Elements of a Successful Cement Job
Designing a cement job is an iterative and collaborative process. The collaboration takes place between the operating company and the service company and begins at the well planning stage. As the drilling process continues, new data are collected and checked against the preliminary expectations for the wellbore environment. Planning the final cement job for each casing string involves:
- Establishing final objectives for the well, including economics
- Studying problems in offset wells
- Identifying likely pressure regimes
- Planning for health, safety and environmental impacts and issues
- Determining the final well geometry, deviation, and static and dynamic temperatures
- Selecting the appropriate equipment and materials
- Finalizing a slurry design
- Selecting a mud displacement strategy
- Selecting the appropriate washes and/or spacers
- Finalizing procedures and pumping schedules with assistance from computer simulations
But even a well-planned and executed cement job requires that:
- The wellbore be drilled true to gauge and in a manner that will minimize the difficulty of removing the drilling mud and cuttings ahead of the cement slurry
- Quality control procedures are followed during cement and additive transport, storage and mixing operations
- The cement slurry design is tested in the laboratory to make certain it will perform as required
- The mixed slurry on location is tested to make certain it performs as designed when field cement and mix water is used
- Pipe centralization, reciprocation and rotation plans are understood by all cementing team members
- Real-time recordings of pump rate, surface pressure and fluid density (Figure 1) are compared with simulation predictions
