Treatment of Hydrocarbon-Based Drilling Waste Using Supercritical Carbon Dioxide

Abstract

Summary Nonaqueous drilling fluids are essential in challenging drill operations. Their use, however, requires special treatment and disposal because of their potential for environmental damage. In light of increasing costs for common treatment technologies and ever-tightening environmental legislation, alternative treatment technologies are being sought by the drilling industry. Supercritical fluid extraction is one such technology that employs a substance higher than its critical pressure and temperature as a solvent. In this paper, the results are presented of a study using supercritical carbon dioxide to treat synthetic based drilling waste. Unlike typical supercritical fluid extraction studies in which the process is optimized using changes in pressure and temperature, this study was undertaken to improve the extraction of hydrocarbons from drilling waste by increasing the supercritical fluid solvent to waste ratio. Efforts focused on improving supercritical fluid/drilling waste contact, eliminating system clogging with waste solids and minimizing solids carryover. Alterations to the waste using additives and alterations to the vessel both led to an increased amount of waste being treated effectively using the same amount of solvent. Optimization of the process yielded efficiencies as high as 97%. Also, it has been determined that the extracted hydrocarbons are unchanged by the supercritical fluid extraction process. This result suggests that the collected hydrocarbons may be reused in the drilling process, resulting in significant cost savings to the industry. Introduction In rotary drilling for oil and gas, drilling fluids are essential to clean the wellbore and to lubricate the drill bit. Nonaqueous-based drilling fluids (NADFs) are thought to be superior over water-based drilling fluids because of their higher natural lubricity and lower reactivity with clays and shales [Canadian Association of Petroleum Producers (CAPP) 2001; Melton et al. 2004]. As such, they are often necessary for challenging drill operations. However, they are much more expensive and, because of their hydrocarbon content, the wastes they generate must be handled and disposed of carefully. Numerous techniques have been developed to treat the wastes generated from drilling with NADFs. These techniques include bioremediation technologies, such as landfarming and cleaning technologies (e.g., incineration or solvent washing) (Saintpere and Morillon-Jeanmaire 2000). As environmental legislation becomes increasingly more stringent and the cost of common treatment techniques increases, the drilling industry seeks out new approaches to the treatment of NADF drilling waste (Minton and McGlaughlin 2003).

Analysis of the catalytic pyrolysis of shale gas oil‐based drill cuttings via TG‐MS

“…Their study provides theoretical support for the selective extraction of light oil. Street et al 8 used supercritical CO 2 to extract petroleum hydrocarbons from synthetic oil‐based drilling waste, and the results show that the extraction rate was as high as 98%; however, this technology has strict technical requirements and increased operational risks. Yan et al 9 applied Pseudomonas aeruginosa F‐2, a microorganism that can produce biosurfactants for recovering crude oil from oily sludge.…”

Comparative simulation research on the stress characteristics of supercritical carbon dioxide jets, nitrogen jets and water jets

“…In addition, it can easily create high-pressure jets at the well bottom, which does less harm to reservoirs than water-based drilling fluid and can increase the recovery ratio of oil and gas (AlAdwani, Langlinais, & Hughes, 2009;Street, Tesche, & Guigard, 2009). As a result, it has potential as a new type of rock-breaking method.…”