I have actually had someone right a similar formula for me in the past, however it doesn't account for seconds and it is very hard for me to read. The formula is below.
=IFERROR(IF(LEN(D3)<=6,LEFT(D3,FIND(" ",D3)-1)*IF(TRIM(RIGHT(D3,3))="Day",24*60,IF(TRIM(RIGHT(D3,3))="Hr",60,1)),IF(LEN(D3)<=15,LEFT(D3,FIND(" ",D3)-1)*IF(MID(MID(MID(SUBSTITUTE(D3," ","^",1),1,256),FIND("^",SUBSTITUTE(D3," ","^",1)),256),2,FIND(" ",MID(MID(SUBSTITUTE(D3," ","^",1),1,256),FIND("^",SUBSTITUTE(D3," ","^",1)),256))-2)="Day",24*60,IF(MID(MID(MID(SUBSTITUTE(D3," ","^",1),1,256),FIND("^",SUBSTITUTE(D3," ","^",1)),256),2,FIND(" ",MID(MID(SUBSTITUTE(D3," ","^",1),1,256),FIND("^",SUBSTITUTE(D3," ","^",1)),256))-2)="Hr",60,1))+MID(MID(MID(SUBSTITUTE(D3," ","^",2),1,256),FIND("^",SUBSTITUTE(D3," ","^",2)),256),2,FIND(" ",MID(MID(SUBSTITUTE(D3," ","^",2),1,256),FIND("^",SUBSTITUTE(D3," ","^",2)),256))-2)*IF(TRIM(RIGHT(D3,3))="Day",24*60,IF(TRIM(RIGHT(D3,3))="Hr",60,1)),(LEFT(D3,FIND(" ",D3)-1)*24*60+MID(MID(MID(SUBSTITUTE(D3," ","^",2),1,256),FIND("^",SUBSTITUTE(D3," ","^",2)),256),2,FIND(" ",MID(MID(SUBSTITUTE(D3," ","^",2),1,256),FIND("^",SUBSTITUTE(D3," ","^",2)),256))-2)*60+MID(MID(MID(SUBSTITUTE(D3," ","^",4),1,256),FIND("^",SUBSTITUTE(D3," ","^",4)),256),2,FIND(" ",MID(MID(SUBSTITUTE(D3," ","^",4),1,256),FIND("^",SUBSTITUTE(D3," ","^",4)),256))-2)))),0)