Liner Cementing Techniques with Small Annular Space for Complicated Deep Wells in the Sun Basin, North Yellow Sea

During the liner cementing with small annular space in the Sun Basin of the North Yellow Sea, lost circulation is severe in gravel layers, and chippings of coal seams cause annular blockage, resulting in low displacement efficiency and poor cementing quality. Considering these problems, this study selected suitable cementing tools and cementing slurry, optimized the wellbore preparation measures, and expanded the annular flow area using the slip-embedded liner hanger with packer. In addition, anti-leakage cement slurry with matrix invasion-resistant fiber was adopted to reduce the risk of lost circulation. In this way, a set of cementing techniques with small annular space were formed for complicated deep wells in the Sun Basin to prevent blockage and lost circulation. These techniques were applied to 4 wells on site, and the results revealed that no blockage and lost circulation occurred during liner cementing. As a result, the cementing quality met standards. Field applications indicated that the developed techniques could effectively solve the problem of poor liner cementing quality in the Sun Basin, suggesting that they could be further promoted and applied. Overall, these techniques are conducive to the further exploration and development of oil and gas resources in this area.