Oil-based Drill Cuttings Research Articles

Utilization Status of Oil-Based Drilling Cutting Pyrolysis Residues in The Field of Building Materials

The exploitation of shale gas generates a large amount of oil-based drill cuttings, which are harmful to the environment due to their content of petroleum hydrocarbons, heavy metals, and organic pollutants. Thermal desorption technology is one of the main techniques for treating oil-based drill cuttings. This paper focuses on oil-based drilling cutting pyrolysis residues and summarizes its current research status in the construction materials field. Currently, the application of oil-based drilling cutting pyrolysis residues has achieved certain results in road fill, cement production, ceramsite production, and wall materials, and further exploration and development are needed in the future to develop high value-added products and expand the pathways for the high-value utilization of oil residues.

Optimization screening, performance and mechanism analysis of green and low-carbon surfactants for oil-based drilling cuttings treatment

Oil-Based Drilling Cuttings (OBDC) have attracted extensive attention from scholars due to their high annual generation and high toxicity. At present, the thermal cleaning technology of surfactant is one of the research hotspots for treating OBDC, but it still faces the problems of high toxicity of surfactant, high carbon emission and unknown treatment mechanism. Therefore, we sequentially optimized screening the surfactants through the perspectives of greenness, treatment performance and costs, and low-carbon. A single-variable experiment was used to optimize the process parameters for treating OBDC, and the oil removal mechanism was explored by oil droplet size, TSI, Zeta potential and SARA fractions. The SLM was the most green and low carbon surfactant in this study, and had a better treatment performance for OBDC (51.56% oil removal rate). The optimal treatment parameters for SLM treatment of OBDC were 70 °C, 45 min, 300 r/min, 1:4 (solid/liquid) and pH 8.2. The lipophilic groups of SLM "striped" the asphaltenes and saturates in oil phase from the solid phase surface and "integrated" them into the water phase by its hydrophilic group. The mean value of the oil droplet sizes (Dmean) and Turbiscan stability index (TSI) value of the OBDC-water mixtures increased and the |Zeta potential| decreased after treatment, and the mixture system became more unstable, which promotes the subsequent separation of the oil phase from the solid phase.

Valorization of oil‐based drilling cuttings as a substitute for bauxite in fracturing proppants application

AbstractThis study aimed to increase the scale of oil‐based drilling cuttings (OBDCs) resource utilization in the ceramic industry. The sintering process and mechanism were explored based on the analysis of physicochemical properties, phase transitions, and microstructure. The results showed that (1) The main ceramic‐technological characteristics of the OBDC were determined, which belonged to high‐silica solid waste with a high Si–Al ratio and a low acid–base ratio of oxides. (2) The low meltability temperature of the OBDC could largely influence the determination of the sintering temperature range for ceramic products. (3) The chemical components OBDC provided were involved in the formation of molten phases, which could affect dimensional accuracy and mechanical properties. Meanwhile, the dolomite promoted the formation of closed pores and enhanced lightweight performance. (4) Before 800°C, dolomite decomposed and reacted with SiO2 to form silicate, and then a new feldspar crystal appeared. After 1000°C, orthoclase completely melted into the molten phase, only two phases of quartz and diopside existed in the material until 1150°C. When the temperature was higher than 1350°C, the glass transition of the phase was basically intensified. (5) In the analyzed scenarios, the results indicated OBDC can only be doped in low contents and degrades the ceramic material properties.

Comparison of Phosphogypsum-Steel Slag-Based cement and Portland cement for stabilization of heavy metals in oil-based drillings cuttings

This research compared Portland cement and Phosphogypsum-Steel Slag-Based (PSSB) cement in terms of their capabilities to stabilize heavy metals (specifically lead and nickel) in Oil-Based Drill Cuttings (OBDC). In the experimental section, the qualitative analysis of heavy metal constituents in OBDC was captured by X-ray Photoelectron Spectroscopy (XPS). Additionally, an acetic acid leaching test was implemented for the heavy metal leaching concentration to evaluate the ceramsite stabilization effect on OBDC. In the simulation phase, cement models, heavy metal ion models, and stabilization models were constructed to explore the stabilization mechanism of heavy metals. Results demonstrated that PSSB cement exhibits superior stabilization effects on OBDC compared to Portland cement. Flame Atomic Absorption Spectrophotometry (FAAS) tests showed that PSSB cement reduced Ni and Pb leaching by 21.87 % and 47.32 %, respectively, compared to Portland cement. In PSSB cement, the diffusion coefficients for Ni and Pb ions were observed to decrease by 42.92 % and 79.63 %, respectively, as revealed through Mean Square Displacement (MSD) analysis. The cohesive energy of PSSB cement was 76.73 % lower than that of Portland cement, and its interaction energies for stabilizing Ni and Pb ions were 59.43 % and 76.22 % lower, respectively, demonstrating greater stability and efficiency in metal stabilization. PSSB cement exhibited lower heavy metal concentration and better structural stability than Portland cement.

