Reserves & reservoir performance

How much is there, and how much will actually come out? This collection covers the estimation and performance side of reservoir engineering: classifying reserves under PRMS, quantifying volumes probabilistically, reading remaining gas from material balance, and improving recovery beyond what primary and secondary methods leave behind.

In this collection

Reserves classification under PRMS — the framework for what counts as proved, probable, and possible.

Hydrocarbon reserves in probabilities — probabilistic volumetrics with Monte Carlo — P10, P50, P90 done properly.

Gas material balance — remaining gas reserves and drive mechanism from p/Z behaviour.

Enhanced oil recovery — improving recovery beyond primary and secondary — methods and screening.

Each article stands on its own, but together they build a single line of reasoning. Read them in order for a structured tour, or jump to the one that matches the problem in front of you.

Frequently asked questions

How are hydrocarbon reserves classified?

Under the Petroleum Resources Management System (PRMS), by commercial maturity (reserves, contingent resources, prospective resources) and by certainty (proved/1P, probable/2P, possible/3P).

What is gas material balance used for?

Gas material balance estimates original gas in place and remaining reserves and identifies the drive mechanism from the trend of p/Z against cumulative production.

What is Monte Carlo volumetric estimation?

A probabilistic method that samples input distributions — area, thickness, porosity, saturation and recovery factor — to produce a reserves distribution with P90, P50 and P10 outcomes instead of a single deterministic number.

What is enhanced oil recovery (EOR)?

EOR comprises methods — thermal, gas or miscible, and chemical — that recover oil beyond primary and secondary production by altering oil viscosity, interfacial tension, or sweep efficiency.