Oil-based Drill Cuttings Research Articles

Total Nitrogen and Bacterial Analysis in Oil-Based Drill Cuttings Contaminated Soils Planted with Grass Species

The possibility of grass species phytoremediating oil-based drill cuttings contaminated soils was examined by assessing changes in bacterial load, bacterial species, and soil nitrogen. The experiment was modelled in a randomized complete block design by factorial of 6 x 3 x 2 x 2 for grass species, drill cuttings, time, and growth stage. The parameters assessed were total nitrogen, nitrogen reduction, bacterial load, and bacterial load reduction in soils. There was significant decrease in nitrogen from day of planting to harvesting. The highest reduction was observed in 0% and 25% treatments in mature P. maximum and young C. virgata. The lowest reduction was seen in A. compressus at 50% treatment. Significant difference in bacterial load was noticed in time in each treatment. Highest reduction of bacterial load was seen in 0% treatment level planted with A. compressus, A. gayanus, young C. virgata, H. contortus, P. maximum, and unplanted soils, which were not significantly different from 25% and 50% oil-based drill cuttings treatment except in young H. contortus and P. maximum. The lowest reduction was observed in 25% treatment level of young H. contortus and P. maximum. Micrococcus sp, Bacillus sp., and Staphyloccocus aureus were found in soils of the three treatment levels at planting. In addition, Protus sp was seen in soils of 0% and 50% treatment levels. Erwinnia sp and Escherichia coli was identified in 25% and 50% oil-based drill cuttings treated soils. Klebsiella sp was isolated from 25% oil-based drill cuttings treated soils. Therefore, Erwinia sp, E. coli, and Klebsiella sp were associated with oil-based drill cuttings contamination.

Case Study: Drill-Cuttings Treatment Alternatives—A Comparative Emissions Assessment

The offshore oil and gas industry has always been cognizant of its impact on the marine environment. The choices that operators make in how they operate, including the disposal of drill cuttings, must address an increasing number of environmental and climate targets in addition to those related to health, safety, and cost. As a typical well will produce approximately 1000 metric tons of oil-based drill cuttings, quantifying greenhouse-gas (GHG) emissions associated with the disposal and treatment of drill cuttings has become an essential step to achieving net-zero ambitions. Since 1991 (1993 for fields in production), strict regulations relating to the discharge of oil-based drill cuttings have been in force under the OSPAR (Oslo/Paris) Convention. Those regulations banned the practice of discharge to sea of untreated oil-based drill cuttings and led to a situation where they were generally shipped to shore for treatment and disposal. In 2020, TWMA engaged DNV, the independent energy expert and assurance provider, to undertake a comparative study between the company’s offshore thermal drill-cuttings treatment solution and conventional alternatives including “skip and ship,” bulk transfer, and cuttings reinjection (CRI) used on the Norwegian Continental Shelf (NCS). It is the first paper to show a direct emissions comparison between offshore processing and alternative methods implemented. The study assessed the carbon dioxide (CO2) footprint and nitrogen dioxide (NOx) emissions for each of the different alternatives. The values were then used to create an interactive emissions calculator that can easily be applied to specific projects to clarify the actual potential for emissions reduction within the drilling waste management process. Background Technological improvements, as well as cost focus on existing solutions, have meant that offshore thermal drill-cuttings treatment has been widely adopted in many offshore basins as one of the safest and most cost-effective approaches. In Norway, which was the subject of the study, adoption of the technology has been slower than in other countries, with onshore thermal treatment of oil-based cuttings applied as the predominant technique, while some fields use offshore slurrification and injection into dedicated disposal wells. However, the cost of drilling new disposal wells and the track record of successful offshore thermal projects in other countries have improved the frame conditions for the use of offshore thermal treatment of cuttings on the NCS. It has also been demonstrated, in an earlier independent comparative study by Carbon Zero (SPE 207519), that the carbon footprint of skip and ship to shore of drill cuttings is 53% higher than that of drill-cuttings treatment at the wellsite (SPE 202639).

