Chuong 26 Phuong Phap Gaslift

BI GING CNG NGH KHAI THC DU KH

PHNG PHP GASLIFT

Ging vin : Email Tel : :

PGS.TS. L Phc Ho [email protected] 84-8-8654086

TNG QUAN V PHNG PHP GASLIFTL phng php khai thc c hc p dng khi ging khng thc hin c qu trnh t phun Bn cht ca phng php: Bm kh nn vo ng bm p lm cho cht lng trong ng bm p di chuyn xung ng nng. Khi mc cht lng n ng nng, p sut nn kh t gi tr cc i, kh nn tip tc i vo ng nng ha trn vi cht lng lm cho t trng dung dch gim dn n P gim P tng cht lng i t va vo y ging v i ln ming ging.

Cng ngh khai thc du kh

786

PGS. TS. L Phc Ho

Tng quanVai net ve lch s cua phng phap khai thac bang gaslift:Vao cuoi the ky 19, ngi ta nen khong kh vao khoang khong vanh xuyen hoac trong can e nang lu chat t gieng va phng phap nay co ten goi la Airlift. Tuy nhien khi s dung khong kh e bm ep a nay sinh nhieu van e nan giai nh gia tang mc o an mon va de tao hon hp chay no. Nam 1920 bat au dung kh ong hanh thu c t qua trnh khai thac dau (hoac kh mo) e ep tr lai xuong gieng va a khac phuc c nhng han che khi dung khong kh bm ep. Phng phap bm kh cao ap (kh ong hanh, kh mo) vao gieng hoa tron vi chat long trong gieng e giam ty trong va a chung len be mat co ten chung la phng phap gaslift.


787

PGS. TS. L Phc Ho

u nhc iem cua phng phapu iem: Co the khai thac san pham co cha cat hay tap chat, nhiet o va cao, yeu to kh dau ln, dau cha parafin Khai thac vi lu lng ln (50.000 thung/ng. che o gaslift lien tuc) va o sau ln t b anh hng cua cac chat an mon en s hoat ong cua cac thiet b so vi cac phng phap khai thac c hoc khac o nghieng va o sau cua gieng t b anh hng en hieu qua khai thac De dang truyen ap xuong ay gieng nh cac van gaslift Co the tien hanh ong bo qua trnh khao sat nghien cu gieng, o a vat ly, lam sach lang ong parafin Khong oi hoi them nguon nang lng bo sung (ien) trong qua trnh khai thac dau Co the chuyen oi linh hoat gia cac che o khai thac (t che o lien tuc sang nh ky) khi ap suat va va lu lng khai thac giam Co the khai thac va ieu hanh nhieu gieng nh he thong gaslift trung tam Chi ph van hanh gieng thap Co the s dung ky thuat cap ti trong viec sa cha cac thiet b long gieng nen tiet kiem c thi gian va chi ph sa cha (v khong can en thap khoan)788 PGS. TS. L Phc Ho


u nhc iem cua phng phapNhc iem: - Chi ph au t ban au cho viec lap at cac thiet b gaslift ln hn so vi cac phng phap khai thac c hoc khac, ac biet la cho nhng gieng sau - Hien tng ap suat ngc (ap suat do cot thuy tac ong len ay gieng) nen co the lam giam lu lng khai thac neu o sau gieng qua ln va ap suat va giam manh - Hieu suat cua phng phap thap, de b hien tng hydrat - Ch ap dung c khi nguon kh cung cap u cho toan bo i mo - Mc o nguy hiem cao v s dung kh nen cao ap, oi hoi o kn va o ben cua ng ong cao - Ong chong khai thac can phai chu c ap suat nen cao


789

PGS. TS. L Phc Ho

C S LY THUYET CUA PHNG PHAP GASLIFTNguyen ly lam viec -Yeu cau: khi gieng dau khong the t phun theo lu lng yeu cau -Nguyen tac: bm nen kh cao ap vao vung khong gian vanh xuyen (hay ngc lai) nham a kh cao ap vao trong ong khai thac qua van gaslift vi muc ch lam giam mat o cot chat long tren van (tang yeu to kh, giam ap suat ay). - Ap suat ay giam dan nh lng kh nen t be mat kt hp vi kh ong hanh cung kh hoa cot chat long. Qua trnh nay xay ra en luc nng lng dng chy ay ging u ln e thang ton hao ap sut doc theo cot ong khai thac va ay toan bo cot chat long a kh hoa len be mat, van chuyen en he thong thu gom va x ly.


