Characterization and Surfactant-Enhanced Washing Treatability of Drilling Fluids Stored for More than 20 Years

Drilling fluids represent a significant environmental hazard owing to the fact that they are frequently stored in open vessels without any treatment. The drilling fluids studied in this work have been stored for 20–30 years in open cesspits in the state of Tabasco (Mexico). The aim of this work was to characterize the drilling fluids produced in this region and to determine their treatability by means of surfactant-enhanced washing. Two anionic and two non-ionic surfactants (sodium lauryl ethersulfate SLES and sodium dodecylsulfate SDS, ethoxylated nonylphenol ENP and an unknown composition ethoxylated nonionic Surfynol 440 respectively) were employed for surfactant-enhanced washing assessments in the presence of a commercial dispersant. Drilling fluids were contaminated with 135,400 mg of total petroleum hydrocarbons (TPH)/kg soil, including seven polycyclic aromatic hydrocarbons (PAHs) from 1.18 to 57.28 mg/kg. TPH removal efficiencies as high as 55.7% were reached when washing drilling fluids with SDS (4%), followed by ENP 906 (1%), which showed a TPH removal of 52.2%, and ENP itself at a lower dose (0.1%). SLES and S440 gave removal of around 10–15% with the assessed doses.

Cellular automaton fluids — A review

This paper is basically a review of cellular automaton fluids, which are the class of cellular automata used for describing fluids. Cellular automaton fluids are discrete analogues of molecular dynamics in which the particles have discrete velocities and move on the sites of a lattice according to some rule of evolution. We restrict ourselves mainly to two-dimensional fluids, but make some comments regarding models for fluids in three dimensions. Analytical as well as numerical simulation results, including ours on the wake behind a cylinder, are discussed for the two-dimensional cellular automaton (ca) models. We also discuss briefly some issues which need resolution before theca models can be used for practical simulations.     

Prediction of transport properties of dense gases and liquids by the Peng-Robinson (PR) equation of state

An attempt is made in this work to combine the Enskog theory of transport properties with the simple cubic Peng-Robinson (PR) equation of state. The PR equation of state provides the density dependence of the equilibrium radial distribution function. A slight empirical modification of the Enskog equation is proposed to improve the accuracy of correlation of thermal conductivity and viscosity coefficient for dense gases and liquids. Extensive comparisons with experimental data of pure fluids are made for a wide range of fluid states with temperatures from 90 to 500 K and pressures from 1 to 740 atm. The total average absolute deviations are 2.67% and 2.02% for viscosity and thermal conductivity predictions, respectively. The proposed procedure for predicting viscosity and thermal conductivity is simple and straightforward. It requires only critical parameters and acentric factors for the fluids.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

LDA Velocity Measurements of High‐Viscosity Fluids in Mixing Vessel with Vane Geometry Impeller

The object of this work was to measure the velocity field in non‐Newtonian fluids inside mixing vessel. The six‐bladed vane rotor used for mixing was designed from rotating vane geometry of a sensor system, commonly used for rheometrical measurements of complex fluids (Barnes and Nguyen, J. Non‐Newtonian Fluid Mech. 98 , 1‐14 (2001); Schramm, 1994). During mixing, the viscosity was determined by measuring the torque at different impeller speeds, and compared to rheologically obtained shear dependent viscosity. The velocity field was determined by LDA measurements at twelve places inside mixing vessel. It was observed that axial and radial component of the velocity were insignificant at all measurement points. On the other hand, the results showed the periodic nature of tangential component of the velocity, which was confirmed with computer‐aided visualization method.     

聚硅氧烷侧链高分子液晶电流变液体的性能研究

研究聚硅氧烷侧链高分子液晶配制成电流变液体的电流变效应 ,以获得高性能的电流变液体 ,应用德国RV2 0电流变仪测试性能。结果表明 ,该电流变液体 5 2℃ ,电场强度由零增至DC 2 0 0 0V/mm ,剪切速率为 30 0s-1时 ,剪切应力由 2 0 0Pa增至 5 4 0 0Pa ,表观黏度由 2 0 0mPa·s增至 10 0 0 0mPa·s;剪切速率为 4 0 0s-1时 ,剪切应力由 2 0 0Pa增至 6 30 0Pa,表观黏度由 2 0 0 0mPa·s增至 76 0 0mPa·s ;剪切速率为 5 0 0s-1时 ,剪切应力由 2 75Pa增至 6 80 0Pa,表观黏度由5 0 0mPa·s增至 90 0 0mPa·s。 77℃时 ,同样条件下 ,剪切速率为 5 0 0s-1时 ,剪切应力达 80 0 0Pa,具有更高的剪切应力 ,说明温度适应性较强。     

