Using relative permeability curves to evaluate phase trapping damage caused by water- and oil-based drilling fluids in tight-gas reservoirs
Geeno Murickan A , Hassan Bahrami A , Reza Rezaee A , Ali Saeedi A and Tsar Mitchel ACurtin University
The APPEA Journal 52(1) 595-602 https://doi.org/10.1071/AJ11048
Published: 2012
Abstract
Low matrix permeability and significant damage mechanisms are the main signatures of tight-gas reservoirs. During the drilling and fracturing of tight formations, the wellbore liquid invades the tight formation, increases liquid saturation around the wellbore, and eventually reduces permeability at the near wellbore zone. The liquid invasion damage is mainly controlled by capillary pressure and relative permeability curves.
Due to high critical water saturation, relative permeability effects and strong capillary pressure, tight formations are sensitive to water invasion damage, making water blocking and phase trapping damage two of the main concerns with using a water-based drilling fluid in tight-gas reservoirs.Therefore, the use of an oil-based mud may be preferred in the drilling or fracturing of a tight formation. Invasion of an oil filtrate into tight formations, however, may result in the introduction of an immiscible liquid-hydrocarbon drilling or completion fluid around the wellbore, causing the entrapment of an additional third phase in the porous media that would exacerbate formation damage effects.
This study focuses on phase trapping damage caused by liquid invasion using a water-based drilling fluid in comparison with the use of an oil-based drilling fluid in water-sensitive, tight-gas sand reservoirs. Reservoir simulation approach is used to study the effect of relative permeability curves on phase trap damage, and the results of laboratory experiments of core flooding tests in a West Australian tight-gas reservoir are shown, where the effect of water injection and oil injection on the damage of core permeability are studied. The results highlight the benefits of using oil-based fluids in drilling and fracturing of tight-gas reservoirs in terms of reducing skin factor and improving well productivity.
Geeno Murickan is a petroleum engineer who graduated from Curtin University (Perth). Prior to this, Geeno had worked for Larsen & Toubro, India, as a design engineer (2007–10). Geeno holds a Bachelor degree in mechanical engineering from Cochin University of Science and Technology, India. murickangeeno@gmail.com |
Hassan Bahrami is a PhD candidate in the Department of Petroleum Engineering at Curtin University, and is now focused on tight sand gas reservoirs’ damage and productivity. Prior to Curtin University, he worked for Schlumberger Data and Consulting Services (DCS) as a borehole reservoir engineer (2003–09), and at Tehran Energy Consultants as a reservoir engineer (2001–03). Hassan holds a BSc in chemical engineering from Persian Gulf University, and an MSc in reservoir engineering from Sharif University of Technology, Tehran, Iran. Hassan.Bahrami@postgrad.curtin.edu.au |
Reza Rezaee is an associate professor at Curtin University’s Department of Petroleum Engineering, and has a PhD in reservoir characterisation. He has more than 20 years’ experience in academia and industry. During his career he has been engaged in several research projects supported by national and international oil companies. With his supervisory work at various universities, these commissions have involved a wide range of achievements. He has supervised more than 50 MSc and PhD students during his university career to date. His research has been focused on integrated solutions for reservoir characterisation, formation evaluation, and petrophysics. He has used expert systems such as artificial neural networks and fuzzy logic, and has introduced several new approaches to estimate rock properties from log data where conventional methods have failed to succeed. He is now focused on unconventional gas, including gas shale and tight gas sand studies, and is the lead scientist for the WA:ERA (EIS) Tight Gas and Shale Gas research projects. R.Rezaee@curtin.edu.au |
Ali Saeedi is a research fellow with the Petroleum Engineering Department at Curtin University (Perth). Ali’s main research interest is the multiphase flow and general reservoir engineering aspects of CCS, and he has been extensively involved in experimental analysis of multiphase flow in porous media for both EOR (enhanced oil recovery) and CCS (carbon capture and storage) processes. He holds an M.Sc and a PhD in petroleum engineering. Ali.Saeedi@curtin.edu.au |
Tsar Mitchel is, at present, pursuing a Master’s degree in petroleum engineering from Curtin University (Perth). He had a brief stint with Kenya Electricity Generating Company Ltd as an exploration geophysicist before joining the National Oil Corpoation of Kenya as a petroleum geophysicist. He holds a Bachelor’s degree in geophysics. M.Tsar@postgrad.curtin.edu.au |