Experimental study on the treatment of oil-based drill cutting by pulsed dielectric barrier discharge plasma at atmospheric pressure

Oil-based drilling cuttings produced in the process of oil exploration and shale gas development are harmful to the ecological environment. The emerging low-temperature plasma technology has shown potential for environmental protection. In this paper, pulsed dielectric barrier discharge (DBD) plasma was used to treat contaminated drilling cuttings at atmospheric pressure. The effect of adding active aluminium oxide (Al2O3) balls to the oil-based cuttings on the degradation rate of mineral oil was evaluated. Results showed that when the oil-based drilling cuttings were mixed with active Al2O3 balls, the highest degradation rate of mineral oil (68.1%) was achieved when the treatment time was 30 min. This rate was 41.8% higher than that obtained by DBD treatment alone. The Fourier transform infrared spectroscopy showed that the content of alkanes in the treated samples decreased significantly. The gas chromatography-mass spectrometry and ion chromatography analysis showed that formic acid, acetic acid, and other by-products were formed. The contents of C and H in the samples treated by DBD decreased. Overall, this study provides much-needed insights into the reaction mechanism and pollutant degradation process of the synergistic treatment system of pulsed DBD and active Al2O3 balls in the field of oil-based drilling cuttings treatment.

Catalytic pyrolysis of oil-based drill cuttings over metal oxides: The product properties and environmental risk assessment of heavy metals in char

Oil-based drill cuttings (OBDC), a hazardous organic waste generated from the exploration and extraction of shale gas fields, have received widespread attention for their safe disposal and utilization. In this study, OBDC pyrolysis experiments were conducted on a fixed-bed reactor. The effects of temperature (450 °C, 500 °C, 550 °C, and 600 °C) and catalysts (MgO, Fe2O3, and CaO) on product distribution, oil quality, and potential ecological risk assessment of heavy metals were investigated. Results revealed that the oil yield reached the maximum (14.94%) at 500 °C in uncatalyzed cases. The addition of catalysts could increase the total yield of oil and gas. In particular, the oil yield increased by 13.32% with CaO catalysis, while the oil recovered by MgO and Fe2O3 was almost the same as without catalyst. In addition, the higher low heating value (LHV) of oil (41.46 MJ/kg) and gas (34.07 MJ/Nm3) were found with CaO catalysis, implying that CaO has better performance on recovery of oil and gas than MgO and Fe2O3. Moreover, the oil content of char was far below 0.3%, the potential ecological risk assessment of heavy metal in char showed slight risks to the environment, suggesting that char can be treated as general solid waste.

Soil Microbial Ecological Effect of Shale Gas Oil-Based Drilling Cuttings Pyrolysis Residue Used as Soil Covering Material

Soil Microbial Ecological Effect of Shale Gas Oil-Based Drilling Cuttings Pyrolysis Residue Used as Soil Covering Material

Emissions of BTEXs, NMHC, PAHs, and PCDD/Fs from Co-processing of Oil-based Drilling Cuttings in Brick Kilns

Oil-based drilling cuttings (OBDC) produced from shale gas development is a hazardous waste that have high calorific values and should be disposed of properly. Burning bricks with OBDC is a promising co-disposal method; however, organic pollutants emitted during this process have not received sufficient attention. In this study, the composition and combustion characteristics of OBDC were determined, and the emissions of typical organic pollutants when burning bricks with the addition of OBDC were investigated; these included benzene series compounds (BTEXs), non-methane total hydrocarbons (NMHC), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). The results showed that OBDC comprised large amounts of alkanes and aromatic hydrocarbons, and combusted mainly in the temperature range of 145–450 °C with an ignition temperature of 145 °C. The co-processing 10% OBDC increased the concentrations of toluene, NMHC, and PAHs in the flue gases by ∼1000%, ∼500%, and 200%, respectively, compared to the control experiment; however, their emission concentrations were within the limits set by the Integrated emission standards of air pollutants of Chongqing. It is worth noting that 26.443 ng/Nm3 PCDD/Fs with a total toxicity of 0.709 ng I-TEQ/Nm3 was generated from the co-processing 10% OBDC, which was ascribed to the high content of chlorine and aromatic hydrocarbons in the OBDC-promoted PCDD/Fs formed during the burning and cooling processes. Though PCDD/Fs in flue gas exceeded the 0.5 ng I-TEQ/Nm3 limit prescribed in the Pollution control standard for hazardous wastes incineration of China, the realistic emission of PCDD/Fs is expected to meet with this emission limit after desulfurization treatment as PCDD/Fs can be absorbed by gypsum. It is recommended that a lower amount of OBDC is added to reduce PCDD/F formation at the source and to take more efficient air pollution control system in order to reach a stricter emission limit of 0.1 ng I-TEQ/Nm3 in EU and USA. Cycling flue gas may also be an effective method to reduce other organic pollutants. Under these conditions, co-processing OBDC in brick kilns can be achieved without serious environmental pollution, making it a potential method for disposal and utilization.