A comparative life cycle assessment (LCA), life cycle cost analysis (LCCA), mechanical and long-term leaching evaluation of road pavement structures containing multiple secondary materials

Oil-Based Drill Cuttings (OBDC) are one of the hazardous wastes of the oil and gas industry. In this study, Reclaimed Asphalt Pavement (RAP), OBDC and Fly Ash (FA) geopolymer were used in Cold Central Plant Recycling (CCPR) mixtures. The dynamic modulus test was used to appraise the viscoelastic properties of CCPR mixtures. The Toxicity Characteristic Leaching Procedure (TCLP) test was also utilized to investigate the long-term contaminants leaching. In addition, a cradle-to-grave Life Cycle Assessment (LCA) and Life Cycle Cost Analysis (LCCA) were conducted to evaluate the potential environmental burdens and economic costs of pavement structures containing CCPR mixtures. Moreover, Multi-Criteria Decision-Making (MCDM) analysis using four different methods was performed to determine the optimal sample. The results revealed that the recycling of OBDC and RAP in stabilized CCPR mixtures with FA geopolymer can improve the viscoelastic properties and prevent the leaching of contaminants from these waste materials. Furthermore, recycling of the mentioned waste materials in CCPR mixtures has caused a significant reduction in global warming, acidification, eutrophication, smog, respiratory effects, Human toxicity, ecotoxicity, and cumulative energy demand up to 41%, 36.6%, 73%, 43%, 47%, 34%, 73%, and 13%, respectively. Additionally, using CCPR mixtures containing the OBCD, RAP, and FA geopolymer in the pavement structure has led to economic benefits of up to 31% compared to the conventional pavement system.

Investigating the potential of mineral precipitation in co-pyrolysis biochar: Development of a novel Cd (II) adsorption material utilizing dual solid waste

Ionic cadmium (Cd (II)) in water is a significant threat to ecosystems, the environment, and human health. Research is currently focused on developing efficient adsorption materials to combat Cd (II) pollution in water. One promising solution involves co-pyrolyzing solid residue from anaerobic digestion of food waste with oil-based drill cuttings pyrolysis residue to create a biochar with high organic matter content. This biochar has a lower heavy metal content and leaching toxicity compared to China's national standards, making it both safe and resourceful. It exhibits a high adsorption capacity for Cd (II) in water, reaching up to 47.80 ± 0.37 mg/g. Raising the pyrolysis temperature above 600 °C and increasing the amount of pyrolysis residue beyond 30 % enhances the biochar's adsorption capacity. The adsorption process is primarily driven by mineral precipitation, offering a promising approach for dual waste resource management and reducing heavy metal pollution.

A TGA-FTIR study on the pyrolysis of oil-based drilling cuttings and the influence of its solids on pyrolysis characteristics

