ECLIPSE is an oil and gas reservoir simulator originally developed by ECL (Exploration Consultants Limited) and currently owned, developed, marketed and maintained by SIS (formerly known as GeoQuest), a division of Schlumberger. The name ECLIPSE originally was an acronym for "ECL´s Implicit Program for Simulation Engineering". Ian Cheshire was the team leader.
ECL was, as its name implied, an exploration oriented consulting firm. Ted Daniels, CEO and Chairman of ECL, decided to expand into reservoir engineering in order to broaden the base of the company and to avoid the cyclic downturns in exploration based revenues, and specified the requirements for corner point geometry in order to better model the subsurface geology. That and the implicit technology enabled ECLIPSE to set new standards in reliability, stability and accuracy for reservoir simulators. ECL had previously been awarded the Queens Award for Exports and, based upon the success of ECLIPSE, was subsequently awarded the Queens Award for Technology.
The first ECLIPSE sale was made to BHP in Australia, followed shortly by major sales to Statoil in Norway. The program ran on a wide range of computers from large IBM systems to the HP 9000, a desk top unit. It is written in Fortran 77 and was used to help debug F77 compilers at IBM and Cray Research.