An Innovative Approach for the Beneficial Reuse of Contaminated Sands and Cuttings from E&P Operations

Abstract

This work is focused on identifying a scenario for the reuse of drilling cuttings and contaminated sands coming from Block 403A, in Algeria (ROM and ZEA fields operated by GSA), which are typical oil exploration and production wastes (e&p waste). The selected treatment was the Solidification/Stabilization (S/S) process using Ordinary Portland Cement as binder matrix and addressed the stabilization of Petroleum Hydrocarbon contaminants. The leaching of organic contaminants from stabilized waste product treated with Portland cement has been reported in some publications. Leaching test results have shown relatively high release of Polycyclic Aromatic Hydrocarbon [1] and methanol 2-chloroaniline [2] and [3]. The mix design consisted in different concrete monoliths prepared to simulate the forms for the future waste reuse made of different ratios of Ordinary Portland Cement (OPC), waste -drilling cuttings (DC) or contaminated sands (CS), superplasticizer (SP) and fly ash (FA). A testing framework was applied to assess the mineralogical composition, microstructural features, leaching behavior as well as the mechanical and physical properties of the stabilized waste. A mineralogical characterization of the cement pastes highlighted the presence of typical hydration products, along with the phase of anhydrous Portland Cement, which are probably related to the detrimental effects on the hydration process caused by contaminants. Microscopic observations suggested that the addition of fly ash should not result in performance improvement and that the cement pastes prepared using a lesser amount of water due to the addition of a superplasticizer exhibited the lowest porosity which strongly influence concrete performance. Organic contaminants are immobilized through a physical entrapment within the binder matrix and sorption onto the surface of binder hydration products given that no contaminants were measured into the eluates. Compressive strength grades measured on pastes prepared with superplasticizer are higher than the ones prepared without the water reducing admixture. Additional criteria to select the best recipe are related to the working applicability, sustainability and optimization of the production process at full scale.