A quantitative experimental study on sand production from unconsolidated sandstone reservoir and gravel-pack plugging performance

Abstract

In order to understand the sand production law of unconsolidated sandstone reservoirs and the plugging performance of packed gravel comprehensively. In this study, the “Multi-Injection and One-Production” (MIOP) sand production simulation experimental system designed and developed independently was used to conduct experimental research on the sand production law of unconsolidated sandstone reservoirs and the plugging performance of packed gravel under different pressure differences and different fluid properties. And two standards of sand production intensity(I_s) and sand production concentration(C_s) were put forward to evaluate the sand production severity of formation and the sand plugging performance of gravel-pack. The results show that: The sand production law of the reservoir shows that the sand production is loose sand and free sand under low pressure difference and low viscosity, which leads to pore throat blockage. With the continuous increase of pressure difference and viscosity, the reopening of pore throat and the peeling of skeleton sand lead to the increase of sand production. At the same time, the critical sand production pressure difference of the target reservoir is 1.9MPa and the critical sand production viscosity is 65-70mPa s. When the packed gravel is 0.425-0.8mm quartz sand, the minimum invaded depth of the gravel-pack is 3.3mm and the I_s and C_s under different conditions are slight sand production, which indicates that the best packed gravel suitable for the target reservoir is 0.425-0.8mm quartz sand. In addition, the experimental results show that the plugging performance of quartz sand is better than that of ceramsite sand under the condition of the same particle diameter. This study has a certain engineering guiding significance for clarifying the sand production mechanism of sandstone reservoir and the design of gravel-pack control scheme.