Sand Retention Testing: Reservoir Sand or Simulated Sand - Does it Matter?

Abstract

Sand retention testing obviously requires sand, and using the reservoir sand is the most straightforward option. However, sometimes reservoir sand is not available in sufficient quantity, and in these instances a particle size distribution matching the reservoir sand is prepared from commercial outcrop sand. The authors were aware that there can be some differences between the results from outcrop and reservoir sands and generally only use reservoir sands, but a recent request for tests using simulated sands gave the impetus for a systematic study of the variations.

Retention tests have been performed with different reservoir sands and two versions of their respective simulated sands; one matched to their laser particle size distribution and one matched to the sieve analysis distribution. Sandpack tests and two slurry test methods (xanthan and caesium formate) have been performed with a range of wire wrap and metal mesh screens. There are quite striking differences in the pressure data recorded between the actual reservoir sands and the simulated sands. The trend in the amount of sand produced between reservoir and simulated sand is still uncertain, but the study has shown some instances that could change the screen recommendations. Efforts have been made to understand the differences between reservoir and simulated sands by examining particle shape.

The results of this study show that using sands simulated from outcrop rock can give retention test results different from those obtained with reservoir sands. This and other potential test artefacts should hopefully discourage reading too much into retention test data; especially for estimating likely sand production. Predictions of sand screen performance based on lab studies will remain problematic until comparisons with field performance (both failures and successes) can be made.