Ain’t This The (Reserve) Life – E&Ps Struggle to Maintain Reserve Life Under the Cash-Return Model

In the upstream oil and gas world, “reserve life” — calculated via the Reserve Life Index (RLI) — is one of the simplest and most widely cited metrics. The calculation is straightforward: divide a company’s proved reserves by its current annual production and you get an estimate of how long those reserves will last. But behind that neat little ratio lies a web of technical, financial and strategic forces that can make RLI a surprisingly nuanced measure of an E&P’s long-term outlook. In today’s RBN blog, we analyze the reserve-life trends of the 39 E&P companies we cover.

At its core, reserve life starts with the size and quality of the rock. Reservoirs with strong porosity, permeability and pressure profiles generate higher recoveries, while effective secondary and tertiary recovery techniques can stretch reserves for decades. Deep offshore basins, like the Gulf of Mexico (GOM), are notorious for short RLIs because the reservoirs have very high decline rates. That is the primary reason most E&Ps left the Gulf decades ago, although production there is on the rise (see Back in the Saddle). Shale reservoirs also have much higher decline rates than conventional resources. A short RLI creates a reinvestment treadmill that makes it very difficult to manage the capital demands on the company. The recent emphasis on shale production means that 90% of capital investment since 2019 has gone to offsetting declines rather than adding to supply. Conversely, a longer RLI makes the pace of reinvestment more manageable.

But geology is not the only factor. The weighting of total proved reserves between proved developed and undeveloped makes a huge difference. (Proved reserves are the estimated quantities of oil and natural gas that geological and engineering data demonstrate — with reasonable certainty — can be economically produced from known reservoirs under existing economic conditions, operating methods, and government regulations as of a specific evaluation date. Proved undeveloped reserves require significant future capital before they can be produced. Companies with vast undeveloped reserves generally have a longer RLI than companies with far fewer undeveloped reserves.) In addition, the pace at which a company develops its acreage is equally important: An aggressive drilling program that drives reserve additions higher will push RLI higher, as reserves are added at a faster clip than production. Conversely, a cash-return model (where E&Ps prioritize generating free cash flow and returning cash to shareholders over production growth) can reduce reserve life as reserves are reduced at a faster rate than production drops. This is illustrated in Figure 1 below, which plots the reinvestment rate and reserve life between 2014-24 for our universe of companies. The RLI (blue bars and left axis) averaged 12.8 years in 2014-15 before gradually falling to 9.9 years in 2024 as the reinvestment rate (orange line and right axis) was reduced from 104% of cash flow in 2014-15 to only 50% in 2024.