790

PGS. TS. L Phc Ho

PHAN LOAI THEO AC TNH NANG1 Phan loai theo che o nen kh cao ap vao gieng (phan loai theo ac tnh nang) Da vao che o nen kh cao ap vao gieng la lien tuc hay nh ky (chu ky), co the chia phng phap khai thac dau bang gaslift thanh che o khai thac gaslift lien tuc va che o khai thac gaslift nh ky


791

PGS. TS. L Phc Ho

PHAN LOAI THEO CAU TRUC LONG GIENGPhan loai theo cau truc long gieng A. Gieng gaslift khai thac theo che o vanh xuyen (vanh khuyen) Trong he thong khai thac vanh xuyen, kh nen i theo khoang khong vanh xuyen gia ong ep kh (ong ngoai) con san pham khai thac i theo ong nang (ong trong) len be mat He thong khai thac vanh xuyen pho bien hn do co the s dung phng phap c hoc e nao vet parafin tch tu tren ong nang va khong mai mon cac au noi ong chong. Nhc iem chnh cua he thong nay la ap suat khi ong gieng ln, do vay can s dung cac van gaslift khi ong. He thong khai thac vanh xuyen co cau truc mot day ong va hai day ong.Cng ngh khai thc du kh 792 PGS. TS. L Phc Ho

PHAN LOAI THEO CAU TRUC LONG GIENGB. Gieng khai thac theo che o trung tam Nguyen ly lam viec: - Kh nen c bm ep vao cot ong khai thac (cot ong trung tam), con dong hon hp san pham khai thac theo khoang khong vanh xuyen i len be mat en he thong thu gom va x ly. - Ong trung tam c goi la ong ep kh, con ong ngoai la ong nang. - He thong khai thac trung tam co cau truc mot day ong va hai day ong.


793

PGS. TS. L Phc Ho

Hiu qu ca phng php gasliftHiu qu ca phng php gaslift ph thuc vo: su dn kh (chiu su nhng chm ca ng nng) Lu lng kh (Qk) p sut trn nhnh x H s sn phm ( cho du ca va) Lng kh tch ra khi du (Ghd) Tnh cht ca du ( , ) Cu trc ng khai thcCng ngh khai thc du kh 794 PGS. TS. L Phc Ho

Phn loiTu theo phng php bm p kh nn v lu lng khai thc m ngi ta chia ra 2 phng php khai thc gaslift: Gaslift lin tc Gaslift nh k


795

PGS. TS. L Phc Ho

Phng php gaslift lin tcL phng php a kh nn vo ging mt cc lin tc v sn phm theo ng nng ln mt t cng lin tc Phm vi ng dng: p dng vi cc ging sau y C lu lng Qkt ln Sn phm c ct hay b ngm nc Sn phm c cao, dng chy c to ln C t sut kh cao ( sn lng ging c th b ) u im: Nng lng kh nn v kh ng hnh ming ging c tn dng a sn phm n h thng thu gom x l Lu lng khai thc tng i n nh (hn ch c nhiu phc tp trong h thng gaslift) iu chnh lu lng kh nn thun li bng cn iu khin Nhc im: Khng hiu qu i vi ging c mc nc ng thp ( mc d Q ging ln) Khng p dng c vi nhng ging c p sut va thpCng ngh khai thc du kh 796 PGS. TS. L Phc Ho

Phng php gaslift nh kL phng php a kh nn vo ging theo chu k v sn phm khai thc theo ng nng ln mt t khng lin tc m nh k. Phm vi ng dng: p dng i vi cc ging sau: C Pd thp nhng h s sn phm cao H s sn phm K thp Mc cht lng thp, ging su C Qkt nh u im: Gi thnh khai thc thp so vi cc phng php khai thc c hc khc khi ging su v mc cht lng thp. Linh hot trn din rng c v Q v chiu su ging Nhc im: Qkt b gii hn (kh t gi tr max) Khng thch hp vi ging su, ng nng nh p sut dao ng mnh dn n ph hu vng y ging Kh iu khin trong h thng gaslift khp kn v nhCng ngh khai thc du kh 797 PGS. TS. L Phc Ho

Plunger lift


798

PGS. TS. L Phc Ho

Plunger lift


799

PGS. TS. L Phc Ho

Plunger lift


800

PGS. TS. L Phc Ho

Thit b khai thc bng gaslift

Thit b b mt Thit b lng ging


801

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1-My nn kh 3-Bnh tch 2 hoc 3 pha 5- Bnh tch sy kh kh 7- Van o lu lng kh 9- ng thu gom sn phm khai thc 11- Ging khai thc du bng gasliftCng ngh khai thc du kh

2-ng dn kh cao p 4- Bnh cha cht lng khai thc 6- Bnh tch condensate 8- Van iu khin 10- ng dn kh thp p 12- Ging khai thc kh cao p802 PGS. TS. L Phc Ho

