Omni Energy Service Corp., Carenco, La., (Nasdaq: OMNI) plans to acquire privately owned Charles Holston Inc., Jennings, La., for $23 million in cash and promissory notes. Charles Holston Inc. recently acquired a long-term contract to provide certain rental equipment to an independent oil and gas company operating in the Rockies. The company also provides environmental services including transportation of non-hazardous byproducts; NORM surveys, cleaning and waste disposal; tank degassing and demolition; and offshore sandblasting and painting. It has facilities in Cameron and Fourchon, La,, and well-site disposal facilities in Richard and Gueydan, La.