Operations II. Watch Circle Assessment of Drilling Risers during a Drift-Off and Drive-Off Event of a Dynamically Positioned Vessel

Transcription

1 th s Name Name f the Pape Sessn DYNMIC POSITIONING CONERENCE Nembe 15-16, 25 Opeatns II Watch Ccle ssessment f Dlln Rses dn a Dft-Off and De-Off Eent f a Dnamcall Pstned Vessel Kenneth halla and Ysn Ca Stess Enneen Seces, Inc. Hstn, Teas. S. Retn t Sessn Dect

2 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses STRCT The pma bjecte f a Dft-Off assessment s t addess the beha f a dlln se when all thstes lse pwe and ae n lne capable f mantann the dlln essel n statn. Wheeas, the bjecte f the De-Off assessment s t assess the beha f the dlln se sstem when the thstes malfnctn and case the dlln essel t me awa fm statn snfcantl. If an f these eents ccs, an emeenc dscnnect mst be ntated between the LMRP and OP, thewse a fale ma cc n the se wellhead sstem. The ppse f the Dft-Off and De-Off assessment s t detemne een, ellw, and ed watch ccles f allwable essel ffset afte whch Emeenc Dscnnect Seqence EDS s ntated wtht damae t the se. fte the essel eceeds the een watch ccle, the essel s n a deadn stats. fte the ellw watch ccle s eceeded, pepaatns ae made f EDS ntatn. t the ed alet, EDS s cmmenced. The Dft-Off and De-Off espnse f a essel s a fnctn f the essel chaactestcs and the ennment. The essel espnse and EDS allw peats t assess the sk asscated wth a en ennment. The De-Off and Dft-Off analss stats wth the efft t detemne ffset and headn as fnctns f tme tajectes f the DP essel n as De-Off and Dft-Off scenas and ennments. Sftwae and technqes hae been deelped t assst the DP essel desne and peat t deelp apppate watch ccles and assess the asscated sk n a en ennment. The nhse sftwae DP-SHIPMO s sed t detemne the essel Dft-Off and De-Off espnse. Cmmecal sftwae S and n-hse sftwae DERP ae sed t deelp the se espnse t the essel Dft-Off and De-Off. 1. METHODOLOGY The fst phase f the pcess s t detemne the essel espnse taject as a fnctn f tme. The essel taject cnssts f: Vessel ffset as a fnctn f tme Vessel aw as a fnctn f tme The ntal cndtns f the essel s ctcal n detemnn the essel taject and cnsst f the fllwn: Vessel headn Ennment Wnd/Wae dectn Cent dectn Thste schedle hw mch thst s appled, n what dectn, and f hw ln e 1 shws an eample f the essel mtn smlatn t a De-Off eent. The taject f the essel s shwn at eqal tme nteals. The thck ed lne shws the essel pstn at the stat f the eent. The thn dak ble lne ndcates the pstn at whch the se wld pat. The smlatn cntnes assmn the se wld nt pat. The pst-fale smlatn des nt Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 1

3 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses smlate the eal statn bt sees a means t ef the accac f the smlatn. The black lne ndcates the fnal pstn f the essel. ame 1 9 p 23 Shp Pstn 2 1 De-ff Smlatn f a DP Dll Shp Cent: 1.5m/s, 27 de Wnd: 15.24m/s, 18 de Wae: Hs=4.57m, Tp=9s, 18 de P-M Spectm Cent Wnd and Wae Y X e 1.1: De-Off Taject f a DP dllshp essel The tajectes ae then sppled t a tme dman fnte element mdel f the se, wellhead and casn sstem. The mdel cnssts f the fllwn dscete cmpnents: ppe fle jnt se tensnes dect actn we-pe telescpc jnt nne bael and te bael all se jnts lwe fle jnt OP/LMRP wellhead cnnect hh pesse wellhead hsn stctal cndct casn ntemedate casns sl mdel Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 2

