In addition to plummeting crude oil prices, oil companies in Oklahoma are faced with another challenge, oil field thefts.According to authorities, at least three oil fields in Canadian County have fallen victim to theft in the last month.Cimarex Energy tells KOCO that someone recently stole a 3500 watt power invertor from one of their oil fields in Union City.“It’s just desperate people with nothing else to do,” said Hardy Taylor, an employee of Cimarex Energy.Taylor said thieves often target oil fields because many of the sites are unmanned.“It’s just easy to take stuff, in particular batteries,” Taylor said. “They can steal a battery, if you make it easy for them.”While the thieves sell it for scrap, the oil companies are left with the hefty expense.“It’s an expense, the battery alone is $200,” Taylor said.When adding up the cost to replace it and the loss of production, Taylor said it can end up costing the company thousands of dollars.Since 2012, Taylor said the Cimarex Energy has lost between $8,000 and $10,000 in oil field thefts.In an effort to stop the oil field thefts, Taylor created a device that he mounts in the battery boxes to make it difficult for a thief to pull the battery out of the box.“It just slows them down so much, that they don’t mess with it,” Taylor said.In addition to Cimarex Energy, Powell Well Service has also been a victim of the recent thefts. A pickup truck and welder were stolen from one of their oil field sites in Canadian County.Devon Energy also reported having a 60-gallon Porter Cable compressor stolen in late January.