After many years of field trials, cased hole frac pack has become the primary sand control and production enhancement method in developing the unconsolidated formations in the Penglai oilfield, Bohai Bay, China. The thick productive formations have low net-to-gross ratios, and the sandstone pays are separated by weak mudstones. This paper presents field cases of successful frac pack design and operations in the Penglai Oilfield.

This study reviews the sand control methods adopted in the Penglai oilfield and presents the major challenges in their field trials. The first cased-hole frac pack pilot was executed in 2008, followed by a four-well extended trial in 2009. After the field proof-of-concept, the large-scale adoption of frac pack began in 2011. Since then, continuous efforts have been made to optimize the key design parameters in successful frac packs, including perforation design, fracturing fluid, gravel placement, job size, downhole tools, etc. Well inflow modeling, laboratory evaluation and field trials have been performed and integrated in these optimization studies.

The study showcases over 400 frac-packed wells and more than 1500 stages, demonstrating the effectiveness of frac pack as an efficient sand control method when appropriately designed. This paper thoroughly examines the reservoir characteristics and key completion parameters during the frac pack, encompassing well architecture, net perforation thickness, perforation flow area, fracturing fluid, proppant, and various frac pack pumping parameters. Additionally, the paper summarizes key challenges, best practices, and valuable insights derived from extensive well data analysis. Results from this study emphasize the importance of maintaining the key design variables and call for the continuous optimization for the frac pack completion technology in waterflooded formations.

The paper also presents an integrated frac pack design approach that combines frac simulation, lab testing, and perforation optimization. This design approach has been successfully implemented in a large-scale well campaign in the Penglai oilfield. These findings contribute to the knowledge base of sand control and production enhancement in unconsolidated formations and provide key insights for improving the frac pack technology.

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