4 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses The eslts ae pst-pcessed t pdce as espnses as fnctns f tme. Of nteest wll be the espnse f the fllwn: tensnes stke telescpc jnt stke ppe fle jnt anle lwe fle jnt anle mamm se stess wellhead bendn mment mamm stess n the stctal cndct casn mamm stess n the ntemedate casns nt check pe PI RP 2 n the cndct casn The tme-dman mdel des nt eplctl nclde the dnamc espnse f the se essel mpsed b waes. Sme f these espnses wll als hae a snfcant wae-feqenc cmpnent t them. eample, stke wll nclde a dnamc cmpnent cased b heae whch s a fnctn f headn. Ths can be calclated sepaatel. Lkewse, the ppe and lwe fle jnt anle wll a as a fnctn f headn. These dnamc anles can be calclated fm an n-hse feqenc dman se mdel. These dnamc cmpnents wll be nclded n the De-Off and Dft-Off analss b spepsn the dnamc cmpnent n the eslts fm the tme-dman mdel. The eslts f the assessment pde a set f plts f each De-Off Dft-Off scena. The plts wll shw the espnse hst f the se/wellhead and casn sstem as fnctns f tme wth the allwable lmts. The pnt at whch the fst lmt s eached ndcates the pnt f dscnnect. Sbtactn the asscated tme f the EDS, fm the pnt f dscnnect, wll lead t the laest allwable ads f the ed watch ccle. In addtn, sbtactn ff the tme eqed t pepae f dscnnect fm the ed watch ccle pdes the allwable ellw watch ccle., desable eslt wld be f the ed and ellw watch ccle t be mch lae than the watch ccle that the DP Vessel wld nmall peate wthn. If the eslts shw watch ccles that ae t small nnestent, then the eslt s a lmtatn n the peatn ennment sme ethnkn f the state f emeenc dscnnect ctea appled t the analss wld be eqed. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 3

5 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses The fllwn flwchat tlnes the pcess sed t detemne the essel watch ccles and cnsde the feasblt f the ennment and ntal cndtns t ense that the ntet f the se/wellhead/casn sstem s nt cmpmsed. Defne: Ennment, headn thste schedle Detemne Vessel Taject Inpt/detemne Vessel Ppetes Ense qalt f taject-pefm self cnsstenc checks Re-ealate essel ppetes YES Defne Dlln se, wellhead and casn mdel Detemne sstem espnse and watch ccles based n EDS tmes Re-ealate ennment Ense watch ccles ae adeqate YES e 1.2: Watch Ccle ssessment lw Chat Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 4

6 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses 2. VESSEL TRJECTORY DETERMINTION The mtn f the essel n the hntal plane se, swa and aw s cnsdeed snce the ffset and aw f the essel fm the well lcatn needs t be detemned. The heae, ll and ptch ae nt nclded n the essel taject smlatns. The effect f the wae ndced heae, ll and ptch mtns waes n the dlln se ae cnsdeed sepaatel. The essel s mdeled as a d bd. Tw cdnate sstems ae sed t descbe the mtn f the essel, a lbal cdnate sstem O X Y and a mn cdnate sstem fed t the essel O e The n f the essel-fed cdnate sstem s at the essel s cente f at. The O as s n the cente plane f the essel. The aw headn anle s defned as the anle f the O as meased fm O X as pste cnte-clck wse. 2.1 Eqatns f mtns The dnamc eqatns f the plane mtn f a d bd s smpl, M X = M Y = Y I = ψ Z X 1 whee M s the mass f the bd, I Z s the mment f neta f the bd abt the etcal as thh the cente f at, X, Y s the cdnate f the cente f at n the lbal cdnate sstem., X Y, and Z ae the ttal fces and mment actn n the bd. The dble dts abe a aable dente the secnd deate wth espect t tme. Y ψ O X e Vessel Cdnate sstems Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 5

7 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Let, be the essel elct cmpnents n the essel-fed cdnate sstem, then we hae, = X csψ Y snψ 2 = X snψ Y csψ X = csψ snψ 3 Y = snψ csψ whee X, Y ae the essel elct cmpnents n the lbal cdnate sstem. Let, be the fce cmpnents n the essel-fed cdnate sstem. Smlal, we hae the fllwn elatn between, and,, Y X = X = = = X csψ Y snψ csψ snψ Y snψ csψ snψ csψ X, Y Dente the aw ate as, =ψ 6 Dffeentatn Eq. 3 wth espect t tme, we hae, X = csψ snψ snψ csψ 7 Y = snψ csψ csψ snψ 4 5 Sbstttn Eqs. 5 and 7 nt Eq. 1, afte manplatn, we btan, M = M M = M I Z = Z 8 Cmbnn Eqs. 3, 6, and 8 es, X = csψ snψ Y = snψ csψ ψ = M = M M = M I Z = 9 Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 6

8 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 7 The etenal fce/mment actn n the essel can be epessed as, = = = se Z thste Z Z hd Z Z se thste hd se thste hd 1 The spescpts hd,, thste, and se dente the fce/mments de t hddnamc lad,, thstes and se n the essel, espectel. The hddnamc lad s fthe decmpsed nt, = = = dft hd Z dft hd dft hd, ~, ~, ~ 11 On the ht-hand-sde f each f the abe thee eqatns, the fst thee tems ae de t the acceleatn f the essel, the fth tem de t the tatnal elct f the essel, the ffth tem de t the elate flw elct mantde and headn t the essel, and the last tem de t the wae dft. Eq. 11 can be ewtten n mat fm, = dft dft dft hd hd hd, ~, ~, ~ 12 The sqae mat n Eq. 12 s efeed t as the added mass mat. Cmbnn Eqs. 9, 1 and 12, we hae the fllwn eqatn n mat fm, X M = 13 whee, = Z I M M M 14

