Experimental and theoretical evaluation of interlayer interference in multi-layer commingled gas production of tight gas reservoirs

Abstract

Tight gas reservoirs are characterized by multiple thin and vertically distributed development layers with similar or different lithology and varying geological conditions. To increase the production per well and reduce development costs, field experts have widely adopted the commingled production of tight gas in multi-layer reservoirs. However, differences in reservoir properties and pressure might lead to interlayer interference which could influence the overall wellhead output. In this study, we propose a mathematical model for predicting the overall wellhead output of single and multi-layer tight gas reservoirs after interlayer interference. A reservoir(a) and process factor(b) were deduced to quantitatively analyze the difference in interlayer interference. The range and accuracy of the model were analyzed through a goodness-of-fit test. The results showed that the interlayer interference in multi-layer commingled production systems with three or more layers was decreasing, and the interlayer interference in multi-layer commingled production systems with three or more layers was not significantly affected by the increment of layers, the accuracy of the model was greater than 80% and closer to the lower limit of the process and reservoir factors. The model will provide a quantitative method for predicting interlayer interference in multi-layer commingled production, a reliable basis for understanding the mechanism of interlayer interference, and a theoretical framework for evaluating the feasibility of commingled production in multi-layer tight gas reservoirs.