Geodetic Measurements of Underground Gas Reservoirs

Transcription

1 Acta Montanstca Slovaca Ročník 16 (2011), číslo 4, Geodetc Measurements of Underground Gas Reservors Jaroslav Šíma 1, Jana Ižvoltová 2 and Anna Sedlová 3 The sze of expected deformatons of underground gas reservors may be dependent on the volume of gas fullness. Accordng to the proportonal gas volume n both of measured gas reservors, the technology of geodetc measurements was taken out. Spatal dsplacements were observed by the method of vertcal lne, wth EDM and vertcal movements of montored ponts were measured by precse levellng. Together wth geodetc measurements, the geologcal survey was also realzed. Key words: gas reservors, precse levellng, spatal dsplacements, vertcal deformaton, method of vertcal lne Introducton The man functon of underground gas reservors conssts n compensaton of the seasonal dfferences of gas consumpton. In summer, the acqured surplus s mpressed nto the reservors, whch are vce-versa released n wnter. The reservors can cover the daly gas varances to ensure the servce securty of the dstrbutve network. In case of a short-tme and long-tme gas breakdown, the reservors ensure the relablty of gas supply (TASR). Deformaton measurement of the object surface s assocated wth the determnaton of subsurface deformatons, whch ndcates a problem of an underlyng geologcal envronment. These deformatons are not mmedately reflected on the geometrcal poston of structural changes. A new method of measurng subsurface deformaton called Tme Doman Reflectometry (TDR) has been mplemented n the geotechncal problems assocated wth the slope deformatons [2], as well as to measure the subsdence of ground objects and structures of Transportaton Engneerng [3]. At the future, a varety of use of TDR technology requres calbraton wth more precse method - lke e.g. geodetc measurement. In wnter 2009, the Department of Geodesy of the Unversty of Žlna performs geodetc measurements of two connected underground gas reservors to determne possble deformatons or shfts of the exposed parts of ther constructon, caused by volume changes of the compressed gas, heght dfferences of the lqud gas level or temperature changes, whch can eventually nfluence the reservors' walls deformatons, surface materal stranng or deformatons of ther technologcal facltes. Geodetc measurements of the both of reservors PZ1, PZ2 consst n fndng out the spatal and vertcal changes caused by mutual gas pumpng through the reservors. The observaton outputs depend on current gas parameters defned by gas level, fllng volume and temperature, weght and pressure of gas (Table 1). The deformaton values were defned by the comparson of both of observaton perods, done n October and November Tab. 1. Physcal parameters of the gas reservors. Frst observaton (October 2009) Second observaton (November 2009) Reservor PZ1 Reservor PZ2 Reservor PZ1 Reservor PZ2 Reservor total volume 500 m 3 500m 3 500m m 3 Gas level 466,0 mm 1 993,0 mm 2 369,0 mm 422 mm Temperature 11,0 C 11,5 C 6,5 C 9,5 C Pressure 0,646 MPa 0,658 MPa 0,628 MPa 0,608 MPa Volume ,07 l ,47 l ,54 l ,40 l Lqud f.+ gas f ,44 kg ,16 kg ,83 kg ,16 kg 1 doc. Ing. Jaroslav Šíma, PhD., Department of Geodesy, Unversty of Žlna, Unverztná 8215/1, Žlna, tel.: , fax: , jaroslav.sma@fstav.unza.sk 2 doc. Dr. Ing. Jana Ižvoltová, Department of Geodesy, Unversty of Žlna,, Unverztná 8215/1, Žlna, tel.: , fax: , jana.zvoltova@fstav.unza.sk 3 Ing. Anna Sedlová PhD., Department of Geodesy, Unversty of Žlna,, Unverztná 8215/1, Žlna, tel: , fax: , anna.sedlova@fstav.unza.sk 307

