Tuygn tap bao cao Hdi nghj KHCN "30 nam DIU khi Viet Nam: Cff hdi mdi, thach thuc mdi" 937
KET QUA AP DUNG CAC PHU-ONG PHAP TAC
D Q N GLEN VUNG CAN DAY GIENG TAI MO BACH HO VA PHU^OHVG
H U ^ 6 N GHOAN
THlisN CONG NGHE CUA CHUNG
• •
Duong Danh Lam XNLD Vietsovpetro N224 (77)
TOM TAT
Bdo cdo neu ra kit qua nghiin ciru thi nghiim vd kit qud thu dugc ngodi thuc ti vi hodn thiin cdng nghi xir ly vung can day giing (CDG) tgi md Bgch Hd & thim luc dia Viet Nam, trong giai dogn 1991 - 2004.
Hiin nay, tgi md Bgch Hd, ddu dugc khai thde tir cdc giing thudc ddi tugng Miocen du&i, Oligocen trin, Oligocen du&i vd tdng mdng dgng khdi (da granit nirt ni). Do viing CDG bi nhiim bdn trong qud trinh khoan, hodn thiin vd sua ehda giing, nin hdu hit cdc giing khai thde & muc thdp hon tiim ndng cua chung.
Trin co s& nghiin ciru, lua chgn vd dp dung nhiiu phuong phdp khdc nhau di xu ly vung CDG trong nhdng diiu kiin dp sudt via thdp (trong mdt sd gieng, dp sudt via thdp hon dp sudt thuy tinh vd cd giing, dp sudt via thdp han dp sudt bdo hda), nhiet do via cao (^ 150 C) vd ddc biit, trong tdng mdng cd nhiiu logi khodng vdt thu sinh, cdc tdc gid chi ra nhirng cdng nghi tdng hgp xu ly viing CDG kit hgp v&i khai thdng vd ggi ddng cdc giing ngay sau khi chung dugc xu ly. Din nay, cdng nghi xir ly vung CDG ciia cdc giing thudc ddi tugng tdng mdng vd Oligocen du&i ddn dugc hodn thiin tdi uu nhdm tdng hi sd thu hdi sdn phdm & nhirng giing hiin cd vd de dgt dugc hi sd thu hdi ddu cao & md Bgch Hd.
G l 6 l THIEU CHUNG
Mo Bach Ho dugc dua vao khai thac tu nam 1986, nhung den nam 1991 moi tien hanh xii ly vung CDG nham gia tang he so san pham gieng khai thac. Tai mo Bach Ho hien dang tien hanh khai thac dau tir 3 doi tugng chu yeu: Mioeen duai, Oligocen duoi va tang mong dang khoi (da granit nut ne).
Khi nghien cuu cae dae tinh cua tung doi tugng khai thac, nhan thay rang, doi voi Miocen duoi va Oligocen duoi: do tham thau nho va trung binh (0,08D va 0,03ID tuong ling); CO nhieu tap via (3 va 10 tap tuong ung) va khong dong nhat (do eat ket ciia Miocen duoi khoang 0,34 - 0.32 va ciia Oligocen duoi -0,18); hau bet cac gieng co cot ong chong khai thac den tan day va phan via san pham dugc due 16 Ing ching; nhiet do via cao (90°C - 130°C trong via Miocen duoi va 130°C - 150°C 6 Oligocen duoi).
Tinh den 1/1/2005, & 2 ddi twgng Miocen dw&i vd Oligocen dw&i cd 65 giing khai thde (trong dd 51 giing khai thde bdng gaslift) vd 18 gieng bom ep. Tdng Iwu Iwgng dau khai thde trung binh dat 3000 tdn/ng.d.
938 Ket qua ap dung cdc phuong phap tac ddng Ign viing can dav gieng tai md Bachjtd.
Tang mong la dang khoi chiia collector granit nut ne co hang ble va 16 r6ng, trong do cac khe nut va vi khe niit la nhung b6n chiia diu. Cac khe niit va vi khe niit co chieu day 0,3 - 3mm. Do r6ng ciia collector khoang 3 - 5%o va do thim thiu thay dii trong pham vi rong tu 0,004 din 464D (trung binh la 0,135D). Nhiet do via trong khoang 130 - 155°C va ap suit via thay dii tu 200 din 320at. (do o do sau 3650m). Theo kit qua nghien ciiu, da mong mo Bach H6 dugc tao thanh chii yeu tir da granit, monsonit thach anh, granodiorit, monsodiorit thach anh, diorit, diorit thach anh [1]. Thanh phin khoang vat da mong mo Bach H6 dugc chi ra trong Bang 1.
