B737-300 FLC HAS RWY INCURSION AT OKC.

Narrative

AFTER ARRIVING AT THE ACFT AND STRUGGLING WITH AN INOP FUEL GAUGE (DIPPING THE TANK; ETC); HAVING TO CHANGE THE ACCULOAD FOR A DIFFERENT WAY; WE FINALLY PUSHED. WE WERE CLRED TO RWY 17R. I HAVE BEEN USED TO GOING TO RWY 17L. I HAD MY TAXI CHART OUT; BUT FELT THAT I KNEW WHERE WE WERE GOING IN ORDER TO GET TO RWY 17R. WE EXITED THE RAMP AT TXWY C. WE SHOULD HAVE TURNED ONTO TXWY A AT A6. AS WE APCHED TXWY A; I SAW THE SIGNS INDICATING RWY 17R. I GOT SOMEWHAT CONFUSED; THINKING THAT RWY 17R WAS STRAIGHT; AND THAT THE RWY WE WERE PARALLELING WAS RWY 17R WHEN IN ACTUALITY IT WAS RWY 12/30. WE CROSSED THE RWY AFTER CLRING BOTH DIRECTIONS AND SEEING NO TFC IN EITHER DIRECTION -- EITHER ON THE GND OR IN THE AIR; AND WITH NO HOLD SHORT CLRNCS GIVEN. UPON EXITING ON THE W SIDE OF THE RWY; GND INFORMED US WE HAD JUST CROSSED AN ACTIVE RWY AND TO TURN AND RE-CROSS THE RWY. AGAIN; NO TFC INVOLVED; EITHER IN THE AIR OR ON THE GND. WE PROCEEDED TO CROSS BACK TO THE E SIDE OF RWY 17R; TAXIED TO THE END AND WERE CLRED FOR TKOF WITH NO FURTHER COMMENT FROM TWR OR GND.