Production Decline Analysis in the Vaca Muerta Formation. The Application of Modern Time-Rate Relations Using Public Data

摘要

Modern time-rate relations in conjunction with diagnostic plots are applied to type production curves of vertical and horizontal wells in the Loma Campana Field of the Vaca Muerta Formation to determine flow regimes and appropriately estimate the ultimate recovery. Additionally, this paper presents a comparison with type oil wells of the U.S. shale formations (Bakken, Eagle Ford and Woodford) and introduces a new decline model: Unconventional Empirical Decline Model (UEDM). Type decline curves of vertical and horizontal wells in the Loma Campana Field are derived analyzing the production data. This paper applies recently developed time-rate relations such as Power-Law Exponential, Stretched Exponential, Duong, Logistic Growth and the new model UEDM, using diagnostic plots "D", "b", "/3 -derivative" and "q/Q" to assess which model best fits the production data and makes the most accurate EUR prediction. Loma Campana's type wells present, on average, a better performance than the type wells of the U.S. shale formations. First, the U.S. type wells show a steeper decline rate than the Vaca Muerta's wells at late production times. Second, the wells in Loma Campana Field are clearly dominated by the linear flow regime (very high conductivity fractures), this flow behavior tends to last longer than in the U.S. plays, and therefore, it contributes to the growth of the EUR. Third, the initial production rate per fracture and EUR per fracture are, on average, greater in the Loma Campana wells than in the U.S. wells. This work presents the type decline curves of vertical and horizontal wells in the Loma Campana Field, it applies not only recently developed time-rate relations but also a new decline model. The methodology of diagnostic functions is applied to estimate their ultimate recovery and to compare their performance with the type wells of Bakken, Eagle Ford and Woodford plays. Finally, we provide concluding observations regarding the application of each rate-time relation.