Those reactors will generate heat. Oil and gas are generated in rocks by the heat and pressure to which the rocks are subjected, generally at depths of 10000 ft. or so for oil, and deeper for mostly natural gas (the heat breaks down the long chain hydrocarbons and little oil is found, depending on the basin). Both can occur at more shallow depths, but often the oil found is a result of previous burial at depth, now more shallow because of tectonic activity and erosion. Natural gas can be found more shallow, commonly emanating from coal seams, but also through migration toward the surface.
With that in mind, will the heat given off by these reactors be sufficient to bring sediments in the vicinity to thermal maturity, that is, to generate oil or gas, and if so, how is that going to be dealt with (a potential problem that could actually become a byproduct if not radioactive as a result of the reactor).
For instance, those same reactors could be buried in the Green River Shale of the Piceance Basin in Colorado, and possibly solve the problem of how to extract oil from the shale there.