It's not easy to in general. Gas plants typically operate via cryogenic processes. The boiling point of ethane at standard pressure is -128.2F, so you need to get below that to get everything but the methane to liquefy. -128.2F by itself isn't terribly difficult but doing so on a highly variable flow, at a well site with questionable power, with 100% reliability will be difficult.

Gas plants typically also operate above atmospheric pressure because the boiling points are higher (meaning less cooling required). That, also by itself, isn't difficult, but does add complexity and cost.