The functions and classification of hydraulic cement retainers

The cement retainer is mainly used for temporary or permanent sealing or secondary cementing of oil, gas, and water layers. The cement slurry is squeezed through the retainer into the well section of the annulus that needs to be sealed or into the cracks in the formation, pores to achieve the purpose of sealing and leak repair.The cement retainer has a compact structure, small outer diameter and is easy to drill out. Suitable for various specifications of casing.As a large number of oil and gas fields enter the advanced stage of development, these constructions are becoming more and more frequent, and some oil fields even require thousands of wells to be constructed every year.

Conventional cement retainers are divided into two types, namely mechanical and hydraulic. Mechanical setting uses rotation and lifting to set the cement retainer at the bottom. In practical applications, this puts higher requirements on the operator’s assembly proficiency and on-site experience, and in wells with large inclinations , due to the inability to effectively transmit torque, mechanical cement retainers are generally not recommended. The hydraulic type can overcome these shortcomings. The hydraulic retainer is simple to use and can be used in inclined wells.

In the existing technology, the conventional mechanical cement retainer can complete the process of setting, setting, sealing, squeezing and releasing in one drilling trip; while the existing hydraulic cement retainer requires two drilling trips. To complete a complete construction, this makes the work process of the cement retainer extremely cumbersome and complicated, and the construction fees and costs are relatively high, which seriously affects the efficiency of the work.