Cac da ting mong mo Bach H6 da bi tac dong boi nhiing qua trinh kien tao, thuy nhiet, phong boa, v.v.. hinh thanh cac 16 h6ng, khe niit va vi khe nut, trong do co chua nhilu khoang vat thii sinh chu yeu la seolit, felfan dugc bien d6i tu plagiocla.
HIU hit o cac gilng, phin tang mong deu than tran. Hien nay co 83 gieng khai thac thuoc dii tugng nay (trong do, 27 gieng khai thac bang gaslift) va 31 gieng bom ep. T6ng luu lugng diu khai thac dat khoang 30000 tin/ng.d. voi 6,4% do ngap nuac san pham khai thac.
Bang 1
Khodng vdt,
%
.Plagiocla Fensfat kali Thach anh Biotit Muscovit Amfibol Loai plagiocla
Granit
20-47 20-50 25-40 2 - 10 0 - 3 0 - 2 Oligocla den Andezin
Monsonit thgch anh
30-40 30-45 5 - 18 5 - 13
-
0 - 3 Oligocla andenzin
Grano- diorit
40-54 16-28 18-24 6- 10
-
0 - 3 Oligocla andenzin
Monso- diorit thgch anh 4 3 - 6 2
10-28 10- 17 5 - 13
-
0 - 1 8 Oligocla andenzin
Diorit
6 2 - 6 8 3 - 5
< 5 13- 15
-
5 - 10 Andezin
Diorit thgch anh
62-80 2 - 7 7 - 17 3 - 10
-
3 - 10 Andezin
TINH HINH CONG VIEC XLT LY VUNG CAN DAY GIENG TAI MO BACH HO TRONG GIAI DOAN 1991 - 2004
Trong qua trinh xay dung, khai thac va siia chua gieng, cac via san phim thuong bi nhiem ban. De gia tang he s6 san pham ciia cac gilng khai thac va do tilp nhan cac gilng bom ep, XNLD Vietsovpetro da ap dung nhilu phuong phap xii ly viing CDG, trong do chii yeu la cac phuong phap:
• Xu ly axit th6ng thuong
• Niit via nho dan chay n l PGD-42T tao khi cao ap, kit hgp voi chit long boat tinh
• Niit via thiiy lire (NVTL) co chen ep cat nhan tao
Ngoai ra. tai mo Bach H6 da filn hanh thii nghiem them nhieu phuong phap xii ly vung CDG khae nhau, do la: phan rQa set nho hoa pham, d6t h6n hgp chay oxy hoa (GOS), xii ly nho t l hgp dan chay n l va bin via MKAV-42 co kich thuoc be, xii ly nho dung m6i ket hgp vai dung dich axit, phuong phap tao xung thuy lire, xii ly bing dien tu.
luygn^tap bao cdo Hdi nghj KHCN "30 ngm Dau khi Viet Nam: Cff hdi mdi, thach thuc mdi" 939 ngan each dong nuoc trong cac gilng khai thac nho b i n hgp AKOP va GALKA, xii ly bing hgp chit boat tinh bl mat (HTBM).
Trong Bang 2 cho bilt khii lugng, he s l thanh eong ciia cac cong nghe xu ly viing CDG ciia cac gilng khai thac va bam ep tai mo Bach H6.
