Improvement in Cement Sealing Properties and Integrity Using Conductive Carbon Nano Materials: From Strength to Thickening Time

Abstract

Cement sheaths are designed to protect the integrity of oil and gas wells by mitigating movement of formation fluids and leaks. A failure of the cement sheath can result in the loss of zonal isolation, which can lead to sustained casing pressure. Gas migration through a cement sheath in the annulus is one of the main challenges that compromises zonal isolation. Failure in cement-casing bonding and micro annulus creation are other huge issues that compromises wellbore integrity. Even though some past studies have shown the application of nanomaterials, very few have conducted full scale tests measuring the compressive strength, thickening time and gas transition time of these materials. In this study, nanosynthetic graphite with designed expansive properties has been introduced to fresh cement slurry. The expansive properties of nanosynthetic graphite were achieved by controlling the preparation conditions. The material was made from synthetic graphite and has a surface area ranging from 325-375 m2/gram. Several tests including compressive strength, rheology, and thickening time were performed. An addition of only 0.5% nanosynthetic graphite with appropriate reactivity was sufficient to maintain expansion in the cement system, leading to an early compressive strength development. It has excellent thermal and electrical conductivity and can be used to design a cement system with short and long-term integrity. Rheology and thickening time tests confirmed its pumpability. Controlling the concentration of the additive is a promising method that can be used to mitigate gas migration in gas bearing and shallow gas formations.

A Review of Past, Present, and Future Technologies for Permanent Plugging and Abandonment of Wellbores and Restoration of Subsurface Geologic Barriers

“…The cement containing Nano-MgO also has higher mechanical strength in terms of both compressive and tensile strength (Gao et al, 2007;Mo et al, 2010;Jafariesfad et al, 2016). Nanosynthetic graphite has been shown to maintain cement expansion as well; quantities as low as 0.5% in the cement composition are enough for expansion maintenance (Ahmed et al, 2018). Nanocalcium carbonate (CaCO 3 ) in cement improves resistance to oil mud contamination; a 1% addition of nano-CaCO 3 and 3% oil mud contamination increases compressive strength by 72% and 10% respectively after 1 and 28 days of curing underwater (Vipulanandan and Amani, 2015).…”

Analysis on Effect of Fullerene Soot on the Chemical and Physical Properties of Cement Mixtures

“…In recent decades, a large number of scientists have tried to improve the properties of cement-based materials using various nanomaterials due to their excellent chemical, physical and mechanical properties [17][18][19]. The influence of a sufficiently small amount of 0.5% BWOC nanosynthetic graphite on grouting slurries was determined [20]. Another modification of graphite, graphite nanoplates, was used [21][22] in order to improve the physicomechanical characteristics and nanoscale reinforcement of cement stone.…”

Reduction of fluid migration in well cement slurry using nanoparticles

“…Some recommendations and guidelines were represented by Dean and Brennen [24]. Ahmed et al evaluated effects of using chemical additives on gas migration [25]. Wilkins and Free demonstrated valuable techniques for gas migration prediction on oil and gas wells [20].…”