Strong Support for Significant Productivity Boost Through Sand Production

ABSTRACT: Centrifuge physical model tests were performed to study the mode of failure during sand production and its concomitant impact on the productivity index. The tests simulated seepage-induced failure around a multi-perforated vertical well. Results indicate that in the presence of a competent cap rock (1) sand production results in the formation of a (truncated) cone-shaped enlarged cavity, (2) surface subsidence of the reservoir due to loss of sand mass may result in opening of flow channels under the cap rock, (3) for a given applied head difference, sand production ceases once the enlarged cavity lowers the flowrate to sub-critical level,. (4) flow becomes diverted towards the upper perfs where the cavity radius is largest, (5) flow rate increase varies between 5 to 10 times depending on whether the mode and volume of sanding is sufficient to result in the formation of flow channels. The study performed shows that (1) the location of perfs affects the mode and magnitude of sand production, and (2) long-term productivity can be improved through managed sand production. Presence of a competent cap rock is the key for maximizing the productivity via sanding.