Bang 2
TT
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Cdng nghe xu ly viing CDG
Bang dung dich muoi-axit Bang dung dich axit-set
Bang dung dich muoi-axit + axit-set Bang nhu tuong dau-axit (goc axit-set) Bing axit + hoa phim "DMC"
Nha bot-axit
Bang dung dich polimer-axit Bang vi nhu tuong axit
Bang dung moi Pl + xii ly axit
Bang nhu tuong dau-axit (goc muoi-axit) Niit via thiiy luc (NVTL)
Nha dan chay no PGD-42T tao khi cao ap + xii ly axit
Bing hoa phim "DMC"
Nho chat boat tinh be mat (HTBM)
Nha to hgp dan chay no va ban via MKAV- 42 CO kich thuoc be
Phan rua set nho hoa pham Xu ly bang dien tu
Tao xung thuy lire
Ngan each nuoc nho hon hgpAKOP Ngan each nuac nha h i n hgp GALKA Xu ly axit duai ap suat cao
Dit hon hgp chay oxy hoa (GOS) Tong
Trong gieng khai thde
Khdi lugng
1 34
0 119
85 1 2 1 4 4 38 26 5 2 8 10
0 4 4 2 9 2 367
He sd thdnh cdng, %
14 53 0 79 62 100
50 0 75 50 61 42 60 50 38 60 0 25 25 0 56 50 62
Trong gieng bam ep
Khdi lugng
3 24
2 6 17
1 1 0 1 0 2 5 5 7 0 4 5 2 0 4 3 0 92
He sd thdnh cdng. %
100 92 100
50 88 100 100 0 100
0 100 100 80
0 0 100
0 100
0 75
0 0 74 C6ng viec xu ly vung CDG theo tung dii tugng khai thac dugc chi ra trong Bang 3.
940 Kgt qua ap dung cac phuong phap tac ddng len vung can day g i g n g t ? i m d ^ 9 £ | l i l O :
Bang 3
Ddi tugng
Miocen duoi Oligocen tren Oligocen duoi Tang m6ng
Tong
Quy giing 48
3 56 119 226
Khdi lugng gieng xu ly
25 1 56 64 146
Phdn quy gieng da dugc
xuly, % 52 33 100 54 65
Khdi luang xir
Iy 42
2 251
164 459
Phdn tdng khdi lugng xu
ly tren todn md, %
9.2 0,4 54,7 35,7 100 Tu cac Bang 2 va 3 nhan thay rang, cac phuang phap xu ly vung CDG dugc ap dung rong rai voi khoi lugng xii ly Ion va dat dugc ket qua dang ke la xu ly bang: dung dich axit-set, nhii tuong dau-axit (g6c dung dieh axit-set), dung dieh axit + hoa pham
"DMC", mit via thuy lire (NVTL) va dan chay n6 PGD-42T tao khi cao ap + xu ly axit.
Tren toan mo Bach H6 da tien hanh 459 ian xu ly vung CDG, trong do eo 251 lan xu ly trong tat ca cac gieng thuoc quy gieng Oligocen duoi va dat 54,1% tong kh6i lugng xu ly, tiep theo la tang mong voi kh6i lugng xii ly vung CDG la 164, dat 35,7%) tong kh6i lugng xu ly tren toan mo.
Tren Hinh 1 bieu thi cac chi s6 xu ly vung CDG trong giai doan 1991 - 2004, bao gom kh6i lugng xu ly gieng, he so thanh c6ng va t6ng lugng dau khai thac (lugng nuoc bom ep) dugc them tu cac gieng xu ly hang nam va nhiJng gieng xii ly 6 nhirng nam truoc do.
1200
1000
,.£ 800 x: W)
c so c ea
'M o
• w
•s -(3
Ji j^
3
•o M c O.
a 600
400
200
0
-200
-400
1991 1992 1993 1994 1995 1996 1997 1998
I I Lugng dau ichai thac gia tang trong nam
" Lupmg diu khai thac gia tang tu cac gieng xu ly nhung nam tarac Tdng luong dSu khai thac gia tang
A Lugng nuac born ep gia tang
• >^ He so thanh cdng
• " Sd lugng xu ly gieng
Hinh 1
Tuygn tap bao cao Hdi nghj KHCN "30 nam D^u khi Viet Nam: Cff hdi mdi, thach thiic mdi" 9 4 1
AP DUNG vA HOAN THIEN CAC CONG NGHE XU LY VUNG CAN DAY GIENG
Nhu da trinh bay o tren, tai mo Bach H6 da tien hanh thu nghiem va iing dung nhieu phuong phap xii ly vung CDG kbac nhau. Moi phuang phap deu co uu, nhugc diem nhat dinh vl mat cong nghe. Tuy thuoc vao cac dieu kien dia chat - ky thuat eiia tung gieng ma chiing ta lira ebon phuang phap phii hgp de xu ly.