Impact of hexafluoroisopropylidene on the solubility of aromatic‐based polymers in supercritical fluids

Three different supercritical fluids (SCF), CO₂, dimethyl ether (DME), and propane, are investigated as potential solvents for processing two lactide‐based terpolymers and two perfluorocyclobutyl (PFCB) aryl ether polymers. The repeat unit of the lactide‐based terpolymers consists of a 1:1:1 ratio of L ‐lactide, diglycidyl ether of bisphenol A (DGEBA), and, in one case, 4,4′‐hexafluoroisopropylidenediphenol (6F‐Bis‐A) and, in the other case, 4,4′‐isopropylidenediphenol (6H‐Bis‐A). The PFCB‐based polymers are synthesized from 1,1‐bis[4‐[(trifluorovinyl)oxy]phenyl]hexafluoroisopropylidene (6FVE) and from bis(trifluorovinyloxy)biphenyl (BPVE). For both classes of polymer the steric effect of the hexafluoroisopropylidene (6F) group reduces chain–chain interactions, disrupts electronic resonance between adjacent aromatic groups, and improves solubility. The two lactide‐based terpolymers do not dissolve in CO₂ or propane, but dissolve in DME. At room temperature the poly(lactide 6F‐BisA DGEBA) terpolymer dissolves at 700 bar lower pressure in DME compared to the poly(lactide 6H‐Bis‐A DGEBA) terpolymer. Although the 6FVE polymer dissolves in all three SCF solvents, pressures in excess of 800 bar are needed to dissolve this polymer in CO₂ and propane while 6FVE dissolves in DME at pressure below 150 bar. The other PFCB‐based polymer (BPVE) only dissolves in DME, again at low pressure, although BPVE drops out of solution as the system temperature is raised above ～40°C, whereas 6FVE remains in solution in DME for temperatures up to 90°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1736–1743, 2005     

超临界流体萃取的溶媒和挟带剂

本文介绍了超临界萃取的原理，溶媒及挟带剂。     

CALCULATION OF THE VAPORIZATION ENTHALPY OF NONPOLAR FLUIDS AT THE STANDARD TEMPERATURE

Different analytical models were used to calculate the enthalpy of vaporization of nonpolar fluids at the standard temperature of 298.15 K. The models considered were some general classical expressions, three group contribution models that allow the property to be calculated at any temperature, another group contribution model specifically designed for calculations at the standard temperature, and finally a molecular model proposed by our research group. The results for 42 nonpolar fluids are compared with the value obtained in the correlation proposed in the DIPPR project.     

Shear and skin friction on particles in power-law fluids agitated by flat-blade and fluid foil impellers

The shear rates that exert angular deformation on spherical particles have been measured. The particles are mimiced by a spherical probe. The probe has been immersed in various impeller-agitated power law fluids. The fluids are aqueous dispersions of polymers, e.g. CMC, xanthan gum and starch. The probe has been positioned in various points of a stirred vessel and at various angles. Angle-averaged shear rate distributions were produced. The distributions obtained are characteristic for the specific impeller flow patterns. The flow patterns have been identified by computational fluid dynamics (CFD). Two types of impellers representative for the flat and the fluid-foil blade design, i.e., a Rushton flat-blade turbine (RT) and a Narcissus impeller (NS) are studied. The effects of rheological properties and blade design on the ‘shear-rate-on-particles’ distribution are examined. The local shear field non-uniformity has been uncovered and compared in terms of the CFD-generated time-averaged velocity and deformation rate profiles. The ‘shear-rate-on-particles’ distribution apart from the impeller is found to follow qualitatively the time-averaged inner flow shear rate distribution. Referring to impeller speed 5-12.5 Hz, the dimensionless wall shear rate varied between 200 and 1000. In power law fluids, the shear rate on particles decreased up to 50%. The fluid-foil NS-generated shear field was found comparable to the shear field induced by conventional flat-blade turbines and appeared in cases less sensitive to polymer presence. The shear rate produced by the fluid-foil impeller in the highly shear-thinning model solution (n∼0.4) exceeded the flat-blade RT-imposed shear rate. The analysis has been extended to skin friction drag on particles. It is shown that, while exerting an undoubtedly greater angular deformation in water-like fluids, in polymer presence the conventional flat-blade turbine introduces a flow geometry that imposes particle drag that is close or in some cases even less than the one generated by the fluid-foil impeller. The fact implies a weak shape effect of radial turbines on shear-sensitive particles or particle dispersions in power law liquids.     

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.