Correlation-based EUR prediction of shale oil wells: A case of the Qingcheng Oil Field in the Ordos Basin

Shale reservoirs are characterized by low permeability and a weak capacity for natural seepage. These reservoirs are commonly developed using a combination of horizontal well drilling and fracturing. The production performance of shale oil wells is evaluated through single-well production decline analysis, with the estimated ultimate recovery (EUR) used as an important indicator of the development outcome. This study predicted the EUR of the X233 well zone in the Qingcheng Shale Oil Field in the Ordos Basin. It reviewed the applicability of production forecasting methods to unconventional reservoirs and put forward a correlation-based approach to EUR prediction. The latter was developed by integrating the characteristics of Qingcheng shale oil production with EURs predicted using empirical methods intended for typical wells. The correlation-based approach was also designed on the basis of the relationship between cumulative oil production and the empirically derived EURs. The results suggest that the proposed method rapidly predicts the EUR of a single well using cumulative oil production from the first one, two, and three years of production. The predictions closely align with the empirically derived values, demonstrating the strong practical effectiveness of the approach put forward in this work. To determine its applicability and limitations, this study examined the EUR distribution characteristics of different well classes (Classes I to III). This research provides a simple and effective approach to rapidly predicting the EURs of shale oil wells, significantly reducing computational time and labor costs.