Yes lots. You need to Google: nigeria cave for a load of information. Meanwhile, my old friend George Szentes visited this cave in 1989:
http://www.showcaves.com/english/misc/showcaves/Ogbunike.html
Sandstone Caves in Nigeria in English and German.
The study includes the Ogbunike Cave in pages 17, 25, 27, 28.
H?hlenforschergruppe Rhein Main Jahresheft 1989.