THAM DO - KHAI THAC D A U KHi
MOT S6 GIAI PHAP NANG CAO HE SO THU H6I DAU CHO THAN DAU TRONG DA MONG TRUOC D £ TAM MO SU TU DEN, SU TU V A N G
ThS. Oang Ngoc Quy, PGS.TS. Hoang Van Quy Tong cong ty Tham db Khai thde Dau khi Email: [email protected] Torn tat
Dge diem dia chdt cua than ddu trong dd mong md SU TdBen - SuTd Vdng khd phdc tgp, trong do cd nhieu yeu td dja chdt dnh hU^g din khd nang thu hoi ddu nhtf: mde do bdt dong nhdt eda md gdyra sUphdn chia nhieu khoi cd cde ehe do thuy ddng life ti/c/ng ddl rieng biet, ddc trUng he thdng ddt gdy vd ndtne thd sinh, nifdc dp sUdn tdedc thdnh hi Oligoeene xam Idn trong qud trinh khai thde 12,4}. Bai bdo gidi thieu mgt sd gidi phdp nham hgn ehe dnh hi/dng xdu va tang ctfdng dnh hu'dng tieh ctfc eda cde yeu tddja chd't dendng eao he sd thu hdl ddu trong dd mdng trude De Tam mo SU TdDen - SU Td Vdng nhU: tdi Uu he thdng gieng khai thde, tdi Uu ehedd khai thde, hgn che dnh hudng xdu cua nude dp sudn vd khoan dan ddy d cdc khdi cd che do thdy dgng lUe rieng biet.
TUkhda: Nudc dp sUdn, he thdng giing khai thde, chi do khai thac, he so thu hoi ddu, trUdng dng sudt thuy dgng lUe va trudng Ung sudt trong trUdng, gradient thuy dpng luc, gradient trong trUdng.
1. Toi iTu he thdng gieng khai thac
D i y la g i i i phap d i e blet quan trpng giup tdi Uu chenh ap gida khoang khai t h i e va mat nude dang nham d i m b i o eho vide duy tri djeh ehuyen dn dinh m i t ranh gidl dau nUde, nghla la dam b i o dat kha nang d i y va quet dau bdi nUde tdi ddi khai thac cao n h l t . Do d i e trUng t h i m chda cCia tang mdng md SUTd Den - SUTd Vang duac khdng che bdi dac diem ddt gay va khe ndt, ndn he thdng gieng (khai thac va bPm ep) gdm mat dd.
vj trf v i quy dao gieng, khoang khai thac eung nha bPm ep dupe thiet ke toi Uu theo sU phan bd cac ddi ddt gay trong md nhU quy dao eda cac gieng khai thac va bom e p c d x u the vudng gdc vdi c i c he thdng ddt gay (chfnh) hadng Tiy Bic - Ddng Nam va Dong Bac - Tay Nam.
2. Toi Uu che do khai thac
Trong qua trinh khai thac vdi viec ap dung bom ep nude hoac vdi anh hudng cua nude ap d i y hoae ap sudn, dau via ludn ehju t i c ddng cua 2 trudng dng s u i t chCi yeu, dd la trudng dng suat thCiy ddng lUc va trUdng dng suat trpng tradng. Hai trUdng dng suat nay sinh ra gradient thuy ddng lUc v i gradient trpng trUdng tUPng dng.
Gradient trpng trUdng dapc tfnh theo cdng thde 11]:
a l - Y . - T o H) Trong dd:
Y_^:Tytrpngcuadauvfa;
y^: Ty trpng cua nude.
Gradient thuy ddng luedupetinh b i n g cdng thde:
(2) Trong dd:
AP v i H: Chdnh ap va dp cao gida mat thu hoi dau va mat dang ldn cCia nUdc;
K^ K^ (i^va ^^: Dd tham pha va dp nhdt cua d i u v i nadctUOng dng.
