Mesa Petroleum Co. Chairman T. Boone Pickens Jr. said yesterday the company plans to repurchase up to $100 million of its common stock.

Pickens, who has launched hostile takeover bids for several major oil companies and urged them to reward stockholders by repurchasing shares rather than investing in uneconomic oil prospects, said Mesa's stock buyback would be conducted through open market purchases. He said the plan still needs the consent of certain lenders, although their approval is expected to be granted at a meeting this Thursday.

"We believe that our shares represent an attractive reinvestment opportunity," Pickens said. "Mesa constantly evaluates alternatives to maximize values for Mesa shareholders, and we believe that share repurchases meet the criteria at this time."

Mesa stock rose 1/4 to 14 3/4 yesterday, as 465,000 shares changed hands. The stock, which traded as high as 22 last year, dropped precipitously recently when Pickens was unsuccessful in his fight to gain control of Unocal Corp.

David Batchelder, the Amarillo, Tex.-based company's vice president for finance, said yesterday the repurchase, which will increase the company's net debt from around $250 million to $350 million, is not the first step in a plan to take the company private. He also said there currently are no plans to conduct future share repurchases.

"We have a substantial amount of liquidity," Batchelder said, "and we are not an aggressive explorer today because of the economics of the oil industry. By repurchasing our own shares, we are finding oil equivalents for around $4 a barrel [Mesa's oil and gas reserves on its books relative to its stock price]. We can't find them [new reserves] for that."

Mesa had revenue in 1984 of $413.5 million and net income of $253.9 million ($3.75 a share). About $214 million of Mesa's profits came from the sale of Gulf Corp. stock, when Gulf was sold for $13.3 billion to Chevron Corp. in order to avoid being acquired by Mesa.

Mesa's profits from oil and gas exploration and sales have been flat for several years. Pretax operating income was $154.7 million in 1984, $158.5 million in 1983 and $152.6 million in 1982.

Mesa, which describes itself as the nation's second-largest publicly traded independent oil company, had proved reserves at the end of 1984 of 1.37 trillion cubic feet of gas and 31.5 million barrels of oil, versus 902 billion cubic feet of gas and 27.9 million barrels of oil at the end of 1983. The dramatic increase in gas reserves reflected Mesa's acquisition of 89 percent of the shares of Mesa Royalty Trust.