Delta Petroleum Corp., Dallas, (Nasdaq: DPTR) plans to acquire Castle Energy Corp. King of Prussia, Penn., (Nasdaq: CECX) in exchange for 8.5 million common shares of Delta. Castle holds $40 million in net cash and producing properties in Western Pennsylvania. Lehman Brothers Inc. is advisor to Delta for the transaction. The merger is expected to close by the end of February. This merger was not possible until the Castle's recent settlement of its litigation with Chevron, which was settled for $5.8 million in September.