846 U''''ng dung phuong trinh khuech tan ban kinh trong nidj^j^ojlg iTNG DUNG PHUTcnVG TRINH KHUECH TAN BAN KINH TRONG MO PHONG KHAI THAC DAU KHi VA NANG CAO HE SO THU HOI D A U Phung Dinh Thuc, Phan Trg[.]
846 U'ng dung phuong trinh khuech tan ban kinh nidj^j^ojlg: iTNG DUNG PHUTcnVG TRINH K H U E C H TAN BAN KINH T R O N G M O PHONG KHAI T H A C D A U K H i VA N A N G C A O H E SO T H U HOI D A U Phung Dinh Thuc, Phan Trgng Toan Cong ty Thdm do, Khai thde Dau TOM TAT Ddng chdy sdn phdm (ddng ddu khi) tdng chira viing can giing khai thac cd dgng hucmg tdm, v&i tdm la vl tri giing tdng chua Cdc phuong trinh liin tuc thiit lap theo md hinh ndy cho phip md td ddng sdn phdm vdo tdm giing giing khai thac Bdo cdo niu cdc phucmg trinh khuich tdn bdn kinh chuyin tu phuong trinh liin tuc di md phdng khai thde ddu viing can giing Niu l&i gidi gidi tich vd thuc hiin l&i gidi sd (trong mdt phdn mim tu viit) cua bdi todn sir dung phuong trinh khuich tdn bdn kinh Gi&i thiiu dp dung thuc tiin kit qud l&i gidi md phdng khai thde vd ndng cao thu hdi ddu GIOI THIEU Mo hinh vung gin gilng khai thac co nhiing dac trung rieng cho phep su dung cac phuong trinh mo phong Dong chay huong tam cua san pham khai thac (chat long, khi) vung gan gieng dugc coi la lien tuc, khong on dinh (mat thay doi theo thai gian), khong xoay (dong chay mong, tron), khong anh huong cua trgng truang, tuan theo dinh luat Darcy va djnh luat Bao toan khoi lugng Hon nOa moi truang quanh gieng eo dang hinh tru, dugc coi dang nhiet, c6 cau triic dong nhat, dang huong; ap suat thay doi vung la nho, phu thuoc vao 16 rong va tinh chat vat ly ciia dong san pham Phucmg trinh lien tuc dugc thiet lap he tga ban kinh co tam la gieng khai thac Cae phuong trinh khueeh tan cho dau va riit tu phuong trinh lien tuc ap dung tot mo phong khai thae, nang cao thu hoi dong san pham PHU^ONG TRINH KHUECH TAN Dang tong quat ciia phuang trinh lien tuc toa tru nhu sau: ^,lA(^K,)+iA(pF„)4(pF.)=o (1) dt r or r du dx Trong tga ban kinh phuang trinh tro thanh: SEPMprV,) = ^ (2) dt r dr Bilu diln van tie, mat do, he sl nen ding nhiet ciia chit long (dau) toa ban kinh theo giam ap suit P viing can gilng, phuong Uinh (2) tro thanh: Tuygn tap bao c^o Hdi nghj KHCN "30 nSm DSu Viet Nam: Cff hdi mdi, thach thuc mdi" dP_ dr r dr dP_ = 7- dt 847 (3) Phuang trinh (3) dugc goi la phuong trinh khuech tan ban kiph viing can gieng, chiing dugc diing thuc tl de mo phong gieng khai thac dau Bieu dien van toe, mat do, he so nen dang nhiet cua chat tga ban kinh theo giam ap suit P viing can gieng, va de y den dinh nghia cua "ap gia", "thofi gian gia", phuang trinh (2) tro thanh: \ d( dP„ r dr dr =K dP^ dt,, (4) Phuong trinh (4) co dang giong voi phuong trinh khuech tan ban kinh (3) su dung cho dau, chiing dugc dung thuc te de mo phong gieng khai thac Thong thuong phuang trinh (3) va (4) thuang dugc phan tich dang khong thu nguyen nhu phuang trinh (5) duoi day: d r,d nt dPi " a nl J di , GIAI PHLTONG TRINH KHUECH TAN De giai phuang trinh khueeh tan can phai biet dieu kien bien va dieu kien ban dau Trong mo hinh dong chay can gieng (tang ehua can gieng) co dang hinh tru voi bien la gieng (r = r,v) va bien ngoai la hinh try (r = v^) Thoi diem chua co dong san pham lay len mieng gieng, ap suat tai moi noi viing bang ap suat ban dau ciia via P| Tai rg dong san pham q = Tai r = r^v dieu kien bien phu thuoc vao phucmg phap khai thac vdi luu lucmg khong doi hoae khai thae voi ap suat day gieng khong doi Bai toan khong thu nguyen cho mo phong khai thac dau luu lugng khong doi la: - Phuong trinh khuech tan (5) - Dieu kien dau: Pd(rd, td= 0) = - Dieu kien bien trong: (6) Dieu kien bien ngoai: 5P/ 50 (7) Nghiem cua bai toan khuech tan co thi giai sl (giai gin diing) hoae bing giai tich (loi giai chinh xac) 848 u'ng dung phuong trinh khugch tan ban kinh mdj^hdngn:, Loi giai chinh xac Phuong trinh (8) rit phuc tap de xac dinh Pj nen thuc tl it diing, o mgt gioi ban thuc tl chip nhan dugc, Pj thuang duge xac dinh gin diing: - Khi gilng khai thac co thai gian khai thac dii IcDn, che dong chay san pham thiet lap trang thai on dinh gia (ap suit thay dii cham theo thoi gian), thi so hang chua ham Bessel (8) c6 thi bo di va Pj xac dinh theo: / ' = ^ +lnr.,-| f'l (9) ca - Mo hinh co bien va bien ngoai nhu bai toan khuech tan co the chuyen sang mo hinh tuong tu voi sua dii ban kinh gieng bang va P -> Pi r -> oo, nghiem ciia bai toan la: i P.=-'-E, J n ^ o / ^ 948c,