the Crustal Magnetic Field for and Any Drilling Time Xiong Li and Benny Poedjono in Paris on March 8, 2013

Transcription

1 An Accurae Deerinain f he rusal Magneic Field fr Any eference Mdel and Any Drilling Tie ing Li and enny Pedjn in Paris n March 8, 03

2 4 Slides fr he Presenain in San Anni Is he vecr crusal agneic field relaive a curren reference field del fr a curren dae sill valid in he years (5, 0, 0) ce? Given he fllwing facs The ain field iself changes wih ie (secular variain) The degree/rder f he spherical harnic (SH) expansin used define he reference field del increases Direcinal drilling invlves he ain field a he aeragneic survey ie and he ain field a he drilling ie

3 Tal Magneic Inensiy Analy Offshre Easern anada The area fr cubes 40 k The IGF-crreced TMI analy is fr he -k GS grid The nly infrain abu he aeragneic surveys The average fligh heigh is 305 abve MSL The survey dae was abu March 0, 986

4 rusal Declinain Perurbains a 4500 Deph

5 hanges in rusal Declinains a 4500 Deph The changes in 0 years are insignifican, and he changes in 5 r 0 years ay be significan depending n he drilling lcain

6 Geagneic eference Mdels: urren Saus Updaed Main field Secular rusal Exernal variain field field IGF Five years 3 8 N N GGM Annually HDGM Annually The nubers are he degree/rder used in spherical harnic (SH) expansin. Only he IGF is a del define he pure ain field. n Specru f Inernal Field rus

7 A igger Quesin Fr a crusal agneic field del creaed earlier, can we cpue accuraely he crusal field alng any well pah a any fuure ie relaive a differen reference field del? ES, under w cndiins. The subsurface vecr crusal agneic field values geher wih is reference field del values are delivered in he vlue fra, and his vlue cnains all fuure wells.. The fuure reference agneic field del cvers he year ha he abve crusal and reference field values are creaed.

8 The Magneic Field ubes declinain inclinain al field 0 reference 4500 SW crusal baseline

9 Se Sybls : he ie f he crusal field del creaed : he reference field del used creae he abve crusal del : he fuure drilling ie use he crusal field del : he reference field del a he fuure drilling ie : he vecr crusal field : he vecr reference field : he vecr baseline field ( ),,

10 Paraeers f he Magneic Field D: Declinain I: Inclinain F: Tal field inensiy O,, cpnens They are linked by

11 ecver he aseline (,, ) Values a he reain Tie The delivered crusal, reference and baseline field cubes are D( ) I( ) F( ) ; D( ) I( ) ( ) ; D( ) I( ) ( ) Their relainships are D I F ( ) D( ) D( ) ( ) I ( ) I ( ) ( ) F ( ) F ( ) F F The aseline (,, ) are cpued by ( ) F ( ) cs [ I ( ) ] cs [ D ( ) ] ( ) F ( ) cs[ I ( ) ] sin[ D( ) ] ( ) F ( ) [ I ( )] sin NEW: Drillers need ipleen his cpuain.

12 Effecs f Tw Differen eference Mdels FAT # - The baseline (i.e., he vecr su f he crusal and reference fields) a he sae ie shuld n change reference fields) a he sae ie shuld n change Fr each f he hree cpnens ( ) ( ) ( ) ( ) ( ) NEW: Drillers need ipleen his cpuain f & NEW: Drillers need ipleen his cpuain f &

13 The rusal Field in he Sae eference Mdel FAT # - The crusal field desn change wih ie (a leas in ens f years) in he sae reference del series Fr each f he hree cpnens ( ) ( ) ( ) ( ) ( ) ( )

14 The rusal Field in he Fuure The crusal analies relaive a fuure reference del a a fuure drilling ie are g ( ) ( ) ( ) arcan arcan D r ( ) ( ) arcan D D ( ) [ ] [ ] ( ) ( ) [ ] ( ) [ ] arcan arcan I r [ ] [ ] ( ) [ ] ( ) [ ] ( ) [ ] [ ] ( ) arcan I I [ ] [ ] ( ) [ ] [ ] [ ] ( ) F F ( ) [ ] [ ] [ ] ( ) F F

15 Or Siply Use he aseline Values a he Fuure Drilling Tie aseline declinain ( ) arcan D aseline inclinain ( ) [ ] [ ] arcan I F aseline al field inensiy ( ) [ ] [ ] [ ] F NEW: Drillers need ipleen his cpuain.

16 Suary Fr a crusal field cpuain A driller cpues a drilling An accurae deerinain als requires a cpuain a drilling All cpuains can be easily ipleened,,

17 Hw abu he rusal Field hanges in he eference Field Mdel? Hw abu he reference field del used a he drilling ie has differen SH degrees fr differen years (higher fr recen years)? This eans ha differen SH degrees are used define he crusal fields a differen years (he ain field is sufficienly defined by SH degrees f up 5) This shuld and can be avided (he crusal field desn change wih ie, and ay be updaed when he crusal agneic analy daabase has significan updaes) If his des happen, he synhesis f he SH expansin fr degrees 6 and up (e.g., up n and n) can give he crusal field differences (due he SH degree differences, ) and he funcin fr his difference cpuain shuld be prvided by he reference del develper

18 nclusins When he subsurface vecr crusal agneic field geher wih he reference field del used in he cpuain are delivered in he vlue fra and he vlue cnains all freseeable wells, hese w ses f agneic field vlues and he fuure reference field del are enugh deerine accuraely he crusal and baseline field values alng any fuure (r pas) well pah a a fuure (r pas) ie. I als iplies ha i desn aer use IGF, GGM r HDGM as he reference del in he creain f he lcal crusal agneic field vlues, and wha is criical is calculae and apply he difference while drilling.

19 Thank yu