Trudng dng suit thuy dpng lUe l i trudng dng suit sinh ra do x u l t hien chenh ap giCifa vijng can day gieng va vung lan can. Chdnh i p cang ldn khi nadc bdm ep hoic nude ap d i y hoic i p sadn tac ddng v i o than dau cang Idn. Dudi t i e ddng cua trudng dng suit thuy ddng lUc, dau via di chuyen t d eic vung xung quanh d i n vung khai thac hay con gpi la vung thu hoi d i u . Toc dp di chuyen dau phu thudc vao nhieu yeu td, trong dd gradient thuy ddng lue la yeu to quan trpng hang dau. Tuy nhien dieu kidn de ndde cd the day dau tdi ddi khai thac vdi he so day cao nhat khi gradient thuy ddng lac nhd hpn gradient trpng trUdng [1]:
a2 < dl ^3' Trong trUdng hop gradient thCiy ddng ldc nhd
hpn gradient trpng trudng thi mat ranh gidl dau nUdc dich chuyen dn djnh, he sd day d i u tdi ddi khai thac dat gia trj cao n h l t , ngUde iai se dan den hinh thanh ludi nudc. Nhidm vu cua viec tdi au ehe dd khai thic, n i n g cao hidu qua thu hdi dau khf la dam b i o sao cho gradient thuy ddng lac khdng dupc t i n g cao v i vUpt f 20 DIUKHI-SO 12/2014
PETROVIETNAM
qua gradient trong trUOng. Ngoai cie thdng sd cd djnh cua dau via v i node, chenh ap AP va do cao H l i yeu t d i n h hudng true t i l p tdi gradient thuy ddng lUe. Chdnh ap AP cang eao thi gradient thuy ddng lUc cang cao va chenh lech dp cao gida mat thu hdi d i u va mat dang len cOa nude cang nhd thi gradient thuy ddng luc eang Idn.
Viy trong qua trinh dieu chinh ehe dp khai thac nhiem vu quan trpng la giam tdi mde nhd n h l t cd the chenh ap AP va day cao k h o i n g c i c h giufa m i t thu hdi d i u va mat d i n g len eua nude.
Khu vUc Tiy Nam cua md SUTd Den ed)j^~1,0cP, cac khu vdc khae eda md Sa Td Den |i^ = 0,85, dd nhdt nUde bom dp, nUdc via i p sUdn j i ^ ~ 0,35eP. Dp t h i m pha thay ddi tuy thudc vao dac trang t h i m chda va dp bao hda nude tai tdng thdi diem cua than dIu.Td ket q u i nghien cdu md Bach Hd, dp t h i m pha dope chia ra 2 trudng hpp [3]: (1) dp tham eua da mdng dao ddng t d 1 - 1 .OOOmD va (2) dd t h i m cua da mdng > 1 .OOOmD. Trong trudng hpp (1), neu do bao hda nude S^ = 40% thi do t h i m pha eua d i u vao khoing 0,33 - 0,35 va dp tham pha eua nUdc rat nhd chi khoing 0,03. Khi do bao hda nude t i n g ldn 55%, dp tham pha cCia dau v i cua nUde bang nhau. Khi do b i o hda nude dat 60%, dd tham pha cua d i u g i i m di d i n g ke, chi edn khoang 0,03 va dd tham pha cua nUdc lai t i n g len 0,09 (gap 3 lan so vdi khi dp bao hda nudc 40%).
