Cementing the annulus in two stages with the ability to bypass loss zones.
Firstly, two stage cementing is a common practice in oil and gas well operations. This practice allows to prevent excessive overpressure buildup and ensure the cement slurry reaches its target destination. The pressure in the casing string annulus becomes controllable by dividing the cementing operation into two stages. It allows companies to optimize this annular pressure to avoid mud losses or fracturing.
Secondly, to perform two stage cementing, companies require specific downhole tools. These tools enable them to place cement at predetermined depths. They also allow to isolate the cemented intervals from the rest of the wellbore. Some commonly used tools for two stage cementing are stage tools or stage collars, liner hangers, and Xpandable steel packers.
Necessary downhole tools in two stage cementing
Furthermore, stage tools or stage collars are versatile devices that can isolate and seal off specific sections of the wellbore. Installed in the casing string, companies can open or close the tool to allow for the placement of cement at different depths. Additionally, liner hangers are vital tools in wells that require a liner to be cemented in place. They hang the liner in the casing string and provide a seal between the liner and the casing.
Moreover, Xpandable steel packers are permanently expandable annular seals to isolate and seal off specific sections of the wellbore. Typically run on a tubing string, operators expand them to create a seal around the casing or liner. By using these tools, companies can ensure that the cement slurry reaches the targeted intervals and achieves the desired strength and hydraulic isolation required for safe and effective well operations.
In contrast, Xpandable Steel Packers are permanently expandable annular seals that companies use to isolate and seal off specific sections of the wellbore. Typically run on a tubing string, operators expand them to create a seal around the casing or liner.
Overall, two stage cementing is an important technique for ensuring a successful cementing operation in long casing strings. The use of specialized tools and equipment helps to optimize the cement placement and prevent unwanted overpressure buildup or fluid loss.
| _ | Xpandable steel ECP-C |
|---|---|
| Mounting | Crimped |
| Valve system | Lock valve closing permanently packer expansion port, and trapping fluid inside packer |
| Sealing System | Deformable corrosion-resistant alloy (CRA) sleeve with elastomer seal |
| Reliability | Life of well valve system |
| Performance | High DeltaP achieved with moderate setting pressures |
| Max DeltaP | Up to 5,000 psi, lower for bigger sizes |
| Max Temp. | 250 degF - 120 degC |
| Qualification | API 19 OH V2 |