2 Jaroslav Šíma, Jana Ižvoltová and Anna Sedlová: Geodetc Measurements of Underground Gas Reservors Observatons n Top Secton of the Reservors Constructon Frstly, the spatal deformatons were observed n top secton of reservors constructon, where the maxmal deformatons were expected. Specfcally, t was on the connectng screws, whch were stuated n the upper parts of four reservor necks. Four permanent ponts, sgnalzed by red marks, were stablzed on every of reservor neck (Fg. 1). Reference system was based on two reference ponts 101, 102, whch were stablzed n upper part of both of constructons by plastc geodetc marks. Qualty of measurements s nvolved nto observaton accuracy estmated by measurements n reference system and was defned by angle standard devaton = 0,5 mgon (Fg. 2). m α Fg. 1. Observed ponts stablzed upon reservor neck. Fg. 2. Accuracy adjustment of angle measurements. Sxteen partcular ponts, stablzed upon the reservors necks were determned by terrestral measurements done wth total staton LEICA TCR 705. Ther precse poston s defned n Cartesan coordnaton system n both of perod of measurements. The coordnatonn dfferences Y, X, Z, whch were calculated from the both of measurement perods represent 3D shfts of the partcular ponts. The spatal deformaton s defnedd by postonal vector estmated accordng to the equaton: 2 p = X 2 + Y + Z 2, (1) The partcular values of spatal deformaton p are estmated n mllmetres and are nvolved n the last slope of Table

3 Acta Montanstca Slovaca Ročník 16 (2011), číslo 4, Tab. 2. Measurement of the spatal deformatons. Pont No. Frst measurements Second measurements Coordnaton dfferences Spatal Y X Z Y X Z Y X Z vector 1 96, , , , , ,6123 1,1-0,5-1, , , , , , ,5888 1,1-1,0-1, , , , , , ,5915-0,8-0,4-1, , , , , , ,6038 0,8-0,9-1, , , , , , ,5894 1,4-0,5-3, , , , , , ,5910 0,2 3,5-3, , , , , , ,5945 1,4-0,5-3, , , , , , ,5901 2,6-1,3-3, , , , , , ,7509-2,3-3,4-3, , , , , , ,7418-2,0-2,9-3, , , , , , ,7460-2,6-3,7-3, , , , , , ,7607-3,0-3,4-3, , , , , , ,7485-2,3-3,9-1, , , , , , ,7511-2,7-3,6-1, , , , , , ,7498-2,4-3,4-1, , , , , , ,7504-2,4-4,1-1,4 5.0 Observatons n Technologcal Part of Reservors Technologcal part of reservors (Fg. 3) s stuated behnd the abutment wall. Geodetc measurements were performed to ndcate the possble deformatons nfluenced by volume of the reservors fllng of gas. Fg. 3 Observaton n technologcal part of the reservors The possble deformatons were observed by the method of vertcal lne, whch s based on determnaton of devaton of partcular ponts from the vertcal lne realzed by two fxed ponts. Observed ponts were sgnalzed by adhesve targets bonded on the abutment wall (ponts 201, 301), on the handle of gas trunk (ponts 202, 203, 302, 303) and on the lower flange (ponts 204, 304). Detaled vew on technologcal part of both of reservors s n Fgure 4. The dstances from the vertcal lne represent the transversal shfts of the partcular ponts, whch were estmated accordng to the equaton: q = s tg ω (2) The partcular values of observed pont's shfts are shown n table 3 and 4 for both of reservors PZ1 and PZ2. The dfferences between basc and second measurements are shown n the last slope of the tables n mllmetres. Tab. 3. Transversal devatons relatng to the vertcal lne of reservor PZ1. Pont Frst perod (F) Second perod (S) (F) (S) No. s ω q s ω q mm