Release characteristics of polycyclic aromatic hydrocarbons (PAHs) leaching from oil-based drilling cuttings

Drilling cuttings, the primary byproduct from the exploration and mining of shale gas, are potentially hazardous wastes that are associated with the serious depletion of land resources and environmental safety problems. In this work, the distribution of polycyclic aromatic hydrocarbons (PAHs) in oil-based residues of shale gas drilling cuttings was studied. Furthermore, a column leaching test was carried out to investigate the leaching behaviour of PAHs. The results showed that (1) the concentrations of 4-ring PAHs were highest among the PAH concentrations detected from the oil-based residues, and the concentration of PAHs decreased with increasing particle size of the residues. (2) The PAH concentration in leachates from all the tested residues differed during the leaching process, and the cumulative amount of each leached PAH accounted for 1.50–3.20% of the total PAHs. (3) The first-order diffusion model (FRDM) was the most applicable model for describing the leaching characteristics of the PAHs, and the leaching rate was initially controlled by surface wash-off and then by diffusion.

Physical characteristics and environmental risks assessment of oil-based drilling cuttings residues used for subgrade materials

Oil-based drilling cuttings residues (ODCRs) can be used as subgrade materials for well site construction. It not only reduces the cost of shale gas development, but also solves the practical problems encountered in shale gas development. The results show that ODCRs contained many carcinogenic pollutants, such as As, Benzo anthracene (a), Benzo pyrene (a), Dibenzo anthracene (a, h). ODCRs have some environmental risks. However, the main mineral components and radioactive strength of ODCRs meets the requirements of Class A materials, which can be used for building materials. The experimental results show that the unconfined compressive strength of ODCRs subgrade materials increases with the increase of cement content. The unconfined compressive strength and compactness first increase and then decrease with the increase of ODCRs content. The optimal content of cement is 4%, and the optimal content of ODCRs is 60%. In addition, ODCRs have pozzolanic characteristics. Active SiO2 and Al2O3 in ODCRs can react with Ca(OH)2 to produce a certain amount of gel materials, such as ettringite (AFt) and gel hydrated calcium silicate (C–S–H). These gel materials can form a network structure to encapsulate heavy metals and macromolecular organic matters. So, no organic pollutants and some heavy metals are detected in the leaching solution of subgrade materials with 60% ODCRs, and there will be no secondary pollution to the external environment.

Drill cuttings waste management from oil & gas exploitation industries through end-of-waste criteria in the framework of circular economy strategy

Worldwide Oil & Gas exploitation industry has a vital and dynamic role to play in the global energy matrix. In any Oil & Gas exploitation mission, drilling operations have the potential to generate substantial quantity of wastes. Drilling fluids and cuttings are considered as hazardous waste, very complex and difficult to be managed due to several impurities (i.,e heavy metals, etc). At the same time, circular economy is gaining cumulative attention in Europe and around the world as a potential way for our humanity to growth prosperity, while reducing dependence on primary materials and energy. The paper through end-of-waste criteria concept and quality protocol development, declassified oil-based drilling cuttings (from Cyprus Oil & Gas Exploitation program) after their treatment through Thermomechanical Cuttings Cleaning process, in order to be used as alternative aggregated and/or construction material and/or cement production (or other civil engineering works), promoting at the same time a valuable and sustainable solution based on circular economy concept. The results showed that, the final solid waste from Thermomechanical Cuttings Cleaning process can be used as raw material for civil engineering works replacing natural resource, if solid waste from the Thermomechanical Cuttings Cleaning process can met the defined quality protocol limits. The results are considered vital for offshores, policy makers, consultant engineers, as well as competent authorities, which try to find an acceptable and at the same time sustainable solution, to monitor and assess drilling waste which should be managed in a safe way, that may not have any undesirable effect on the environment.

