Oley's prelude to the chorale "Danket dem Herren" is a densely written manualiter piece with the chorale melody in a canon in the fourth. Oley really liked canons, though I tend to think that he liked them more than he was actually able to write them. Oley makes a few odd alterations to the chorale melody that are not necessary to maintain the canon. The chromatic character of the piece is in itself a nice detail, but it doesn't really fit the text ofthe chorale, so I am left wondering why Oley wrote it this way.
Score available here: https://partitura.org/index.php/johann-christoph-oley-danket-dem-herren