Subsurface Oil Reservoirs Productivity Forecast with Depletion-Damage, Geomechanical Elastic Parameters, and Pores Collapse

The monitoring and remediation of compaction formation damage are essential to prevent early pore collapse, which could impair the recovery factor of an entire field project. Thereby, its effect on the oil flow rate, qo, and, consequently, on the productivity index, PI, may be irreversible. Moreover, a proper understanding of the depletion mechanisms may be useful for underground storage purposes of geological CO2 and H2 to support decarbonization. This work develops a new theory to compute the steady-state oil flow rate, qo(Δp), PI(Δp), incorporating the pressure drawdown. The analytical model is derived by integrating the Dupuis formula with depletion-dependent rock and fluid properties, e.g. reservoir compaction, Δh(Δp), formation volume factor, Bo(Δp), oil density, po(Δp), dynamic viscosity, µo(Δp), reservoir porosity, ϕ(Δp) and permeability, k(Δp). After carrying out the integration, the model developed in this paper allows the computation of the depletion-dependent oil flow rate and PI, analyzing the effects of the reservoir extension (re), wellbore radius (rw), Young’s modulus (E), Poisson ratio (v), undamaged net pay on initial condition (hi), and Biot’s coefficient (α). The validation of the proposed model is carried out by comparing the results with several depletion field data values, which are accurate (R2 = 0.998). A sensitivity analysis using some log-log tornado charts regarding the key elastic and fluid parameters was carried out to investigate which one had the most sensitive behavior in the oil flow rate and PI. A transient modeling is suggested for the way ahead of this modeling using the line-source solution given by the combination of several Ei(U′) functions, Ei(U′)=−∫0U′(e−U′/U′)dU′. The proposed solution’s main advantages are its accuracy, ease of implementation, and computational cost savings. Thus, the model developed constitutes a valuable and attractive mathematical tool for calibrating new models and supporting well-reservoir performance management.