* Virgin Islands company to make cash offer after buying stake
* CAT Oil shares gain 3.6 pct (Adds CAT oil comment, background)
VIENNA, Oct 31 (Reuters) - British Virgin Islands-based Joma Industrial Source acquired an indirect 47.7 percent voting stake in CAT oil AG this week and will make a mandatory offer to other shareholders of the German-listed Austrian company, Joma said on Friday.
"Joma Industrial intends to offer the shareholders of C.A.T. oil AG...a price in cash equalling the domestic weighted average stock exchange price of the C.A.T. oil share during the last three months prior to the publication of the acquisition of control," it said in a regulatory release.
A spokeswoman for CAT oil said it had taken notice of the release from Joma and would comment on it later.
CAT oil shares closed up 3.6 percent at 15.20 euros, off a session high at 15.94.
CAT oil's operations focus on Russia and Kazakhstan, with customers including Lukoil, Rosneft, TNK-BP, Gazprom and Kazmunaygaz. It specialises in boosting the productivity of wells via hydraulic fracturing, or "fracking".
The release said Maurice Gregoire Dijols was among the investors who had acquired indirect control of CAT via the deal. It was not immediately clear whether this was the same Maurice Dijols who was head of oil services company Schlumberger Russia. (Reporting by Shadia Nasralla and Michael Shields)