Abstract Experimental results for flow rates and production from gravity drainage experiments involving water and aqueous surfactant solutions are presented. Computer Aided Tomography (CAT scan) results are also given which show through vertical saturation distributions that significant capillary connectivity occurs across horizontal fractures during drainage. Flow rate and cumulative flow are shown to be increased by lowering the surface tension of the liquid undergoing drainage. Some theoretical discussions of the mechanism of drainage across such horizontal fractures are presented, leading to the proposal of effective area as a parameter for simulation of flow in fractured porous media.