High quality oil recovery from oil-based drill cuttings via catalytic upgrading in presence of near-/supercritical water and different industrial wastes

Near-/supercritical water (N/SCW) is a green and excellent medium for extracting and upgrading heavy oil from oil-based drill cuttings (OBDC). In order to improve the quality of recovered oil, five typical industrial wastes were adopted as the costless addictives, namely municipal sewage sludge (MSS), zinc-rich electroplating sludge (Zn-EPS), nickel-rich electroplating sludge (Ni-EPS), red mud (RM) and hot steaming steel slag (HSSS). The results indicate that the MSS deteriorates the recovered oil because the inferior bio-diesel was generated from the organics of MSS. The others exhibit positive effects more or less due to their dual functions of absorption and catalysis. The active components were found to be mainly metallic oxides in RM, ferrite in HSSS and metal hydroxides in EPS, respectively. Of which, the dehydration of metal hydroxides plays an important role in the N/SCW upgrading reactions, i.e., in-situ formation of high active compounds of ferrite and metallic oxides, and micro-mixing well with OBDC. In summary, the catalytic activity of tested industrial wastes was found to be in an order of Ni-EPS > Zn-EPS > HSSS > RM. High quality oil with zero asphaltene and extremely low heteroatom was obtained by N/SCW upgrading of OBDC with the addition of EPS. This study provides an alternative process for the sustainable and cleaner co-treatment of OBDC and various industrial wastes, and the obtained information is also helpful for the catalyst development of hydrothermal upgrading technology.

Particular pollutants, physical properties, and environmental performance of porous ceramsite materials containing oil-based drilling cuttings residues.

The mineral compositions of oil-based drilling cutting residues (ODCRs) were similar to that of clay, which could be used as raw materials for ceramsite. In this study, the maximum addition of ODCRs and the optimum calcination conditions were studied by single factor experiment. The microstructure, phase composition, and element distribution of ceramsite were studied by means of SEM, XRD and EDS. The ceramsite, with a 40% ODCRs content, was calcined at 1000 °C for 2 h. After cooling down, the ceramsite had good physical properties, including low density, low water absorption, and high compressive strength. The bulk density was 850-970 kg/m3, the water absorption was 2.1-10%, and the cylinder compressive strength was 6-11.8 MPa. And most of the heavy metals in ODCRs were effectively solidified. The organic toxic substances were completely burned. The leaching amount of harmful elements met the requirements of Chinese standards. The ceramsite would avoid secondary pollution to the environment. So the ceramsite made from ODCRs can not only improve the processing speed of ODCRs, but also be used as building materials, greening materials, industrial filter materials, etc., and increase its environmental and social benefits.

Treatment of oil‐based drill cuttings by hydrophobic deep eutectic solvents

AbstractDuring the exploitation of shale gas, there are many oil‐based drill cuttings (OBDC) produced, which are hazardous waste. In this paper, the characteristics of OBDC were analyzed and 25 hydrophobic deep eutectic solvents (DESs) were prepared as extractants for treating OBDC. The results showed that the DES formed by lauric acid and thymol had the highest extraction efficiency. The significant parameters of the extraction process were studied by using total petroleum hydrocarbon (TPH) as an index and the rational extraction conditions were recommended as follows: 0.8:1 mole ratio of lauric acid to thymol, 10:1 mass ratio of DES to OBDC, and 1 h extraction time at 60°C. The TPH of OBDC can be decreased from 14.75 to 0.87 wt.% at this recommended condition. The high extraction efficiency was also confirmed by energy dispersive spectrum results of treated OBDC. In addition, the lauric acid/thymol DES can be recycled and the TPH was still smaller than 1% after three cycles. This research suggests that hydrophobic DES extraction is an effective technology for TPH removal from OBDC.