Sau day, chiing ta se xem xet nhQng dae diem ap dung va huong hoan thien c6ng nghe ciia mot s l phuong phap xii ly vung CDG da va dang dugc sii dung rong rai tai mo Bach Ho.
1. Phu'OTig phap xu- ly bang axit
Hien nay, xu ly vung CDG bang axit la phuong phap chu yeu tai mo Bach Ho. Tuy nhien, c6ng nghe nay can phai dugc nghien ciiu day dti boi cac yeu t6 anh huong khi xu ly trong dieu kien nhiet do via cao (toi 155°C), co che tae dong ciia hon hgp axit len thanh phan khoang vat ciia dat da tang mong, v.v..
Doi vai collector tram tich luc nguyen, dung dieh axit-set tac dong voi cac thanh phan chu yeu Si02 va H4Al2Si209 (eaolin) c6 trong viing CDG. Do dung dich axit bi trung hoa trong dieu kien nhiet do cao, san pham Si(0H)4 (a dang gel kho boa tan) dugc tao thanh sau phan iing nhu sau:
Si02 + 4HF = 2H2O + SiF4
san pham phan ling SiF4 tiep tuc tac dong voi nuoc:
3SiF4 + 4H2O = Si(0H)4+ 2H2SiF6
Tuong tu, khi dung dich axit-set tac dong vai H4Al2Si209 (eaolin):
. H4Al2Si209+ 14HF = 2AIF3 + 2SiF4 + 9H2O 3SiF4 + 4H2O = Si(0H)4 + 2H2SiF6
Dung dich axit H2SiF6 boa tan trong nuac, con san pham phan iing dang gel Si(0H)4 CO the lam giam do tham thau vung CDG.
Doi voi tang mong, trong phong thi nghiem cung da tien hanh nghien ciiu tac dong ciia dung dich mu6i axit vai aliumosilicat (seolit, clorit, v.v.). Phan iing trao d6i xay ra nhu sau:
MeSiAIOn + HCL -^ MeCL + H2Si03 + AL203nSi02nH20 Trong do: Me - kim loai (Ca,Mg, Na,K)
H2Si03 - gel axit silic
AL203nSi02nH20 - gidrogel oxit nhom-oxit silic voi ty le thay doi giQa AL2O3 va Si02 cung nhu giQa cac oxit va nuoc
Voi muc dich nhanh chong thao rua nhiing san pham phan iing (san pham dang gel) ra day gieng ngay sau khi xii ly axit, mot so c6ng nghe xii ly axit da dugc nghien cuu hoan thien nhu sau.
942 Kgt qua ap dung cac phuong phap tac ddng len viing can day gieng tai md B^chjtd^^^
a. Thdo rwa nhanh cdc sdn phdm phdn irng khi xir ly axit nho hdn hgp hda phdm
"DMC"
Tai mo Bach H6, khi chua co he th6ng khai thae dau bing gaslift, qua trinh goi dong sau khi xii ly vung CDG gieng thuang dugc tien hanh bing each thay thi chat long trong gilng bang dau, tiep theo la ep xen ke vao gieng cac tap khi co ap suat cao dugc lay tu mieng cac gieng ian can. Tuy nhien, phuong phap goi dong ke tren thuong lam cham qua trinh thao nia tu via ra day gieng nhQng san pham phan iing sau khi xu ly axit. Vi le do, XNLD Vietsovpetro cung voi C6ng ty Dung dich khoan va Hoa pham Dau khi da nghien cuu, ling dung thanh c6ng giai phap khoi th6ng gieng ngay sau khi xu ly vung CDG nho hon hgp boa pham bi phan giai duoi tac dong eiia nhiet do via cao (> 80 C) tao ra mot kh6i lugng Ion khi tro N2 [2].
Phuong trinh phan iing ciia h6n hgp h6a chat xay ra nhu sau:
NaN02 + NH4Cl => NaCI + 2H2O + N 2 t
Nhan thay rang, san pham sau phan ung eo mot kh6i lugng Ion khi tro N2 (uoc tinh Im^ dung dich hoa pham 6 nhiet do > 95°C thu dugc 150m"^ khi N2). Sau khi tao ra su chenh ap Ion giua day gieng va via (P(j > Pv) do cot chat long - khi bi nen trong gieng nho hon hgp boa pham bi phan giai, gieng dugc mo nhanh tao nen chenh ap tiic thai giQa via va day gieng (Py > Pd) lam cho cac san pham phan ung sau khi xii ly axit viing CDG dugc day thao ra day gieng va dua len be mat trong qua trinh goi dong gieng.