During the drilling process in oil and gas fields, rock cuttings and other solid impurities are returned to the wellhead along with oil-based drilling fluids, forming oil-based drill cuttings. Organic pollutants in oil-based drill cuttings can be removed through pyrolysis. Although there has been some research on the pyrolysis of oil-based drilling cuttings, there is little analysis of the impact of rock-solid impurities in oil-based drill cuttings on the pyrolysis of organic components. Therefore, in this study, thermogravimetry coupled with infrared spectroscopy was used to analyze the pyrolysis characteristics of oil-based drill cuttings, exploring the major volatile components at different pyrolysis temperatures. Meanwhile, the oil and solids in oil-based drilling cuttings were separated by Soxhlet extraction, and the influence of solids on pyrolysis characteristics was studied. The results showed that the average pyrolysis activation energy and pre-exponential factor of the main pyrolysis stage of oil-based drill cuttings obtained by the FWO method were 50.6 KJ/mol and 3.951×104 s−1, respectively, while those of the separated residual oil were 84.7 KJ/mol and 2.905×109 s−1, respectively. This indicates that solids in oil-based drilling cuttings is increasing the mass loss rate during pyrolysis. The difference in pyrolysis kinetics between oil-based drilling cuttings and residual oil indicates that the solid in oil-based rock cuttings provides a surface for the reaction, which provides a reaction site for the decomposition of hydrocarbons to produce lighter volatile hydrocarbons. Additionally, the results of infrared spectroscopy indicated that the volatile products of the pyrolysis of oil-based drilling cuttings include CH4, CO, CO2, H2O, aldehydes, organic acids, etc. CH4 is the main product of the first weight loss stage, mainly released between 150°C and 200°C. With the increase in temperature, the concentrations of H2O, CO2, aldehydes, and organic acids gradually increased. At 600°C, the maximum concentration of CO2 release occurred, and the release of CO2 was the main reason for the third-stage weight loss in the pyrolysis of oil-based drilling cuttings

Engineering design and application of large-scale oil-based drilling cuttings treatment project.

Thermal phase separation technology is a new comprehensive treatment technology, which heats oil-based cuttings to a certain temperature to vaporize oil and water components. Based on a large oil-based drilling cuttings comprehensive utilization project, the engineering design and application effect of thermal phase separation technology were analysed. The practice shows that thermal phase separation technology can reduce the oil content of purified residue to 0.1-0.2%, the average recovery rate of base oil is 94.12% and the annual recovery of base oil is about 4800 t; the purified residue does not have corrosive, leaching toxicity and other dangerous characteristics, and can be used for making bricks or building materials. Thermal phase separation technology is a comprehensive utilization and treatment technology with excellent engineering and environmental benefits, which has a high promotion value.

The Damage Characteristics of Oil-Based Drilling Cuttings Coke Based on Ultrasonic Vibration

The Damage Characteristics of Oil-Based Drilling Cuttings Coke Based on Ultrasonic Vibration

Cleaning Oil-Based Drilling Cuttings with Synthetic Gemini Surfactants.

The chemical cleaning method is the simplest approach for degreasing oil-based drilling cuttings (ODCs), with the effectiveness of the treatment relying mainly on the selection of the surfactant and the cleaning conditions. However, achieving the standard treatment of ODCs directly using conventional surfactants proves challenging. In light of this, this study introduces a synthesized and purified Gemini surfactant named DCY-1. The structure of DCY-1 was confirmed through Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analyses. The characterization in this article encompasses the use of an interface tension meter, nanoparticle size analysis, scanning electron microscopy, and infrared oil measurement. The critical micelle concentration (CMC) of DCY-1 was determined to be 3.37 × 10-3 mol/L, with a corresponding γcmc value of 37.97 mN/m. In comparison to conventional surfactants, DCY-1 exhibited a larger micelle size of 4.52 nm, approximately 24.52% larger than that of SDS. Moreover, the residual oil rate of 3.96% achieved by DCY-1 was the lowest among the chemical cleaning experimental results. Through a single-factor experiment, the optimal cleaning ability of DCY-1 for ODCs was determined as follows: a surfactant concentration of 3 mmol/L, a temperature of 60 °C, an ODC/liquid mass ratio of 1:4, a cleaning duration of 40 min, and a stirring speed of 1000 rad/min. Under these optimal conditions and after merely two cleaning procedures, the residual oil content of ODCs was reduced to 1.64%, accompanied by a smooth and loose surface structure.

Human health risk assessment of volatile organic compounds in oil-based drill cuttings of shale gas.

