Sand on Demand for Horizontal Wells: Tracking Behaviour with the CT Scanner

Abstract

The cold production recovery process is successful in vertical wells in western Canada. In this process, large amounts of sand are produced on a continuing basis along with heavy oil. Attempts at cold production in horizontal wells have not been particularly successful. When sand production has been generated in horizontal wells, these wells have tended to become plugged with sand. This paper presents the results of experiments performed to assess the feasibility of applying cold heavy oil production with horizontal wells using less aggressive (i.e., managed) sand production strategies. Specifically it describes the impact of relatively small changes in flow rate on sand production behaviour. The effects on the porosity distribution within the sand pack due to sand production were monitored during one experiment through computed tomography (CT) imaging. The experimental results indicated that the effects of sand production were confined to localized regions (channels) within the sand pack where there was a large permeability and porosity increase. Outside these regions no changes in permeability and or porosity were observed. Channel growth could be controlled successfully (i.e. stopped/started) through flow rate changes. Another experiment demonstrated that continuing sand production at low sand cuts could be achieved if the initial flow rates were low and later increased in small increments. This suggests that if the latter operating strategy is implemented in the field, sand production may be sufficiently high to generate regions (wormholes) with high permeability but sufficiently low to allow produced sand to be transported along a horizontal well.

Sand on Demand: A Laboratory Investigation on Improving Productivity in Horizontal Wells Under Heavy-Oil Primary Production—Part II

“…Typically, the arch radius calculated in this manner will be an upper bound on the radius of the arch around the cavity formed by sand production. For example, in related visualization experiments using computed-tomography scanning (see Meza-Díaz et al 2010), the production of small amounts of sand created a cylindri-cal cavity with a hemispherical tip. The radius of the hemispherical tip is equal to the radius of the cylinder, and somewhat less than the radius of a sphere of equal volume.…”