As the calendar passes from one year to the next, there’s a natural tendency to look back to see how some of the energy landmarks have shifted over time.

This rang especially true last year, when energy stocks seemed at one point to disconnect from the commodity. As the price of West Texas Intermediate moved up into the mid-$50s, energy stocks’ divergence from the commodity expanded to the largest level in 15 years, according to a Goldman Sachs report discussing a possible resurgence in M&A activity.

M&A is, of course, just what’s needed to jolt interest into an energy sector that’s been beleaguered by investor indifference of late. However, there have been false starts before. In the spring of 2016, in the wake of Royal Dutch Shell Plc’s acquisition of BG Group, one report questioned “whether the deal is one-off or whether it launches a frenzy of M&A activity.” Its answer: “We think the latter.”

Granted, there have been some significant M&A transactions in the last couple of years. But these are hardly comparable to the waves of corporate M&A that led to the creation of the supermajors in 1998 to 2001 or the international diversified oils in 2001 to 2006. Goldman data indicate corporate M&A deals averaged 4.1 per year in 1998 to 2006, but fell to 2.4 deals per year since then.

Another area where projections have been pushed to the right is the approaching precipice of major project start-ups. Following the sharp decline in oil prices in late-2014 and into 2015—and the resultant drop in capex—a common thought was that the impact of successive years of severely reduced levels of final investment decisions authorizing major projects would begin to show up in 2017.

However, major project databases—admittedly complex to construct and maintain—have delivered differing forecasts over time. A December 2016 report by Simmons & Co., for example, firmly predicted that “the major project start-up queue evaporates in 2018.” Some six months later Simmons said the project backlog was expected to experience “a step function decline beginning in 2018.”

In its latest report, published in December, Simmons said it expects the “start-up queue to decline considerably by 2019 and to remain depressed for a number of years.” It cited annual average capacity of major projects starting up in the 2019 to 2021 period at just 1.05 million barrels per day (MMbbl/d) tracking 48% below the 2013 to 2018 average of 2 MMbbl/d.

As a sign of tightening world oil supply, this is definitely good news for investors—even if it arrives a little later than originally anticipated.

Another indicator of a tighter oil market is a recent Rystad Energy report estimating that discoveries of conventional reserves in 2017 came in as low as 6.7 billion barrels of oil equivalent (Bboe). This compares to roughly 30 Bboe in 2012 and around 15 Bboe each in 2013, 2014 and 2015, and drops the reserve replacement ratio (vs. global production of more than 55 Bboe) to a mere 11%!

While major projects coming to fruition usually unfolds over a multiyear period, the possibility of M&A striking could materialize much more quickly. In late-December, for example, The Wall Street Journal ran an article suggesting Saudi Arabia had inquired about acquiring assets in the Permian and Eagle Ford.

In its M&A report, Goldman Sachs saw potential accretion of returns at $50/bbl, even if the average E&P were acquired at a 30% premium. It cited, among other factors, operational synergies (e.g., longer laterals, improved productivity) and balance sheet synergies (e.g., interest expense savings if an investment-grade company were to buy all outstanding debt of a high-yield E&P).

Tudor, Pickering, Holt & Co. also anticipates M&A, but puts the odds on a more extended timeframe.

“Consolidation is something that typically happens when things are either really bad or really good, and I think we’re headed back to really good,” said president Dan Pickering in a Bloomberg interview. “I don’t think anyone wants to give away the farm here at $58/bbl and energy stocks that have dramatically underperformed. I think consolidation is going to happen when people feel better, both investors and the oil markets.”

“The oil market is feeling better than stocks right now. As stocks start to pick up, I think that will give companies confidence,” added Pickering. “When that occurs, that’s when you’ll see consolidation. It feels to me like it’s a late 2018 issue, not an early 2018 issue.”