Drawdown Management Optimization from Time-Lapse Numerical Simulation

Abstract

The Choke Management has been one of the "hot topics" in Unconventional Reservoirs since the negative impact in using an accelerated flowback has been demonstrated in many documented cases. Modern production practices have migrated from a Choke Management to a Drawdown Management Strategy to improve the control on the effective net stress over the proppant in order to prevent hydraulic fracture conductivity damage and maximize ultimate recovery. The strategy optimization is a complex problem that reservoir engineers are still trying to solve using different tools from empirical observations up to complex reservoir simulators that includes reservoir physics and the most advanced rock mechanics. This work contributes introducing an innovative workflow using a state of the art non-coupled numerical simulator, with the addition of time-steps one-way coupled calculations. The methodology consists in using a commercial reservoir simulator to History Match Completion Treatment Pressures and then Production. Once this first step has been completed, a Pore Pressure Grid is extracted at different times and then used to calculate changes in the minimum stress according to the isotropic poroelastic equation. Finally, the effective net stress over the proppant is calculated. This process is repeated with different Drawdown Management Strategies until the optimization. The complete workflow is introduced in a real case example where a robust dataset was available for a horizontal well. Finally, some assumptions and considerations are discussed and conclusions are extracted from this study.

Pressure Drawdown Management Strategies for Multifractured Horizontal Wells in Shale Gas Reservoirs: A Review

“…Crespo et al 21 believed that under high pore pressure–high stress conditions, the proppant in hydraulic fractures may be squeezed, deformed, and damaged, which would seriously damage the conductivity of hydraulic fractures. The critical period for optimizing pressure drop management is considered to be the initial production stage of the well, and the mathematical relationship between the geological maximum horizontal stress and the bottom hole net pressure is proposed.…”

“…Adopting numerical simulations considering reservoir physical properties and rock mechanical properties, Crespo et al 21 fitted the completion casing pressure and production data and then established the relationship chart of the effective stress versus production time based on the heterogeneous pore elastic equation. The proppant change was obtained, and the pressure drop strategy optimization analysis was carried out.…”

Bottom-hole pressure drawdown management of fractured horizontal wells in shale gas reservoirs using a semi-analytical model

“…Formulating a reasonable pressure-controlled production plan is the key to obtaining ideal productivity of over-pressured fractured shale gas reservoirs. The common research methods for the dynamic performance analysis of shale gas wells with pressure drawdown management mainly includes: field test 11 , physical simulation [12][13][14] , and numerical simulation 11,15,16 . Restricted to the strong regionality and high research costs, field tests are mostly used in large-scale field tests to provide engineering practice knowledge for theoretical scientific research and physical simulation work.…”