The "28-32°" riddle, finally solved.
For years, two densities circulated for Chadian crude. The answer is one word — Ronier — and it explains why Doba’s acidity dictates the metallurgy of our future mini-refineries.
Open two technical sheets on Chadian oil: one says 28° API, the other 32°. Four density points apart is no rounding error: it is the difference between a medium crude and a distinctly light one, and it changes everything for refining. So who is right?
Both. And that is exactly where the story begins.
Chad does not have one crude — it has several
The mistake rests on an implicit assumption: that there is such a thing as "the" Chadian crude. In reality, the subsurface produces (at sector level) distinct qualities by basin. The Doba blend, in the south, is a heavy, highly paraffinic (very waxy) crude: dense, with a high pour point. At the other end, the Bongor basin fields — including Ronier — deliver a markedly lighter crude.
The "28-32°" range is therefore no contradiction: it is the signature of a basket of crudes. Depending on Ronier’s share in the average, the needle moves. Blend Doba and Ronier and you get the whole spectrum.
| Parameter | Doba blend (south) | Bongor · Ronier |
|---|---|---|
| Density | ≈ 21–24° API — heavy | ≈ 32–40° API — light |
| Paraffins | High — very waxy | Moderate |
| Acidity (TAN) | ≈ 4.7 mg KOH/g — very high | Low |
| Pour point | High | Low |
| Refining implication | Anti-corrosion metallurgy + dewaxing | More standard scheme |
The real lesson is not density — it is acidity
Fixated on density, many miss the decisive parameter: acidity. Doba crude shows a total acid number (TAN) of around 4.7 mg KOH/g — very high. Those naphthenic acids become corrosive at high temperature, exactly where crude is heated for distillation.
The practical consequence: a unit designed for a "sweet" crude gets eaten away. Refining Doba requires adapted metallurgy in the hot zones (stainless steels with higher molybdenum content, or better alloys), corrosion management and handling of the waxy character (pour point, dewaxing).
Know the molecule before you cut the steel: that is the first competitive advantage of a refiner in Chad.
Three concrete consequences for a refiner
Going from the data sheet to the process scheme means translating those two parameters — density and acidity — into engineering decisions. Three of them change everything:
- Metallurgy first. In hot zones (furnace, column, bottom lines), Doba’s high TAN requires stainless steels with higher molybdenum content, or superior alloys. Choosing ordinary steel means scheduling corrosion — and shutdowns.
- Dewaxing is not optional. The waxy character raises the pour point: without paraffin management (heating, additives, an adapted scheme), the crude sets in the lines. A detail in the lab, a production shutdown in the field.
- The basket as a control variable. Ronier’s share in the blend becomes a lever: adjust the blend to hit the fuel yield you want — provided you know, batch by batch, what goes into the tank.
Why this matters to EnerTchad
Our ambition of modular mini-refineries is not about dropping a generic skid at the edge of a field. A standard skid, designed for a neutral crude, would fail on Doba — corrosion, fouling, shutdowns. The challenge is to design for this crude: the right metallurgy, the right process scheme, the right paraffin management.
It is also the purpose of our Atlas of the Chadian oil sector. Reconciling contradictory figures, documenting density, acidity and basins is no academic exercise: it is the condition for sizing correctly, de-risking a project and talking to investors with facts, not approximations.
The "28-32°" riddle looked anecdotal. It sums up our conviction: in Chad, value begins with knowledge of the resource — and that is where we intend to be the best.