Thit b b mtCc thit b b mt bao gm: H thng my nn kh H thng dn kh cao p H thng bnh tch 2 hoc 3 pha Bnh cha cht lng khai thc x l tip H thng bnh tch sy kh kh H thng bnh tch condensate H thng van o lu lng kh H thng van iu khin H thng ng ng thu gom sn phm khai thc H thng ng dn kh thp p H thng u ming ging khai thc Ging khai thc kh cao p Ton b cc thit b ny to thnh mt h thng phn phi kh khp knCng ngh khai thc du kh 803 PGS. TS. L Phc Ho

Thit b b mtH thng bnh tch 2 hay 3 pha: C chc nng tch s b sn phm khai thc, chuyn cht lng v lng kh ng hnh khai thc n cc h thng thu gom, x l tip theo H thng bnh cha cht lng khai thc: dng tip nhn cht lng c tch ra t cc bnh tch tip tc x l hay l trm trung chuyn bm du n cc h thng thu gom x l tnh cho n du thng mi H thng bnh tch condensate: C chc nng tch cc thnh phn condensate khi kh ng hnh H thng bnh tch sy kh kh: Dng tch ton b cc thnh phn pha lng cn li khi kh ng hnh trc khi i vo my nn u ming ging: C nhim v treo ton b cn OKT v h thng chn cch ly lm kn ming gingCng ngh khai thc du kh 804 PGS. TS. L Phc Ho

Thit b lng gingTi cha chuyn dng (mandrel) Van gaslift


805

PGS. TS. L Phc Ho

H thng ti chuyn dng (mandrel)C nhim v lp t cc van chuyn dng: Van tun hon Van Gaslift Van bm ho cht vo trong ti C chc nng nh hng thit b lp t v tho d cc loi van chuyn dng mt cch chnh xc v d dng nh k thut cp ti Do c cu to khng ng tm vi OKT nn khng nh hng n dng sn phm chuyn ng ln. Cho php cc thit b k thut cp ti v thit b nghin cu ging su di chuyn ln xung d dngCng ngh khai thc du kh 806 PGS. TS. L Phc Ho


807

PGS. TS. L Phc Ho

Mandrel


808

PGS. TS. L Phc Ho

Loi c mt ct hnh ovan(Oval body side pocket mandrel)

p dng: L thit b iu kin dng chy c lp t v tho d di p sut phng php a vt l chun. Dng trong ging khoan thng hoc nghing tu thuc loi mandrel. Li ch: Chim t khng gian hn so vi mt ct trn nn c th th vo ging c ng knh ng chng khai thc nh hn Khng hiu qu trong trng hp khai thc vi p sut cao


809

PGS. TS. L Phc Ho

Loi c mt ct trn (Round body side pocket mandrel)p dng: L thit b iu kin dng chy c lp t v tho d di p sut phng php a vt l chun. Dng trong ging khoan thng hoc nghing tu thuc loi mandrel. Li ch: C nhiu u im khi khai thc vi p sut cao B hn ch trong vic khai thc vi ng knh ng chng khai thc nh


810

PGS. TS. L Phc Ho

Round solid body side pocket mandrelp dng: L thit b iu kin dng chy c lp t v tho d di p sut phng php a vt l chun. Dng trong ging khoan thng hoc nghing tu thuc loi mandrel. Li ch: ng bc nh hng m ng ny c ni phn cui trn, cho php xc nh v tr cc thit b Kickover c canh hng thng vi ti ca cc thit b iu khin dng chy ang hot ng v ang ko trong cc ging khoan c gc nghing ln. Tng thch vi cc thit b iu khin dng chy ca cc nh sn xut khc.Cng ngh khai thc du kh 811 PGS. TS. L Phc Ho

TUBING RETRIEVABLE CONVENTIONAL MANDRELSp dng: Thit b iu khin c ci t bng vic vt mng n gn trong gi p sut dc NPT c kch thc 12.7 mm, n c gng ti y ca mandrel. Vi qu trnh hot ng dng chy trong ng khai thc, dng chy i vo l thng ca thit b iu khin dng chy, xung gi p sut v vo mandrel thng qua cc l thng ca n (l thng giao tip vi ng khai thc). Li ch: Lm gim vn tc va p ca kh vi thnh mandrel. Vic t bo v kch c qu nng l bc kim loi bn ngoi ca mandrel chng s ph hu khi ci t trong qu trnh hon thin ging. Tng thch vi cc thit b iu khin dng chy ca cc nh sn xut khc.Cng ngh khai thc du kh 812 PGS. TS. L Phc Ho

Van gasliftc t trong mandrel su thit k nhm kh ho ct cht lng pha trn van Van c cu to c bit cho php iu khin qu trnh ng m van mt cch d dng nh p sut kh nn hay bng p sut ct cht lng khai thcCng ngh khai thc du kh 813 PGS. TS. L Phc Ho


814

PGS. TS. L Phc Ho

Cu to ca van gasliftVan gaslift c cu to ch yu t nhng b phn sau: Thn van Bung cha kh nit Ti van L dn kh


