Simulation Research on Coal-Water Slurry Gasification of Oil-Based Drill Cuttings Based on Fluent

In this paper,based on Fluent software,a five-nozzle gasifier reactor was established to simulate the gasification process of oil-based drill cuttings coal-water slurry.The influence of concentration and oxygen/carbon atomic ratio on the gasification process of oil-based drill cuttings coal-water slurry was investigated.The results show that when the oxygen flow is constant,the outlet temperature of gasifier decreases,the content of effective gas increases,and the carbon conversion rate decreases with the increase of concentration;When the ratio of oxygen to carbon atoms is constant,the effective gas content rises and the temperature rises with the increase of the concentration,and the carbon conversion rate reaches the maximum value when the concentration of oil-based drill cuttings coal-water slurry is 65%;When the concentration is constant,the effective gas content decreases and the outlet temperature rises with the increase of the oxygen/carbon atom ratio,and the carbon conversion rate reaches 99.80%when the oxygen/carbon atom ratio is 1.03.It shows that this method can effectively decompose the organic matter in oilbased drill cuttings and realize the efficient and cooperative treatment of oil-based drill cuttings.

Gas-hydrate formation,agglomeration and inhibition in oil-based drilling fluids for deep-water drilling

One of the main challenges in deep-water drilling is gas-hydrate plugs,which make the drilling unsafe.Some oil-based drilling fluids（OBDF） that would be used for deep-water drilling in the South China Sea were tested to investigate the characteristics of gas-hydrate formation,agglomeration and inhibition by an experimental system under the temperature of 4 ？C and pressure of 20 MPa,which would be similar to the case of 2000 m water depth.The results validate the hydrate shell formation model and show that the water cut can greatly influence hydrate formation and agglomeration behaviors in the OBDF.The oleophobic effect enhanced by hydrate shell formation which weakens or destroys the interfacial films effect and the hydrophilic effect are the dominant agglomeration mechanism of hydrate particles.The formation of gas hydrates in OBDF is easier and quicker than in water-based drilling fluids in deep-water conditions of low temperature and high pressure because the former is a W/O dispersive emulsion which means much more gas-water interfaces and nucleation sites than the later.Higher ethylene glycol concentrations can inhibit the formation of gas hydrates and to some extent also act as an anti-agglomerant to inhibit hydrates agglomeration in the OBDF.

Rheological properties of oil-based drilling fluids at high temperature and high pressure

The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.

Synthesis of melamine-formaldehyde microcapsules containing oil-based fragrances via intermediate polyacrylate bridging layers

A general and versatile strategy to prepare melamine-formaldehyde(MF)microcapsules encapsulating oil-based fragrances by combining solvent evaporation and in situ polymerization was proposed in this work.The oil-based fragrance was pre-encapsulated by an inner polyacrylate membrane via solvent evaporation,followed by in situ polymerization of MF precondensates as an outer shell.The polyacrylate membrane is used as an intermediate bridging layer to stabilize the oil-based fragrance,and to provide driving forces for in situ polymerization of MF precondensates through electrostatic attractions between carboxyl groups and ammonium ions.It was demonstrated that MF microcapsules containing clove oil were prepared successfully.The amount and the composition of the intermediate polyacrylate bridging layer were critical.Smooth and sphere-shaped MF-clove oil microcapsules were prepared when the weight ratio of polyacrylate to clove oil was over 60 wt%and the concentration of acrylic acid(AA)increased to 10 wt%in polyacrylate.In addition,MF microcapsules containing sunflower oil and hexyl salicylate were prepared by using this method.The work suggests that this new approach can be potentially used to encapsulate various core materials,tuning the shell properties of microcapsules such as thickness,mechanical strength and release properties.

Squeeze-Strengthening Effect of Silicone Oil-based Magnetorheological Fluid

In order to study the squeeze-strengthening effect of silicone oil-based magnetorheological fluid （MRF）, theoretical basis of disc squeezing brake was presented and a squeezing braking characteristics test-bed for MRF was designed. Moreover, relevant experiments were carded out and the relationship between squeezing pressure and braking torque was proposed. Experiments results showed that the yield stress of MRF improved linearly with the increasing of external squeezing pressure and the braking torque increased three times when external squeezing pressure achieved 2 MPa.