9 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 8 = Y X ψ X and = Y X ψ X 15 and = se thst dft se thst dft se thst dft, ~, ~, ~ cs sn sn cs ψ ψ ψ ψ 16 The hddnamc deates,.e.,, and the added mass mat, ae the essel s hddnamc chaactestcs and nl depend n the essel emet and the wate denst. The nesn f Eq. 13 s, M X 1 = 17 Eq. 17 s a sstem f dna dffeental eqatns abt the state aable ect X wth espect t tme, pded the added mass mat,,,, ae knwn. Seeal standad nmecal ODE sles ae aalable f sln Eq. 17 f X. The ehlbe fth-ffth de Rne-Ktta methd whch s e stable and accate s chsen. 2.2 ce/mment Calclatns ce/mment de t the elate flw elct t the essel sall, the fces and mment f ths nate ae assmed t be qadatc fnctns f the elate elct and ae epessed as, = = = 2 2 2, ~, ~, ~ C C C c c c 18 The hae the same fm as thse f fce/mment de t a cent n the statna essel. The hddnamc ceffcents, c C, c C and c C ae efeed t as the cent fce/mment ceffcents and can be detemned b the mdel tests. The cent dectn s defned n the essel-fed cdnate sstem, meased fm the as.

10 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Mean fce/mment de t wae dft The mean wae dft fces and mment a wth the wae dectn wae elate t the essel. The can be calclated sn altnsen, 199, dft dft = 2 S ω C ω; dω wae wae dft dft wae = 2 S ω C ω; wae dω 19 dft dft wae = 2 S ω C ω; wae dω whee wae s the wae dectn meased n the essel-fed cdnate sstem. dft dft dft C ω ; wae, C ω ; wae, and C ω ; wae ae the qadatc dft fce/mment tansfe fnctns. The can be calclated sn WMIT. Sω s the wae spectm f a en ennment ce/mment de t the Smla t the fce and mment elatnshps de t the flw elct f the essel, the fces and mment n the epsed pat f the essel fm ladn ae assmed t hae the same fm f qadatc fnctns f the elate elct,,,, = C = C = C whee s the dectn meased n the essel-fed cdnate sstem. C, C, and C ae the fce/mment ceffcents ce/mment de t the thstes Each thste s assmed t pde a cncentated thst fce at the pnt the thste s lcated and n the dectn f the thste s amthn meased n the essel-fed cdnate sstem. Snce the thste s sall nt lcated at the essel s cente f at, t als pdes a mment n the essel. Let T be the thst fm the th thste, then the ttal fces and mment pded b all the N thstes ae, thste thste thste Z N = T cs = 1 N = T sn = 1 N thst thst [ T cs ˆ T sn ˆ ] = = 1 thst thst 21 Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 9

11 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses thst whee s the amth anle f the th thste. ˆ, ˆ s the lcatn f the th thste n the essel-fed cdnate sstem. Thst T s assmed t be the nl fnctns f the ppelle RPM and the elate elct f the flw enten the thste n the ppste dectn f the thste amth anle, efeed t as the adance elct, a V als a T = f RPM, V 22 T a ll the thstes n a essel ma tpcall hae the same fnctn f T RPM, V, whch s aphcall pesented n e Gen the ppelle RPM and the adance elct as a fnctn f tme, the thst can be detemned b nteplatn fm the thst~rpm ces n the fe V= knts V= 3 knts V= 6 knts V= 9 knts V= 12 knts V= 15 knts m Thst Data Thst kn RPM n % e Thst s. RPM ces f dffeent adance elctes. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 1

