Definition - What does Wireline seals mean?
Wireline Seals, also known as slickline seals are the pressure liquid seal heads that were developed so that mechanical packing assemblies can be replaced from conventional stuffing boxes which used to house such mechanical packing assemblies. The liquid seal head contains a combination of wireline seal bores and a gas control mechanism. The design allows for superior control of well pressure within a shorter assembly length.
Petropedia explains Wireline seals
Wireline seals seal two or more equipment parts. These seals help to contain the pressure which originates from the wellbore. They also hold the wireline tight preventing them from falling downhole should the line pull out of a rope socket. A good example of the wireline oilfield seals is the O-ring. An O-Ring, also known as a toric joint is a packing or sealing material used to seal two or more mechanical equipment parts. These rings act like a mechanical gasket which has the shape of torus, and a loop of elastomer with a rounded cross section.