TY  - EJOU
AU  - Liu, Tianen 
AU  - Dai, Kun 
AU  - Ren, Shiju 
AU  - Zhang, Chuanxiang 
AU  - Tang, Xiaoling 
AU  - Hu, Jinghong 
AU  - Cai, Yidong 
AU  - Lu, Jun 

TI  - Sand Production in Unconsolidated Sandstone: Experimental Analysis of Multiphase Flow During Cyclic Injection and Production
T2  - Fluid Dynamics \& Materials Processing

PY  - 2025
VL  - 21
IS  - 12
SN  - 1555-2578

AB  - Many mature onshore oilfields have entered a high-water-cut stage, with reservoir recovery approaching economic limits. Converting these depleted or nearly depleted reservoirs into underground gas storage (UGS) facilities offers an efficient way to leverage their substantial storage potential. During cyclic gas injection and withdrawal, however, the reservoir experiences complex three-phase flow and repeated stress fluctuations, which can induce rock fatigue, inelastic deformation, and ultimately sand production. This study uses controlled physical experiments to simulate sand production in reservoir rocks subjected to alternating gas injection and production under three-phase conditions. After preparing oil-water-saturated cores through waterflooding, gas is introduced to perform repeated displacement cycles. Polynomial models relating core mass loss to water-oil ratio and cycle number are developed using the Newton interpolation method, enabling prediction of sand production under various operating conditions. Results show that, within the critical pressure-difference range for sand onset, permeability increases with water-oil ratio. When the water-oil ratio lies between 0.3 and 1, sand production decreases progressively; beyond a ratio of 1, sand production increases with further increases in water-oil ratio. The number of displacement cycles exerts a dominant influence: sand production remains relatively stable between 25 and 55 cycles but rises sharply thereafter. Average sand production during cycles 55–100 is 5.27 times higher than during cycles 5–55. These findings indicate that cumulative structural damage to the rock framework intensifies significantly with repeated cycling, making cycle number a critical factor governing sand production in UGS operations.
KW  - Sandstone gas storage; reservoir sand producing; three-phase; alternating displacement

DO  - 10.32604/fdmp.2025.073859