England beat Colombia 4-3 on penalties on Tuesday after Eric Dier scored the decisive spot kick to send them through to a World Cup quarter-final against Sweden on Saturday.
Gareth Southgate's side won a World Cup shootout for the first time in their country's history, and he was thrilled with how his players had stayed focused.
"We had talked long and hard about owning the process of a shootout," he told ITV. "They kept calm. The players have taken it all on board, it's a special moment for us.
"We looked at technique, how we needed to be as a team, the goalkeeper's role. A special moment but now I'm thinking about Sweden."
England had looked on course for their first win in a knockout round of a tournament in 12 years when captain Harry Kane struck a well-taken penalty in the 57th minute.
But Colombia defender Yerry Mina snatched a dramatic stoppage-time equaliser with his third goal in three matches to force extra time which ended with the game level at 1-1.
Jordan Henderson had missed first for England in the shootout, but Mateus Uribe hit the bar with his effort for Colombia, before Jordan Pickford saved Carlos Bacca's effort.
Butland told the BBC: "I did all my research. I've got power and agility. I don't care if I'm not the biggest keeper because it's about being there in the moment and making the save and I was.
"It's all about the set position and I got a hand to it. We knew we had this game, even if it had to go to penalties, we knew we were capable of winning."
England have previously been eliminated from World Cup 1990, 1998 and 2006 on penalties, and also at the European Championships in 1996, 2004 and 2012.
Sweden earlier beat Switzerland 1-0 in their last 16 game to advance.
World Cup 2018: Day 20 updates - Colombia v England