Methods and systems for ballooned hydraulic fractures and complex toe-to-heel flooding

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2017-12

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Abstract

Hydrocarbon recovery from both conventional and unconventional reservoirs is very low. The hydrocarbon recovery factor for conventional reservoirs is typically between 5% and 15% after primary recovery and between 35% and 45% after secondary recovery. The hydrocarbon recovery factor for organic shale reservoirs is typically between 5% and 10%, and around 70% of the hydraulic fractures created in such reservoirs do not produce. To increase hydrocarbon recovery from both conventional and unconventional reservoirs, this dissertation develops two completion strategies that are each more productive than existing strategies. The first strategy, named “Complex Toe-to-Heel Flooding (CTTHF),” increases oil recovery from sandstone formations under specific reservoir conditions. CTTHF is an improvement upon conventional Toe-to-Heel Waterflooding and uses gravity segregation to increase the oil production rate and the total oil recovery. The second completion strategy, named “Optimized Zipper Frac (OZF),” increases hydrocarbon recovery from organic shales. OZF is an improvement upon Zipper Frac (ZF), Alternate Fracturing (AF), and Modified Zipper Frac (MZF). It uses ballooned fractures to create stress shadows that minimize stress anisotropy and thereby maximize near wellbore complexity. This study used an advanced commercial reservoir simulator to evaluate the feasibility of CTTHF and OZF. Conventional Toe-to-Heel Waterflooding was used as a point of comparison in evaluating CTTHF. Zipper Frac, Alternate Fracturing and Modified Zipper Frac were used as points of comparison in evaluating OZF. The results confirm the feasibility of the two developed completion strategies. Any increased production that results from this work will help the petroleum industry to meet its ever-increasing demand.

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Keywords

Zipper frac, Modified zipper frac, Optimized zipper frac, Ballooned fracture, Toe-to-heel flooding, Complex toe-to-heel flooding

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