Xii ly axit vung CDG theo eong nghe nay da dugc ap dung ph6 bien a cae gieng khai thac thuoc doi tugng Oligocen duoi va tang mong mo Bach H6 va he s6 thanh c6ng xu ly dat 62% (Bang 2). Tuy nhien, hieu qua kinh te chua eao, do phai chi phi nhieu cho hoa pham. Ke tu nam 1997, sau khi he th6ng gaslift dugc dua vao khai thac, c6ng nghe xu ly axit ket hgp khoi thong, goi dong gieng bang gaslift duge ap dung rong rai va mang lai hieu qua cao.
b. Gidi phdp nhd twong khi- ddu - axit
Trong dilu kien nhiet do via cao, khi be mat tilp xiic giua axit trong hon hgp nhii tuong dau - axit va dat da giam thi h6n hgp nay se di vao via sau ban so voi bin hgp axit binh thuong, d6ng thoi giam kha nang an mon kim loai ciia dung dich axit. Pha khi trong h6n hgp nhu tuong khi - dau - axit lam tang nhanh kha nang goi dong, th6ng via ngay sau khi gieng da dugc xu ly. Giai phap sii dung nhu tuong khi - dau - axit [3] do nh6m tac gia a XNLD Vietsovpetro de xuat xu ly trong mot s6 gieng thuoc tang mong. Giai phap nay dugc tien hanh bang each bom d6ng thoi hoae ke tiep nhau cac thanh phan nhu tuong khi - dau - axit (axit, dau diezel hoae dau tach khi va khi dau) vao cot 6ng khai thac (OKT) cua gieng xu ly. Ty le the tieh ciia cac thanh phan va trinh tu bom chiing dugc lira ebon sao cho dat dugc kha nang boa khi Ion nhat trong hon hgp dung dich nhu tuong diu - axit va dam bao chac chan h6n hgp nhu tuong khi - dau - axit xam nhap sau vao cac khe niit ciia via. Nhu vay, a nhung d6i tugng xu ly c6 ap suat via thap thi ngay sau khi xu ly, vung CDG dugc khoi th6ng manh va ting thao nhung chat gay ban va cac san pham phan ung tir via ra day gieng va theo san pham khai thac di len. Tuy nhien, do ban cbl vl ap suit
Tuygn tap bao cao Hdi nghj KHCN "30 nam Phu khi Viet Nam: Cff hdi mdi, thach thuc mdi" 943
nen va lugng khi diu tach ra tu cac gilng tu phun ian can, nen giai phap nay kh6ng dugc tiep tuc ap dung tai mo Bach Ho.
c. Xu- ly axit dw&i dp sudt cao
Khi xu ly vung CDG bing axit duai ap suit cao, mot kh6i lugng Ion dung dich axit dugc bom ep true tilp vao gilng qua thiet bi long gieng (TBLG), tren do da lap dat san van gaslift. Dl tiln hanh xu ly vung CDG theo c6ng nghe nay [4], cac thiet bi va dung dich axit diing dl xu ly dugc dat tren tau dieh vu. Trong qua trinh xu ly, dung dich axit dugc bom toi mieng gilng qua 6ng mem chiu ap, n6i tu tau toi gian khoan.
Nhung uu diem chii yeu ciia cong nghe xu ly axit duoi ap suat cao so voi c6ng nghe nut via thuy lire (NVTL) la: qua trinh xu ly don gian, giam bot nhieu c6ng doan siia chua gieng (trong do co qua trinh dap gieng) gay nhiem ban viing CDG, giam thai gian va chi phi cho chuan bi gieng truoc khi tien hanh xii ly.
So voi xu ly axit th6ng thuang, c6ng nghe xii ly axit duoi ap suat cao c6 mot so uu diem sau: khoi lugng dung dich axit bom ep co the dat toi 120m (d6i voi xii ly axit th6ng thuang, kh6i lugng axit trung binh la 24m^) va ap suat bom ep dat toi 350at. (so voi 250at.
khi tien hanh xii ly axit thong thuong).
