NEW YORK (Bloomberg) — Bermuda-based Nabors Industries Ltd., the largest onshore petroleum driller, is buying Superior Well Services Inc. for $735.6 million in cash, adding pumps and services used to free oil and natural gas from rock.

Holders of about 34 percent of Superior Well's stock accepted the $22.12 a share offer, Nabors said yesterday in a statement. The offer represents a 21 percent premium to the August 6 closing price. The sale is valued at about $900 million, including debt, according to the statement.

Superior Well's largest business unit injects water, sand and chemicals into rock, helping gas or oil to flow from unconventional deposits such as shale. Demand for the pressure-pumping service has surged as producers seek better production from each well, said Roger Read, a Houston-based analyst for Natixis Bleichroeder Inc.

"Pressure pumping is setting new record highs in utilisation," Read, who rates Nabors's shares at "buy" and owns none, said today. "It's clearly growing faster than drilling."

Successful pressure pumping relies on specialised machinery and experienced operators, and Nabors gets both by buying this company, Read said.