815

PGS. TS. L Phc Ho

Van gaslitfChc nng ca van gaslift

T ng ng m, cch ly hoc khai thng vng khng gian bn ngoi v bn trong ng nng

Gim p sut khi ng tng hiu qu s dng nng lng ca thit b nn kh (cng cng sut my nn kh, chiu su kh nn vo ng nng tng ln)


816

PGS. TS. L Phc Ho

Phn loi van gasliftTheo ch lm vic chia ra: Van gaslift nh k Van gaslift lin tc Theo chc nng chia ra: Van gaslift khi ng Van gaslift lm vic Theo nguyn l lm vic chia ra: Van gaslift iu khin bng p sut Van gaslift ng m nh s chnh p Van gaslift ng m bng c hc Theo cu trc chia ra: Van gaslift dng bung kh Van gaslift dng l xo Van gaslift dng kt hp Theo phng php lp t chia ra: Loi c nh Loi c th tho m Theo thit b lp t chia ra: Loi lp t nh dng c cp ti Loi lp t nh thu liCng ngh khai thc du kh 817 PGS. TS. L Phc Ho

Phn loi theo chc nngVan gaslift khi ng: Dng tng su dn kh vo ct OKT bng cch ln lt kh ho ct cht lng bt u t van trn cng Cc van gaslift khi dng s ln lt ng cho n khi kh i vo van gaslift lm vic Khi a ging vo hot ng n nh, tt c cc van gaslft khi ng phi ng kn C th dng cho c ging khai thc lin tc v ging khai thc nh k Van gaslift lm vic: Dn kh vo ct OKT, duy tr qu trnh kh ha ct cht lng lin tc Ph thuc vo chnh lch p sut ca kh nn v ca ct cht lng ti ni t van m van gaslift lm vic c th t iu chnh lng kh nn theo yu cuCng ngh khai thc du kh 818 PGS. TS. L Phc Ho

Phn loi theo nguyn l hot ngVan gaslift iu khin bng p sut: qu trnh ng m van c iu khin bng p sut ca kh nn hay p sut ca ct cht lng khai thc Van gaslift iu khin bng chnh p: qu trnh ng m van c iu khin bng chnh p ca ct cht lng khai thc v kh nn Van gaslift c hc: t c s dng do cha hon thin v cu to v bt tin v iu khin. Qu trnh ng m ph thuc vo tc ng c hc t trn b mtCng ngh khai thc du kh 819 PGS. TS. L Phc Ho

Phn loi theo cu trcVan gaslift dng bung cha kh Nit: Tc nhn ng loi van ny l do lc p sut ca kh Nit nn trong bung cha kh Van Gaslift dng l xo: Tc nhn ng loi van ny l do lc n hi ca l xo thay v kh Nit nn trong bung cha kh Van gaslift dng kt hp: Tc nhn ng van ca loi van ny l do tng hp lc n hi ca l xo v lc p sut nn ca kh Nit trong bung cha khCng ngh khai thc du kh 820 PGS. TS. L Phc Ho

Phn loi theo phng php lp tVan gaslift c nh: c lp t ngay trn ct OKT v th cng vi ct OKT vo ging Hin nay hu nh khng c s dng v tnh bt tin do phi tin hnh qu trnh ko-th ton b ct OKT tho d van Van gaslift c th tho d: c lp t vo mandrel nh k thut cp ti Ti cha c ni v th cng ct OKT vo ging theo chiu su thit k.Sau van gaslift c lp t hay tho d thay th nh k thut cp ti m khng cn phi ko th ton b ct OKT


821

PGS. TS. L Phc Ho

INJECTION PRESSURE OPERATED GASLIFT VALVESDng trong ging khai thc gaslift lin tc hoc nh k c iu khin bng p sut kh nn Lp vo bn trong mandrel, dng kim sot kh nn v dng chy t KKVX vo ct OKT Gm 1 bung kn, vi 3 lp ng xp cha kh N2 c np trc-cung cp lc ng cho van, khi p sut kh nn vut qu lc ng ca van, ng xp b nn li, cho php kh y qua van c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong gingCng ngh khai thc du kh 822 PGS. TS. L Phc Ho

PILOT OPERATED GAS LIFT VALVESDng trong ging khai thc gaslift nh k c iu khin bng p sut kh bm p Dng iu khin dng kh vo ct OKT trong sut qu trnh khai thc gaslift nh k Van c thit k vi 1 khoang kn, gm 3 lp, cha kh N2 c np trc cung cp lc ng cho van, khi p sut kh bm p vt qu lc ng van, ng xp b nn li, kh sau khi qua v tr ny, b nn bi piston, nn s cho php 1 lng ln kh bm p nhanh vo ct OKT c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong gingCng ngh khai thc du kh 823 PGS. TS. L Phc Ho

