Reaching three targets from a single wellpad.
Mud motor, rotary steerable, MWD, LWD: how a well is curved, how you know where it goes — and why Chad’s landlocked geography makes directional drilling an economic evidence.
From the road, a well looks vertical: a derrick, a hole, straight down. Modern reality is more elegant — and more useful in Chad than almost anywhere. Directional drilling deliberately curves a well’s trajectory to reach the target where it lies, not where the derrick stands. From a single wellpad you reach three, five, eight targets. For a landlocked country where every hectare of pad is won against the rainy season, this is as much civil engineering as geology.
Why deviate a well?
Three reasons command it. Footprint: one wellpad serves several wells — less earthworks, fewer tracks, fewer quagmires, the argument readers of our wellpads interview already know. Geology: a reservoir is not a point but a sheet; an inclined or horizontal drain crosses more useful rock than a vertical that merely pierces it. Access: some targets sleep under a village, a wetland, a protected area — you reach them from the side, without setting foot there.
How do you turn a hole?
Two families of tools. The mud motor: a bent section of a fraction of a degree, driven by mud circulation; orient the bend, drill without rotating the string, and the well inclines — a few degrees every thirty metres, the build-up rate. The rotary steerable system (RSS): steered pads push against the wall while the whole string keeps rotating; smoother trajectory, better hole cleaning. In both cases the drilling mud — the one from our fluids line — carries the energy, cools the bit and lifts the cuttings.
MWD: knowing where you are
Curving a well without knowing where it goes would be costly blindness. Measurement while drilling (MWD) continuously reads inclination and azimuth a few metres behind the bit, and telemeters them… through the mud itself: coded pressure pulses climb the column like a hydraulic telegraph. At surface, the engineer compares the actual trajectory with the well programme and corrects — a few metres of drift can be recovered, a few dozen are paid for.
LWD: reading the rock while drilling
The same toolstring can carry logging sensors (LWD): gamma ray to tell shales from sands, resistivity to scent hydrocarbons. This is geosteering: no longer following a purely geometric path but the rock itself — the drain stays within the few metres of reservoir that pay, rising or diving as the sheet undulates.
Precision, and its limits
Every measurement carries uncertainty; their sum draws an ellipse of uncertainty around the well that swells with depth. Anti-collision discipline keeps neighbouring wells outside that ellipse — vital on a wellpad where eight wellheads sit metres apart. It is a specialists’ craft, with its software, its geomagneticians and its cross-checks.
What it changes for Chad
The Doba and Bongor basins lend themselves to it: shallow reservoirs, mature fields where every additional barrel counts, an imperative of minimal footprint. Three targets reached from one wellpad means two pads not built, two tracks not opened, two rainy seasons not endured — the cost per barrel remembers. That is why directional drilling sits in our catalogue as an integrated line: specialists and tools contracted and supervised by EnerTchad, from well programme to final report, under our project management and HSE-Q foundation — the exact scope is stated on the E&P services page.