Upstream · Drilling & completion
Drilling & completion
A well is a hole a few tens of centimetres wide that goes down one to two kilometres, lined with steel and cement, equipped to produce for twenty years. Drilling is the heaviest spend in Exploration & Production; doing it right — in the right place, on the right path, with the right completion — decides the economics of everything that follows.
From wellpad to target
It starts with the wellpad: a compacted platform, its pits, its cellar, its rig access. From a single pad, directional drilling reaches several targets — three is our standard — which divides land take, roads and gathering lines. The rig drills in sections of decreasing diameter; each section is cased then cemented, to isolate aquifers, hold the wall and contain pressure.
The steps, in order
- Drilling programme — trajectory, muds, casings and cements sized from reservoir data and offset wells.
- Mobilisation — rig, muds, tubulars, measurement services; in Chad logistics is half the schedule.
- Drilling by sections — surface, intermediate, reservoir; measurement while drilling (MWD/LWD) to hold the path.
- Casing and cementing — the barrier that protects fresh water and secures the well for life.
- Completion — perforating the pay zone, production tubing, packers, safety valve; the artificial-lift choice (beam pump, PCP, ESP) is made here.
- First oil and well tests — rate, pressure, water cut: the first weeks calibrate the reservoir model.
After first oil: well intervention
A well lives. It sands up, scales, wears its pump, sees its water cut rise. Interventions — wireline, coiled tubing, or a full workover — return the well to nominal production without redrilling. On mature fields like those of the Doba basin it is the cheapest production lever there is, and the core of our oilfield services.
What we put in place
Three directional wells per pad: less land, fewer lines, fewer roads — and one cellar to watch.
Light rigs suited to the basin’s depths, completion and intervention units mobilised for our fields and for third parties.
Controlled cementing, barrier tests, annulus pressure monitoring: well safety is a file that starts at the drilling programme.
Site managers, drillers, completion operators trained by the Tchaditude academy — before the rig arrives, not after.
Benchmarks
| Item | Order of magnitude | What moves it |
|---|---|---|
| Onshore well duration | 15 to 40 days | depth, path, incidents |
| Drilling share of field cost | 40 to 60% | well count, logistics |
| Targets per wellpad | 3 | reservoir geometry |
| Artificial lift | from completion | heavy crudes, reservoir pressure |
Industry orders of magnitude for African onshore; each well gets its own programme.