For the unconsolidated gas reservoir with sand production, when the gas well produces water, the flow in wellbore is essentially gas-liquid-solid three-phase flow. The flow mechanism and sand-carrying capacity tend to obviously affect the artificial lift system operational situation and optimization. In this paper, the gas-liquid-solid multi-phase flow with different water-gas ratio (WGR) and sand concentration were experimentally simulated to investigate the flow mechanism and sand-carrying capacity of gas-liquid flow. The results indicate that once the well starts to produce water, it's more difficult for the gas to carry produced sand than there is no water produced. Gas flow rate and WGR are the dominant factors affecting the flow mechanism. As WGR increasing from zero, the flow pattern tend to be mud-gas flow with no sand carried, annular flow with sand, plug flow with sand and further patters similar to these of normal gas-liquid two phase flow with the same WGR. The prerequisite of sand-carrying can be described as that the gas be able to carry liquid flow to a certain velocity, at which the liquid has enough velocity to carry the sand flowing contained. According to the systematic experimental results, the critical sand-carrying gas rate and the quantitative relationship of sand rate and gas flow rate were obtained. Based on the experimental data, a sand-carrying evaluation model for gas well with and without water production are developed. The model is used to predict the critical sand-carrying gas flow rate with certain sand diameters and the maximum sand rate carried by a given gas flow rate. Finally, considering the characteristics of sand-carrying in wellbore, a new integrated coordination chart for gas well with water and sand production is put forward to evaluate the real well operational situation and help to make decision of well measurement such as adjusting gas nozzle, sand control and others. The method has been applied in Sebei gas filed, a typical gas filed with serve sand and water production, and the effect is good.

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