Quantitative characterization of horizontal well production performance with multiple indicators: a case study on the Weiyuan shale gas field in the Sichuan Basin, China

To quantitatively characterize the horizontal shale gas well productivity and identify the dominant productivity factors in the Weiyuan Shale Gas Field, Sichuan Basin, a practical productivity method involving multiple indicators was proposed to analyze the production performance of 150 horizontal wells. The normalized test production, flowback ratio, first-year initial production and estimated/expected ultimate recovery (EUR) were introduced to estimate the well productivity in different production stages. The correlation between these four indicators was determined to reveal their effects on production performance forecasts. In addition, the dominant productivity factors in the present stage were identified to provide guidance for production performance enhancement. Research indicates that favorable linear relations exist between the normalized test production, first-year initial production and EUR. The normalized test production is regarded as an important indicator to preliminarily characterize the well productivity in the initial stage. The first-year initial production is the most accurate productivity evaluation indicator after a year. The flowback ratio is a supplementary indicator that qualitatively represents the well productivity and fracturing performance. The well productivity is greatly dependent on the lateral target interval, drilling length of Long-maxi111 (LM111) and wellbore integrity. The first-year recovery degree of EUR is 24%–58% with a P50 value of 35%.