"The additional barrel": the oil we thought was lost.
A conventional oil field leaves, at the end of its primary life, most of its crude underground. Enhanced oil recovery aims to reclaim a share of it — and it is often the cheapest barrel to produce.
Here is an uncomfortable number: a field produced conventionally delivers, on average, only a fraction of the oil it contains. The rest — often the majority — stays trapped in the rock, for lack of pressure to push it up. In Chad as elsewhere, "declining" fields keep most of their value underground.
That is the whole point of enhanced oil recovery (EOR): going after the barrel left in place, without restarting a costly exploration campaign.
The paradox of the barrel left underground
A field produces in three stages. Primary recovery uses the reservoir’s natural pressure: it typically frees only a limited share of the oil in place. Secondary recovery (water or gas injection) maintains pressure and extends the field’s life. Tertiary recovery, or EOR, changes the very properties of the fluid or the rock to unstick the residual oil.
The key point is economic: that oil sits beneath a field already discovered, already drilled, already connected. Geological risk is gone. The infrastructure exists. What remains is investing in the right recovery technique — marginal capital, compared with the cost of a new field.
ASP, gas, steam: three levers, one goal
Each EOR family answers a type of reservoir:
- Chemical EOR (ASP). Injecting alkalis, surfactants and polymers lowers the tension between water and oil and improves reservoir sweep. It is the most promising route for crudes like Chad’s — and the one where local inputs (natron-based) can play a role.
- Gas EOR. Injecting gas (associated gas, CO₂) re-pressurises the reservoir and mixes with the oil to mobilise it — a route that converges with putting today’s flared gas to work.
- Thermal EOR. Heat (steam) thins heavy, viscous crudes. Relevant for some paraffinic crudes, but more energy-intensive.
The best field, sometimes, is the one you have already drilled. You still need the right chemistry to talk it into coming up.
Why EOR makes sense in Chad
Three reasons converge. First, the country has mature fields in the Doba and Bongor basins, natural candidates for enhanced recovery. Second, the capital required is marginal: you build on existing wells and facilities rather than a new development. Third, the recovery chemistry can be anchored locally — formulating surfactants and polymers from Chadian natron turns one of the country’s mineral resources into a lever of oil production.
That is the logic of the additional barrel: producing more while investing less, keeping the value — and the inputs — in Chad. Our additional-barrel calculator lets you gauge the order of magnitude, and the Enhanced recovery page details the approach.
None of these steps is acquired yet: EnerTchad is a company in formation, and these volumes are targets, paced by pilots. But the direction is clear — in Chad, part of the oil future is already underground, in fields we stopped producing too soon.