Abstract

A new approach to cementing allows the design of high- performance slurries at low as well as high densities. The technology decouples slurry and set cement performance from the slurry density. Using this technique new lightweight cement slurries as low as 10 PPG can be designed with high compressive strength, low permeability, and low porosity for applications such as completion in reservoirs with low fracture gradients, matched density kickoff plugs, geothermal wells, single slurry for both lead and tail, grouting jobs and many more.

The technology is based on the correct selection of components for the dry blend with compounds of proper specific gravity and in an optimum ratio. The subsequent reduction in usage of liquid for slurry preparation leads to beneficial effects on set cement properties.

The advantageous properties provided by the proposed system are:

  • Very high compressive strengths of 2000 psi at 10.0 PPG and 4000 psi at 12.0 PPG, at low densities

  • Very low permeability and porosity of set cement

  • Improved stability, fluid-loss control and in most cases no free water compared to conventional systems

  • Excellent perforability for the set cement

  • Improved robustness to possible density fluctuations

In this paper the technology is presented and illustrated through a comprehensive set of laboratory data. Also, results are presented from various field applications where the technology has been used. Significant savings have resulted for the operator, especially when replacing conventional multistage operations with single-stage ones.

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