Influence of Curing Time on Oil Well Cement Properties Using Nanoclay

Abstract

ABSTRACT: Cement matrix is exposed to several loadings, which can harm its key properties and impede its functions, especially at the early age of forming the cement matrix where its properties are not entirely developed. Nanoclay is a powder material with very fine-grained particles which was used as a secondary additive to enhance the properties of cement. This work evaluates the early-time properties of oil well cement prepared with nanoclay powder and compares it with the properties of the base cement (without nanoclay). Several cement samples were prepared and cured for different times (12, 24, 48 and 72 hours) where the compressive strength, permeability, Poisson’s ratio and Young’s modulus of each sample were examined. The results indicated that the compressive strength of both cement systems increased with the increase of the curing time and the nanoclay-based sample had higher strength than base cement. The permeability of the cement decreased as the time of curing increased for the two cement systems and nanoclay cement had lower permeability. Moreover, the Poisson’s ratio decreased and Young’s modulus increased with curing time for both systems and the addition of nanoclay increased its Poisson’s ratio and reduced its Young’s modulus. 1. INTRODUCTION During the practice of drilling operations, cement slurry is pumped into oil and gas wells for the purpose of sealing the rock formation from the well by cementing the steel casing to the wellbore (Backe et al., 1998). Moreover, cement slurry is also used for controlling a zone where considerable losses of drilling mud are happening and setting a kickoff plug for the wellbore (Nelson and Guillot 2006). The main requirements for long term zonal isolation are the proper placement of the cement, providing low permeability, good mechanical durability and the ability to be adapted during the changing conditions of the wellbore (Zhang et al., 2020).