi nhau nham cung cap tai lieu cho ngudi su dyng dugc thuan lgi nhat, dd la dua ra dugc cdt dja tang DC - DCTV Id khoan dy kiln theo tai lieu DVL vdi 3 tham sd chinh la: vi tri tang chua nude, luu lugng va do tdng khoang boa.
3. Ve chieu sau khao sat: Trong thdi diem hien nay, cac Id khoan tim kiem nude ngam deu tap trung d chieu sau 80 - 150m hoae ndng hon. D I dap ung yeu cau thyc tien Vien Dau Khi dang tiep tyc nghien cuu de tang them chieu sau khao sat, dac biet la trong khoang chieu sau 500 - 1000m. Trong chuang trinh tim kiem nude ngam cac bdn chua dia nhiet d chieu sau ldn cdng nghe mdi se duge chu y d hai mang: may mdc DVL va phan mem chuyen dyng. Sap tdi, Vien Dau Khi se dau tu mua may cua hang IRIS cd do phan giai cao (IpV), cdng suat ldn nhung ggn nhe. Ve phan mem chuyen dyng se hoan thien theo hudng thuang pham.
4. Vien Dau Khi san sang dua cdng nghe nay phye vu cho nhu cau tim kiem nude ngam va bdn chua dia nhiet cho cae don vi trong va ngoai Nganh.
