Improved EUR prediction for multi-fractured hydrocarbon wells based on 3-segment DCA: Implications for production forecasting of parent and child wells

A substantial number of methods has been proposed as part of the quest for better production forecasting and hence more accurate reserves estimations, especially for multi-fractured shale wells producing either gas or liquids (or both). However, none of the current methods stand out to be robust and practical enough to give reliable results for all field cases. The current study proposes a novel 3-segment decline curve analysis (DCA) method that uses the unique flow regime sequence of shale wells to delineate the periods for each of the three segments used in the DCA. The production data of 6 Eagle Ford wells (4 parents and 2 infills) was modeled with over 95% history matching quality. The proposed method, validated using hind-casting, proved to be extremely successful in predicting the production of the child wells, when production data is available from either parent wells or first generation child wells. The proposed method is based on the widely-used Arps' equation and honors the principal flow regimes recognized in recent studies. The improved history matching capability of the proposed method leads to a much reliable production forecast. Hence, the uncertainty in the reserves estimations significantly reduces, which is why this study argues for conclusive categorization of the estimated reserves based on type curves of later generation parent wells as P90 (proved reserves) rather than P50 (proved plus probable reserves).