Monitoring and Characterization Based Upon Geophysical Onset Times*

Transcription

1 Mnitring and haracterizatin Based Upn Gephysical Onset Times* Dn Vasc 1 Search and Discvery Article #4237 (217)** Psted March 2, 217 *Adapted frm ral presentatin given at AAPG Internatinal nference & xhibitin, Barcelna Spain, April 3-6, 216 **Datapages 217 Serial rights given by authr. Fr all ther rights cntact authr directly. 1 Lawrence Berkeley Natinal Labratry (rdica_negulescu@htmail.cm) Abstract Gephysical methds are increasingly called upn t mnitr fluid injectin and prductin. Gephysical mnitring f flw related prcesses is hampered by difficulties in relating changes in fluid saturatin and pressure t bservable quantities such as seismic amplitude changes, variatins in electric fields, and surface defrmatin. Prblems are particularly acute when relating changes in the amplitudes f bservable gephysical quantities t the magnitudes f fluid related changes in a reservir. In such cases the relatinship depends strngly upn the rck physics mdel that is chsen. In this presentatin I present an alternative apprach t reservir mnitring and characterizatin that is based n the ntin f an nset time. An nset time is the calendar time at which a measured quantity begins t deviate frm its backgrund r initial value. In many cases invlving injectin and prductin, the nset time is related t the arrival f a fluid frnt r a rapid increase in pressure. Under the relatively general cnditin that a change in fluid saturatin and/r pressure leads t a change in a gephysical attribute, it can be shwn that nset times are sensitive t flw prperties, such as permeability, and nt sensitivity f the details f the rck physics mdel. Several examples f the use f nset times fr mnitring and characterizatin will be given, invlving bth gedetic and seismic bservatins. One example invlves the gedetic mnitring f grund defrmatin assciated with the gelgical strage f injected carbn dixide at In Salah, Algeria. Seismic timelapse mnitring f injected carbn dixide at the Fri site in Texas prvides yet anther example. References ited Vasc, D.W., A. Bakulin, H. Baek, and L.R. Jhnsn, 215, Reservir characterizatin based upn the nset f time-lapse amplitude changes: Gephysics, v. 8, January-February. Vasc, D.W., T.M. Daley, and A. Bakulin, 214, Utilizing the nset f time-lapse changes: a rbust basis fr reservir mnitring and characterizatin: Gephysical Jurnal Internatinal.

2 Presenter s ntes: Our gal is a very cmplete reservir characterizatin/making use f all majr data types. mphasis n practicality f the algrithms. It is imprtant t include all available reservir engineering data as this is directly sensitive t reservir flw prperties. Field testing is imprtant t ensure that ur methds are truly effective. Finally, we need t get these tls int the hands f industry.

3 Issues: Wuld like t estimate prperties such as permeability Gephysical data indirectly related t flw prperties ven time-lapse bservatins depend upn a rck physics mdel AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

4 Apprach: Avid using the magnitude f gephysical changes due t variatins in the state [saturatin, pressure, stress] f the reservir Use the nset time f changes in gephysical bservatins AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

5 Outline: Onset times Illustratin based upn time-lapse seismic amplitude changes Inversin fr reservir permeability nclusins AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

6 Definitin: Onset time - The time at which a seismic bservatin begins t change frm its backgrund value. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

7 Seismic Time-Lapse Reflectin Amplitudes AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

8 Apprach: Use reservir mdel t cmpute seismic amplitude changes due t O 2 injectin mpare inversin based upn seismic amplitudes with ne based upn nset times AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

9 AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

10 1.RO Km..c 1: z <D U L 2 '" BIV r:tt AJ\B F.AS"'" OJ} 2 24O PI"':S.5UII: (M -)A) ItH, Km Km 185.<: 1: Z 13 " U l "' '"".<: Z <D U -;;; l :S Distance ast (m). Arrival -ime (cays) 2O. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

11 . IX=3, IY=4.1 IX=4, IY= "----' I f D- w I I 2. i=======;::=:-l== L I I (j) I- Z => U w.5 U.u => t: -,5 --' L :::;; <:(.1 U :::;; {I) -.15 W (f) , , ,.5G TIM (5) '-I------'I r- I ,LI OMPRSS IONA L V LOITY (KMjS) AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

12 Issues: The relatinship between the reservir state and seismic velcities is cmplicated Thught t depend upn messcpic [cm t m] variatins in saturatin, pressure, and mechanical prperties AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

13 Seismic velcities depend upn hw fluids are distributed and averaged by the prpagating wave. K Vigt = 1 = K Reuss 3 ås K i i i=1 3 å S i K i=1 i Vigt average Reuss average K = 1 ( Hill 2 K + K ) Hill average Vigt Reuss AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

14 3.4 (j)..y. '--" >- -+- U Q) > Reuss (j) (j) (]) I..... U Sa tura ti n (f rlct i n ) AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

15 Hi li , 185 '--./ '-- c 13 Q) U +- (/) _ _ _ Dista nce e a s t (m ) Amplitude c ha n ge (fractin) 1. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

