Since the 2014 season, the Denver Broncos have participated in joint practices with another NFL team. The joint practices usually take place for the Broncos during week two of the preseason. So, whomever Denver plays for their second opponent (it will be their third opponent due to the Hall of Fame game) is usually whom they have for joint practices.
This season, it will be the San Francisco 49ers. The team announced they will host joint practices with the NFC West team during week two of the preseason. Both teams will practice with each other on the Friday and Saturday before they face off on Monday Night Football August 19th.