抄録
Due to reservoir heterogeneity and the complexity of development technologies, tight oil reservoirs exhibit complex single-well production dynamics and multi-solution issues in reserve evaluation, posing significant challenges in reservoir engineering. Focusing on single tight oil wells with multistage fractured long horizontal sections in the Xi 233 well block of the Ordos Basin, this study systematically investigates the evolution of flow regimes and the dynamic characteristics of reserve changes. By integrating the normalized material balance time method with log-log diagnostic curve techniques, the characteristic signals of boundary-dominated flow were accurately identified, effectively addressing the subjective errors associated with the selection of the decline exponent in the traditional Arps decline method. For new wells with insufficient initial production data, an analog prediction model based on regional “seed well” big data was constructed, enabling rapid reserve estimation using key indicators such as the cumulative oil production in the first year. Empirical results demonstrate that the correlation coefficient of the analog model exceeds 0.88, and the accuracy of reserve prediction using the material balance time method is significantly improved during the pseudo-steady-state flow phase. The research reveals that the productivity of a single tight oil well is jointly controlled by the quality of the geological “sweet spot” and the intensity of the fracturing engineering, with the initial flowback period of 2–3 months being the primary cause of early production decline fluctuations. The “classified evaluation and staged evolution” differentiated reserve assessment system proposed in this paper provides a scientific basis for the accurate evaluation of single-well reserves and the optimization of dynamic development plans in tight oil reservoirs, offering substantial engineering application value and promotion prospects.