16 Re uss ====== , V igt , r "..c L L 13 13O OJ OJ U U III 75 III 75!J O D D DD!: _,r_ _,r_ Distance east ( m ) Distance east ( m ) Amplitude change (fractin) 1. Amplitude change (fractin) 1. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

17 5 5,.-." 4 - U1 V 3 - '-' <l> «1 - A, nset ', I \ I I \ I.\..... '- \ , "'- ++,-,-,,, r, I I I i'2!._, \"iill r " Reuss ,, '. nset.,,.,",, I I I I,\, " +... Vigt, ' \ '...,.' -\ + +'t! Reuss a S u rvey t im e ( d ays ) B, S u rvey time (days) AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

18 Re u ss 24-r V igt 24, '--../ 185 '--../ 185 L: L: "-- Z 13 "-- Z 1.3 Q) U (!) 75 Q) U (!) 75 2-r _, r_ r , ,, i 2 75 Dista n ce 13 a st 185 (m) Distance 13 ast 185 (m) 24 Onset time (days) 9 Onset ti m e (days) 9 AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

19 Iterative inversin AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

20 Presenter s ntes: (1) In ur apprach we intrduce a new methd fr the matching f reservir engineering data, based upn streamline simulatin. (2) With this new methd we can develp efficient ways t integrate prductin and seismic data. (3) Field applicatins are an imprtant part f ur apprach as they indicate what will be feasible.

21 Iterative Updating Algrithm Iterative mdificatin f the reservir mdel t better match nset times: K m = K m-1 +DK m That is, t better match bservatins in a least squares sense: Misfit = ( dt - AdK ) T ( dt - AdK ) m m quivalent t slving the linear system: A T AdK m = A T dt AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

22 Influence f the rck physics mdel AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

23 Time-Lapse Amplitudes d F ( K) Hill Hill dreuss FRe uss ( K) d F ( K) Vigt Vigt Hill Inversin rrect Sensitivities T Reuss Inversin Vigt Inversin A A K A d Hill Hill m Hill Hill T T Hill Hill m Hill Reuss A A K A d T A A K A d Hill Hill m Hill Vigt T T AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

24 1 Amplitude Inversin "- '", Reuss , "a , Vigt Hill 'a._ Hill Reuss _ Vigt "t I t--t--t--+-+-i Iterat i n 15 AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

25 Km Hil l ::: lase.r:: 1: s: Z 13e- Z 13 " c " c Q> " Vl 7Stl 75 '" 2 2 2:) O Reuss Vi t 2>1 24 O. 185 ISSG.r:: -<= 1: L Z 13 Z Ql Q) U " Ui i 75 Vl , , , le Distance a st (m) Lg 1K Mu ti plier 1. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

26 Onset times d F ( K) Hill Hill dreuss FRe uss ( K) d F ( K) Vigt Vigt Hill Inversin rrect Sensitivities T Reuss Inversin Vigt Inversin A A K A d Hill Hill m Hill Hill T T Hill Hill m Hill Reuss A A K A d T A A K A d Hill Hill m Hill Vigt T T AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

27 Onset Time Inversin 2 -;;- + Q) I- ::J U) Hill Reuss _ Vigt + Vl > x -+ '+ Vl 4 - I 2,, I 4 6 Itera tin I.L.L I 8.L 1 AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

28 Km Hi ll 24) J '85.c 1:: '- '- z 13:> Z ' 3 " OJ <.l <J Vl 7S Vl '" 75:) lbse." 2 2J GO 185 2/ Reu ss V igt '\ c 15 '- r.c -;: L Z 13 Z 13 (1J w U U Vl 7.') Vl , , , , r------, l :.1 u lj.ou -1. Lg ' U K \lultiplle' 1. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

29 Variatin in the time inverval between seismic surveys AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

30 Da y Interval 6 Day Interva l 185 '" L Z 13 w U 75 2':) +----,-----,----, ,-----,----, ec' ' Day Interva l 3 Day Inter va l ll:io Ie L Z 13 r c -;;; ,,----,----, ,-----,----, e [,::1 Distance ast (m ) Dista nce ast (m) On s et time (days ) 9 Onset time (days) 9 AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

31 1 5 Day I nt e r va I 6 Day Int e rval "" t Z ID U c Day In t e rvl I 3 Day I nt e rva I?.ir, 24, I SSG 1 gs "" Z v u c. w I I 'iO I.'O Distance ast (m) Distance ast (m) -1.:) Lg 1K Multiplier Lg 1K Multiplier 1, AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

32 nclusins Relatinship between changes in the state f a reservir and gephysical bservatins can be cmplicated and cnfunded by prly knwn equatin-f-state parameters Inversin based upn nset times appear stable with respect t variatins in the saturatin/velcity relatinship AAPG/SG Internatinal nference and xhibitin 216, 3-6 April

33 Acknwlegments This material is based upn wrk supprted by the U. S. Department f nergy, Office f Science, Office f Basic nergy Sciences, hemical Sciences, Gesciences, and Bisciences Divisin under cntract number D-A2-5-H Additinal supprt was prvided by Aramc Research. AAPG/SG Internatinal nference and xhibitin 216, 3-6 April