In an all-stock transaction with an enterprise value of $5.4 billion, Patterson-UTI Corp. said Thursday it is merging operations with NexTier Oilfield Solutions to become the second largest oilfield services (OFS) company in North America.

The combined company, which would remain headquartered in Houston, would have 172 super-spec drilling rigs and 45 active fracture spreads. The company also would be the second largest pressure pumper in the United States, trailing only Halliburton Co.

“This merger unites two top-tier and technology-driven drilling and well completions businesses, creating a leading platform at the forefront of innovation,” Patterson-UTI CEO Andy Hendricks said. “As one company, we will have a significantly expanded, comprehensive portfolio of oilfield...