Co-pyrolysis of waste polyvinyl chloride and oil-based drilling cuttings: Pyrolysis process and product characteristics analysis

Oil-based drill cuttings (OBDC) and waste polyvinyl chloride (waste PVC) both are solid wastes. The pyrolysis/co-pyrolysis characterizations of OBDC, waste PVC and OBDC/waste PVC at varying heating rates were investigated using thermogravimetric analysis (TG/TGA). Coats-Redfern and Kissinger integration methods were employed to fit the TG curve. The optimal fitting effect was obtained with reaction order at 2 and Kissinger integration method was better than Coats-Redfern integration method for co-pyrolysis of OBDC/waste PVC. The practical co-pyrolysis condition was optimized using batch experiment and the optimal condition was as following: final temperature for 600 °C, holding time for 60 min, heating rate at 10 °C/min and ratio of PVC as 10% PO. The gas, solid and liquid phase products of pyrolysis/co-pyrolysis were characterized and analyzed using thermogravimetry-mass spectrometry (TG-MS), gas chromatography-mass spectrometry (GC-MS) and X-ray diffraction (XRD). The gas product of pyrolysis/co-pyrolysis indicated the inhibitory effect on HCl emission due to the positive synergic effect of OBDC and PVC. High pyrolysis temperature was beneficial to increase the content of hydrocarbons, which enhanced the quality of oil recovery. This study indicated that the co-pyrolysis of OBDC and waste PVC is a promising method for waste disposal and oil recovery.

Treatment of oil-based drilling cuttings using the demulsification separation-Fenton oxidation method.

In this study, demulsification separation-Fenton oxidation technology was employed as a combined technology to treat total petroleum hydrocarbons (TPH) in oil-based drill cuttings (OBDC). Batch experiments were carried out to optimize the technology parameter. Under the optimal condition, 70% and 51% TPH removal rate was obtained for demulsification technology and Fenton oxidation technology, respectively. Eighty-five percent of TPH removal rate was obtained using combination technology of demulsification separation and Fenton oxidation. Multiple characterizations were used to analyze the physical and chemical properties of treated OBDC. The result of XRD pattern indicated the combination technology had no obvious effect for structure phase of OBDC. The results of FTIR, GC-MS, TG-DTG and SEM were used to characterize the treated OBDC. This paper provides an efficient and feasible combined technology for OBDC treatment, which expands a new strategy for the removal of TPH from solid waste.

Activation of Peroxymonosulfate Using Secondary Pyrolysis Oil-Based Drilling Cuttings Ash for Pollutant Removal.

In this study, the utilization of secondary pyrolysis oil-based drilling cuttings ash (OBDCA-sp) to activate peroxymonosulfate (PMS) for pollutant removal was investigated. The chemical and physical properties of OBDCA-sp were explicitly analyzed via multiple characterization. The activation efficiency of OBDCA-sp for PMS was tested using humic acid (HA) as the target pollutant. 92% of HA and 52% of total organic carbon in solution could be removed using OBDCA-sp-activated PMS under optimal conditions: OBDCA-sp dosage at 4 g/L, PMS concentration at 4 mmol/L, HA concentration at 10 mg/L, and pH value at 7. After four cycles, 84% removal rate of HA could still be achieved using OBDCA-sp to activate PMS. The main catalysis elements for PMS activation in OBDCA were postulated to be Fe(III), Co(III), and Mn(III), based on X-ray photoelectron spectroscopy and X-ray diffraction results. The results of the quenching experiment indicated that SO4•–, •OH, and 1O2 were the main reactive oxygen species (ROS) and that 1O2 was the dominant ROS in the HA removal process. Radical trapping experiments indicated the presence of SO4•–, •OH, and 1O2 in the reaction system. This study presented a novel utilization path of OBDCA in the field of environmental remediation.

Development of supercritical water oxidation technology for application to hazardous waste treatment: An extreme case study

Batch and continuous co-treatment of two typical hazardous wastes via supercritical water oxidation technology (SCWO) was investigated, that is, oil-based drill cuttings (OBDC) from a shale gas field and high-nickel-content electroplating sludge (Ni-EPS) from an electroplating factory. OBDC, an extreme representative of hazardous waste rich in organic materials, acts as an auxiliary fuel that provides heat from exothermic reactions during SCWO. The average reaction temperature in the continuous reactor increased from 378 °C to 495 °C. Ni-EPS, an extreme representative of hazardous waste rich in metals, acts as both a diluent and a catalyst. Metals in the Ni-EPS tend to form NiFe2O4, ZnFe2O4, and NiCr2O4 after SCWO treatment, and when OBDCs are present, they are transformed into metal oxides (MOx). All the metal oxides are in the form of nanoparticles and exhibit catalytic activity. Owing to the synergistic effect of high temperature and in-situ formation of nanocatalyst materials, the total organic carbon (TOC) in the effluents was as low as 8 mg L−1, and the TOC removal efficiency (CRE) reached as high as 99.96%. This study provides an alternative process for the efficient and complete treatment of hazardous waste, and the obtained information will be helpful for commercialization of SCWO technology.

