Evaluating the Impact of Lateral Landing,Wellbore Trajectory and HydraulicFractures to Determine Unconventional Reservoir Productivity

摘要

Inconsistent production performance from wells completed in similar pay zones has been observed whenshale formations are exploited through horizontal wells.Ineffective completion practices,fracture design,and reservoir heterogeneity have generally been blamed for the variability in the performance.Limitedimportance has been attached to drilling quality and well trajectory placement in the current approachesby the operators.The objective of this study is to demonstrate an engineered lateral landing approach forimproved long-term productivity in the unconventional reservoirs.Coupling the reservoir model to the wellbore and accounting for the transient flow behavior are importantfor improving deliverability in horizontal wells.The study in this paper encompasses a field case studyof a geocellular and geomechanical earth model in the Permian basin,which involves hydraulic fracturingmodeling,reservoir simulation,fluid flowback,and transient wellbore flow modeling.Pressure lossesaccounted for in the reservoir,in the near-wellbore region,and in the wellbore profile are modeled andcalibrated with bottomhole and surface gauge measurements.Complex hydraulic fracture geometry andnumerical reservoir simulation are used to characterize the pressure losses in the reservoir.Transientwellbore fluid flow considerations are used to evaluate the pressure losses in the wellbore.Based on the fracturing fluid type,the conductivity profile of the hydraulic fractures,connection to thewellbore,and coverage of the pay zone are important criteria in considering the landing location for wellsin unconventional reservoirs.However,having the most effective hydraulic fracture design is not enoughto decide the well trajectory.Mitigating liquid loading,fluid flowback,proppant settling,and cross-flowof reservoir fluid helps to diagnose the true production potential.Therefore,transient flow models werecoupled to the reservoir and fracture models to design a more-effective well trajectory.The study demonstrates the need to couple the wellbore model to the reservoir simulation and hydraulicfracturing model in shale formations to optimize well landing,trajectory profile,and long-term productivity.The methodology provides the first integrated data workflow for well drilling and trajectory planning inunconventional reservoirs that is generated from the perspective of reservoir potential and deliverability.Although variances exist in completion effectiveness due to reservoir heterogeneity,applying the robustmodeling workflow as discussed in this study would help deliver consistent results that can be used in fieldmanagement and EUR estimates across various shale basins.