ABSTRACT:

Cold heavy oil with sands is a primary recovery method widely used in the world as a profitable and easily technology. This single well technique produces massive sand due to high oil rates. Foamy-oil flow and wormholes formation are the governing mechanisms of the massive sand influx. The wormholes are channels of high-porosity and high-permeability, which are created during the early stage of aggressive sanding. These channels are cavities or volumes in which there is no grain-to-grain contact, and are full of slurry. In this paper, a new methodology is proposed to model the initiation and propagation of wormholes under critical production conditions incorporating failure criteria, and porosity and permeability changes during massive sanding. The wormholes initiate due to mechanisms such as in-situ stresses, failure criteria, pressure gradient and erosion, defining four zones around the well: liquefied zone, yielded zone, transition zone and intact zone, each one with different mechanical and petrophysical properties, which are changing during the oil and sand production. A single well model that couples a fluid flow model and an elastoplastic geomechanical model is the tool to implement the wormhole methodology. The general characteristics of the coupled model are described, a flow chart is defined for the implementation of the methodology and the definition of the four different zones. A preliminary case is run to illustrate the wormhole formation and its effect on the well productivity with suitable results in terms of increment in porosity and permeability, and a advance in the wormholes up to 0.5 ft.

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