12 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses ce/mment de t the dlln se The dlln se pdes a estn fce/mment t the essel. small essel ffset <15% f the se lenth, the effect f the se n the essel s mdel as a spn wth a stffness f, T K = 23 L whee T and L ae the se s tp tensn and the lenth, espectel. It s als easnable t assme that the chanes n T and L ae small when the essel s ffset s small, and theefe eman cnstant. The fce and mment n the essel de t the se ae then, se = K csψ K snψ se = K snψ K csψ 24 se se Z = D c whee, s the lcatn f the se tp t the essel., s the lcatn f the wellhead., and, ae meased n the lbal cdnate sstem. D c s the hntal dstance f the se tp fm the essel s cente f at. It s assmed that bth the se tp attachment pnt and the essel s cente f at ae n the cente plane f the essel. It shld be pnted t that the fces and mments fm essel mement, cent,, wae, and thstes ae epessed n the essel-fed cdnate sstem. ecase f the essel mement, the elate flw elct and dectn t the essel, the elate wae and dectns, the fces and mments de t the cent, wae dft and ae tme dependent. In addtn, becase f chanes n the ppelle RPM and the amth anle and the essel mement, the fces and mments b the thstes ae als tme dependent. cmpte cde DP-SHIPMO has been deelped t sle the tme dependent eqatns f mtn and pefm Dft-Off and De-Off smlatns. 2.3 Hddnamc Deates The hddnamc deates, the added mass mat and,,, need t be detemned befe Eq. 17 can be sled. Smetmes, becase f nsffcent data, sme appmatns ae made. d ndestandn f the phscal meanns f these deates s e helpfl n makn easnable appmatns. dded mass mat : -- hddnamc eactn fce n the essel n the se as dectn de t a nt acceleatn f the essel n se. The effect f ths fce s sall snfcant. -- hddnamc eactn fce n the essel n the se as dectn de t a nt acceleatn f the essel n swa as dectn. If the essel hll s fe-aft smmetc, ths fce shld be e. slhtl fce-aft asmmetc hll, ths fce shld be elatel small and ma be nelected. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 11

13 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses -- hddnamc eactn fce n the essel n the se as dectn de t a nt aw acceleatn f the essel abt the etcal as. If the essel hll s fe-aft smmetc, ths fce shld be e. slhtl fce-aft asmmetc hll, ths fce shld als be elatel small and ma be nelected. -- hddnamc eactn fce n the essel n the swa as dectn de t a nt acceleatn f the essel n se as dectn. If the essel hll s fe-aft smmetc, ths fce shld be e. slhtl fce-aft asmmetc hll, ths fce shld be elatel small and ma be nelected. -- hddnamc eactn fce n the essel n the swa as dectn de t a nt acceleatn f the essel n swa as dectn. The effect f ths fce s sall e snfcant. -- hddnamc eactn fce n the essel n the se as dectn de t a nt aw acceleatn f the essel abt the etcal as. If the essel hll s fe-aft smmetc, ths fce shld be e. slhtl fce-aft asmmetc hll, ths fce shld als be elatel small and ma be nelected. -- hddnamc eactn mment n the essel abt the as de t a nt acceleatn f the essel n se as dectn. If the essel hll s fe-aft smmetc, ths mment shld be e. slhtl fce-aft asmmetc hll, ths fce shld be elatel small and ma be nelected. -- hddnamc eactn mment n the essel abt the as de t a nt acceleatn f the essel n swa as dectn. a essel wth pt-stabad smmet whch s the case f mst essels, ths mment s e. We assme the pt-stabad smmet. Theefe, ths tem anshes. -- hddnamc eactn mment n the essel abt the as de t a nt aw acceleatn f the essel abt the etcal as. The effect f ths fce s sall e snfcant. Hddnamc deates,, : --hddnamc eactn fce n the essel n se de t a nt aw tatnal elct aw ate. If the essel hll s fe-aft smmetc, ths fce shld be e. slhtl fce-aft asmmetc hll, ths fce shld als be elatel small and ma be nelected. --hddnamc eactn fce n the essel n swa de t a nt aw tatnal elct aw ate. If the essel hll s fe-aft smmetc, ths fce shld be e. slhtl fce-aft asmmetc hll, ths fce shld als be elatel small and ma be nelected. --hddnamc eactn mment n the essel de t a nt aw tatnal elct aw ate. The effect f ths fce s sall e snfcant. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 12

14 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses In ne case that was cnsdeed, and was fnshed. The hll f essel cnssted f a lae ptn f paallel md-sectn, t can be cnsdeed as nl slhtl fe-aft asmmetc. The emann deates n, and wee appmated as e, based n the ndestandn f the phscal snfcance. was the emann deate that was snfcant and can nt be nelected, bt nt eadl aalable. In ths case, was cllabated and detemned ndectl b cmpan the essel taject f a tnn ccle test sn the nmecal smlatn wth the meased taject n the sea tal. In the cllabatn, an ntal ess f was made, then the same sea tal eent was smlated wth the same essel s ntal speed, cntl schedles f the thstes RPM and amth anles sed n the sea tal. The nmecall smlated taject was cmpaed t the meased ne. was adjsted based n the cmpasn and anthe smlatn was pefmed and cmpasn made. The pcess epeated ntl the nmecal smlatn cmpaed easnabl well wth the sea tal measement sal aphcal jdment. e shws the cmpasn f the nmecal smlatn wth the sea tal data sn an adjsted. Shp taject Smlatn Sea tal Yc m Xc m e Cmpasn f the smlated essel taject wth a sea tal measement The cmpasn shwed n e was deemed acceptable snce a pefect match was cnsdeed mpssble and nnecessa t attempt becase f the ncetant n the actal ennmental cndtns dn the sea tal and e n the measement. The ennment was cetanl nt pefectl calm dn the sea tal, whle the nmecal smlatn assmed n, cent and waes. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 13

