1. Project Overview
The FJZ178‑MLTC non-drillable stage cementing collar successfully completed on-site cementing operation in Well HZK14. It achieved high-quality primary and secondary cementing in one run, automatic opening and closing of the stage collar, and reliable pressure-release shear of internal components. No milling operation was required throughout the process, which greatly improved construction efficiency and reduced operational risks. This marks an important application breakthrough of non-drillable stage collar technology in cementing of brine production wells.
Well HZK14 is a directional brine production well drilled by Drilling Team 50501, with a total depth of 2378 m. Φ177.8 mm casing was run in the fourth spud section to a setting depth of 2336.01 m. The stage collar was set at 1106.92 m where the well deviation was only 1.23°, presenting stable downhole conditions. The non-drillable stage cementing collar adopted in this operation is manufactured by Hebei Shangshan Petroleum Machinery Co., Ltd., complying with industry standard SY/T 5150‑2013, featuring stable performance and reliable quality.
2. Construction Process and Achievements
The operation was implemented strictly in accordance with the staged primary and secondary cementing process. Stable pressure and precise tool actions were maintained throughout the whole process without downhole complications.
Primary CementingPre-flush fluid, lead slurry pad, lead cement slurry and tail cement slurry were injected in sequence. A precise displacement volume of 45.1 m³ was achieved, and bump pressure of 18 MPa held stable to meet acceptance criteria. A gravity plug was dropped, which seated in approximately 22 minutes. The stage collar circulation port was successfully opened by pressurizing at a low pumping rate of 6.6 MPa. The wellbore was circulated and cleaned for 8 hours to guarantee a clean annulus.
Secondary Cementing
Surface pipeline pressure test passed at 27 MPa. Spacer fluid and high-density cement slurry were injected. After releasing the closing plug, a precise displacement of 21.42 m³ was completed. Bump pressure of 18 MPa enabled reliable closure of the stage collar. Repressurization to 25 MPa ensured full pressure shear of internal components. Backflow cut off when releasing pressure, marking a one-time successful operation.
3. Technical Advantages and Promotion Value
Compared with conventional products, the non-drillable stage collar applied in this operation boasts remarkable advantages:
No milling required: The internal assembly is pressure-sheared directly after cementing, eliminating the milling operation and saving substantial construction time and equipment costs.
Improved operation safety: It avoids milling risks in deep wells and directional intervals, reduces casing damage and the likelihood of downhole complications.
Wide operating condition adaptability: The opening, closing and pressure-shearing actions complete in one sequence with reliable sealing, suitable for various well types including brine production wells and directional wells.
The successful application in Well HZK14 fully verifies the reliability and cost-effectiveness of the non-drillable stage collar technology for cementing of deep directional wells and production wells. It provides a replicable and promotable mature construction scheme for cementing operations of similar wells, and will effectively drive the high-quality, efficient and safe development of cementing technology in oil & gas and salt brine exploitation sectors.
