I usually use that said or that being said etc.
Today, for the first time in my life probably I read an email with This said.
Is This said correct? If so then why we don't commonly use it instead of that? In fact Wiktionary and macmillandictionary and many others have the phrase this said and not that said
After all, texts are written a text like so:
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
That said, Lorem ipsum dolor etc..
The two paragraphs are in the same dialogue, one paragraph apart. So if this said is an option, then perhaps we should use it more commonly than that said since the events in the dialogue aren't far apart.