U.S. oil and gas mergers and acquisitions hit a 10-year low during the first quarter of 2019, a downturn that, if it continues, could negatively affect revenue at the numerous Texas firms dependent on upstream M&A work.

But shortly after the end of the three-month period of unusually soft numbers, California’s Chevron Corp. announced it would acquire Anadarko Petroleum Corp., an energy company based in The Woodlands, north of Houston, in a deal valued at $33 billion.