ORIFICE VALVES

Dng iu khin kh nn hoc cht lu t khong khng vnh xuyn vo ct OKT c dng nhng ni c p sut iu khin khng c nh mong mun v c thit k khi p sut ct ng chng v OKT xc nh. 1 thit b van kim tra s ngn khng cho dng chy ngc qua van c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong gingCng ngh khai thc du kh 824 PGS. TS. L Phc Ho

Production-Pressure-Operated Gas Lift ValvesDng trong khai thc gaslift lin tc hoc nh k. L la chn tuyt vi cho nhng ni p sut kh bm p thp hoc khng n nh c iu khin chnh bng p sut ca dng cht lu khai thc uc lp vo mandrel v dng kim sot khi dng kh i vo cht lu khai thc c thit k vi 1 ng xp cha 1 l xo nn cung cp lc ng cho van.Khi p sut vt qu lc ng ca l xo, ng xp b nn li v cho php kh i qua van Khng b nh hng bi t0 y l khoan v thit b chng chy ngc s kim sot khng cho cht lu khai thc chy ngc qua van c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong gingCng ngh khai thc du kh 825 PGS. TS. L Phc Ho

DUMMY VALVESc lp vo bn trong ca mandrel nh 1 thit b c lp, gi cho maldrel bt kn l khoan t lu cht khai thc cho n khi chng di chuyn xong c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong ging


826

PGS. TS. L Phc Ho

EQUALIZING DUMMY VALVESc lp vo bn trong mandrel nh l 1 thit b tch cn bng c s dng khi tn ti s chnh lch p sut ln gia ct OKT v KKVX, nu s chnh lch p sut ca ca mandrel gy ra s mt cn bng t ngt ca lu cht c th gy nguy him cho cc thit b trong ging c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong ging


827

PGS. TS. L Phc Ho

SHEAR ORIFICE VALVES Dng iu khin dng kh hoc cht lu t KKVX vo ct OKT, v hat ng nh 1 dummy valve trc khi n hot ng c s dng khi cn t c s chnh lch p sut gia KKVX v ct OKT, van ch m ra khi p sut ca KKVX tng ln v ln hn p sut ct OKT c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong ging


828

PGS. TS. L Phc Ho

CIRCULATING VALVES S dng nhm to s lin h gia vng KKVX v bn trong ct OKT c lp t vo bn trong ca mandrel ngn cn dng kh hoc cht lu gy hi cho mandrel trong sut qu trnh tun hon vi tc cao c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong ging


829

PGS. TS. L Phc Ho

CHEMICAL INJECTION VALVES

Dng kim sot cht lu y vo trong ct OKT, kim sot s n mn trong ging, x l parafin, mui ho tan v ngn cn qu trnh hydrate trong ging c thit k vi 1 l xo lm bng hp kim Nikel cung cp lc ng cho van L xo nn cho php thay i p sut lm vic t 500 4000 psi c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong gingCng ngh khai thc du kh 830 PGS. TS. L Phc Ho

CHEMICAL INJECTION CHECK VALVES Ngn cn khng cho dng kh hoc cht lu chy ngc t ct OKT vo khang khng vnh xuyn, c lp t bn ngoi mandrel C th s dng mt mnh hoc lin kt vi 1 van c hc tng kh nng bo v c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong ging


831

PGS. TS. L Phc Ho

HYDRAULIC MULTI-POSITION GAS LIFT VALVE

Dng kim sot th tch kh hoc cht lu t khong khng vnh xuyn vo ct OKT HMPGLV cn 1 ng iu khin nc n. Loi van ny c th chy c c v tr ng hoc m


832

PGS. TS. L Phc Ho

REVERSE FLOW CHECK VALVES L loi van dng ngn cch khng cho dng kh hoc cht lu i ngc tr li khong khng vnh xuyn v c lp t bn ngoi mandrel

c ch to bng thp khng g hoc hp kim Nikel chng li s n mn ca CO2 v H2S trong ging


833

PGS. TS. L Phc Ho


834

PGS. TS. L Phc Ho


835

PGS. TS. L Phc Ho

Nguyn tc hot ng ca van gasliftKhi nim chung Thng s dng van gaslift dng bung kh nn Bung kh nn l b phn quan trng nht ca van Van gaslift dng bung kh nn c 3 chi tit quan trng sau: Tit din bung kh nn Ab Tit din ca l dn kh Ap Tit din hiu dng ca bung kh nn Ab - Ap Trn c s cc tit din trn ta c cc khi nim: Yu t bung kh nn: Fb = Ab / (Ab Ap) Yu t l dn kh: Fp = Ap / (Ab Ap)


