A Scaled Model Study of Water Coning

An experimental study has been carried out on a 3 dimensional scaled model which employed porous media and analog fluids to stimulate oil reservoirs produced by natural water drive or waterflooding. The reservoirs modeled were either horizontally stratified or had relatively thin oil column heights. The model tests were performed under varying conditions of production rate, mobility ratio, and relative permeability to water in the water-invaded region of the oil zone. The ratio of oil to water-sand thickness was also varied. A record was made of water-oil contact positions at different times during the model runs. This record consisted of sets of tracings of the water cone positions at different times during production. The fluid production from the model and the water-cut value for each tracing was also noted. The data indicate that the degree of water coning and the value of the water cut increase with: (1) production rate, (2) mobility ratio across the moving boundary, (3) mobility ratio across the fixed boundary, and (4) ratio of aquifer to oil-sand thickness. A technique is provided for applying the laboratory data to field situations.