Ne'u coi d i chda trong mdng cua khu vUc md Su Td Den - Sa Td Vang cd do tham pha tupng t a trudng hpp dd t h i m trong khoang t d 1 - 1.OOOmD, thi dp linh dpng Tl eda d i u khi bj nadc day phu thudc vao do b i o hda nudc:
S^=40%,Ti = 0,09 S ^ = 5 5 % , i i ^ 1 . 0 7 S^ = 60%, ^ = 3,22
Thay ddl dp linh ddng eda d i u khi bj nudc d i y v i o cong thde (2) ta cd:
Nha vay trong trudng hpp:
S^ = 40%, gradient thuy ddng luc 02^-77(1-10,60) AP S =55%, gradient thuy ddng lac o2=—^-(1-0,92) AP S^ = 60%, gradient thuy ddng lUc a 2 = — ( 1 - 0,31) AP
Td ket qua ti'nh t o i n gradient thuy ddng lUc cho thay, trong tradng hop ddi khai thae cd dp bao hda nUde
< 40%, tham chf dat tdi 45% thi gradient thuy ddng lUc khu
vUcTiy Nam md SuTdDen ludn cd g i i tn am khi dd mat ranh gidi dau nude djch ehuyen dn djnh khdng hinh thanh eac ludl nude (c6 nghia l i khai thac trong dieu kien nay ludn dat dupe he sd thu hdl dau khf cao dd k h i nang d i y dau bdi nude van dat g i i tri cao nhlt).Tuy nhien, neu nhip do khai thic cao sd dan den nhieu khi nang lUdi nude tien thang vao gieng khai thic. Trong trUdng hop dp bao hda nudc ddl khai thac cao hdn 45 - 50% thi gradient thuy ddng lUco2 ludn cd g i i tri dUOng. Ddi vdi md SuTdDen - SuTd Vang, t>' trong dau via vao khoing 0,84 - 0,85g/cm^ hay 35 - 36API, ty trong eua nUdc via hay nUde bdm ep tam lly l i 1,04g/em^ ndn gradient trong tradng tinh dUdc la 1,80MPa/
km. Nhu viy, de mat ranh gidi dau nudc dich chuyen on dinh can dieu chinh che dp khai thac sao cho gradient thuy ddng luc phai d i m b i o < 1,80MPa/km.Ddl vdi cae khu vUe khac dp nhdt cua dau kha cao (0,85cP), dd linh ddng cua d i u khi bi nadc day khi thap nen dieu kidn d i m bao de mat ranh gidi d i u nude djeh chuyen dn dinh lai cang khic nghiet hdn. Do nhu cau ke hoach khai thac cao nen vide d i m b i o gradient thCiy ddng lUc khdng vUpt q u i gradient trong trUdng trong qua trinh khai thac la mdt dieu kien khd ed the thac hien dMc. Vi vay nha dieu hanh khai thic ein quan tam nham hai hda c i yeu cau ve d i p Ung ke hoaeh khai thac va nang cao he sd thu hdi dau.
3. Han che anh hudng cua nUdcapsUdn
Ket q u i p h i n tfch khai thac cho thay nadc ap sudn t d cac thanh tao Oligoeene xam nhap vao t h i n dau trong da mdng trUde Dd Tam khi ap suit via suy giam sau mdt thdi gian khai t h i e (Hinh 1) cd anh hudng den k h i nang thu hdi dau: Nude i p sudn giup ap suit via dupe duy tri k h i dn djnh, song cung ed kha nang x i m nhap khdng deu vao phan tren cua than dau khien q u i trinh day dau tdi ddl khai t h i c khdng xay ra t d d u d i ldn, dan den hidu q u i day d i u tdi ddl khai thac t h i p (khoang 0,69 - 0,71), trong khi hudng d i y d i u dat hidu qua cao nhat t d dudi Idn la 0,89.
Vi viy, de nang cao he sd thu hdl d i u khi than d i u trong da mdng md SuTdDen - SuTdVang, nhdng ddi ddt gay cd dp ngap nadc eao can han che hoic ngdng khai thac, dieu nay ed the thuc hidn bang each sd dyng cdng nghe hoan thidn gieng lUa ehpn. Trong trudng hpp nudc x i m nhap vao hoac tien sit dOl khai thac cua gieng, Idu lupng khai thac can dMc nghien cdu dieu ehinh hpp ly, t h i m chf ddng khai thac hoae khai thac vdl luu lupng tdi thieu. Cac gieng each xa vung nUdc xam nhap cd the khai thac tang cudng.