836

PGS. TS. L Phc Ho

Nguyn tc hot ng ca van gaslift

1- Thn van 3- Ti vanCng ngh khai thc du kh

2- Bung cha kh nit 4- L dn kh837 PGS. TS. L Phc Ho

Nguyn tc hot ng ca van gaslift kiu bung cha kh nit iu khin bng p sut kh nnPhng trnh cn bng p sut khi m van: khi van chun b m ta c phng trnh cn bng lc: Pkm( Ab Ap) + Plm Ap = PbAb (1)

m: ch trng thi van khi chun b m Nu van gaslift kiu kt hp (c l xo h tr lc ng van) th phng trnh tr thnh: Pkm( Ab Ap) + Plm Ap = PbAb + Plx(Ab Ap) Plx: p sut n hi ca l xo (2)


838

PGS. TS. L Phc Ho

Nguyn tc hot ng ca van gaslift kiu bung cha kh nit iu khin bng p sut kh nn

Chia (1) v (2) cho (Ab Ap), ng thi thay cc yu t bung cha khi nit Fb = Ab/ (Ab Ap) v yu t l dn kh Fp= Ap/ (Ab Ap) ta c pt: Pkm + PlmFp = Pb Fb Pkm + PlmFp = Pb Fb + Plx Khi bit p sut Pkm, Plm, p sut cn np vo bung kh nn c dng: Pb=(Pkm + PlmFp Plx) / Fb Hoc t (1) ta c: Pb = Pkm - (Pkm Plm) Ap/ AbCng ngh khai thc du kh 839 PGS. TS. L Phc Ho

Phng trnh cn bng p sut khi ng vanKhi van chun b ng ta c pt cn bng lc: Pkd(Ab Ap) + PkdAp = PbAb K hiu d ch trng thi van chun b ng Nu van Gaslift kiu kt hp th: Pkd(Ab Ap) + PkdAp = PbAb + Plx (Ab Ap) C th a ra cng thc xc nh p sut ng theo cng thc m hay ngc li: Pkd = Pkm (Pkm Plm)Ap/Ab


840

PGS. TS. L Phc Ho

Nguyn tc ca van gaslift kiu bung cha kh nit iu khin bng p sut ct cht lng Phng trnh cn bng p sut khi m van: Plm(Ab Ap) + PkmAp = PbAb (*) Trong m ch trng thi van chun b m Nu van gaslift kiu kt hp th ta c: Plm(Ab Ap) + PkmAp = PbAb + Plx( Ab Ap) (**)


841

PGS. TS. L Phc Ho

Nguyn tc ca van gaslift kiu bung cha kh nit iu khin bng p sut ct cht lng Chia (*) v (**) cho (Ab Ap), ng thi thay yu t bung cha kh nit Fb = Ab/(Ab Ap) v yu t l dn kh Fp = (Ab Ap) ta c: Plm + PkmFb = PbFb Plm + PkmFb = PbFb + Plx Khi bit p sut Pkm v Plm, p sut cn np vo bung kh nn c dng: Pb = (Plm + PkmFp Plx)


842

PGS. TS. L Phc Ho

Phng trnh cn bng p sut khi ng vanKhi van chun b ng th pt cn bng lc: Pld(Ab Ap) + PldAp = PbAb K hiu d ch trng thi van khi chun b ng Nu van gaslift kiu kt hp ta c: Pld(Ab Ap) + PldAp = PbAb + Plx(Ab Ap) Ta c cc phng trnh tng ng: Pld = Pb Pld = Pb + Plx / Fb Kt hp hai cng thc tnh p sut ng v p sut m van ta c: Pld = Plm (Plm Pkm) Ap / AbCng ngh khai thc du kh 843 PGS. TS. L Phc Ho

Nhn xt Van ch nh li khi p sut ct cht lng cao hn gi tr cn thit m van Trong thc t khai thc du bng gaslift, van gaslift loi bung cha kh nit iu khin bng ct p sut cht lng thng c s dng kiu kt hp


844

PGS. TS. L Phc Ho

Nguyn tc np kh cho van gaslift kiu bung cha kh nit Qu trnh np kh v hiu chnh cho ng vi gi tr thit k c tin hnh trm np kh v th van gaslift p sut np cho bung cha kh nit thng c hiu chnh nh ga tr p sut np biu kin Trn c s cng thc xc nh p sut m van ta c: Pko(Ab Ap) + 0 = PboAb + Plx(Ab Ap) Pko = FbPbo + Plx Pbo- p sut cn np vo bung kh nit 15.5oCCng ngh khai thc du kh 845 PGS. TS. L Phc Ho

S nguyn l cu to ca trm np kh v th van gaslift 1- Van gaslift 3-4 p kCng ngh khai thc du kh 846 PGS. TS. L Phc Ho