De nang cao cac chi tieu kinh te - ky thuat xii ly axit duoi ap suat eao trong nhiing gieng CO khoang mo via san pham Ion, XNLD Vietsovpetro dang nghien ciiu, hoan thien va dua vao sii dung thiet bi mai (cac may bom, binh chiia va duong 6ng bom ep axit, v.v.) dugc lap dat tren gian khoan nham dam bao kh6i lugng va ap suat bom ep axit di sau vao via.
d. Xii: ly axit dw&i dp sudt cao co chen ep proppant v&i nong do thdp
Trong qua trinh khoan, sua cbQa va khai thae nhiing gieng thuoc tang mong, dung dich set va cac tap chat lang dong tao thanh nhQng mang bao boc tren be mat khe niit va vi khe nut. Ngoai ra, d6i voi cac gieng khai thac, trong qua trinh lam viec cua chiing, ap suat via giam dan theo thai gian lam cho cac khe nut a trong vung CDG co xu huong khep lai do bien dang dan h6i ciia dat da. Doi vai cac gieng bom ep, cac phan tu ciing trong chat long bom ep co the lam bit cac kenh dan hoae nhQng lop set trong cac khe niit bi truang no khi tac dung voi nuoc. Cac nguyen nhan ke tren lam giam do chay tham ciia dong chay a viing CDG. Trong truong hgp nay, xii ly axit duoi ap suat eao co chen ep proppant voi ham lugng thap da mang lai ket qua dang ke [4]. Sau khi xii ly axit, do chuyen dong ciia chat long mang cat voi van toe Ion lam be mat ciia cac khe niit va vi khe nurt bi bao mon va riia xoi manh. Cac vi khe niit va khe nut (ehu yeu 6 phan du6i) dugc kh6i phuc hoae dugc mo rong them. Sau do, cac khe nut va vi khe nut nay dugc chen ep boi propant de chiing khoi bi khep lai.
Phuong phap xii ly axit duoi ap suit cao co chen ep proppant voi n6ng do thap kh6ng con dugc tiep tuc ap dung tai m6 Bach H6 do cong nghe xii ly phiic tap va chi phi Ion cho c6ng viec chuan bi, xii ly gieng va bom riia proppant sau khi xii ly. Tuy nhien, c6ng nghe nay dang dugc tiep tuc nghien ciiu hoan thien nham nang cao hieu qua kinh te - ky thuat khi xu ly vung CDG ting mong.
944 Ket qua ap dung cac phuong phap tac ddng len vung can day gigng tai md_BgchJj^^^^
2. Cong nghe xij ly gieng bang dan chay nl PGD-42T tao khi cao ap, ket hop voi chat long hoat tinh
Nhu chiing ta da biet, d6i tugng Oligocen duai tao boi nhilu tap via nam xen ke nhau va khong d6ng nhat, con tang mong dugc ma co do day via san pham rat Ion. De tang hieu qua xu ly vung CDG trong nhung dieu kien dia - ky thuat nay, tai mo Bach H6 da filn hanh thu nghiem phuong phap xii ly t6ng hgp nha dan chay n6 PGD-42T tao khi cao ap, kit hgp \6i xu ly axit. C6ng nghe xii ly dugc tien hanh bing each tha mot so ian xulng gilng nhung bang dan PGD-42T co kich thuoc be, tren cap dia vat ly qua cot OKT tai cac khoang xii ly xac dinh. Sau m6i ian tha, bang dan dugc kich chay n6, tao khi cao ap o day gilng vugt qua ap suat niit via, chat long ciia gieng cung vai mot phan khi eo kha nang ep sau vao trong via lam mo rong cac khe niit san co va tao them he th6ng khe nut moi. Cac khe mit sau khi dugc tao ra do dan chay no, tiep tue dugc xu ly bang axit lam tang them do tham thau viing CDG xii ly.
U'u diem ap dung c6ng nghe ke tren la trong qua trinh xii ly, kh6ng can phai tien hanh dap gieng va nang - tha cot OKT. Tuy nhien, trong khi xii ly, xung ap suat o day gieng CO the dat toi 1800at. lam anh huong chat lugng vanh xi mang tram va cot 6ng ch6ng khai thac. dan toi xuat hien ap suat giua cac cot ong chong hoae lam mop 6ng chong khai thac. Ngoai ra, cac khe niit tao thanh sau khi xu ly kh6ng dugc chen ep boi proppant. nen sau khi xii ly mot thai gian, cac khe niit nay dong khep lai, dan den he s6 san pham ciia gieng giam nhanh (th6ng thuang thai gian hieu qua khoang 3 - 6 thang) [5].
