Significance of Well Orientation on Cumulative Production From Wells in the Bakken Region

摘要

We conducted a comprehensive analysis of approximately 7000 horizontal wells drilled in the Middle Bakken formation between 2007 and 2016 to assess the impact of well orientation on cumulative production.While it is common practice to drill horizontal wells"on-azimuth”,that is,in the direction of the minimum horizontal stress(S_(hmin)),there is a diversity of well orientations in the Bakken.S_(hmin)is consistently oriented N42°W throughout the production area.Our analysis clearly demonstrates that wells drilled in the direction of S_(hmin)(“on-azimuth”)produce more barrels per foot than wells in other directions,both in the core area and across the entire Bakken play.However,the amount of uplift gained from drilling on-azimuth wells decreases as the field matures,which we hypothesize is due to depletion.We found that the relationship between production and well orientation is consistently observed,regardless of the amount of proppant used.An economic analysis indicated that for wells of equal length,it is clearly beneficial to drill wells in the direction of S_(hmin).However,wells in the direction of S_(hmin)are consistently shorter in length than off-azimuth wells,and it is generally more efficient to drill longer laterals on a given leasehold.Nevertheless,using the average oil price at the time the wells we studied were drilled,we find that the shorter wells in the on-azimuth direction have a significant economic uplift of several million dollars per well relative to the longer wells drilled in the off-azimuth direction.