Abstract
This paper analyzes the problem of heel coning under a variety of drive mechanisms and studies how deployment of downhole flow control devices along the length of the horizontal well affects this phenomenon. To reproduce the heel coning effect for homogeneous permeability fields, wellbore hydraulics must be taken into account. The control approach adopted in this work aims to achieve equal inflow from the heel and toe halves of the completion by adjusting the choke position in accordance with the in-situ flow rate. This strategy likens the behavior of the instrumented well to an infinite conductivity well, as far as inflow is concerned. The control strategy, however, has an outflow/lift cost, as it requires running stinger tubing inside the liner. For water-drive, this scheme results in delay of water breakthrough and extension of the pure oil production plateau. Alternatively, plateau production could be increased. For gas cap-drive, analogous conclusions hold except that the gas/oil ratio constraint necessitates a cycled production scheme with rate cutbacks for successive cycles. For the combined aquifer- and gas cap-drive, control mitigates gas coning more than water coning, because the well is positioned nearer the water-oil contact to satisfy the maximum recovery criterion within the operational constraints adopted in this study. Active control by downhole valves, therefore, is an effective means of overcoming the problem of heel coning where the displacing phase is water, gas, or both. Drainage becomes isotropically more uniform. In practice, realization of this scheme requires a fully coupled flow monitoring and control system.
