These core tests are one of the most important ways of estimating the success of an unknown venture. But the tests are imperfect because they sample only an exceedingly small portion of the reservoir. Consequently, questions arise about how well the core represents the reservoir. One of my earliest tasks in the industry was to design a pilot test that, it turned out, would have taken at least ten years to complete. Since only a few pilots can be done, they always leave questions about the statistical significance of their results.
Numerical simulation remedies the deficiencies of laboratory and pilot-scale testing.
Numerical simulators are computer programs that mimic the entire process of flow and production of hydrocarbon from a reservoir. Immensely complex, simulators are free from most of the problems of other tests. They can be run several times, they can be made as realistic as necessary, and, best of all, each execution takes at most an hour or so even for complex cases. Indeed, most large projects done in the oil industry have been simulated, at least to some degree. While numerical simulation has been a boon to the oil industry, it also brings its own set of problems.