4 Jaroslav Šíma, Jana Ižvoltová and Anna Sedlová: Geodetc Measurements of Underground Gas Reservors Tab. 4. Transversal devatons relatng to the vertcal lne of reservor PZ2. Pont Frst perod (F) Second perod (S) (F) (S) No. s ω q s ω q mm Fg. 4. Detal of the technologcal sector of the both of reservors PZ1 a PZ2. Vertcal Observatons n Top Secton of Reservors Top secton of the reservors was also observed by the method of precse levellng wth dgtal level LEICA NA 3003 wth ts accessores to determne the vertcal deformatons of the constructons. The technology of measurement was based on the determnaton of vertcal dfferences between reference system and observed ponts, whch were stablzed upon the revealed reservors constructon. Vertcal shfts of the constructons were then estmated from the heght dfferences between the frst and second perod of measurements, related to the heght level of reference system. Reference system composed fve ponts stablzed n the surroundngs of the reservors. The stablty of the system was estmated by the comparson of vertcal dsplacements wth the tolerance, whch s nvolved n t = 2 multply of heght standard devaton, wth the probablty α = 0, 05 (Tab. 5): h > 2. m h m h = m 2L (3) 0 Tab. 5. Verfcaton of the stablty of reference system. Frst perod (m 0 = 0,24 mm) Second perod (m 0 = 0,25 mm) h [mm] 0,01 0,05 0,07 0,12 0,02 0,03 0,07 0,10 2m h 0,13 0,10 0,12 0,13 0,11 0,09 0,10 0,11 Observed ponts were stablzed n the top part of the reservors constructon where the maxmal deformaton was expected, namely, n every reservor neck (yellow marks n Fgure 1) and n the hangng control caps. The vertcal dfferences between the both of perods are lsted n the Table 6. Tab. 6. Vertcal shfts between the frst and second perod. Hangng control caps Reservors necks Reservor PZ1-2,3 0,0-0,6-0,3-1,1-1,5-1,5-1,1-1,2-1,1 Reservor PZ2 3,1 2,9 3,0 3,6 1,7 0,9 1,7 1,1 1,1 1,1 310

5 Acta Montanstca Slovaca Ročník 16 (2011), číslo 4, Contrbuton In respect of the great experence wth the deformaton measurements, the estmated deformaton of gas reservors can be consdered to be sgnfcant wth an applcaton of statstcal hypothess testng. Defnng the null hypothess aganst an alternatve one H 0 : = 0 H 1 : 0 (4) we are able to judge the constructon deformaton wth respect to the crtcal value m p. Null hypothess s confrmed, when an nequalty exsts m On the other sde null hypothess s not accepted f > 2 m where m = m p = 0,5 mm s equal to the spatal standard devaton estmated from the observatons n top secton of reservors m = mq = 0,2 mm s equal to accuracy of determnaton of transversal shfts estmated from the measurements n technologcal part of reservors m m = 0,2 mm s heght standard devaton estmated from the precse levellng. = h The both of perods of measurements were realzed under two alternatves, the frst one represents the stuaton where the left reservor was released and the second one was full and the second one was not the case. Summarzng both of cases, the left end of reservors constructon seems to be n movng. The estmated vertcal deformatons 2-4 mm does not ndcate to the meanngful motons n the base layers of the reservors. On the rght sdes of reservors, the deformatons are not confrmed, too. Realzed observatons confrm that up to now acqured deformatons are n the frame of constructon tolerances, but the tendency and drecton of the measured deformaton vectors seems to be notable. For the purpose of obtanng more objectve results, long-tme observatons are necessary. References [1] Fnal report from deformatons observatons of underground gas reservors. Unversty of Žlna, [2] Drusa, M., Chebeň, V.: Geotechncal montorng of road embankment n landslde area by Tme Doman Reflectometry technology, 11th Internatonal Multdscplnary Scentfc GeoConference SGEM2011, Conference Proceedngs ISSN , June 20-25, 2011, Vol. 1, pp. [3] Drusa, M., Masarovčová, S., Chebeň, V.: Experence wth the mplementaton of TDR technology for slope deformaton montorng. Proceedngs of XX POLISH - RUSSIAN - SLOVAK SEMINAR Theoretcal Foundaton of Cvl Engneerng, Warszawa - Wroclaw Sept. 5 10, 2011, BTO Prnt [4] Hodas, S.: Long-tme geodetc observatons of deformatons. In: Geodesy, Photogrametry and Engneerng Geodesy n nformaton socety. Internatonal conference hold on the occason of 50th annversary of the Department of Geodesy foundaton, STU Bratslava 2001, ISBN , p [5] Vllm, A., Mužík, J.: LMVQUIE applcaton to EDM parameters estmaton. In: Annotaton collectons. 13th Techncal conference of PhD. study, VUT Faculty of Cvl Engneerng, Brno JUNIORSTAV 2011, p. 7, ISBN [6] Černota, P., Staňková, H., Fečko, P., Pospíšl, J., Bedrunka, M.: Connectng and Orentaton of the Horzon of Mne Workngs, 11th Internatonal Multdscplnary Scentfc GeoConference, SGEM2011 Conference Proceedngs/ ISSN , Vol. 1, pp. 311