Environmental risks of shale gas exploitation and solutions for clean shale gas production in China

Shale gas is a relatively clean-burning fossil fuel, produced by hydraulic fracturing. This technology may be harmful to the environment; therefore, environmentally friendly methods to extract shale gas have attracted considerable attention from researchers. Unlike previous studies, this study is a comprehensive investigation that uses systematic analyses and detailed field data. The environmental challenges associated with shale gas extraction, as well as measures to mitigate environmental impacts from the source to end point are detailed, using data and experience from China’s shale gas production sites. Environmental concerns are among the biggest challenges in practice, mainly including seasonal water shortages, requisition of primary farmland, leakage of drilling fluid and infiltration of flowback fluid, oil-based drill cuttings getting buried underground, and induced seismicity. China’s shale gas companies have attempted to improve methods, as well as invent new materials and devices to implement cleaner processes for the sake of protecting the environment. Through more than 10-year summary, China’s clean production model for shale gas focuses on source pollution prevention, process control, and end treatment, which yield significant results in terms of resource as well as environmental protection, and can have practical implications for shale gas production in other countries, that can be duplicated elsewhere.

Enhancing the anode performance of microbial fuel cells in the treatment of oil-based drill sludge by adjusting the stirring rate and supplementing oil-based drill cuttings

This was the first attempt to investigate the bioelectricity output based on a solid–liquid cooperation in the microbial fuel cell (MFC) treatment of oil-based drill sludge by adjusting the stirring rate and supplementing oil-based drill cuttings (OBDCs).

Low-temperature thermal desorption and secure landfill for oil-based drill cuttings management: Pollution control, human health risk, and probabilistic cost assessment

Oil-based drill cuttings (OBDCs) were managed in two scenarios including low-temperature thermal desorption (LTTD) and secure landfill through a case study. The removal of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in OBDCs by LTTD under different conditions was investigated. Probabilistic human health risk assessment was performed to quantify the health risk posed to waste management workers under the two scenarios, while the associated costs were also analyzed. The results show that LTTD at 300 °C for >20 min could remove 96.27% of PAHs in OBDCs but its removal effect on heavy metals was not significant. It was found that cancer risks posed by PAHs in both securely landfilled and LTTD-treated OBDCs were not significant (<1e-06); however, significant cancer risks (7.95e-05–9.45e-05) were identified for exposure to toxic heavy metals. Increased health risk was observed as a result of exposure to LTTD treatment residues compared to securely landfilled OBDCs. Inhalation of chromium(VI) and oral ingestion of arsenic in OBDCs were critical exposure routes. Both cancer and non-cancer risks in the secure landfill scenario were negligible. The cost analysis results suggest that LTTD combined with stabilization/solidification could be more economically attractive than secure landfill for the handling of OBDCs.

Resource utilization of secondary pyrolysis oil-based drilling cuttings ash for removing Cr (VI) contaminants: Adsorption properties, kinetics and mechanism

Secondary pyrolysis oil-based drilling cuttings ash (OBCDA-sp) was employed as a new absorbing material to remove Cr (VI) in wastewater. Varying factors, including pH value, dosage of OBCDA-sp, reaction time and original Cr (VI) contents were studied to investigate the Cr (VI) removal efficiency. Elovich and Pseudo-second-order models were fitted well with the adsorption kinetics process. In addition, the Langmuir model was well employed to fit Cr (VI) adsorption isotherm on OBCDA-sp. The calculated Cr (VI) theoretic adsorption quantity of OBCDA-sp was 48 mg/g. XPS, SEM-EDS, FTIR and XRD were used to characterize the physicochemical properties of OBDCA-sp. The result shows that the complex process of the Cr (VI) removal involves physical and chemical adsorption, and co-precipitation and reduction. Ba, Fe, S and P element onto OBCDA-sp surface have exerted significant role in Cr (VI) removal.