Ngoai ra, do nude xam nhap tdi gieng khai thie, lapng nudc khai thac tang len, dan den g i i m chenh i p hoac cd 21
THAM DO - KHAI THAC D A U K H I
Hinh I . Nude dp si/dn tUede thanh lao Oligoeene xdm idn vao than ddu trong 3d mdng md Su TUDen - SuTUVdng sau m^t thdi gian khai thde [2]
Jtt
Hinh 2. B^e trUng Ufng thdi khai Ihdc tiong khdi A khu vi/c Idy Nam md SUTHBen [21
Hinh J. Ddc tntdg dong thdi khai thde tmng khSi 8 khu vuc Tdy Nom md SuTiiDen (12))
t h i l i m cho g i l n g ngCtng khai thie, vl v^y c i n phii i p dyng khf n i n g (gaslift) d l t i n g chdnh i p hojc duy tri khai t h i c cua g i l n g .
4. T«ng cudng khai th^c il cic kh6l co c h i tf^
thdy tf^ng \\fc tuong d6\ rling bl^t Khdl d i mdng md SuTdDen, SUTCrVangdUpc p h i n ehia t h i n h nhieu khdi, trong dd moi khdl c6 d i e trung t h i m chda khic nhau vdi mde dd lUu thdng thCiy dpng ii^c gida cie khdi k i m . Md SuTil Den dapc chia t h i n h cic khdi A, B, C, D, E. Md SuTiJ Ving dupc p h i n chia t h i n h cic khdl A l , A2, B, C, Dl,D2.Td k i t q u i phan tich PVT cCia cie m i u dSu li'y dupc, ed t h i chia khu vyc n l y t h i n h eae don vj thuy ddng li/c Idn hdn:Tiy Nam md SuTdDen, Odng Bic md SuTdDen, khu vyc md SUTd Ving.
Hinh 2 v i 3 t h i hien dae trUng ddng t h i i khai thic trong khdl A v i B k h u v y c T l y NammdSdTdDen.
Hinh 2 v i 3 cho t h i y ddng t h i l khai thac khdl A v i B r l t khic nhau, d i e bl^t v l dd ng^p nudc vS luu lupng khai thac, chdng td khdi A va khdi B c6 sy khic bidt v l c h i dp thuy dpng lyc. D i y la 2 khdi cung p h i n bd d khu vyc Tiy Nam md Su Td Den.
Ddng t h i i khai t h i c eua khdl B, khu vyc Tiy Nam vS khdl E, khu vUcDdng Blc eung cd khic b i l t Idn. Bdc tranh n i y tUPng t u khdi mdng n i n g md Bach Hd, la mdt ddl tupng bj p h i n ehia t h i n h nhiJfng khdi cd mde dd lUu thdng thuy ddng lUc kem, trong dd khdi 1 I I khdl chinh ehilm khoing 60% tdng trO lupng t o i n t h i n d i u . Vile p h i n chia khdl mdng nOt ne trade D|Tam md SuTdDen, SuTdVang thinh eac khdl cd c h i d p t h i j y d d n g lyc khic nhau cd Inh hudng r l t Idn den he sd thu hdl d i u cua toan md Vdi cung mpt sd lupng g i l n g khai thic, md cing bj chia eit ra nhieu khdl nhd cd e h i dp thuy ddng lUc khac nhau thi kha nang thu hdi cang t h i p . Do dd, cic g i l l phap can t h i l t 6^ n i n g cao he sd thu hdl trong trudng hop t h i n d i u bj p h i n chia thinh cic khdi cd che dp thCiy dpng luc rieng biet, d^c bi^t ddl vdl eic khdi cd dae trung tham chda thip c i n dupe thye hien. Hien nay tai md SuTdDen, cac g i l n g khai t h i c ehu y l u t i p trung d khdi B, khu vyc Tiy Nam. Cic khdi C, D, ngay c i khdl E c i n phii dupc xem xdt bd sung g i l n g khai t h i c .
