Enhancing Hydrocarbon Recovery and Sensitivity Studies in Tight Liquid-Rich Gas Resources
Abstract
Unconventional tight reservoirs refer to the formations with a permeability ranges from 0.001 to 0.1 millidarcy. Horizontal drilling coupled with multistage hydraulic fracturing is required in these formations to achieve economic production rates. Recovery factor in tight gas formations is typically less than 25% of the original gas in-place. Such low recovery is a strong motivation to investigate the application of enhancing hydrocarbon recovery methods in these reservoirs.
In this study, enhanced hydrocarbon recovery methods are investigated for a Montney liquid rich gas reservoir, located in the Western Canadian Sedimentary Basin. Firstly, a heterogeneous reservoir model is built and history-matched based on the production data collected from the field. Production performance of three EHR methods including cycling gas injection, CO2 flooding and water injection are then compared and their economic feasibility are evaluated. Sensitivity analysis of operational and geological factors including primary production duration, bottom hole pressures (BHP) during primary production and EHR process, pressure-dependent matrix permeability, non- Darcy effects and hydraulic fracture conductivity is conducted and their effects on the well production performance are studied. Experimental design is adopted to further study the mechanism and optimize the enhancing recovery process by cyclic gas injection and CO2 injection.
Results show that both cumulative oil and gas production are increased with fluid injection compared to primary depletion methods. In addition, cyclic gas and CO2 flooding is more feasible for the ultra-low unconventional tight gas reservoir than water flooding due to the water injection difficulty and low sweep efficiency in the reservoir. Cycling gas injection leads to both a higher gas and oil recovery and lower injection cost due to the on-site available gas source and minimal transport/purchase costs, gaining more economic benefits than that of CO2 flooding. Thus, it can be concluded that cyclic gas flooding in tight liquid rich gas reservoirs with hydraulically stimulated fractures could be a good way to enhance oil and gas production. Optimization study results indicate that two injection wells, short primary production time, high primary BHP and injection BHP, short injection time and low later period BHP lead to an optimal scheme of cyclic gas flooding and CO2 flooding methods.
Description
Keywords
Engineering--Petroleum
Citation
Wang, M. (2017). Enhancing Hydrocarbon Recovery and Sensitivity Studies in Tight Liquid-Rich Gas Resources (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25905