It is well-known that floating impurities can cluster into narrow, elongated stripes. Existing theories predict the occurrence of clustering in the compressible velocity fields. When we consider a velocity field with potential (compressible) and solenoidal (incompressible) components, complete clustering is possible only if the potential component magnitude exceeds the solenoidal one. However, this result is valid only asymptotically. In the ocean, the ageostrophic component of the velocity field is, in most cases, small. Thus, for floating particles the potential component of the velocity is also small in comparison with the quasi-geostrophic incompressible component. In the present work, we investigate numerically clustering of floating impurities in a stochastic velocity field with a small potential component. We show that, in such flows, clustering of the impurities can occur. However, unlike the case with a large potential component, only a fraction of the initial impurity clusters. Furthermore, we investigate the dynamics of clustering by means of statistical topography characteristics.