2- Bung th p sut

Nguyn tc np kh cho van gaslift kiu bung cha kh nit i vi van gaslift loi bung cha kh nit iu khin bng p sut ct cht lng, Pbo = 0 nn: Pko = Plx Do lc n hi khng b nh hng bi yu t nhit ca cc ging khai thc nn: Pko = Plm + PkmFb


847

PGS. TS. L Phc Ho

Nguyn tc np kh cho van gaslift kiu bung cha kh nit i vi van gaslift c np kh nit vo bung kh, ngha l Pbo khc khng: H s iu chnh nhit Ct = Pb/Pbo Ct = [460 + (1.8t + 32)]z1 / 520z15 t- nhit ti su t van z1 v z15- h s nn ca nit iu kin nhit t v 15.5oC Lc ny gi tr p sut np biu kin: Pko = (Pkm + PlmFb) / CtCng ngh khai thc du kh 848 PGS. TS. L Phc Ho

nh hng ca nhit ti cc thng s lm vic ca van gasliftTh hin qua thng s hiu chnh nhit Ct Tn ti 2 ch nhit khc nhau ph thuc vo ging lm vic hay ngng: Nu ging khng hot ng th ng phn b nhit dc theo thn ging tng t nh ng phn b a nhit Nu ging t phun th ng phn b a nhit ph thuc vo: trng a nhit, l lng khai thc, kch thc ng khai thc, ngm nc. Tng t i vi ging khai thc bng gaslift i vi ging khai thc bng gaslift, van gaslift cn chu nh hng bi hiu ng lm lnh do kh nn gin n ra khi i qua van.Cng ngh khai thc du kh 849 PGS. TS. L Phc Ho

nh hng ca ng knh l van gaslift ln lng kh nnLu lng kh nn qua van gaslift c xc nh:k +1 2 2 438.3d P k P2 k P2 k 1 qk = kr(273+ t) k 1 P1 P1

k- h s n on nhit ca kh c xc nh k = Cv/Cp Cv v Cp l nhit dung ring ca kh khi th tch v p sut khng thay i tng ng: P1 v P2 p sut trc v sau l dn kh d- ng knh l dn khCng ngh khai thc du kh 850 PGS. TS. L Phc Ho

nh hng ca ng knh l van gaslift ln lng kh nn Ngoi ra c th xc nh qk bng biu c xy dng sn theo P1 v P2, ng knh l dn d v mt kh nn kr Gi tr lu lng kh nn qua van gaslift c xc nh bng biu phi chia cho h s hiu chnh Khc

K hc= 0.0544 kr (492 + 1.8t ) H s hiu chnh Khc cng c th xc nh bng biu xy dng theo cc gi tr nhit t v mt ring ca hn hp kh nn krCng ngh khai thc du kh 851 PGS. TS. L Phc Ho

Biu xc nh ng knh l van gaslift khi bit trc p sut v lu lng kh nn


852

PGS. TS. L Phc Ho

Biu xc nh h s hiu chnh ph thuc vo mt v nhit kh nn


853

PGS. TS. L Phc Ho

Cc ng c trng ca van gasliftCc ng cong trn biu din s thay i lu lng kh nn i qua van qk khi thay i ct p sut cht lng P1: Khi Pk = Pl v ln hn Pkd th van m nhng cha c kh i qua Khi Pk Pl > 0 kh bt u qua van kh ha ct cht lng qua van Lu lng qua van tng dn v t l thun vi chnh p v t n gi tr cc i Nu tip tc gim Pl th lu lng s gi nguyn mc cc i (ng 1), hoc l gim (ng 2 hay ng 3)Cng ngh khai thc du kh 854 PGS. TS. L Phc Ho

Cc ng cong c trng dng kh chy qua l ca van gaslift

1- Lu lng kh nn gi nguyn mc cc i 2-3- Lu lng kh nn gim iCng ngh khai thc du kh 855 PGS. TS. L Phc Ho

ng c trng ca kh nn kiu dng chy qua l c nh van gasliftDng chy kiu qua l: khi gimPl t gi tr Pk n gi tr p sut Pk khng i th lu lng kh tng dn, t gi tr cc i, sau gi khng i(ng 1) Dng chy kiu qua l chia lm 2 phn: Dng chy di ti hn: Lu lng qk tng dn khi Pl gim trong khi gi Pk khng i Khi lu lng qk cc i, Pl gi l p sut ti hn Plth Dng chy ti hn: Khi p sut Pl gim thp hn Plth y l vng p sut kh nn Pk kh nng gi van m hon ton m khng cn s h tr ca p sut ct cht lng PlCng ngh khai thc du kh 856 PGS. TS. L Phc Ho

c trng ca kh nn kiu dng chy tit lu qua van gasliftDng chy kiu tit lu (ng 2): Gim Pl t gi tr Pk n p sut kh quyn trong khi Pk khng i th lu lng qk tng dn, t cc i sau gim n 0 ti 1 gi tr Pl no Khi Pl cn ln th tng p lc ca kh nn v ct cht lng thng c p lc ca bung cha kh Nit van m Khi qk t gi tr cc i nu tip tc gim gi tr Pl th tng p lc khng cn thng c p lc ca bung cha kh nit din tch l van gim, lng kh nn qua van gim dn theo kiu tit lu.D tng chnh p sut qua van, lng kh nn qua van tip tc gim n bng 0 Gi tr p sut Pl ti thi im van ng gi l p sut ng van ca ct cht lng Pld


