The Athletic understands that the two clubs have agreed a fee of considerably more than the £52.5million quoted in reports last night.
Levi Colwill, Chelsea’s 19-year-old central defender, will join Brighton on loan for the upcoming season.
An announcement confirming both deals is expected tomorrow.
Cucurella had been told to stay away from first-team training this week, with head coach Graham Potter keen to avoid any distractions ahead of Sunday’s opening Premier League game against Manchester United.
The 24-year-old Spanish left-back handed in a transfer request amid interest from Manchester City.
But the reigning Premier League champions pulled out after falling well short of Brighton’s valuation.
Cucurella joined Brighton from Spanish side Getafe for £15million ($18.25m) last summer.
He impressed for Potter’s side, featuring at left-back, left centre-back and left wing-back over the course of 35 Premier League appearances.
The Spaniard scored once for Brighton, against Manchester United. He won Brighton’s Players’ Player of the Season award and their Player of the Season honour.
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