Development of key additives for organoclay-free oil-based drilling mud and system performance evaluation

Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system was studied, the synthesis methods and functioning mechanism of key additives were introduced, and performance evaluation of the system was performed. The rheology modifier was prepared by reacting a dimer fatty acid with diethanolamine, the primary emulsifier was made by oxidation and addition reaction of fatty acids, the secondary emulsifier was made by amidation of a fatty acid, and finally the fluid loss additive of water-soluble acrylic resin was synthesized by introducing acrylic acid into styrene/butyl acrylate polymerization. The rheology modifier could enhance the attraction between droplets, particles in the emulsion via intermolecular hydrogen bonding and improve the shear stress by forming a three-dimensional network structure in the emulsion. Lab experimental results show that the organoclay-free OBM could tolerate temperatures up to 220 ?C and HTHP filtration is less than 5 m L. Compared with the traditional OBMs, the organoclay-free OBM has low plastic viscosity, high shear stress, high ratio of dynamic shear force to plastic viscosity and high permeability recovery, which are beneficial to penetration rate increase, hole cleaning and reservoir protection.

Comparison and application of different empirical correlations for estimating the hydrate safety margin of oil-based drilling fluids containing ethylene glycol

As the oil and gas industries continue to increase their activity in deep water, gas hydrate hazards will become more serious and challenging, both at present and in the future. Accurate predictions of the hydrate-free zone and the suitable addition of salts and/or alcohols in preparing drilling fluids are particularly important both in preventing hydrate problems and decreasing the cost of drilling operations. In this paper, we compared several empirical correlations commonly used to estimate the hydrate inhibition effect of aqueous organic and electrolyte solutions using experiments with ethylene glycol （EG） as a hydrate inhibitor. The results show that the Najibi et al. correlation （for single and mixed thermodynamic inhibitors） and the Ostergaard et al. empirical correlation （for single thermodynamic inhibitors） are suitable for estimating the hydrate safety margin of oil-based drilling fluids （OBDFs） in the presence of thermodynamic hydrate inhibitors. According to the two correlations, the OBDF, composed of 1.6 L vaporizing oil, 2% emulsifying agent, 1% organobentonite, 0.5% SP-1, 1% LP-1, 10% water and 40% EG, can be safely used at a water depth of up to 1900 m. However, for more accurate predictions for drilling fluids, the effects of the solid phase, especially bentonite, on hydrate inhibition need to be considered and included in the application of these two empirical correlations.

Calculation and application of partition coefficients of light hydrocarbons in oil-based mud system

To find out the relationship between the oil-based mud,the formation fluid and the extracted gas,we use a thermodynamic approach based on static headspace gas chromatography technique to calculate the partition coefficients of 47 kinds of light hydrocarbons compounds between nC5 and nC8 in two kinds of oil-based mud-air systems,and reconstruct the original formation fluid composition under thermodynamic equilibrium.The oil-based drilling mud has little effect on the formation fluid compositions in the range of nC5-nC8(less than 1%for low-toxicity oil-based mud and less than 10%for oil-based mud).For most light hydrocarbon compositions,the partition coefficients obtained by vapor phase calibration and the direct quantitative methods have errors of less than 10%,and the partition coefficients obtained by direct quantitative method are more accurate.The reconstructed compositions of the two kinds of crude oil have match degrees of 91%and 89%with their real compositions,proving the feasibility and accuracy of reconstructing the composition of original formation fluid by using partition coefficients of light hydrocarbon compositions between nC5 and nC8.

