Mechanical - Type 778MC
While now established as a field proven tool, this tool continues to be the subject of research and development to find new materials for faster drill-out time, greater PDC bit drillability and better metal-to- metal sealing. Features of the 778 MC Stage Cementing Collar include:
- Tools can be made from material grades up to 150,000 psi minimum yield, including material suitable for sour gas service.
- All parts are custom fitted and subjected to extensive quality control standards for maximum performance downhole.
- The connection that adjoins the stage collar body and the bottom sub affects a metal-to-metal seal and engages a back-up elastomer seal, the two of which are designed to provide gas-tight pressure integrity.
- No welds are used on any portion of the tool.
- The reduced length of the tool minimizes the effect of bending stresses.
- The seals providing internal and external pressure integrity are housed in the stage collar body and remain stationary throughout operation, minimizing chances of their being damaged.
- The pressure-relief design prevents fluid trapping and compression between the opening device and the closing plug during the closing phase of the tool’s operation.
- The closing sleeve is held in the closed position by an internal lock ring.
- Both the opening and closing sleeves lock against rotation for easy drill-out.
- A minimum amount of aluminum and rubber are the only materials encountered during drill-out. Plug sets for four different cementing applications are available.
Type 778 MC Mechanical Stage Cementing Collars
Hydraulic - Type 777HY
This stage collar features an opening sleeve with area differences on opposite ends that allows it to be manipulated hydraulically. The closing sleeve is identical to the one contained in the Type 778 MC Mechanical Stage Cementing Collar. The development and introduction of this model was spurred on by the tremendous upswing in horizontal drilling activity that has occurred in recent years. The hydraulic opening feature makes this tool’s use very practical in horizontal wells.
The elimination of the need to use a mechanical opening device has several other merits. Casing runs in highly deviated wells can now be two-stage cemented without having to use continuous displacement type plugs. In certain applications, liners run with drill pipe can be run in conjunction with one or several inflatable packers and used to isolate and selectively cement certain casing intervals. Slotted or pre-drilled liner can be run below a Forum inflatable packer/hydraulic stage collar assembly, allowing cement to be pumped above the packer and isolated from highly sensitive producing zones.
Along with all the features inherent in the 778 MC Stage Cementing Collar, the Type 777 HY offers:
- Effective differential area on the opening sleeve that generates a high opening force while requiring only optimal pressure to do so.
- The ability to open immediately upon the completion of first-stage cement displacement.
- Opening pressure values that can be adjusted at the time of assembly to assure that all inflatable packers or other hydraulic tools present in the casing string will be triggered at the correct juncture.
Packer Stage Collar
Forum Energy Technologies’ Davis-Lynch packer stage cementing collar (PSC) helps ensure proper placement of competent cement in the intermediate casing string, while expanding the operating envelope. By combining an inflatable packer and a stage cementing collar, the PSC reduces NPT and well construction costs, while complying with regulatory requirements and minimizing HSE risks.
The packer stage cementing collar can assist with:
- Isolating the hydrostatic head of the second-stage cement from the first-stage cement, and from pressure-sensitive zones below it
- Keeping cement from falling around pre-drilled or slotted liners
- Selectively placing cement across widely separated zones of interest
- Preventing gas migration that can ruin primary cement jobs and lead to annular gas problems at the surface and expensive squeeze work
Although the combination packer stage collar serves two purposes, it is only one tool. This means that it can be serviced by one person, which eliminates the cost of the second person who would be required if a stage collar and inflatable packer were individually purchased from two separate companies.
- Helps ensure zonal isolation, especially through trouble zone with one easy-to-use tool
- Reduces HSE risks associated with trouble zones and incorrectly placed cement jobs
- Eliminates flat time
- Reduces the chance of remedial squeeze cementing
- Eliminates the need to bump first-stage cementing plug
- First- and second stage plugs
- Can be run in sequence
- Compatible in oil- and water-based muds
- Able to pump second-stage cement immediately
- Combines two tools into one