Improving Local Class A Cement to Oil Well Cement Using Polyethylene Terephthalate Plastic Waste

Addition of polyethylene terephthalate (PET) waste plastic in cement mixtures tend to negatively affect cement matrix properties. Mainly, decreasing final compressive strengths and impacting cement slurry properties. However, recent studies on concrete cement mixtures show that through prior pretreatment of plastic waste material, via irradiation technique or using oxidizing solutions, the strength of PET plastic containing cement mixtures is regained. This study focuses on promoting similar sustainable practices by investigating the prospect of using PET plastic waste in cementing of shallow oil and gas wells. PET plastic waste was processed into fiber and powder additives and incorporated into locally manufactured general-purpose Class A cement, which was formulated or enhanced into standard oil well cement through addition of a variety of cement additives. The PET derived additives, namely, untreated PET fibers, irradiated PET fibers, and Bis (2-hydroxyethyl) Terephthalate (BHET) were incorporated at dosages of 0.2, 1.0, and 1.8% by weight of cement (bwoc) to assess their influence on oil well cement slurries and matrices. It is observed that plastic viscosities of prepared slurries increased with increasing incorporation dosages of the PET derived additives. Slip effects frequently occurred due to the addition of PET fibers as additives. The addition of untreated PET fibers, irradiated PET fibers, and BHET additives optimally increased final compressive strengths by 22.05, 19.34 and 81.82%, respectively. Addition of a superplasticizer among the additives is crucial in controlling rheological behavior and most importantly in improving compressive strength of PET plastic incorporated oil well cements. Thus, PET fibers have potential to be used as reinforcements while BHET can be readily used as an oil well cement additive.