Development of a High Temperature and High Pressure Oil-Based Drilling Fluid Emulsion Stability Tester

When drilling deep wells and ultra-deep wells, the downhole high temperature and high pressure environment will affect the emulsion stability of oil-based drilling fluids. Moreover, neither the demulsification voltage method nor the centrifugal method currently used to evaluate the stability of oil-based drilling fluids can reflect the emulsification stability of drilling fluids under high temperature and high pressure on site. Therefore, a high-temperature and high-pressure oil-based drilling fluid emulsion stability evaluation instrument is studied, which is mainly composed of a high-temperature autoclave body, a test electrode, a temperature control system, a pressure control system, and a test system. The stability test results of the instrument show that the instrument can achieve stable testing and the test data has high reliability. This instrument is used to analyze the factors affecting the emulsion stability of oil-based drilling fluids. The experimental results show that under the same conditions, the higher the stirring speed, the better the emulsion stability of the drilling fluid;the longer the stirring time, the better the emulsion stability of the drilling fluid;the greater the oil-water ratio, the better the emulsion stability of the drilling fluid. And the test results of the emulsification stability of oil-based drilling fluids at high temperature and high pressure show that under the same pressure, as the temperature rises, the emulsion stability of oil-based drilling fluids is significantly reduced;at the same temperature, the With the increase in pressure, the emulsion stability of oil-based drilling fluids is in a downward trend, but the decline is not large. Relatively speaking, the influence of temperature on the emulsion stability of oil-based drilling fluids is greater than that of pressure.

Stable dispersibility of bentonite-type additive with gemini ionic liquid intercalation structure for oil-based drilling

In this study,the direct intercalation of gemini ionic liquids(ILs)with different alkyl chains into the bentonite(BT)interlayer as a high-performance lubricating additive for base oil 500SN was investigated.The purpose of modifying BT with an IL is to improve the dispersion stability and lubricity of BT in lubricating oil.The dispersibility and tribological properties of IL–BT as oil-based additives for 500SN depend on the increase in interlamellar space in BT and improve as the chain length is increased.More importantly,the IL–BT nanomaterial outperforms individual BT in improving wear resistance,owing to its sheet layers were deformed and sprawled in furrows along the metal surface,thereby resulting in low surface adhesion.Because of its excellent lubrication performance,IL-modified BT is a potential candidate for the main component of drilling fluid.It can be used as a lubricating additive in oil drilling and oil well construction to reduce equipment damage and ensure the normal operation of equipments.

Pyrolytic gas analysis and evaluation from thermal plasma pyrolysis of simulated oil-based drill cuttings

Oil-based drill cuttings(OBDCs)are hazardous wastes generated during shale gas exploration,and the rapid,efficient and safe disposal methods for OBDCs have attracted the attention of many researchers.Plasma pyrolysis technology is widely used in solid waste treatment due to its extremely high temperature and reaction activity.A laboratory-scale thermal plasma pyrolysis system was built to investigate the plasma pyrolysis mechanism of simulated OBDCs.The thermal decomposition characteristics of OBDCs were studied by thermogravimetric-derivative thermo gravimetric-differential scanning calorimetry(TG-DTG-DSC)analysis in the range of 50–1300℃.The thermal decomposition process of OBDCs was divided into the following four stages:evaporation of water and light oil,evaporation and decomposition of heavy oil,carbonate decomposition,and phase change reaction from solid to liquid.The effects of the oil ratio,water content,and water/oil(W/O)ratio of OBDCs on the composition and gas selectivity of pyrolytic gas were investigated.The results show that thermal plasma can crack the mineral oil in the OBDCs into clean gases such as H_(2),CO and C_(2)H_(2),while water can promote the decomposition of the heavy oil molecules and enhance the H_(2)production.The energy consumption model calculation for the pyrolysis and melting of OBDCs shows that the highest energy utilization and the lowest molar energy consumption of H_(2)were achieved at a W/O ratio of 1:4.Based on the thermal plasma pyrolysis system used in this study,the commercial application prospects and economic benefits of the plasma pyrolysis of OBDCs were discussed.

Fish oil-based lipid emulsion:current updates on a promising novel therapy for the management of parenteral nutrition-associated liver disease

