Oil & gas explorer San Leon Energy has signed a joint venture deal with Palomar Natural Resources (PNR) to explore in Poland's Permian basin.PNR has paid $5m and $15m cash upfront for a 65% working interest in each of the Southern Permian Basin and Northern Permian Basin concessions, respectively.It will pave the way for an initial work programme aimed at bringing the Rawicz and Siekierki fields into production as soon as possible. PNR will run all the concessions.San Leon's Chairman Oisin Fanning said: "PNR bring a team of US-based industry experts with the expertise to maximise production and ultimate recovery from these significant gas fields."Shares in San Leon rose 0.69p or 34.7% to 2.68p at 11:17 in London.PW