15 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses The aeement between the nmecal eslt and the meased data s als a e d ndcatn that the appmatns f the the hddnamc deates wee adeqate. It was beleed that f ne f the deates had been wn, t wld hae been nlkel that a d aeement between the nmecal smlatn and the sea tal data cld be acheed b smpl adjstn. The qalt f the hddnamc mdel f the essel was fthe assed wth sme selfcnsstenc tests. These ma nclde, bt ae nt lmted t: Smmet tests: nstance, the essel tns t stabad when the tw aft thstes amth t the pt sde wth emann thstes pntn ahead. The essel shld tn t the pt sde f the aft thstes amth t the stabad wth the same anle, and the essel s taject shld be a pefect mae f the fme case abt the essel s cente plane. Tnn ccle tests: Cnsden the same eample n the smmet test, the lae the thste s amth anle, the shape the essel shld tn and the smalle the damete f the tnn ccle f the taject shld be. Cash Stp asten tests: In a cash stp asten test, the essel s ntall taeln aln a staht lne at a cnstant speed wth all the thstes nnn at sme RPM and pntn staht ahead. Gen the stp cmmand, all the thstes tn 18 deees and n at the fll desn RPM t stp the essel. The hhe the ntal speed, the lne t takes t bn the essel t the fll stp and the lne the essel taels befe the stp. Effect f Ennment The essel shld tn and dft t stabad sde f the cent waes cmes fm the bw at a cetan anle < 9 deees n pt sde. Smlal, the essel shld tn and dft t pt sde f the ennment cmes n stabad sde. The nmecal tests qaltatel cnfmed the cect pefmance f the smlatns. Theefe, the hddnamc mdel can be sed, wth a hh deee f cnfdence, f smlatns and analses f De-Off and Dft-Off eents. 2.4 Eample Case The fllwn shw eamples f tme hst tpt essel pstn and aw fm the DP- SHIPMO pam: e shws the hst f the essel pstn pltted ee 1 secnds. In ths case, the essel ntall heads n the as. The cent cmes fm the pt sde 27 and the and waes cme fm the bw at an anle n the pt sde 195. s seen, the essel s dfts and ts pstn s detemned b the ennmental fces afte the thstes lst the pwe RPM=. The pstn maked n ed s the pnt n tme when the ffset f the se tp attachment pnt has eached a en essel ffset. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 14

16 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses The essel pstn maked n black appeas t shw a statc eqlbm at ths pstn de t the ennmental fces and se estn fce/mment. e shws the taject f the essel s CG and e shws the cdnates, as well as the ffset, f the essel s CG as fnctns f tme. e shws the essel s aw anle as a fnctn f tme. s seen n e and e 2.4.5, the CG and the aw anle ae appachn t a cnstant ale, ndcatn a statc eqlbm pstn. The cdnates and ffset f the se tp attachment pnt ae shwn n e e shws the se ffset f the fst 3 secnds. m e 2.4.7, ne can detemne hw mch tme t takes befe the se attans a en ffset. ame 1 17 N 22 Shp Pstn 1 5 Dft-ff Smlatn Cent: 1.5m/s, 27 de; Wnd: 15.24m/s, 195 de; Wae: Hs=4.57m, Tp=9s, 195 de, P-M Spectm Y X e Hst f the essel pstn Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 15

17 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Taject f the Vessel's C.G. Dft-ff; Cent: 1.5m/s, 27de; : 15.24m/s, 195 de; wae: Hs=4.57m, Tp=9s, 195 de, P-M Spectm; Vessel ntal headn: de Sees Y m X m e Taject f essel CG Vessel Offset s. tme Case 1: Dft-ff; Cent: 1.5m/s, 27de; : 15.24m/s, 195 de; wae: Hs=4.57m, Tp=9s, 195 de, P-M Spectm; Vessel ntal headn: de 6 5 Xc Yc SqtXc^2Yc^2 4 3 Offset Xc, Yc m t s e Vessel CG X and Y Cdnates Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 16

18 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Vessel's Yaw anle s. tme Case 1: Dft-ff; Cent: 1.5m/s, 27de; : 15.24m/s, 195 de; wae: Hs=4.57m, Tp=9s, 195 de, P-M Spectm; Vessel ntal headn: de 6 Sees1 4 2 Yaw de t s e Vessel aw anle Rse tp attachment pnt s. tme Case 1: Dft-ff; Cent: 1.5m/s, 27de; : 15.24m/s, 195 de; wae: Hs=4.57m, Tp=9s, 195 de, P-M Spectm; Vessel ntal headn: de 6 5 Xa Ya Ra=sqtXa-Xa^2Ya^2 4 3 Xa, Ya m t s e Cdnates and ffset f se tp attachment pnt Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 17

