(Reuters) - Large oil companies are racing to sell land in the largest U.S. shale formation as rising crude prices present them with a golden opportunity to jettison unwanted acreage and meet shareholder demands to lower costs, people involved with transactions told Reuters. Worldwide oil demand rebounded faster than expected in 2021, boosting prices to more than $80 a barrel. Output has also bounced back in the Permian, the pillar of U.S. oil production, based in Texas and New Mexico, where buyers are paying for land at lofty values not seen in three years. The flurry of purchases kicked into high gear with big sales from Royal Dutch Shell, which sold its Permian assets here for $9.5 billion in September, and followed with this week"s land sale by Pioneer Natural Resources here to Continental Resources for $3.25 billion. The rally in oil prices has encouraged public shale producers to cash in on unwanted assets rather than ramp up drilling, instead focusing on reducing debt or boosting shareholder returns. So far this year, 53 upstream asset sales have been launched in the Permian Basin, compared with just 16 last year, IHSMarkit senior analyst Atul Raina said. In total, there are approximately 77 asset sales worth $12 billion to $15 billion, currently on the market in the Permian Basin, he said. “It’s still the best-producing onshore field in North America,” said Mike Blankenship, managing partner of lawfirm Winston and Strawn’s Houston office. “I think it still has a long, bright future ahead.” Oil production in the Permian was forecast to be 4.89 million barrels per day (bpd) in November, just below its record of 4.91 million bpd hit before the coronavirus pandemic crushed demand and prices, according to the U.S. Energy Information Administration. Private operators have been a driving force for the rebound in output, while public operators remain less inclined to drill. (Graphic: Private operators lead shale rig count recovery: ) Royal Dutch Shell decided to sell its assets in the Delaware Basin portion of the Permian in September as it faces pressure to cut greenhouse gas emissions following a recent Dutch court ruling. It sold 225,000 net acres (910 square kilometers) to ConocoPhillips for $9.5 billion, translating to a price of $54,286 per barrel, analysts from IHSMarkit told Reuters. Pioneer’s $3.25 billion sale to Continental surpasses that, working out to $59,091 a barrel, the highest price paid in the Delaware Basin since 2018. Earlier this year, the land for sale was valued at roughly $2 billion, two people familiar with the transaction said. (Graphic: Delaware barrels get more expensive: ) Those sales have encouraged other producers in the region to either launch new sales or seek stronger valuations from prospective buyers for assets on the block, sources familiar with the matter told Reuters. Companies have focused on assets in the Delaware section of the Permian Basin, Blankenship said, adding that activity has been less robust in the Midland portion of the basin, where costs can be higher as companies need to drill deeper to extract crude. The Delaware region has also had less consolidation, leaving more smaller parcels for buyers to scoop up, analysts said. The Delaware Basin accounts for about $6 to $9 billion of the total Permian assets up for sale, Raina said. Public producers Chevron Corp here and Centennial Resource Development Inc here and privately owned Ascent Energy LLC have been trying to offload assets in the region, according to marketing documents seen by Reuters. Other sellers could include Matador Resources and privately-held Colgate Energy, according to people familiar with the talks. Occidental Petroleum is looking to sell land in the New Mexico portion of the Delaware Basin, according to a marketing document seen by Reuters. Colgate, Matador, Ascent and Occidental did not respond to requests for comment. (Graphic: Permian leads shale recovery while other regions lag: )