Rejuvenation of a Mature Tight Sandstone Oil Reservoir through Multistage Hydraulic Fracturing: A Case Study of a North African Basin

نوع مقاله : مقاله پژوهشی

نویسندگان

1 School of Energy Engineering, University of Portsmouth, Portsmouth, UK

2 Faculty of Earth Sciences, Kharazmi University, Tehran, Iran

3 School of Engineering, University of Portsmouth, Portsmouth, UK

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چکیده

Development of mature oil fields has been increasingly attractive in recent years as a significant amount of world oil and gas production is being extracted from these formations. Hydraulic fracturing (either as a selective corrective stimulation method or as a preliminary completion approach) is a well-established technique in mature oil field rejuvenation to improve productivity and deliverability of such a diminishing field. After many years of successful production in A1 and A2 reservoirs, A3 and A4 reservoirs were developed with only one hydraulically fractured vertical well (Well #1). As the production from well #1 in A3/A4 reservoirs was below the expectation, the well was shut down after 3 years of production. Therefore, the main objective of this research paper is to investigate re-development options for A3/A4 reservoirs due to the low deliverability and productivity of the vertical well #1. Sensitivity analysis for history matching, critical conductivity, and optimum dimensionless fracture conductivity (Cfd) was performed followed by forecasting and multistage hydraulic fracturing. Numerical results showed that there is a critical conductivity beyond which production is insensitive to the conductivity, for a specific propped length and production time. Results also showed that critical conductivity increased with propped length and decreased with production time. After 25 years of forecasting, the recovery factor for the 900m lateral with eight fractures and 110m spacing was the highest at 2.65%. The corresponding values for the 300m and 600m laterals were 2.37% and 2.42%. Therefore, the study suggests that horizontal wells with a longer length and optimized number of fractures and spacing will provide maximum well recovery.

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