Biodegradable eco-friendly drilling fluid: a study on the use of peanut shell with different particle sizes as sustainable additives

Abstract Meeting the global energy demand and sustainable development of conventional petroleum reserves necessitates the development of high-performance and environmentally friendly water-based drilling fluids (WBDF). Nevertheless, one of the major concerns of using WBDF is the fluid loss due to its penetration into the formation during the drilling operation. Various additives (fluid-loss agents) in the industry have been introduced to tackle the issue but at the cost of non-biodegradable hazardous chemicals. Due to the recent interest in environmentally friendly WBDF additives, this study looked at the suitability of the composite part of peanut shell powder (CSP). The CSP was selected because of affordability, accessibility and fibrous content. Following the American Petroleum Institute (API) guidelines for preparing the drilling mud additives, six different laboratory experiments were carried out for biodegradable drilling fluids prepared from CSP at different concentrations of 1, 2 and 3 wt% and particle sizes (fine, 224 μm and medium, 1.12 mm). Major elemental and temperature analyses of the samples were conducted using Energy-dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared spectroscopy (FTIR) and a Thermogravimetric Analyser (TGA). Comparing the results with the referenced WBDF indicates that adding 1, 2 and 3 wt % fine CSP decreases the fluid loss by 37%, 50% and 65%, respectively. In addition, using medium-size CSP in the same concentration of 1, 2 and 3 wt % reduced the fluid loss by 30%, 39% and 53%, respectively. Based on the results, the use of fine particle size CSP with a 3 wt % weight concentration is recommended, as it creates a thin mud cake with lower permeability, allowing for better control of fluid loss.