Trong pham vl bai b i o nly, nhdm t i e g i i chi d l cap CP sd khoa hpc n h i m n i n g cao hd sd thu hdi d i u khi, bd qua cic han e h i v l cdng n g h i va kinh
22 DAUKHI-SP 12/2014
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t l vdi hy vpng l i m n l n t i n g khoa hpc cho cAc md cd d i e d i l m dja c h i t tUdng ty. Ddl vdl cic md hay khdi vdl trd lapng d i u thu hdi dudi 10 t r l | u t i n , mang ludi g i l n g khai t h i c ed t h i p h i i dan d i y tdi 0,5 - 1,5km. Trong d i l u kidn n g o i i b i l n , mde dd b i t ddng n h l t cua d i chda qua cao, khd cd t h i dan d i y m?ng ludl g i l n g theo ly t h u y l t ndn c i n p h i i nghidn cdu t h i t ky d$e d i l m p h i n bd eie ddi ndt n l bao gdm hudng d6, m i t d d - d^ t h i l t k l g i l n g sao cho cd t h i g$p c i c ddi nuT n l cao n h l t .
5. K i t lufin
D l n i n g cao h^ sd thu hdl d i u ddi vdl than d i u trong d i mdng trudc D|Tam md SuTdDen, SuTd Ving cd t h i i p dyng g i i i phap h^n c h i i n h hudng x l u va t i n g cudng i n h hudng tieh eye eic y l u td dja e h l t nha: tdi uu he thdng gieng khai thac v i bom dp, tdi Uu c h i dd khai thie, han e h i I n h hudng eua nUde i p sudn va khoan dan d i y d eic khdl ed c h i dd thCiy ddng lyc ridng bidt. Day la v | n d l dupe nhdm t i e g i i tdng hpp va de x u l t , c i n t i l p tue dypc
nghidn cdu v i khic phyc cic han c h i v l edng ngh|, gdp p h i n n i n g cao h | sd thu hdl dSu khf cho t h i n d i u trong mdng md SuTdDen, SuTd Ving va cie md khie cd d i e d i l m dja chat tUdng ty.
T i i ligu tham khdo
1 H.P. JledeflMHey. tlay^enue u paspadomKa HetpmaHbiXMecmopOiiedeHuOempeuiUHHbixKonneKmopax.
M3fl. HayKa. MocKBa. 1997.
2. Cdng ty Lidn doanh D i l u h i n h Cdu Long.
Geological and reservoir simulation - Advance Halo Model - SuTu Vang. 20^3.
3 Hoing V i n Quy v l nnk. Sa d6 cdng nghi vd xdy dung hiiu ehinh md Bgch H6. Vietsovpetro. 2008.
4. D^ng Ngpc Qu;?, Hoing Vin Quy. Thdn ddu trong dd mdng trudc Di Tam md 5U TdDen, SU Td Vdng vd cdc yeu tddia chdt dnh hudng tdi khd ndng thu h6l ddu. Tap chf D i u khi.2014;2:trang12-16.
Solutions for enhancing oil recovery factor for fractured basement reservoirs of Su Tu Den and Su Tu Vang oil fields
Dang Ngoc Quy, Hoang Van Quy
Petrovietnam Exploration Production Corporation Summary
The geological characteristics of fractured basement reservoirs ofSu Tu Den and Su Td Vang oil fields art very com- plicated. Many geological factors, such as the geological heterogeneity that causes separated hydrodynamic blocks, the characteristics and densities of faults and fracture systems, and the presence of edge water drive (aquifer) from Oligoeene, may Influence oil recovery. In order to Increase and enhance oil recovery factor for Su Tu Den and Su Tu Vang basement reservols, some solutions are proposed in this paper for limiting the negative Impact and enhancing the possitlve impact of geological factors such as optimising production well system and production monitoring plan, reducing the Invasion of edge water, and intensifying oil recovery in separated hydrodynamic blocks.
Key words: Edge water, optimise production system, production monitoring plan, oil recovery factor, hydrodynamic force, gravity, hydrodynamic gradient, gravity gradient
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