Waste oil-based drill cuttings contain dioxins and volatile organic compounds (VOCs), which have the potential to cause serious health effects in humans. Therefore, this paper took oil-based drill cuttings (OBDCs) as the research object and carried out the testing of VOCs and dioxins content by using GC-MS and HRGCS-HRMS and comprehensively evaluated the content, composition and distribution pattern of VOCs and dioxins and the risk to human health posed by the two pollutants in OBDCs. The results showed that the VOCs did not exceed the emission limits in ESPPI (GB 31571-2015), but it is vital to recognise that 1,2-dichloropropane has the potential to cause cancer risk, with soil and groundwater risk control values of 662.95mg·kg-1 and 0.066mg·kg-1, respectively. Benzene, 1,2-dichloropropane and 8 other VOCs pose a non-carcinogenic risk to humans. The levels of polychlorinated dibenzofurans (PCDFs) exceeded those of polychlorinated dibenzo-p-dioxins (PCDDs), which accounted for 95.76 percent of the total PCDD/Fs, 2,3,4,7,8-P5CDF (56.00%), 2,3,7,8-T4CDF (9.20%), 1,2,3,6,7,8-H6CDF (8.80%) and 1,2,3,7,8-P5CDF (8.00%) were the main contributing monomers. The findings of the assessment on exposure risk indicate that there is a respiratory risk to oil-based drill cuttings dioxins for adults and children exceeded the World Health Organisation (WHO) acceptable daily intake (ADI) (1-4 pgTEQ/kg/d). Finally, three aspects of solid waste pre-treatment prior to incineration, the incineration process and post incineration were used to reduce the environmental and human health risks from dioxins.

Construction of Shale Gas Oil-Based Drilling Cuttings Degrading Bacterial Consortium and Their Degradation Characteristics.

Oil-based drilling cuttings (OBDCs) contain petroleum hydrocarbons with complex compositions and high concentrations, which have highly carcinogenic, teratogenic, and mutagenic properties. In this study, three highly efficient petroleum hydrocarbon-degrading bacteria were screened from OBDCs of different shale gas wells in Chongqing, China, and identified as Rhodococcus sp. and Dietzia sp. Because of their ability to degrade hydrocarbons of various chain lengths, a new method was proposed for degrading petroleum hydrocarbons in shale gas OBDCs by combining different bacterial species. Results showed that the bacterial consortium, consisting of the three strains, exhibited the highest degradation rate for petroleum hydrocarbons, capable of degrading 74.38% of long-chain alkanes and 93.57% of short-chain alkanes, respectively. Moreover, the petroleum hydrocarbon degradation performance of the bacterial consortium in actual OBDCs could reach 90.60% in the optimal conditions, and the degradation kinetic process followed a first-order kinetic model. This study provides a certain technical reserve for the bioremediation of shale gas OBDCs.

Switchable hydrophilicity solvents incorporating hydrophilic deep eutectic solvents: A sustainable alternative for oil-based drilling cuttings washing

Oil-based drilling cuttings (OBDC) contaminated by total petroleum hydrocarbons (TPH) causes detrimental environmental consequences. Solvents washing is capable of separating TPH from OBDC efficiently, but their high volatility and toxicity limit the large-scale application. Here a sustainable OBDC washing strategy is developed by using a heterogeneous mixture (SHSs&HDESs) which is consisted of switchable hydrophilicity solvents (SHSs) and hydrophilic deep eutectic solvents (HDESs). N, N-Dimethylcyclohexylamine (DMCHA) and CHEG (choline chloride/ethylene glycol) is respectively selected as the optimum SHSs and HDESs, considering the miscibility with TPH and recovery capacity. The advantage of the sustainable washing strategy originates from the synergistic effect for enhancing forward the TPH removal efficiency, where DMCHA plays the role on TPH extraction and dilution, and CHEG promotes the detachment of TPH from sands surfaces. Based on the Box-Behnken experimental design of response surface method, the TPH removal efficiency reaches a maximum value of 96.02 % at the derived optimal washing conditions, including 32 °C, 19.81 mL DMCHA, and 9.62 mL CHEG. TPH can be separated from DMCHA by CO2-induced hydrophobicity transformation, DMCHA is recovered upon N2/65 °C afterwards, and CHEG is recovered by liquid separation. The recovered SHSs&HDESs heterogeneous mixture shows good reusability in subsequent OBDC washing processes. Our findings offer a sustainable approach for efficiently OBDC washing, which is expected to overcome the inherent defects of solvents washing methods.

