The biggest investment of £500 million is in the Forties Pipeline System (FPS), which will transform the asset and extend the life of the pipeline by at least 20 years, into the 2040s.
Ineos said it intends to overhaul the reliability of the 310-mile (500km) North Sea pipeline system, including modernising the environmental systems.
Opened in 1975, FPS is a strategic UK asset that can transport up to 600,000 barrels of North Sea oil onshore for refining every day. The pipeline transports 40% of the UK’s oil and gas to the mainland.
Ineos is investing £350 million at its Grangemouth site in Scotland to develop a new steam and power plant, delivering “significantly improved” energy efficiency and long-term reliability.
Ineos will also invest £150 million in a new plant in Hull.
Sir Jim Ratcliffe, founder and chairman of Ineos, said: “Ineos is a supporter of British manufacturing and this £1 billion investment underlines our confidence in our business in the UK.
“These investments will ensure that our UK assets continue to be world-class for many years to come.”
Andrew Gardner, chief executive of Ineos FPS, said: “North Sea oil and gas producers are telling us that they want to be in the North Sea well into the 2040s, so we are making this commitment to be there with them.
“Following acquisition of FPS in 2017, we are now embarking on a period of investment that will guarantee that the system can support them for decades to come.”
Commenting on the Grangemouth investment, Tobias Hannemann, of Ineos, said: “This investment forms part of our wider plans to secure a bright future for manufacturing at Grangemouth and will continue its renaissance as a world-class petrochemicals site while supporting the refinery, FPS and wider UK economy.”
A new Vinyl Acetate Monomer (VAM) plant will be built in Hull, which Ineos said will bring production of an important raw material back to the UK.
VAM is a key component in a wide range of products including laminated windscreens, toughened glass, adhesives, coatings, films, textiles and carbon fibre.
Graham Beesley, chief executive of Ineos Oxide, said: “This is an exciting time for Ineos and great news for manufacturing in the region.
“We are proud to be bringing production of this important material back to the UK. This will not only strengthen UK manufacturing but boost exports from the UK to Europe and the rest of the world.”
Around 300 jobs will be created building the new plant in Hull and it will employ around 30 people when it is operational.
Ineos asked the Government for financial support towards the project but has not received anything.
Group director Tom Crotty told the Press Association: “We are still in debate.”
Ineos closed its operation in Hull a decade ago because it was uncompetitive but Mr Crotty said the market for its products was “much healthier”.
The new plant will be built on the same site and products will mainly be exported.
The investment at Grangemouth will mainly be spent replacing a 40-year-old power station.