19 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Offset f se tp attachment pnt s. tme Case 1: Dft-ff; Cent: 1.5m/s, 27de; : 15.24m/s, 195 de; wae: Hs=4.57m, Tp=9s, 195 de, P-M Spectm; Vessel ntal headn: de 4 35 R=SqtXa-Xa^2Ya^ Offset, R m t s e Rse ffset Case 1 Same as n e pltted f the fst 3 secnds Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 18

20 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses 3. WTCH CIRCLE DETERMINTION The ppse f the Dft-Off and De-Off analss s t detemne een, ellw and ed watch ccles f allwable essel ffset afte whch Emeenc Dscnnect Seqence EDS s ntated wtht damae t the se, wellhead and the stctal cndct casn. fte the essel eceeds the een watch ccle, the essel s n a deadn stats. fte the ellw watch ccle s eceeded, pepaatns ae made f EDS ntatn. t the ed alet, EDS s cmmenced. Rse dscnnect n a Dft-Off De-Off scena mst cc befe an f the fllwn ctea s eached: le jnt anles mst be less than the allwable mama Stke-t f the telescpc slp jnt TJ Stke-t f the tensnes Mamm eqalent stesses n the se mst be eld Mamm eqalent stesses n the 36-n stctal cndct casn mst be eld Mamm bendn mment n the wellhead mst be less than ts allwable based pn tensn and pesse. Mamm bendn mment n the stctal cndct casn mst be less than ts allwable. Mamm nt checks, pe PI RP 2, mst be less than 1. The se s mdeled n S; S s a eneal-ppse fnte element pam, whch can mdel nn-lneat f emet, mateal ppetes, and spn defntns. S ncldes the feate specfcall desned f the analss f beam-lke stctes nstalled ndewate and sbject t ladn b wate cents and wae actn. The Dft-Off and De-Off analss empls the tme dman capablt f S. The essel ffset e as shwn n fe and s mpsed as a fnctn f tme n the Dft- Off and De-Off analss, whch tethe wth the cent eslts n the netal mass effects affectn se espnse. The fllwn ae tled n the analses: the Dft-Off and De-Off analss, the essel ffset s a fnctn f tme. Nte that wae feqenc mtns wee nt nclded n the mdel. Hwee, sepaate analses wee pefmed t estmate the dnamc fle jnt anles and essel aw at a en ffset and headn. lnea mateal stess-stan law, nn-lnea thee-dmensnal spn elements t mdel the tensnes, slde/cntact elements t mdel the mtn between the nne and te bael f the telescpc jnt, nn-lnea spns t mdel the sl chaactestcs, beam elements t mdel all ppe sectns. The fnte elements tled wee the S PIPE31 thee-dmensnal beam element. Ths element accnts f ntenal and etenal hdstatc pesse effects, sn the HP ptn, whch calclates the cect hp stesses n the ppe de t fld pesse, and then calclates the cect n Mses stess wtht an fthe pst-pcessn. theme, S allws f pesse end lads t be mdeled cectl,.e. when thee s a chane n ntenal etenal damete f the se. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 19

21 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses We pe tensnes dect actn tensnes ae mdeled as thee-dmensnal nn-lnea spns. The tensnes ae assmed t be peatn at a en stke ane, t s cnseate f the De-Off and Dft-Off analss t assme the smallest allwable stke n the stke ane, ths leadn t smalle watch ccles. Dn Dft-Off De-Off, the tensne spns ntall espnd accdn t the spn ate defned b the PV, accmlats, a lme, etc, ntl ethe a tensne stkes t the slp jnt stkes t fll. The SPRING element was sed t mdel the tensnes. fte a tensne stkes t, the tensne espnds, at a mch hhe spn ate/stffness, essentall n a d manne. The fle jnts wee mdeled n a smla manne sn SPRING2 elements. elatel fne mesh was empled. the mesh was adjsted ntl the effecte tensn and stess dstbtn as pedcted b S was wthn 1% f that pedcted b an ndependent pam wth the essel lcated e the well % ffset. The fnte element analss fst cnssts f pe-ladn the se wth ts dstbted wet self weht, fllwed b ntenal and etenal hdstatc pessatn. The essel s then ffset as a fnctn f the npt tme tace. The RESTRT and NLGEOM nn-lnea emet ptns ae tled afte each step t accnt f the se cnfatn n the pecedn step. In addtn: Rse cntact mdeln wth the essel sb-stcte s nt sall cnsdeed, hwee the tp anle f the ppe fle jnt s mnted. t the stat f the cmpte smlatn, the apppate tp tensn was appled whch mes the TJ te bael p fm ts ntal pstn. s the essel mes n the lateal dectn, the ttal dsplacement f the tensnes s eqal t the ntal stetch f the se pwad mtn f the slp n when the tp tensn s appled pls the ales f tensne stke. The weht f the telescpc jnt nne bael, dete hsn and ppe fle jnt ae assmed t be caed b the essel. Sl sppt s sall assmed and mdeled b eqalent sl spns, based pn sl data at the ste pded and sn PI RP 2. the Dft-Off/De-Off analss, the se stke ncldes cntbtns fm: Tde Heae nctn f headn..e. T ttal = Intal Stke T Offset t T Tde < Stke-Lmt *T Heae /2 25 The ttal stke s defned as the aalable stke pls the stke de t ffset f the essel and de t tde. Ths ttal stke mst be less than the stke lmt mns the mst pbable heae. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 2