Preparation and characterization of high-performance ceramic proppant from recycling utilization of oil-based drilling cuttings pyrolysis residues

Oil-based drilling cutting pyrolysis residues (ODCPRs), bauxite, and sintering additives were applied to manufacture ceramic proppants with low density and high strength in this work. The effect of ODCPRs ratio, sintering temperature, holding time, and the content of additives on the performance of the proppants was comprehensively investigated, respectively. And the sintering mechanism of proppants was also discussed according to the phase, microstructure, and thermal behavior analyses. The results revealed that at the best sintering condition (1280 °C, holding for 60 min), and a mass ratio (ODCPRs: bauxite: MnO2 at 3:7:0.1), the well-developed granular corundum and acicular mullite formed inside the proppants and interspersed with each other to form a dense structure. The proppants presented low density and high strength as the bulk density of 1.48 g/cm3, the apparent density of 2.94 g/cm3, a breakage ratio of 5.25% under 52 MPa closed pressure, and the acid solubility of 4.80%, which could well meet the requirement of the standards of SY/T 5108-2014. This work provided a new pathway for recycling ODCPRs and the fabrication of high-performance proppants.

Rotary thermal desorption technology for treatment of oil-based drilling cuttings in shale gas industry

Oil-based drilling cuttings are hazardous wastes in shale gas exploitation and need careful treatments to reduce environmental pollution and waste of resources. One of most widely employed waste-treatment technologies is the thermal desorption due to its high oil recovery efficiency. However, it usually suffers low heat exchange efficiency, thus leveraging operation costs and equipment instability. Toward the end of alleviating limitation, this study rationally designs the structure of the heating component under the guidance of the flat wall heat conduction theory, and uses numerical simulation to analyze the heat transfer of the structure. A rotary thermal desorption technology was thus developed and evaluated. The simulation results showed that given a short time of 800 s the temperature difference between device and cuttings became less than 5 K, indicating good heat exchange efficiency. Large inlet radius of device and high inlet velocity of heat transfer oil were critical parameters to maintain high heat transfer rate. Through industrial experiments verification, the 0.14–0.2 % oil content of treated cuttings qualified the environmental standards. The components of the recovered oil were recyclable C9-C23 alkanes, and the dichromate oxidizability of recovered water was less than 500 mg/L limit. Comparing with other technologies, the scores suggested that this technology was a promising candidate for treating oil-based drilling cuttings.

Treatment of oil-based drilling cuttings by floatation-advanced oxidation two-step process.

In this paper, a floatation-advanced oxidation two-step process was proposed for deep oil removal of oil-based drilling cuttings (OBDC). In the first stage, a novel and simple degreasing solution was prepared and most of the base oil contained by OBDC was removed by flotation; in the second stage, the oil content of OBDC was further reduced by combined ultrasound + ozone (US + O3) advanced oxidation. The recommended degreasing solution was a mixture of methanol, ammonium chloride, and water with a mass ratio of 1.48.1 : 0.25. The best flotation process was as follows: a mass ratio of OBDC to degreasing solution of 1 : 10, stirring speed of 400 rpm and N2 flotation with a flow rate of 400 mL min-1 for 60 min. The oil content of OBDC can be reduced from 14.57% to 1.42% after flotation treatment and the degreasing solution can be reused more than five times. The optimal process of US + O3 advanced oxidation was as follows: a mass ratio of OBDC to water of 1 : 10, ultrasonic power of 1000 W, and an ozone flow rate of 4.0 L min-1 for 100 min. The oil content of OBDC can be reduced from 1.42% to 0.14% after US + O3 treatment at room temperature. The results of this paper provide a new method and idea for OBDC treatment.

Insights on dielectric barrier discharge plasma treatment of oil drilling cuttings

Oil drilling cuttings produced during oil exploration and extraction contain a high percentage of crude oil, ranging from 5% to 20% weight ratio (w/w) on a dry basis, and must be managed and treated properly before their release to the environment. In this study, non-thermal plasma (NTP) was investigated as an advanced oxidation process for the efficient, sustainable and cost-effective treatment of oil drilling cuttings. To this end, a plane-to-grid dielectric barrier discharge (DBD) reactor operating at atmospheric pressure was tested under different plasma conditions. The effect of treatment time, DBD power and air flow rate on the total organic carbon (TOC) removal efficiency was assessed and the energy efficiency of the process was determined. Within 10 min of plasma treatment, a very high TOC and total petroleum hydrocarbons (TPH) removal (∼90% and ∼99%, respectively) was achieved, while polycyclic aromatic hydrocarbons (PAHs) were degraded by ∼50% within 2 min of treatment. Depending on the experimental conditions, the energy efficiency of the process varied from 5 to 35 mg/kJ. From GC-MS analysis, several byproducts of the oxidation of oil drilling cuttings were identified, while the analysis of exhaust gases revealed that ∼85.1% of the removed organics from oil drilling cuttings was transformed to CO2 and CO. This study provides critical information on the effectiveness of the NTP process for the treatment of heavily contaminated solid wastes and can be considered as the critical step for its application for the treatment of solid wastes from the oil industry.

