My current process is to write scenes in notes in Evernote, and then copy them into a master file in Google Docs. Evernote handles disconnection from the network better than Google (Google's offline mode does not work with my phone, I think because Google assumes your offline device will have enough memory to store your entire drive) and neither program is good at files of more than a few thousand words when open on the phone, so this way I don't end up with my Google drive full of a hundred tiny files.

It's not graceful, but it works for me. -_-