22 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses The pcedes t detemne ellw and ed alams/watch ccles ae as fllws: The tme f dscnnect s sall dentfed f each Dft-Off and De-Off cndtn ennment, md weht, tensn as the tme at whch the fst lmtn cten eceeds ts cespndn allwable mamm. The Red watch ccle s then defned b sbtactn ff a specfed tme bffe fm the pnt f dscnnect. The Yellw watch ccle s then defned b sbtactn ff a specfed tme bffe fm the Red watch ccle. Hwee, altenate cten can als be sed t detemne the watch ccles, f nstance: OR DRILLING: - The ffset cespndn t the ellw alam s assmed t be en, let s sa 5-ft, f nstance. The ed alam settns ae selected t allw a mamm f a en tme nteal, let s sa a 9-secnd bffe between the tme that the essel s at ths ffset and the tme that dscnnect seqence mst ntate. It then takes an addtnal tme nteal, let s sa 7- secnds fm the bennn f EDS ntl the LMRP s fee t lft-ff the OP,.e. Y 5-ft Offset Y-R 9-secnds R-Dscnnect 7-secnds OR N-DRILLING: - The ma be assmed t be n pepetall n the ellw mde. The dscnnect tme ma be assmed t cc when the eaches a en headn. The Red watch ccle s then defned b pdn a 7-secnd bffe between dscnnect and ths en headn. e 3.1 shws and Table 3.1 the espnse chaactestcs f a en ennment as a fnctn f tme. These fes ae pdced f a nmbe f ennments and dlln/nn-dlln tensns. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 21

23 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Tme secs De Off Headn de Snfcant Heae - S.. ft -based n Headn Cndct Casn VME Stess ks Ttal Lwe le Jnt nle de Ttal Intemedate le Jnt nle de Ttal ppe le Jnt nle de TOTL TENSIONER STROKE ft LLOWLE TENSIONER STROKE ft Table 3.1: De-Off Reslts 99% NX Wnte Stm - 15-pp 1327-kps W e 3.1: De-O NLYSIS RESLTS - TOP TENSION = 1327-KIPS 99% NX Wnte Stm, Hs = 12.2-ft, Tp = 9.3-sec, γ = 1, Md=15-pp VESSEL [CLIENT - SITE Cnnected nalses n XXXX-ft Wate Depth, X-de Headn Intal Headn] 12 8 OSET % nle de / Offset pecent f wate depth 11 Yeld Stess 65-ks 1 1-de Ma nle Tme secs Stess ks Stke ft Ttal Lwe le Jnt nle de ppe le Jnt nle de Cndct Casn VME Stess ks TOTL TENSIONER STROKE ft LLOWLE TENSIONER STROKE ft Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 22

