CemSTRESS Cement Sheath Stress Analysis Software

Understanding Stresses in the Cement Sheath

A lack of understanding of the stresses a cement sheath experiences and when or why the sheath may fail can lead to loss of zonal isolation, jeopardizing the future of the well. The lack of zonal isolation adversely affects all subsequent operations and degrades potential well performance and productivity.

CemSTRESS software is the key to understanding stresses in the cement sheath. This software can model up to 10 strings simultaneously, analyzing the stress imposed on each string by a well event, such as pressure testing. CemSTRESS analysis of radial and tangential stresses can determine cement sheath performance in compression, tension, or both, enabling the design of the set cement behind the casing to be optimized.

Unique sensitization ability

In addition, CemSTRESS software has the unique ability to “sensitize” many parameters, including formation flexibility support and standoff, so the decision about the best cement system to use can be based on the level of risk. Often, the best system is one with a low Young’s modulus, such as a flexible cement system using FlexSTONE technology.

CemSTRESS methodology

CemSTRESS software aids in selecting and designing a cement system that can extend well life and reduce the need for costly remediation—a system that can withstand stresses and maintain a 100% hydraulic seal for many years. This is accomplished using a three-stage methodology called the Cement Sheath Integrity Suite.

1. System selection
   In the first stage, the CemSTRESS software is used to determine whether the well requires a conventional cement system or a specialized system. This provides direction for the next two stages.
2. Engineered design
   In every well, there can be many different scenarios for cement sheath failure. The second stage of the methodology uses CemSTRESS analyses of these scenarios to design a cement system— typically incorporating FlexSTONE technology—to keep the Young’s modulus below the stress level predicted to induce failure.
3. Slurry optimization
   In the third stage of the methodology, Schlumberger cementing engineers use proprietary software to optimize the cement slurry design.

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