Continuous or intermittent artificial lifting technology is competing today with electrical submersible progressive cavity (PC) pumping and sucker rod pumping for producing fluids from low-pressure reservoirs. If the shut-in fluid level is less than 45% of the depth of the well, finding A suitable and economic artificial lifting technology is a challenging task. There are thousands of dormant gas wells where bottom water accumulations of 50 in or less impede gas production. Similar conditions are often found in coalbed methane reservoirs. Due to variable (and shallow) water levels and gas presence, rod pumping cannot be used and submersible electric pumps often pose operational problems. Depending on local conditions and economics, gas lifting, alone or associated with other artificial lifting technologies, can be used for producing such reservoirs. Within a limited range of gas-liquid flow rates, depth, and reservoir pressure, the use of small-diameter pipes for gas lifting technology can become a viable technology. Laboratory investigations dedicated to small-diameter gas lifting operations have been so far limited to fluid transfer operations requiring a maximum of 10 - 20 m. This study uses mechanistic modelling approaches to respond to the industry's need for a better evaluation of depth/diameter flow rate limitations in view of assessing potential field applications of gas lifting for low reservoir pressures and relatively small liquid flow rates. Laboratory tests were conducted in a specially designed fig. Experimental results were used to evaluate the accuracy of the existing model predictions and for assessing the effect of injected gas flow rates, reservoir pressure, and liquid interfacial tension on the liquid production rates. To improve predictions of existing mechanistic models, particularly for small-diameter tubings and low pressure reservoir conditions, a new model is proposed and compared first with experimental results. The new model is then used as a scaling tool for assessing critical field depth conditions.