* CEO departure not a sign company is on the block
* Interim-CEO says Eresman had expressed fatigue
* Executive search to take 3-6 months
* Shares fall 2.3 pct
CALGARY, Alberta, Jan 14 (Reuters) - Encana Corp, Canada's largest natural gas producer, quashed speculation on Monday that the company may be up for sale following the unexpected retirement of its chief executive.
The appointment of an interim CEO, Encana director Clayton Woitas, was seen by some analysts as a signal that the company could be put on the market.
Encana has massive natural-gas reserves from conventional and shale-gas fields which could attract international oil companies, but Woitas said the departure of Randy Eresman announced late on Friday was not a sign that the board would seek a buyer for the company.
"Encana is not up for sale," Woitas said in an interview.
Eresman, who led the Calgary, Alberta-based company for seven years, faced criticism from investors because of a poor share price performance due to low natural prices and U.S. Department of Justice probe into whether the company illegally colluded with Chesapeake Energy Corp to lower the price of Michigan exploration lands.
"Randy had expressed to board members a high degree of fatigue in dealing with the public marketplace," Woitas said. "We were also getting feedback from the public marketplace that the fatigue was ... evident."
He added that the Michigan investigation played no role in Eresman's departure. Encana in September cleared itself of any wrongdoing in an internal investigation that was not made public.
"It had nothing to do Randy's departure. Zero," he said.
Woitas is best known as the former chief executive of Renaissance Energy Ltd, a publicly traded natural-gas producer he left a few months before it was bought by Husky Energy Inc for C$4.3 billion ($4.36 billion)in 2000.
He went on to found Profico Energy Management and sold it in 2006 to Focus Energy Trust for C$1.1 billion. He has been on Encana's board since 2008.
Woitas said he expects the hunt for a new chief executive to take between three and six months and that it will be "business as usual" at the gas producer until the search concludes.
The search will look at both internal and external candidates.
Encana shares fell 2.3 percent, or 45 Canadian cents, to C$19.05 on Monday on the Toronto Stock Exchange.