Comparison of stabilised/solidified mixes of model drill cuttings based on the North Sea and Red Sea Areas

Following the global stringent legislations regulating the wastes generated from the drilling process of oil exploration and production activities, the management of hazardous drill cuttings has become one of the pressing needs confronting the petroleum industry. Most of the prevalent treatment techniques adopted by oil companies are extremely expensive and/or the treated product has to be landfilled without any potential end-use; thereby rendering these solutions unsustainable. The technique of stabilisation/solidification is being investigated in this research to treat drill cuttings prior to landfilling or for potential re-use in construction products. Two case studies were explored namely North Sea and Red Sea. Given the known difficulties with stabilising/solidifying oils and chlorides, this research made use of model drill cutting mixes based on typical drill cutting from the two case studies, which contained 4.2% and 10.95% average concentrations of hydrocarbons; and 2.03% and 2.13% of chlorides, by weight respectively. A number of different binders, including a range of conventional viz. Portland cement (PC) as well as less-conventional viz. zeolite, or waste binders viz. cement kiln dust (CKD), fly ash and compost were tested to assess their ability to treat the North Sea and Red Sea model drill cuttings. The dry binder content by weight was 10%, 20% and 30%. In addition, raw drill cuttings from one of the North Sea offshore rigs were stabilised/solidified using 30% PC. The characteristics of the final stabilised/solidified product were finally compared to those of thermally treated cuttings. The effectiveness of the treatment using the different binder systems was compared in the light of the aforementioned two contaminants only. A set of physical tests (unconfined compressive strength (UCS)), chemical tests (NRA leachability) and micro-structural examinations (using scanning electron microscopy (SEM), and X-ray diffraction (XRD)) were used to evaluate the relative performance of the different binder mixes in treating the drill cuttings. The results showed that the observed UCS covered a wide range of values indicating various feasible end-use scenarios for the treated cuttings within the construction industry. The teachability results showed the reduction of the model drill cuttings to a stable non-reactive hazardous waste, compliant with the UK acceptance criteria for non-hazardous landfills: (a) by most of the 30% and 20% binders for chloride concentrations, and (b) by the 20% and 30% of compost-PC and CKD-PC binders for the Red Sea cuttings. The 20% and 30% compost-PC and CKD-PC binders successfully reduced the leached oil concentration of the North Sea cuttings to inert levels. Copyright 2007, Society of Petroleum Engineers.

Palm frond biochar production and characterisation

Palm oil has been the world's main source of oil and fats since 2004, producing over 45 million tonnes in 2009. Malaysia alone has over 4·5 million hectares planted with oil palm and, based on common practice, ~300 palm fronds are pruned per hectare per year. This agricultural waste is currently either being used as roughage feed or, more frequently, being left between rows of palm trees to prevent soil erosion, or for nutrient recycling purposes. This paper proposes an alternative use for palm frond as a source of biochar. A traditional method commonly use by gardeners in Malaysia to improve soil fertility was used to produce the biochar. A shallow earth pit was dug in the ground for the carbonisation process. The process is described and the impact of carbonisation on the earth wall is analysed and presented. The process was later re-assessed by using TGA-FTIR. Most of the hemicelluloses had fully disintegrated, but the depolymerisation of the cellulose was still incomplete at the carbonisation temperature. Most of the lignin aromatic structure was still present in the biochar. The carbonisation process was repeated in the laboratory and biochar was characterised by using BET, SEM and FTIR. An adsorption isotherm study was conducted and the experimental data were fitted to the Langmuir model. The model predicted Pb2+ adsorption rates of 83·3 mg/g, Cu2+ 41·4 mg/g, Ni2+ 13·0 mg/g and Zn2+ 19·7 mg/g. Copyright © The Royal Society of Edinburgh 2012.