Intestinal failure is characterized by loss of enteral function to absorb necessary nutrients and water to sustain life.Parenteral nutrition(PN)is a lifesaving therapeutic modality for patients with intestinal failure.Lifelong PN is also needed for patients who have short bowel syndrome due to extensive resection or a dysmotility disorder with malabsorption.However,prolonged PN is associated with short-term and long-term complications.Parenteral nutrition-associated liver disease(PNALD)is one of the long-termcomplications associated with the use of an intravenous lipid emulsion to prevent essential fatty acid deficiency in these patients.PNALD affects 30–60%of the adult population on long-term PN.Further,PNALD is one of the indications for isolated liver or combined liver and intestinal transplantation.There is no consensus on how to manage PNALD,but fish oil-based lipid emulsion(FOBLE)has been suggested to play an important role both in its prevention and reversal.There is significant improvement in liver function in those who received FOBLE as lipid supplement compared with those who received soy-based lipid emulsion.Studies have also demonstrated that FOBLE reverses hepatic steatosis and reduces markers of inflammation in patients on long-term PN.Future prospective studies with larger sample sizes are needed to further strengthen the positive role of FOBLE in PNALD.

A Gel-Based Solidification Technology for Large Fracture Plugging

Fault fractures usually have large openings and considerable extension. Accordingly, cross-linked gel materials aregenerally considered more suitable plugging agents than water-based gels because the latter often undergo contaminationvia formation water, which prevents them from being effective over long times. Hence, in this study, aset of oil-based composite gels based on waste grease and epoxy resin has been developed. These materials havebeen observed to possess high compressive strength and resistance to the aforementioned contamination, therebyleading to notable increase in plugging success rate. The compressive strength, thickening time, and resistance toformation water pollution of these gels have been evaluated indoors. The results show that the compressivestrength of the gel can reach 11 MPa;additionally, the related gelation time can be controlled to be more than3 h, thereby providing a safe construction time;Invasion of formation water has a small effect on the gel strengthand does not shorten the thickening time. All considered performance indicators of the oil-based gel confirm itssuitability as a plugging agent for fault fractures.

Combination of diketone and PAO to achieve macroscale oil-based superlubricity at relative high contact pressures

1-(4-ethylphenyl)-nonane-1,3-dione(0206)is an oil-soluble liquid molecule with rod-like structure.In this study,the chelate(0206-Fe)with octahedral structure was prepared by the reaction of ferric chloride and 1,3-diketone.The experimental results show that when using 0206 and a mixed solution containing 60%0206-Fe and 40%0206(0206-Fe(60%))as lubricants of the steel friction pairs,superlubricity can be achieved(0.007,0.006).But their wear scar diameters(WSD)were very large(532µm,370µm),which resulted in the pressure of only 44.3 and 61.8 MPa in the contact areas of the friction pairs.When 0206-Fe(60%)was mixed with PAO6,it was found that the friction coefficient(COF)decreased with increase of 0206-Fe(60%)in the solution.When the ratio of 0206-Fe(60%)to PAO6 was 8:2(PAO6(20%)),it exhibited better comprehensive tribological properties(232.3 MPa).Subsequent studies have shown that reducing the viscosity of the base oil in the mixed solution helped to reduce COF and increased WSD.Considering the COF,contact pressure,and running-in time,it was found that the mixed lubricant(Oil3(20%))prepared by the base oil with a viscosity of 19.7 mPa·s(Oil3)and 0206-Fe(60%)exhibited the best tribological properties(0.007,161.4 MPa,3,100 s).

Carbon dioxide/calcium oxide responsive behavior and application potential of amine emulsion

Green and low cost CO_(2) and CaO were used to stimulate amine emulsions to reveal the responsive behavior of amine emulsions.On this basis,oil-based drilling fluids responsive to CO_(2) and CaO were formulated and their properties were evaluated.The results showed that the amine emulsions inversed from water-in-oil state to oil-in-water state readily and their rheological behavior underwent transitions of decreasing,rising again and decreasing again via induction by CO_(2).These CO_(2) responsive behaviors could be reversed by CaO.Oil-based drilling fluids prepared based on the amine emulsions with oil-water volume ratios of 50:50 to 70:30,densities of 1.4-2.0 g/cm^(3) had good rheological and filtration properties at 160℃;and be readily cleaned up using CO_(2) bubbling.The useless solid phase with low density could be removed efficiently via reducing the viscosity of emulsion by CO_(2) and the residual liquid phase could be restored to the original state by CaO and reused to prepare drilling fluid.The mechanisms analysis indicated that CO_(2)/CaO induced the reversible conversion between amine emulsifiers and their salts,which enabled the reversible regulation of both the hydrophilic-lipophilic balance of amine emulsifiers and the emulsion particles’size and finally caused the controllable-reversion of the form and rheology of amine emulsion.

