Evaluation of damage mechanisms and skin factor in tight gas reservoirs
Hassan Bahrami A , Reza Rezaee A , Delair Nazhat A and Jakov Ostojic ACurtin University of Technology
The APPEA Journal 51(1) 639-652 https://doi.org/10.1071/AJ10045
Published: 2011
Abstract
Tight gas reservoirs normally have production problems due to very low matrix permeability and significant damage during well drilling, completion, stimulation and production. Therefore, they may not flow gas at optimum rates without advanced production improvement techniques.
The main damage mechanisms and the factors that have significant influence on total skin factor in tight gas reservoirs include: mechanical damage to formation rock; plugging of natural fractures by mud solid particle invasion; relative permeability reduction around wellbore as a result of filtrate invasion; liquid leak-off into the formation during fracturing operations; water blocking; skin due to wellbore breakouts; and the damage associated with perforation. Drilling and fracturing fluids invasion mostly occurs through natural fractures and may also lead to serious permeability reduction in the rock matrix that surrounds the natural or hydraulic fractures.
This study represents an evaluation of different damage mechanisms in tight gas formations, and examines the factors that can have significant influence on total skin factor and well productivity. Reservoir simulation was carried out based on a typical West Australian tight gas reservoir to understand how well productivity is affected by each of the damage mechanisms, such as natural fracture plugging, mud filtrate invasion, water blocking and perforation. Furthermore, some damage prevention and productivity improvement techniques are proposed, which can help improve well productivity in tight gas reservoirs.
Hassan is a PhD candidate in the department of petroleum engineering at Curtin University, Perth. He has focused on tight gas sand reservoirs damage and productivity. Prior to Curtin University, he worked for Schlumberger Data and Consulting Services (DCS) as borehole reservoir engineer (2003–9) and Tehran Energy Consultants as Reservoir Engineer (2001–3). Hassan holds a Bachelor of Science in chemical engineering from Persian Gulf University, and a Master of Science in reservoir engineering from Sharif University of Technology, Tehran, Iran. Hassan.Bahrami@postgrad.curtin.edu.au |
Reza Rezaee is an associate professor at Curtin’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. These commissions, together with his supervisory work at various universities, 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 failed to succeed. He is presently 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 |
Delair Nazhat is an MSc petroleum engineering candidate in the Department of Petroleum Engineering at Curtin University in Perth, Western Australia. He worked on core flood simulation for tight gas reservoirs as his thesis project. He pursued engineering experiences as a mechanical maintenance engineer at Bazian Cement Company in 2008 in Iraq, and as a PVT Analyst at Core Laboratory in 2008–9. He was granted a BSc in mechanical engineering from Al-Mustansiria University in Baghdad, Iraq. D.bmnazhat@postgrad.curtin.edu.au |
Jakov Ostojic is a Masters candidate with the Department of Petroleum Engineering at Curtin University in Perth, Western Australia. Prior to enrolling in the Master’s course at Curtin University he completed his Bachelor’s degree in Petroleum Engineering at the University of Western Australia. His present focus is on tight gas reservoirs production performance. Jakov.Ostojic@postgrad.curtin.edu.au |
