The company is selling Anasuria, a manned floating production, storage and offloading installation, and the Nelson and Sean manned platforms.
It said its investment strategy is to focus on assets where it sees an opportunity for growth.
Staff were told of the plans this week. The company said it was too early to talk about implications for staff.
Glen Cayley, vice president of Upstream Shell UK and Ireland, said: "The UK is an important business region for Shell, and our investment strategy continues to focus on assets where we see an opportunity for growth using our world-class technological know-how.
"We have 50 years of investment and operations in this region, including some of the landmark developments in the history of the North Sea.
"We are focusing and strengthening our portfolio for the decades ahead with many exciting projects such as new wells we are drilling at Shearwater, our investment in extending the life of Gannet, our investments in the non-operated ventures of Schiehallion and Clair and our purchases, last year, of a further interest in Beryl and the Curlew floating production, storage and offloading (FPSO) vessel.
"These changes are very much in line with our strategy and will allow us to focus on where we can add value to ensure a long-term future for Shell in the basin.
"We are talking to staff about the proposal to sell the assets in order to be as open as possible, whilst confirming our commitment to the North Sea."
Anasuria, which is operated by Shell, is located 115miles east of Aberdeen and produces gas and oil.
Shell has a 50% equity share, and the joint venture partner is Esso Exploration and Production UK Ltd with a 50% holding.
Shell-operated Nelson is located around 124miles east-north-east of Aberdeen and exports oil and gas. The co-venturers are Shell (58.1%), Esso Exploration and Production UK Ltd (21.23%), Apache North Sea Ltd (11.52%), Idemitsu Petroleum UK Ltd (7.48%), and Premier Oil ONS Ltd (1.66%).
Sean, which is Shell-operated, is located in the Southern North Sea, 68 miles north east of Lowestoft and produces gas.
Shell has a 25% equity share, and the co-venture partners are Scottish and Southern Energy (50%), and Esso Exploration and Production UK Ltd (25%).