Analysis of Inorganic Cement Retarders and their Performance in Deep Shale Reservoirs

Abstract

The cementation process is used extensively in casing programs in oil & gas wells.
Portland Cement, primarily used in construction, is modified through the use of
certain additives, which adjust the behavior of slurry under a wide range of
downhole conditions.
Shale reservoirs are generally found at depths characterized by high Temperature
and Pressure conditions. Hence, one of the primary characteristics of cement slurry
mixed to operate in such conditions must be its late setting time i.e. late strength
development, and late thickening time. Cement additives used to imbibe these
properties to cement mixtures are called Retarders.
This article discusses some common inorganic cement retarders classified to be used
at high Temperature and Pressure conditions, such as those provided by shale
formations, and reviews the performance of different types of slurries formulated
using these substances.
The experimentation for this article was performed in laboratory conditions.
Different sets of cement mixtures were prepared, with each set containing the same
substances but in different compositions. The mixtures were subjected to a high
Temperature conditions inside a Temperature adjustable oven, and their setting
durations were measured.
Based on the data obtained from the experiment, the cement mixtures have been
reviewed, comparisons have been made between them, and based on them
recommendations have been provided for the composition of the cement slurry for
use in deep shale reservoirs.