Sand Production and Critical Rate in Stress-Sensitive Unconsolidated Sandstone: An Experimental Study

During the development of gas reservoirs, the constant changes in water saturation and effective stress often lead to sand production, which is difficult to control. Therefore, preventing sand production through rational production adjustments has become a key focus of current research. This study analyzed six core samples from the Q gas reservoir using seepage experiments to systematically investigate sand production patterns under varying conditions of effective stress, water saturation, and porosity. Particular attention was paid to the counteracting effect of displacement pressure difference on effective stress. By considering the combined influence of these three factors, a critical gas production rate calculation model was established, and critical gas production charts were developed for each condition to guide reasonable production adjustments and prevent sand production. The results show that: (1) Higher effective stress enhances structural stability and reduces sand production risk in the reservoir. (2) Increased water saturation deteriorates cohesive strength, consequently elevating sanding potential. (3) Elevated porosity weakens internal cohesion, rendering the reservoir more susceptible to sanding. The experimental findings provide operational guidance for gas well management in stress-sensitive reservoirs. Based on the critical sand-free gas production rate chart, a dynamic production adjustment strategy is proposed: a 15% production rate reduction is required for every 10% increase in water saturation; 8% production rate increase is permissible for each 1 MPa increment in effective stress.