Underwater digging water jet

Well it looks like he is using the well pressure (natural gas) to jet water/sand/mud etc. from the "celler" around that well. The gas could be coming from this well or another well close by. WHY he is doing this is a harder question to answer.

The well is connected to the "Christmas tree" That is the thing with the rotary valve handles. There are usually 3 or more valves in the Christmas tree. Probably the 3rd valve is underwater and maybe buried in the mud/sand that has filled up the celler. He may be trying to close the lower valve but has to "clean it up a bit to
be able to get it to turn. Or maybe he was at the well when he accidentally dropped his dentures. and now is searching for them down below.

Underwater digging water jet - GIF