24 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses In addtn Table 3.2 and 3.3 shws the watch ccle/eds tmes f a nmbe f ennments f dlln and N-dlln cndtns. nmbe f cnclsns and bseatns can be made. nstance, t s edent fm table 3.2, f DRILLING that thee ae adeqatel defned watch ccles f the 95% NX WS and the 99% NX WS f the Dft-Off and De-Off cndtns. Mee, t s appaent that thee ae n watch ccles f the 1- WS DRILLING mde f the Dft-Off and De-Off cndtns. Ths, t ma be pdent t cnsde the 1- WS as a N-DRILLING ennment. N-DRILLING, the essel s n the ellw alam mde pepetall and dscnnect wll cc p t the essel eachn a en headn fm an ntal headn. 7-secnd nteal s sed t defne the ed watch ccle fm ths dscnnect cten. In ths case the smallest watch ccles ae defned b De-Off; the 99% NX WS, 1- Lp, 1- WS and 5- WS ed watch ccles ae 84-ft, 9-ft, 34-ft and 26-ft, espectel. 4. CONCLDING REMRKS pcede has been deelped t pedct the essel taject n a De-Off Dft-Off eent based pn an ennment. The eslts fm measements f the essel tests e.. the maneen tests and sea tal tests ae e sefl f detemnn/cllabatn the mptant hddnamc deates f the essels t bld a d smlatn mdel f the essel tajectes. The essel s hddnamc deates, hwee, ma als be estmated sn theetcal nmecal appmatns when the test data s nt aalable nsffcent. cmbned se f the test data and theetcal /nmecal appmatn has shwn t be a pdent appach. The essel taject can be sed t detemne the pnt f dscnnect and ed, ellw and een watch ccles based pn the EDS tmes. Ths, the ntet f the se s nt cmpmsed n sch an eent. Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 23

25 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Table 3.2: Watch Ccle Defntn f Dlln Weathe CSES DRILLING Md pp Tp Tensn kps YELLOW WTCH CIRCLE OR EDS sec Tme at whch 5-ft Offset s eached RED WTCH CIRCLE OR EDS sec RED WTCH CIRCLE OR EDS ft RED WTCH CIRCLE OR EDS % Offset DISCONNECT TIME sec DISCONNECT OSET ft DISCONNECT % Offset Hae the Tensnes Stked-Ot? ppe le Jnt nle de Dlln Rse Respnse at Dscnnect Tme Lwe le Jnt nle de Intemedate le Jnt nle de VME Stess 36-n Casn ks PI nt Check PI Ma nt Check 95% NX DRIT-O % NX DRIT-O % NX DRIT-O % NX DRIT-O % NX DRIT-O 12 99% NX DRIT-O ** 1 WS DRIT-O ** 1 WS DRIT-O 12 ** 1 WS DRIT-O YES YES > > % NX DRIVE-O % NX DRIVE-O % NX DRIVE-O % NX DRIVE-O % NX DRIVE-O 12 99% NX DRIVE-O ** 1 WS DRIVE-O ** 1 WS DRIVE-O 12 ** 1 WS DRIVE-O YES YES > > ** lmt has been eceeded befe the defned dscnnect ffset/tme. Ths, the watch ccles f theses cases ae ben edefned belw : Weathe DRILLING Md pp Tp Tensn kps YELLOW WTCH CIRCLE OR EDS sec YELLOW WTCH CIRCLE OR EDS ft RED WTCH CIRCLE OR EDS sec RED WTCH CIRCLE OR EDS ft RED WTCH CIRCLE OR EDS % Offset ** 1 WS DRIT-O ** 1 WS DRIT-O 12 ** 1 WS DRIT-O DISCONNECT TIME sec DISCONNECT OSET ft DISCONNECT % Offset Hae the Tensnes Stked-Ot? YES ppe le Jnt nle de Dlln Rse Respnse at Dscnnect Tme Lwe le Jnt nle de Intemedate le Jnt nle de VME Stess 36-n Casn ks PI nt Check PI Ma nt Check ** 1 WS DRIVE-O ** 1 WS DRIVE-O 12 ** 1 WS DRIVE-O YES Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 24

26 K. halla, Y. Ca, Stess Enneen Seces Watch Ccle ssessment f Dlln Rses Table 3.3: Watch Ccle Defntn f N-Dlln Weathe CSES N-DRILLING Md pp Tp Tensn kps RED WTCH CIRCLE OR EDS sec RED WTCH CIRCLE OR EDS ft RED WTCH CIRCLE OR EDS % Offset DISCONNECT TIME 3-de Yaw nle sec DISCONNECT OSET ft DISCONNECT % Offset Hae the Tensnes Stked-Ot? ppe le Jnt nle de N-Dlln Rse Respnse at Dscnnect Tme Lwe le Jnt nle de Intemedate le Jnt nle de VME Stess 36-n Casn ks PI nt Check PI Ma nt Check 99% NX DRIT-O % NX DRIT-O % NX DRIT-O Lp NX DRIT-O Lp NX DRIT-O Lp NX DRIT-O WS DRIT-O WS DRIT-O 12 1 WS DRIT-O WS DRIT-O WS DRIT-O 12 5 WS DRIT-O % NX DRIVE-O % NX DRIVE-O % NX DRIVE-O Lp NX DRIVE-O Lp NX DRIVE-O Lp NX DRIVE-O WS DRIVE-O WS DRIVE-O 12 1 WS DRIVE-O WS DRIVE-O WS DRIVE-O 12 5 WS DRIVE-O Dnamc Pstnn Cnfeence Nembe 15-16, 25 Pae 25