Petroleum Engineering, from rock to barrel
A structured, exhaustive self-study that takes you from "what is a petroleum system" to designing a multi-stage lateral and a field development plan. Six discipline modules, real equations, real diagrams, and the regional practice that makes the Permian different from the North Sea.
What this is #
This is a curriculum, not an encyclopedia. The goal is specific: at the end of six months you should be able to read a well plan, a log suite, a frac design, and a decline curve, and have an informed engineering opinion about each — the working competence of an early-career petroleum engineer.
Petroleum engineering is the discipline of getting hydrocarbons from a rock that is two miles down, under pressure, at temperature, through a hole the width of a dinner plate, economically and without killing anyone. It sits on four legs: geoscience (where the oil is and why), drilling (how you reach it), formation evaluation (how you know what you found), and reservoir, completion and production (how you get it out and keep it flowing). This study is organized around those legs.
Every module returns to one question: how does this change between a vertical well and a horizontal (lateral) well? The shale revolution is, at bottom, a story about turning the well sideways. If you understand why and what it costs in each discipline, you understand modern upstream practice.
How to study it #
Read a module front to back once for the shape of it. Then go back and work the equations by hand — derive the radial flow equation, plug real numbers into Archie, size a casing string. The reading gives you vocabulary; the arithmetic gives you intuition. Engineers are paid for the second thing.
- Pace. One module per month. Each is dense enough to fill four weeks of evening study without rushing.
- Cross-links. A → Connects callout points to where a topic is picked up in another module. Follow them; the disciplines are not actually separable.
- Primary sources. When a topic strays past the scope of a chapter — a regulation, a standard, a landmark paper — the text links the source directly (SPE, API, BSEE, EIA) rather than paraphrasing it. Tap through and read the original.
- Units. The industry runs on oilfield units (bbl, psi, md, °F) with SI as the academic backstop. The units primer is worth memorizing early; unit errors are the most common way an otherwise correct calculation goes wrong.
The six-month plan #
The modules are organized by discipline, but they are sequenced the way a well's life runs: you find it, you drill it, you measure it, you understand the reservoir, you complete and produce it, and finally you see how it all plays out differently around the world.
| Month | Module | What you can do after | Lateral spine |
|---|---|---|---|
| 1 | Geoscience & geophysics | Read a seismic line, explain a petroleum system, judge whether a target exists | Where laterals can and can't be landed |
| 2 | Drilling engineering | Plan a well trajectory, size casing, run the numbers on mud and cement | The build section: turning vertical into horizontal |
| 3 | Formation evaluation | Interpret a triple-combo log, compute water saturation, pick pay | LWD and geosteering inside the target |
| 4 | Reservoir engineering | Do material balance, decline analysis, basic simulation and reserves | Stimulated rock volume and shale decline |
| 5 | Completions & production | Design a multi-stage frac, run nodal analysis, pick artificial lift | Plug-and-perf, stage spacing, cluster efficiency |
| 6 | Regional atlas + capstone | Build a field development plan and defend it economically | How each basin drills its laterals |
Vertical vs lateral, the whole study in one picture #
A vertical well drills straight down and produces from wherever it happens to cross pay. A horizontal well drills down, curves through a build section, and then runs sideways for thousands of feet inside a single target layer — exposing orders of magnitude more reservoir rock to the wellbore. In a tight shale, where the rock barely flows, that exposed length is the entire economic case. Everything in this curriculum is, in some way, about making that sideways section pay.
Hold this picture. In Module 1 the question is geological — is the target layer continuous and thick enough to land a lateral in. In Module 2 it is the mechanics of the build section and staying in zone. In Module 3 it is measuring rock quality while drilling sideways. In Module 4 it is why shale wells decline so steeply. In Module 5 it is the frac stages drawn in sienna. The regional module is how the Permian, the Bakken, and the Marcellus each answer these differently.
The module index #
Each module is its own page, built in this same style and readable on a phone. Module 1 is complete; the rest are being written in sequence.
