As the Oil and Gas industry looks forward to perforating next-generation complex wells (including but not limited to HPHT, deepwater, geothermal, multi-stage long horizontals etc.), computational modeling tools have been increasingly used to predict the transient flow physics that govern the design and optimization of perforating jobs. In particular, it is crucial to accurately predict the unsteady wellbore flow dynamics and relevant shock physics that typically occur during perforation jobs. Such modeling capabilities provide us the ability to prevent downhole equipment failures that may result from shock loading as well as lead to accurate predictions of perforation cleanup process which depends on balance of pressures in the reservoir, wellbore and gun. In addition, as complex completions such as those found in subsea wells and long horizontal wells are becoming more important, so is the need to extend such a predictive capability to higher-pressure and higher-temperature environment that often accompanies such wells.
To address the above, this study is focused on the development and verification of a next-generation transient wellbore flow simulator that is used in conjunction with our existing perforation modeling software. The use of appropriate numerical algorithms allows the simulator to accurately capture unsteady compressible wellbore flows with large gradients of flow quantities. The set of governing equations for compressible flows are closed with improved thermodynamic equations of state, specifically designed to model extreme high pressure (up to 40,000 psi) and temperatures (up to 600 °F).
Computational results from various shock-tube test cases show good agreement among exact solutions, single-phase numerical solutions, and the new three-phase solutions. Compared with our existing perforation modeling software, the next-generation simulator exhibits improved accuracy for HPHT environment, better shock-capturing properties, and improved computational efficiency. This unique computational tool has been integrated into an existing perforation job-design workflow to realize significant improvements in risk mitigation and design parameter optimization. This improved workflow enables a new decision process to better model and design challenging deepwater/HPHT perforating applications.