The OPM project aims to create a fully featured open source reservoir simulator. The open source nature of OPM makes it a very convenient platform for research on all aspects of reservoir simulation, but in addition to serving as a research platform it has all the way been a premise for the OPM development that the simulator should have industrial relevance. OPM/flow reads and writes the file formats of ECLIPSE.
Does OPM/flow work with your model?
At https://github.com/OPM/opm-data and https://github.com/OPM/opm-tests you can find several datasets which are used for continous testing of the OPM codebase, that should give you an impression of the current capabilities. When it comes to your particular model it is of course impossible to give a general answer, but if you are willing to change some keywords in the .DATA file - often the exact same reservoir behavior can be achieved with different keywords, chances are good that OPM/flow will be able to run your model. In general the set of commonly used keywords is smaller and simpler for the historical phase than for the prediction phase, so your chances of success will probably be better for a simulation of the historical phase.
I can provide consulting services with help to set up OPM inside your organisation, in addition to actually installing OPM/flow that can include minor changes to your .DATA file, and possibly also minor developments on the OPM codebase itself. OPM/flow works nicely with ERT and is well suited for a multi-realisation workflow.