Research on High Temperature and High Density White Oil Based Drilling Fluid and Its Application in Well 201H7-6

As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory.Research shows that the drilling fluid system has good rheological property,low filtration loss,strong anti-debris pollution capability and good plugging performance at high temperature and high density.The system has been successfully applied in the 201H7-6 well.Application results show that the drilling fluid rheology,high temperature and high pressure fluid loss and demulsification voltage meet the field requirements.The drilling fluid performance is stable in drilling an 1800 m horizontal section,and no stuck or shale swelling and wellbore collapsing are induced.It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region.It also sets several new records including the deepest well,the shortest drilling cycle,and the fastest drilling speed in that region,which provides valuable experience for the future drilling activities.

Micro/nano structured oleophobic agent improving the wellbore stability of shale gas wells

Through embedding modified nano-silica particles on the surface of polystyrene using the method of Pickering emulsion polymerization,a kind of nano/micro oleophobic agent named OL-1 was developed.The effects of OL-1 on the rock surface properties and its performance in inhibiting the oil phase imbibition into the rock were explored.The performance and mechanisms of OL-1 in improving the wellbore stability of shale gas wells were evaluated and analyzed.OL-1 could absorb on the surface of the shale core to form a membrane with a micro-nano two-stage roughness,making the surface energy of the core decrease to 0.13 mN/m and the contact angle of the white oil on the core surface increase from 16.39°to 153.03°.Compared with the untreated capillary tube,when immersed into 3#white oil,the capillary tube treated by OL-1 had a reversal of capillary pressure from 273.76 Pa to-297.71 Pa,and the oil imbibition height inside the capillary tube decreased from 31 mm above the external liquid level to 33 mm below the external liquid level.The amount of oil invading into the rock core modified by OL-1 decreased by 64.29%compared with the untreated one.The shale core immersed into the oil-based drilling fluids with 1%OL-1 had a porosity reduction rate of only 4.5%.Compared with the core immersed in the drilling fluids without OL-1,the inherent force of the core treated by 1%OL-1 increased by 24.9%,demonstrating that OL-1 could effectively improve the rock mechanical stability by inhibiting oil phase imbibition.

Oil Saturation Is Determined by Different Experimental Methods

Oil saturation was an important parameter of reservoir evaluation, which had important guiding significance for oilfield development. In this paper, the oil saturation of tight oil in G area was studied, and the original oil saturation of the study area was studied by using the comprehensive experimental method. The original oil saturation of tight oil in the study area was determined by J function method, rock electricity method and oil-based mud coring method. The results showed that through the comparison of three experimental methods, it could be concluded that the J function method leads to the low value of oil saturation in the study area. The oil-based mud coring method was more suitable for the determination of oil saturation in this area than the other two methods because it needs to meet too many conditions and the calculation results were also low. G area was located in Qili Village, Ordos Basin.

Applications of sum-frequency generation vibrational spectroscopy in friction interface

Sum-frequency generation(SFG)vibrational spectroscopy is a second-order nonlinear optical spectroscopy technique.Owing to its interfacial selectivity,SFG vibrational spectroscopy can provide interfacial molecular information,such as molecular orientations and order,which can be obtained directly,or molecular density,which can be acquired indirectly.Interfacial molecular behaviors are considered the basic factors for determining the tribological properties of surfaces.Therefore,owing to its ability to detect the molecular behavior in buried interfaces in situ and in real time,SFG vibrational spectroscopy has become one of the most appealing technologies for characterizing mechanisms at friction interfaces.This paper briefly introduces the development of SFG vibrational spectroscopy and the essential theoretical background,focusing on its application in friction and lubrication interfaces,including film-based,complex oil-based,and water-based lubricating systems.Real-time detection using SFG promotes the nondestructive investigation of molecular structures of friction interfaces in situ with submonolayer interface sensitivity,enabling the investigation of friction mechanisms.This review provides guidance on using SFG to conduct friction analysis,thereby widening the applicability of SFG vibrational spectroscopy.