Do nhQng nguyen nhan nay, phuong phap xii ly t6ng hgp nho dan chay n6 PGD-42T tao khi cao ap, ket hgp \oi xu ly axit dugc ap dung rat ban che.
3. Nut via thiiy lyc co chen khe nut tao thanh boi proppant
Trong nhung nam gan day, phuong phap NVTL eo chen proppant dugc tiln hanh trong nhieu gieng thuoc Oligocen duai tai mo Bach H6. Day la phuong phap mang lai hieu qua cong nghe nhat d6i voi d6i tugng khai thac nay.
Ket qua NVTL phu thuoc rat nhieu vao trang thai va dac tinh dia - ky thuat ciia gilng (ap suat \ia. s6 lugng va do day cac tap via san phim, do day ciia cac tap via ngan each giua cac via san pham, tinh trang cot Ing ching khai thac, chit lugng bom tram xi mang, miic do ngap nuoc ciia chat long khai thac, v.v.). Nhin chung, cac gilng da dugc thuc hien NVTL thanh c6ng deu co lugng dau gia tang Ion va thoi gian dat hieu qua keo dai khoang 2 - 3 nam. Tuy nhien, 6 cac gieng xu ly khong thanh c6ng hoae dat kit qua kh6ng tit la do mot so ngu}en nhan chii yeu sau:
- Theo thiet ke, can phai tiln hanh NVTL 2 hoae 3 ting trong 1 gilng, nhung khi tien hanh a tang duoi thi xay ra hien tugng thong via len tren (chit long di len tang tren qua phia ngoai cot ong ch6ng khai thac do chat lugng tram xi mang ngoai cot 6ng chong kh6ng bao dam), nen phai tien hanh 2 hoae 3 ting nhap mot.
- Khi tien hanh NVTL kh6ng ep hit proppant vao via va proppant con lai nhilu trong cot OKT. De giai phong packer trong gieng. da phai tien hanh bom rua proppant trong OKT nha sii dung ong mem.
- Sau khi kit thiic N'VTL, kh6ng dua packer len dugc do cot 6ng ch6ng khai thac bi mop.
- Khi tiln hanh NVTL a ting tren bi thong via xu6ng tang duoi.
luygn^tap bao cao Hdi nghj KHCN "30 nSm Phu khi Viet Nam: Cff hdi mdi, thach thuc mdi" 945
Khi tiln hanh NVTL ting duoi bi th6ng via, chit long mang proppant di len ting tren qua phia ngoai cot Ing ching khai thac. Sau khi ngung bom, proppant dong lai tren packer gay nen su c l (kh6ng keo packer len dugc). Voi muc dich de phong ket packer, co thi diing "sum packer" thay thi packer th6ng thuong de tien hanh NVTL nhieu tang trong cac gilng thuoc dii tugng Oligocen duoi. U'u diem eua viec sii dung packer nay la khi proppant ling dong tren packer, cot OKT dugc keo len de dang va de lai "sum packer"
trong gilng, sau do packer dugc giai phong nho khoan pha.
Cong nghe NVTL co chen proppant cung dugc tien hanh thii nghiem trong mot s6 gieng tang mong mo Bach H6, nhung he s6 thanh c6ng dat kh6ng cao. Den nay, cac hang dau khi n6i tieng tren the gioi chua c6 mo hinh chuan de thiet ke NVTL cho tang mong.
Theo chiing t6i, nguyen nhan chii yeu c6 sir kbac biet giQa kh6i lugng proppant theo thiet ke va kh6i lugng proppant thuc te ep dugc vao via la do miic do mat nuoc trong tang mong rat manh, ap suat va luu lugng chat long cua he th6ng may bom chua dii kha nang de tao nen khe nut moi trong tang mong.
