Abstract

Reservoir management in fields with geomechanical issues such as subsidence and dilation due to injection and production activities is challenging where it is crucial to prevent well failures due to resulting shear or compaction stresses that might lead to serious losses owing to well and facility failures and impact success of production operations. A robust understanding of changes in reservoir parameters that influence subsurface recovery is as important to predict the adverse effects of compaction in the reservoir. The objective of this study is to investigate the effects of injection and production not only on compaction and dilation but also on reservoir fluid flow phenomenon including the significance of rock properties on flow due to changes in permeability in order to outline the significance of decision or control parameters of injection/production along with uncertainty parameters of reservoir rock. The results will provide useful in observing the significance of each parameter on production and recovery.

In our study, a full-physics commercial numerical reservoir simulator has been utilized where it is coupled with an optimization and uncertainty tool to investigate the significance of decision parameters such as amount and rate of injection and production as well as the uncertainty parameters such as rock properties with different Young's Modulus. Different rock types are assigned in the geomechanics section due to different Young's modulus on each layer. Different constitutive models are assigned on rock layers. Linear elastic model and nonlinear elastic model are employed. Output stresses, subsidence and displacement vector are used to evaluate the influence of injection and production.

Effect of production on compaction with decrease in permeability has been observed under different scenarios that include different operating conditions such as rates and different uncertainty parameters such as rock types with unique Young's modulus and permeability. The significance of each parameter is presented to provide a better understanding on reservoir management for reservoirs where geomechanical stresses are crucial in decision making on operational constraints and design.

Numerical reservoir simulation with geomechanics option is a convenient tool to predict not only the reservoir performance but also the reservoir stresses occurring due to injection and production. The reservoir model with geomechanics-dependent permeability provides a more realistic forecast for recovery compared to the models where geomechanics is ignored. The understanding of effect of injection and production on stresses generated in reservoir enables more optimum operation of wells to minimize such effects that may lead to well failure. Injection and production are optimized in a way where stress distributions are more even that lead to more control on geomechanics that results in mitigation of well failures and minimal loss.

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