Several simple examples are presented that demonstrate the application of an ensemble-based method to production optimization. In particular, some practical aspects of the method such as ensemble size, perturbation, regularization and smoothing, and robust gradient estimation are discussed by comparison with an adjoint approach. The controls in the presented examples are inflow control valve settings for fixed time intervals or well position. We find that the performance of the method is clearly affected by the correlation time scale that is assumed for the controls, as reflected both by the quality of the gradient estimation and the subsequent optimization. The well placement optimization problem is studied for two cases: one is a homogenous reservoir with a sealing fault, and the other a non-homogeneous case. The ensemble optimization method is found to work well for both these simple well placement problems.