"Yuanlu X Well successfully completed the cementing of a variable-diameter large annular casing."

On May 22, 2023, Sinopec Exploration Company's Yuanlu X Well successfully completed the cementing operation of a φ139.7mm production casing. The cementing operation employed the Chengdu Oumaike granular elastoplastic anti-gas migration cement slurry system, which exhibited excellent cement slurry performance, resulting in outstanding cementing quality. This achievement was highly recognized by the contracting party and the cementing company.

The Yuanlu X Well is a pre-exploratory well located in the Jiulongshan Anticline Zone in the northeastern part of Sichuan Province, deployed by Sinopec Exploration Company. It features a four-section wellbore structure with a 3042-4346m sealing of the φ244.5mm technical casing across three sections. After the cementing operation, gas migration was observed both above and below. The four-section wellbore was drilled to a total depth of 5707m using a Ф215.9mm drill bit, with a maximum vertical depth of 4399m. The well's bottom hole static temperature is 120℃, and the circulating temperature is 100℃. A φ139.7mm casing was run and cemented to address the upper gas migration.

Due to the non-make-up of the φ244.5mm casing, the annular space gap increased from 38.83mm to 87.8mm, resulting in lower return speed in the upper well section, impacting the displacement efficiency of oil-based mud. This made it challenging to address the gas migration and ensure the integrity of the cement ring seal. To overcome these difficulties, a granular elastoplastic anti-gas migration cement slurry system was employed. The design included a pre-flush with high-density cement slurry and five stages of cement slurry with varying densities for the leading, middle, and trailing sections. A total of 317m³ of cement slurry was pumped into the well. The system required the anti-gas migration coefficient to be less than 2. With the large temperature differential, the top strength development was fast, effectively addressing the challenge of annular gas migration.

This cementing operation with varying casing sizes and annular space gaps posed a significant challenge for the company.

Faced with opportunities and challenges, Oumaike employees bravely embraced the challenges. Under the leadership of the company's executives, they gathered the high-quality talents of the technical team to optimize a high-temperature granular elastoplastic anti-gas migration cement slurry system. This system exhibited excellent stability, rapid development of top strength, high compressive strength, and good toughness. Oumaike successfully completed the cementing technology service for the well, achieving an excellent overall cementing quality rate of 96%.

The high-quality cementing of the production casing in the Yuanlu X Well has laid the foundation for the subsequent evaluation of large-scale fracturing in the tight oil and gas reservoirs in northeastern Sichuan. It also serves as a technical reference for subsequent casing cementing with varying diameters, reducing the need for first-run casing cementing and lowering drilling costs. The successful completion of this challenging cementing operation highlights Oumaike's strong technical capabilities and the team's spirit of overcoming difficulties, deepening the company's positive reputation in the market of Sinopec Exploration Company.

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