Treatment of Non-Aqueous Drilling Waste Using Supercritical Carbon Dioxide
Bibliographic record
Abstract
Abstract Non-aqueous drilling fluids, both synthetic and oil based, are essential in challenging drill operations. However, their use requires costly handling, treatment and disposal. Supercritical fluid extraction is investigated as a novel technology to treat this waste. Supercritical fluid extraction employs a substance above its critical temperature and pressure as a solvent; in this state the substance has both liquid- and gas-like properties that can be controlled by the pressure and temperature of the extraction process. In this paper, results of studies using supercritical carbon dioxide to remove non-aqueous fluids from drilling waste are presented. Current work investigates the extraction of hydrocarbons from centrifuge underflow synthetic based drilling waste. Although the extraction process is not yet fully optimized, extraction efficiencies as high as 98% have been observed. Additionally, results of both past and current studies indicate that non-aqueous drilling fluids are unchanged by extraction process and that the recovered hydrocarbons may potentially be collected and reused. Introduction In drilling for oil and gas, drilling fluids are essential to lubricate the drill bit and circulate the drill cuttings to the surface. It is well documented that non-aqueous drilling fluids (NADFs) have several advantages over water based drilling Fluids(1,2). NADFs have a higher natural lubricity, making them suitable for challenging drilling operations. NADFs are less reactive with clays and shales, thereby preventing hole enlargement and producing smaller volumes of waste overall. However, NADFs are more expensive and the waste generated from their use must be carefully handled and treated prior to disposal. There are a number of options available to treat and dispose of NADF wastes (land spreading and landfilling for example), however the cost of handling and disposing of drilling waste is increasing. The drilling industry is now turning to novel approaches for the treatment and disposal of drilling wastes in order to meet more stringent environmental guidelines(3). Supercritical fluid extraction (SFE) is an extraction technique that uses substances at or above their critical pressure and temperature as solvents. In the vicinity of the critical point, the liquid and vapour phases of the substance merge producing a fluid with gas-like diffusivity and viscosity and liquid-like density(4,5). These properties provide favorable mass transfer of the NADF hydrocarbons from the drilling waste to the bulk supercritical fluid. The density of the fluid is defined by the pressure and temperature; small changes in processing conditions can fine-tune the solvating power of the fluid(6). Additionally, supercritical fluids have zero surface tension thereby allowing easy penetration into most matrices(4). Several studies have documented the treatment of NADF drilling waste using SFE. In 1984, a patent by Eppig et al. detailed a system suitable for the removal of organic contaminants from inorganic matrices(7).This patent specifically lists the treatment of oil contaminated drill cuttings as a suitable application of the technology, and that propane, Freon and carbon dioxide would be suitable supercritical fluids for this purpose. A later study by Eldridge investigated the use of a pilot-scale SFE system to treat oil contaminated drill cuttings from North Sea drilling platforms(8).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".