Characterization of agro-waste resources for potential use as proppant in hydraulic fracturing

Utilization of deformable substrates as proppant with sparse distributing for Hydraulic Fracturing (HF) is contributed to the improvement of fracture conductivity. Agro-waste resources, specifically shells of tropical plants such as coconut shell and palm kernel shell are two environmentally friendly and potential renewable resources that can be utilized as propping agents in HF. Nevertheless, they are not yet widely studied as such. Given this lack of particular technical and reliable data, their conversion into proppant cannot be designed with confidence as it happens with other studied biomass feedstock such as walnut-hull. This paper includes a study on the experimental characteristics of two agro-wastes or biomasses, coconut shell and palm kernel shell, as possible resources as proppants in HF. The main characteristics envisaged are particle size distribution, roundness and sphericity, density, specific gravity, bulk density, turbidity, crush resistance, single particle compression test, and fracture conductivity. The results obtained from the analyses are compared to the commonly known walnut-hull particles. These biomasses show promising results and meet some of established API/ISO standards. This paper is intended to provide technical information on the characteristics of new agro-wastes resources and to emphasize their major strengths; that have not been highlighted in the literature. These results are of key importance for the consequent development of high-strength composite proppants. Recommendations are also proposed for future improvement in increasing the quality of the results.