Evaluation of glutenite reservoir using nuclear magnetic resonance T2 spectrum of oil-based drilling cuttings

Cores and cuttings are the only materials that directly show characteristics of glutenite reservoirs, and most wells have few or no cores. This raises the question of whether cuttings can be used to evaluate glutenite reservoir. In this study, six key issues related to the application of cuttings in evaluating reservoir firstly were analyzed. Then glutenite reservoir of Baikouquan Formation in Jungar Basin was taken as the research object, and experiments of cuttings and cores were carried out. Repeated experiments confirmed the stability of cuttings performance. T2 spectrum of glutenite cuttings after treatment exhibits a single peak with a relatively short T2 time, which indicates pore structure and sorting of rock change due to mechanical effects and gravity. By comparing T2 spectra of cores and artificially crushed debris, it can be found that sandstone cuttings are less affected by mechanical effects, while for glutenite, macropores decrease a lot, mesopores increase, and micropores have few changes. Afterwards, a method of cuttings depth correction is proposed based on comparing the morphology of the spectra corresponding to micropores in T2 spectra of cuttings and nuclear magnetic resonance (NMR) logging. Finally, irreducible water saturation and porosity are calculated and corrected using T2 spectrum of cuttings, and results are in agreement with those obtained from logging data, which confirm the feasibility of evaluation method using cuttings.

Conversion Mechanism of Organic Matter While Cleaning Oil‐Based Drilling Cuttings Using Surfactant‐Free Microemulsions

AbstractSurfactant‐free microemulsions (SFMEs) cleaning technology can effectively separate and recover petroleum pollutants from oil‐based drilling cuttings (OBDCs). The identification of the molecular composition of OBDCs is helpful to accurately grasp the conversion mechanism of organic matter. Therefore, the understanding of the mechanism of petroleum removal at the microscopic molecular level in the cleaning process needs to be further studied. The conversion mechanism of organic matter during the use of SFMEs to clean OBDCs was investigated by positive ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (+APPI FT‐ICR MS). The results show that the SFMEs cleaning technology can separate and recover CH and CHO organic matter in OBDCs, but there is still a small amount of organic matter with high molecular weight and unsaturated degree in OBDCs that has not been separated. The majority of this organic matter is CH, accounting for 91 %, and it is mainly polycyclic aromatic hydrocarbons. A total of 255 kinds of organic matter in 110# industrial white oil were detected in the recovered oil after treatment, accounting for more than 99 % of the total, which has a certain recoverable value. This study can provide a theoretical reference for the efficient degradation of OBDCs.

Ultrasonication-flotation-advanced oxidation tertiary treatment of oil-based drilling cuttings

The treatment of oil-based drilling cuttings (OBDCs) with high oil content is difficult. In this study, a tertiary treatment of ultrasonication–flotation–advanced oxidation for treating OBDCs with a high oil content of 20.10 wt% was proposed for the first time. All stages of the treatment processes were optimised. The recommended parameters for ultrasonication at room temperature were a mass ratio of OBDCs to the degreaser of 1:8, an ultrasonication power of 600 W and treatment time of 30 min. After the ultrasonication treatment, the oil content of the OBDCs decreased from 20.10 wt% to 5.00 wt%. Flotation was performed at room temperature with a mass ratio of OBDCs to the degreaser of 1:10, a stirring speed of 400 rpm, an aeration head aperture of 3 μm and airflow rate of 400 mL/min under N2 injection for 60 min. After the flotation treatment, the oil content of the OBDCs decreased from 5.00 wt% to 2.01 wt%. Advanced oxidation was performed at room temperature with a mass ratio of OBDCs to water of 1:10, 3.57 wt% sodium persulphate in water, 4.17 wt% ferrous sulphate heptahydrate in water and ultrasonication power of 1000 W for 100 min. Following the advanced oxidation treatment, the oil content of the OBDCs decreased from 2.01 wt% to 0.58 wt%. The results of this study provide a new method and idea for treating OBDCs with high oil content.