Ngoai nhiing phuong phap xii ly vung CDG chii yeu ke tren, tai mo Bach H6 da nghien ciiu dua vao thii nghiem mot s6 phuong phap xu ly khae nhu: phan rQa set nho boa pham, d6t hon hgp chay oxy hoa (GOS), xii ly nho t6 hgp dan chay n6 va ban via MKAV- 42 CO kich thuoc be, xii ly nho dung moi ket hgp voi dung dich axit, phuang phap tao xung thuy lire, xii ly bang dien tu, ngan each dong nuoc trong cac gieng khai thac nho h6n hgp AKOP va GALKA, xii ly bang hgp chat hoat tinh be mat (HTBM). Ket qua xii ly vung CDG nho cac phuong phap nay dugc ehi ra trong cac bao cao [5].
Nhan thay rang, kh6i lugng xu ly cua tung phuong phap thu nghiem eon it, viec lira chon gieng de xii ly chua t6t, mgt so phuong phap khong mang lai hieu qua kinh te - ky thuat cao va pham vi ap dung cua chiing eon ban che. Hien nay, cac phuong phap nay dang dugc tiep tuc nghien ciin, lira chon va ap dung eho tung d6i tugng trong nhiing dieu kien dia - ky thuat thich hgp.
KET LUAN
• Xii ly nhu tuong dau - axit ket hgp voi goi dong bang gaslift la phuong phap tac dong len viing CDG eo hieu qua kinh te - ky thuat nhat trong cac gieng khai thae mo Bach H i .
• Ap dung c6ng nghe xu ly axit duoi ap suat cao (true tiep qua TBLG de kh6ng can phai cac quy trinh nang - tha cot OKT va dap gieng se nang cao hieu qua kinh te - ky thuat. De tang hieu qua xu ly axit, can dau tu trang thiet bi chuyen dung (may bom co c6ng suat Ion, he th6ng thiet bi 6ng mem, v.v.) tren cac MSP va BK.
• Niit via thuy lire co chen ep khe mit tao thanh boi proppant la phuang phap xu ly vung CDG CO hieu qua c6ng nghe nhat a cac gieng khai thac thuoc Oligocen duoi mo Bach H6. Khi tien hanh nut via thiiy luc nhieu tang tach biet, nen sii dung "mit cau" va
"sum packer" de ngan each tang duoi va tien hanh niit via tang tren nham giam thieu cac sir c6 co the xay ra.
• Tiep tuc hoan thien c6ng cac nghe nut via thiiy lire axit co chen proppant voi nong do thip, xii ly gieng bing dan chay n l PGD-42T tao khi cao ap kit hgp voi chit long
946 Kgt qua ap dung cdc phuong phap tac dgng len viing can d^y gieng tai md Bach Hd..--
boat tinh va mot s6 c6ng nghe khae da dugc thu nghiem tai mo Bach H6 nham xac dinh cong nghe t6i uu cho tung d6i tugng xii ly cu thi, ding thai nghien ciiu lira ebon, dua vao ap dung mot s6 c6ng nghe moi tac dong len via san phim, nhim nang cao he s6 thu h6i dau ciia mo.
TAI LIEU THAM KHAO
1. Bao cao dl tai NCKH Nhir-21 ciia Vien NCKH & TK D I U khi biin, XNLD Vietsovpetro, 1997.
2. Duong Danh Lam va n.n.k., 1996. Hodn thiin cdng nghi xir ly bdng axit vung can day gieng thudc tdng mdng md Bgch Hd. Tuyen tap Hoi nghi Khoa hoc Dai hoc Mo - Dja
chat. Ha Noi.
3. Duong Danh Lam va n.n.k., 1997. Sdng kiin cdi tiin ky thugt - hgp ly hda sdn xudt
"Cdng nghi xir ly bdng nhii tuang khi - ddu - axit vung can day giing thudc ddi tugng tdng mdng md Bgch Hd trong diiu kiin dp sudt via thdp". N°. 568, XNLD
" Vietsovpetro.
4. Duong Danh Lam va n.n.k., 1999. Co chi vd cdng nghe nut via thuy luc - xu ly axit ddi v&i cdc giing thudc tdng mdng md Bgch Hd. Tap chi Dau khi, S6 3.
5. Cac bao cao dl tai NCKH, Nhir-16, 21, II1.6, IV.2 cua Vien NCKH va TK DIU khi biin, XNLD Vietsovpetro, 1994 - 2004.
