Every technology the calculations screen, in one place. Each entry says what the method is and when it is the answer; the calculation it belongs to is named beside the heading.
Ways of lifting the fluid a well no longer lifts by itself. Each has a page of its own.
Electric submersible pump (ESP, submersible). A multistage centrifugal pump and its motor hang on the tubing at the bottom of the well, fed by a cable strapped alongside.
Gas lift (continuous gas lift). Gas is injected down the annulus and into the tubing through valves, lightening the column until the well flows.
Jet pump (hydraulic jet pump, free pump). Power fluid pumped down the well accelerates through a nozzle and drags the well fluid up with it. Nothing moves downhole.
Plunger lift (plunger). A free piston falls to the bottom of a gas well, the well's own pressure drives it back up, and it carries the accumulated liquid with it.
Progressing cavity pump (PCP, PC pump, screw pump, Moineau pump). A steel rotor turns inside an elastomer stator; cavities travel up the pump and carry the fluid with them.
Rod pump (beam pump, sucker-rod pump, pumpjack, nodding donkey). A surface unit works a rod string up and down; a plunger at the bottom of it lifts the well a stroke at a time.
What to do about a well that under-produces: treat the damage around the wellbore, or fracture the rock. Which route the rock allows is the calculation's first question.
Matrix acidizing (carbonate). Carbonate with permeability the acid can enter without fracturing. Hydrochloric acid dissolves the rock itself and etches wormholes past the damage.
Acid fracturing (carbonate). Carbonate too tight for the acid to penetrate at matrix rates. The fracture is opened first and the acid etches its faces so it stays open under closure stress.
Matrix acidizing (mud acid) (sandstone). Sandstone where the damage is near the wellbore and the rock will take fluid below fracture pressure. Hydrofluoric acid dissolves the clays and fines that plug the pores; it does not dissolve the sand.
Proppant fracturing (sandstone, shale, coal, other). The rock is too tight for a matrix treatment to change anything. A propped fracture creates the flow path the formation does not have.
A lateral drilled out of the existing hole, and the three reasons it produces more than the vertical it replaces.
Water or gas coning. A lateral spreads the same rate over a long contact, so the drawdown at any point is smaller and the cone is slower to reach the well. This is the reason that does not show up in a productivity ratio at all.
More contact with the pay. A thin pay zone gives a vertical well a few feet of contact and a lateral several thousand. This is what the productivity ratio below measures.
A different flow pattern. Flow arrives from the sides and from above and below rather than converging radially, which is why vertical permeability decides so much of the answer.
The methods a reservoir is screened against, in the families the screening table uses.
Gas injection (miscible)
Nitrogen and flue gas. Injected at high pressure, a lean gas strips the light ends out of the oil and develops miscibility — which is why it needs a light, deep, high-pressure oil.
Hydrocarbon gas. Enriched or high-pressure hydrocarbon gas, usually the field's own. Miscibility comes cheaper than with nitrogen, but the gas has an alternative buyer.
CO₂ flooding. The widest window of the miscible methods and the one that has kept growing. It needs a source of carbon dioxide within reach and metallurgy that survives it.
Gas injection (immiscible)
Immiscible gas. Below miscibility the gas still helps: it repressures, swells the oil and drains it downdip. Far more tolerant of heavy oil than any of the miscible routes.
(Enhanced) waterflooding
Micellar / polymer, ASP and alkaline flooding. Surfactant lowers interfacial tension so trapped oil can move at all; polymer carries the slug. The chemistry sets hard limits on temperature and depth.
Polymer flooding. Thickens the injected water so it pushes the oil instead of fingering past it. It improves sweep; it does not reduce residual oil the way surfactant does.
Thermal / mechanical
In-situ combustion. Part of the oil is burned in place to heat and drive the rest. It reaches depths steam cannot, and it is the hardest thermal method to control.
Steam flooding. Heat cuts the viscosity by orders of magnitude. It dominates world enhanced-recovery production, and it is shallow work: the heat has to arrive at the sand.
Steam-assisted gravity drainage. A steam chamber above and a producer below, draining by gravity. It is what the tar sands are actually developed with, and it post-dates most of the projects the table surveys.
Surface mining and extraction. Not a well method at all: the sand is dug up and the bitumen washed out. It is in the table because it is what the shallowest, heaviest deposits actually get.