Title: A numerical method for potential implementation of underbalanced drilling in high pore pressure reservoirs

Authors: Oveis Farzay; Seyedalireza Khatibi; Azadeh Aghajanpour; Ali Shakhouri; Adel M. Al-Ajmi

Addresses: Department of Environment, Land and Infrastructure (DIATI), Polytechnic di Torino, Turin, Italy ' Petroleum Engineering Department, University of North Dakota, Grand Forks, ND, USA ' Norwegian University of Science and Technology, Høgskoleringen 1, 7491 Trondheim, Norway ' Petroleum Engineering Department, Petropars Company, Tehran, Iran ' Department of Petroleum and Chemical Engineering, Sultan Qaboos University, Oman

Abstract: Rising demand to increase productivity as well as reducing drilling damages has encouraged companies to use underbalanced drilling (UBD) technology. In this study, a numerical simulation is applied to evaluate the feasibility of UBD in high pore pressure reservoirs. To achieve this objective, the minimum possible mud weight that ensures wellbore stability is estimated by considering an elastoplastic model. Furthermore, the growth of the plastic area around the wellbore is studied and utilised as an indicator of wellbore instability. When the growing plastic volume around the wellbore equals the drilled wellbore's volume, the finite-difference model results in the optimum mad weight for the formation. Moreover, a detailed study is conducted in the zones with no safe mud windows to determine the optimum applications. The work of the paper is applied to real field data for justification, where the feasibility of UBD implementation in high pore pressure reservoirs is acknowledged. [Received: March 12, 2021; Accepted: September 27, 2021]

Keywords: underbalanced drilling; UBD; numerical simulation; high pore pressure reservoir; elastoplastic model; plastic zone.

DOI: 10.1504/IJOGCT.2022.123207

International Journal of Oil, Gas and Coal Technology, 2022 Vol.30 No.3, pp.283 - 299

Received: 11 Mar 2021
Accepted: 27 Sep 2021
Published online: 01 Jun 2022 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article