Units & nomenclature #
Upstream runs on oilfield units. They are not tidy, but they are universal in the field, and every equation in this study that carries a numeric constant (like Darcy's 1.127×10⁻³ or 141.2) assumes them. Learn the table; the constants come from it.
| Quantity | Oilfield unit | Symbol | SI / note |
|---|---|---|---|
| Oil volume | barrel | bbl / STB | 1 bbl = 42 US gal = 0.159 m³. STB = stock-tank barrel (surface conditions) |
| Gas volume | standard cubic foot | scf / Mscf / MMscf | M = thousand, MM = million (Roman, not metric) |
| Pressure | pound per sq inch | psi / psia / psig | 1 psi = 6.895 kPa. "a" = absolute, "g" = gauge (= a − 14.7) |
| Permeability | millidarcy | md | 1 darcy ≈ 0.987 µm². Shale matrix is nanodarcy (10⁻⁶ md) |
| Temperature | Fahrenheit / Rankine | °F / °R | °R = °F + 459.67. Gas-law work uses absolute °R |
| Rate (oil) | barrels per day | bopd / STB/d | BOE = barrel of oil equivalent (~6 Mscf gas ≈ 1 bbl) |
| Density (mud) | pounds per gallon | ppg | 1 ppg ≈ 0.0519 psi/ft of hydrostatic gradient |
| Depth | feet | ft (MD / TVD) | MD = measured along hole; TVD = true vertical depth |
That last row matters more than it looks: in a vertical well MD = TVD, but in a lateral they diverge by thousands of feet. Pressure depends on TVD; pipe and wireline depend on MD. Confusing the two is a classic error.
Master formula sheet #
The equations you will end the study able to use without looking up. They are derived and worked in their home modules; this is the index. Variables are flagged in sienna.
Hydrostatic pressure (Module 2)
Archie's water saturation (Module 3)
Darcy radial flow, oil, steady state (Module 4)
Material balance (general, Module 4)
Arps decline (Module 4)
Productivity index & nodal (Module 5)
Don't memorize these cold yet. Each one is derived from first principles in its module, where you'll also see the assumptions it rides on — which is where engineering judgment actually lives.
Regions at a glance #
The same physics, six very different games. Full treatment in the regional atlas; here is the shape of each.
| Region | Signature play | The hard part |
|---|---|---|
| Gulf of Mexico | Deepwater & subsalt turbidites | Water depth, subsea hardware, HPHT, hurricanes, blowout risk |
| Permian (US) | Stacked shale: Wolfcamp, Bone Spring, Spraberry | Parent-child interference, water handling, takeaway capacity |
| North Sea | Mature sandstone & gas | Decline, decommissioning liability, harsh weather, high cost |
| Middle East | Giant carbonate fields | Reservoir management at scale, sour gas (H₂S), water flooding |
| Indonesia | Mature basins, deepwater gas, CBM | Gross-split PSC fiscal terms, logistics across an archipelago |
| Arctic | North Slope, Barents, frontier | Permafrost, sea ice, ultra-short season, zero spill tolerance |
Companion: the Upstream Field Manual #
This study is the engineering. Its companion, the Upstream Field Manual, is the business and land side — leases and the PLSS, API well numbers, AFEs, regulators, midstream and refining, crude grades and pricing, trading and hedging, the majors and OPEC, and HSE/ESG. Where this curriculum says "and the economics are covered elsewhere," that's where to go. The two are meant to be read together.
Primary sources #
Read the originals. These are the institutions whose pages this study links to when a topic goes past its scope.
- SPE / OnePetro — the Society of Petroleum Engineers paper library; the discipline's primary literature.
- API Standards — the American Petroleum Institute specs for casing, wellheads, drilling equipment.
- BSEE and BOEM — US offshore safety and ocean-energy regulators (Gulf of Mexico).
- EIA Petroleum — US Energy Information Administration data on production, reserves, and prices.
- NSTA — the UK North Sea Transition Authority (formerly the Oil & Gas Authority).
- USGS Energy Resources — assessment methodology and basin studies.