The suitability of eggshell for improving the performance of water-based drilling mud in a high-temperature well

Abstract

The selection of water-based mud for drilling a high-temperature and high-pressure (HTHP) well is the choice of many drilling mud engineers. This choice of mud is more attractive because it is cost-effective, eco-friendly, and easy to prepare but its reliability for drilling shale formations and geothermal resources optimally depends on the design and inclusion of the necessary additives to the drilling fluid. An HPHT-resistant deficiency of the drilling mud has been an age-long jeopardy of the development of a harsh elevated temperature reservoirs such as geothermal formation. Consequently, it has become imperative to innovate a thermal resistance material that is capable of serving as an additive and ensuring thermal stability for drilling mud through the drilling operation at the desired temperature ranges. Studies reported in the literature have revealed that, eggshell nanoparticles (ESN) withstand a lot of heat and at the same time retain their properties under extreme conditions. This study examines the viability of employing eggshells to enhance the efficiency of water-based drilling fluid in elevated-temperature wells. ESN was added at various weighted amounts to the petroleum industry's approved mud composition for an elevated temperature well to design eggshell-boosted water-based mud samples. In accordance with the American Petroleum Institute (API) mud test technique, evaluation of the prepared mud samples was done by performing filtration, and rheological tests under HPHT conditions. The outcomes of the study show how ESN helps water-based drilling mud to withstand drilling operations in elevated temperature formations by delaying thermal degradation up to 270 °C. Specifically, the Fluid sample with 5 lb./bbl of ESN exhibited an 8 % reduction in HPHT filtrate vol when compared with an equal volume of commercial calcium carbonate (CCC), while a larger quantity of ESN (6 lb./bbl) yielded a 17 % reduction. Additionally, the inclusion of 5 lb./bbl of ESN was observed to be more effective than an equal quantity of CCC at 250 °C as it yielded a 28 % increase in 10 min gel strength. However, the rheological properties of 5 lb./bbl of ESN were not as effective as CCC at low-pressure low-temperature (LPLT) conditions which may be due to the presence of organic matter as a constituent of ESN at any temperatures below 200 °C.