B777 TAXIED ONTO THE OVERRUN AREA OF RWY 9R WHEN TAXIING INTO POS ON RWY 27L. WRONG TAXI RTE WAS USED.

Narrative

GND CTL HAD GIVEN US CLRNC TO RWY 22L FOR TKOF. AT THE LAST MOMENT TWR CHANGED US TO RWY 27L. I TURNED ONTO A TXWY THAT LOOKED LIKE THE ENTRANCE TO RWY 27L. I THEN TURNED ONTO THE OVERRUN AREA AND TAXIED TO THE THRESHOLD OF RWY 27L. AS I APCHED THE RWY END MARKER; I NOTICED A LARGE GREEN BAND ACROSS THE OVERRUN AREA AND I REMEMBER THINKING 'WHAT'S THAT DOING HERE; I'VE NEVER SEEN IT HERE BEFORE.' AS I PASSED OVER THE RWY END LINES THE TWR INFORMED ME THAT WE HAD USED THE 'OVERRUN AREA' AND CLRED US FOR TKOF. IT APPEARS THAT I USED TXWY Q WHICH IS A HIGH SPD TURNOFF FOR RWY 4R; WHICH CROSSES THE OVERRUN FOR RWY 27L/9R; AND ENTERS THE RWY 27L PAD FROM WHICH WE WERE COMING. A FACTOR IN MAKING THIS MISTAKE WAS THE LAST MIN CHANGE IN RWYS AND MY CONCERN THAT THE FO WAS SETTING FMC UP CORRECTLY. I HAD PICKED A RTE TO THE END OF RWY THAT LOOKED LIKE THE MOST 'NATURAL WAY' THERE. CONSIDERING ANOTHER FACTOR; WE HAD AN EARLIER PROB WITH AUTOTHROTTLE AND I WAS PLANNING ON WHAT TO DO IF WE GOT A SPLIT THROTTLES SIT. IT WAS ABOUT THIS TIME ALSO THAT THE FO FINISHED HIS FMC WORK AND I STARTED DISCUSSING THE THROTTLE PROB AND WHAT WE MIGHT DO. I GUESS I WAS NOT PAYING ATTN TO WHERE I WAS GOING. I HAD ALSO MISSED THE NOTE ON ARPT 20-9 PAGE FOR ORD.