Hydraulic Fracturing Performance Evaluation in Tight Sand Gas Reservoirs with High Perm Streaks and Natural Fractures

Abstract

Abstract Hydraulic fracturing in tight gas sandstone reservoirs increases the connectivity of the well to more reservoir layers and farther areal regions, thus boosting the production as well as the net-present-value of the project. When comparing different well performances, wells that far outperform other wells are usually connected to high permeability streaks or natural fractures. This paper demonstrates the analysis and performance evaluation of hydraulic fractures that are connected to high permeability streaks or natural fractures. In order for oil and gas operators to consider the development of tight gas sandstone reservoirs economically feasible, stimulation operations such as a large hydraulic fracture treatment of the wells are required. However, the induced fracture is not the main reason for the success of many of the field development in tight gas sandstone reservoirs. In the Southern North Sea, the more productive multiple hydraulically fractured horizontal wells (MHFHW) are usually connected to high permeability streaks or natural fractures. In this work, a reservoir with high permeability streaks and natural fractures was then modelled. This is then calibrated against several years of production and pressure history. The analysis of core data, borehole image logs, well tests and geomechanics data demonstrated the existence of high permeability streaks or natural fractures in the reservoir. The data derived from the analytical methods were then captured in the simulation model. The simulation model shows a very good match with the history data and when compared with a 3-week long shut-in, the build-up pressure response and its derivative displayed an excellent match. This study shows that, in addition to the role played by the hydraulically induced fractures, natural fractures and high permeability streaks also serve as dominant factors in success of tight gas sandstone reservoir development. This study demonstrates a practical integrated approach towards the modelling of high permeability streaks and natural fractures that are connected to hydraulic fractures. This can be used to better understand hydraulic fracturing and tight gas sandstone reservoirs in the Southern North Sea.