857

PGS. TS. L Phc Ho

c trng ca kh nn kiu dng chy chuyn tip qua van gaslift Vng tn ti dng chy chuyn tip l vng gia 2 dng chy kiu l v dng chy tit lu Khi gim Pl t gi tr Pk n p sut kh quyn trong khi gi Pk khng i th lu lng qk tng dn, t gi tr cc i, sau gim dn nh kiu tit lu nhng khng gim n 0 (ng 3) Nh vy: Nu Pkd < Pk < Pkm :dng kh nn qua van theo kiu tit lu Nu Pkm < Pk : dng kh nn qua van gaslift theo kiu dng qua l c nhCng ngh khai thc du kh 858 PGS. TS. L Phc Ho

NGUYEN LY HOAT ONG CUA VAN GASLIFT VA TNH TOAN O SAU AT VAN KHI ONG

Nguyen ly hoat ong cua van gaslift Co hai loai van gaslift: van dang buong kh va van lo xo 1. Nguyen ly hoat ong cua van gaslift dang buong kh - Van chu tac ong cua hai lc ngc chieu nhau: ap suat nap san ban au trong buong kh tao mot lc gi van trang thai ong va lc ong van do cac ap suat trong ong khai thac va ong chong gay ra 2. Nguyen ly hoat ong cua van chu tai lo xo - Van chu tai lo xo khong duy tr ap suat nap san ban au ma dung lc lo xo e ong van. Lc ngc chieu co xu hng m van la ap suat ong chong va ap suat ong khai thac 3. Nguyen ly lam viec cua van co c cau ong m (pilot operated valve) - ay la loai van trch dung dch cung cap thuy lc e ieu khien s ong m cua van. Van co c cau ong m tng t nh van chu tai lo xo dang n nhng co gan them phan van chnhCng ngh khai thc du kh 859 PGS. TS. L Phc Ho

TNH TOAN O SAU AT VAN KHI ONG - e tnh toan o sau at van khi ong, can biet cac thong so sau: - o sau cua gieng - ng knh ong - o dai cot ong nang - Mc thuy tnh - Ty trong cua chat long - The tch kh khi ong : H (m) : D (mm) : L (m) : Htt (m) : cl (m3/T) : V0 (m3)

- ng knh cot ong nang : d (mm)

- Ap suat tren ng ong khi ong mieng gieng: pkhd (at) - Ap suat e cot ong nang khi gieng lam viec bnh thng: plv (at) - e hieu phng phap tnh toan o sau at van kh ong can phai biet qua trnh a gieng co trang b thiet b khi ong vao hoat ong.


860

PGS. TS. L Phc Ho

oi vi gieng khai thac theo che o vanh khuyen, kh c bm vao gieng se ay chat long t khong gian ngoai can vao trong ong nang qua cac van gaslift ang m. Nh vay mc chat long trong khoang khong vanh xuyen t t giam dan. Khi mc chat long at en o sau L1 cua van khi ong th nhat, kh se i vao ong nang qua van va lam cho mat o cot chat long tr len giam nhe i va ong thi lam cho ap suat ong nang giam theo. Chat long tiep tuc i qua cac van khi ong at pha di. Do o mc chat long ngoai can cung giam e cho can bang vi ap suat trong ong nang. Sau mot thi gian kh nen i qua van khi ong th nhat th ap suat tai ay se on nh va mc chat long ngoai can cung giam en o sau L1 tng ng. Nh vay van khi ong th hai phai at o sau cao hn o sau at van khi ong th nhat mot t nham muc ch tao ra o chenh lech ap suat e kh nen co the i qua van th hai. Kh nen luc nay se i qua ong thi ca hai van. Neu nh the tch kh nen vao vung ngoai can nho hn tong lng kh i qua hai van khi ong th ap suat ngoai can se giam i, khi no at en gia tr ong cua van th nhat th van nay se ong lai. Nh vay luc nay kh nen ch i vao van th hai ma thoi. C nh the mc chat long ngoai can tiep tuc giam en o sau cua van khi ong th ba va qua trnh tren c lap lai cho en khi nao mc chat long at en o sau cua van lam viec.Cng ngh khai thc du kh 861 PGS. TS. L Phc Ho

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Chuong 26 Phuong Phap Gaslift