II. Sensitivity and reliability of the discontinuous vacuum stability test

Abstract

Gas evolution, due to phase expansion, remains an attractive and sensitive method for stability evaluation. Unfortunately, this technique is also sensitive to errors. Numerous factors such as pressure, volume, temperature, volatiles, and solubility, may significantly affect the results. The effect of such factors is evaluated. A better control of the test conditions prevents errors and makes the discontinuous VST a fast and accurate technique for stability/compatibility evaluation.     

A New Approach to Calculate the Mud Density for Wellbore Stability Using the Asymptotic Homogenization Theory

Abstract

This study addresses mud density prediction as part of wellbore stability analyses considering effective rock properties and using friction and elastic theories to determine the deviator stress at failure. The effective rock properties for different sandstone porosities were obtained through the theory of asymptotic homogenization, and the wall vicinity stresses at the borehole wall were estimated considering friction and elastic theories. The use of the method of asymptotic homogenization (MHA) allows obtaining effective rock mechanical properties varying in porosity and saturation conditions.     

Thermal stability and sorption properties of asphaltene sulfocathionites

Abstract

Using simultaneous thermogravimetry and differential scanning calorimetry, thermal stability and possible phase transitions of asphaltene sulfocationites and native asphaltenes have been evaluated; the kinetic characteristics of heating have been determined, namely, onset temperature of decomposition, stages of decomposition, and temperature ranges of stability. It has been determined that asphaltene sulfocationites retain structural-group features (IR spectroscopy method) and sorption characteristics while heating up to 350?°C.     

Polynitroaliphatic explosives containing the pentafluorosulfanyl (SF5) group: The selection and study of a model compound

Abstract

An investigation concerning the effect of the pentafluoro-sulfanyl (SF₅) group on the properties of explosive nitro compounds is described. The investigation includes: (a) the preparation of several polynitro SF₅ model compounds; (b) the selection of the best model compound (based on overall properties such as melting point, stability, ease of synthesis, etc.); (c) the subjection of this compound to calorimetric determination of the heat and products of detonation. The initial results from the investigation support the hypothesis that the SF₅ group can provide explosives with improved properties (increased density, decreased sensitivity and good thermal stability) as well as produce energy in the detonation.     

AN IMPROVED METHOD FOR MEASURING HYDROPEROXIDES IN FUEL USING POTENTIOMETRY AND ALTERNATIVES TO CHLOROFLUOROCARBON SOLVENTS

ABSTRACT

A critical aspect in the assessment of thermal and storage stability of jet fuels is the measurement of hydroperoxide concentrations. The accepted procedure for this determination employs manual titration with standard thiosulfate using a visually detected color change to detect the endpoint. In many fuels, particularly when stressed, intense coloration of the fuel prevents accurate visual endpoint detection. This problem can be overcome by using a potentiometric method of endpoint detection with an automatic titrator. These two techniques are shown to provide identical results. The method also specifies the use of CFC-113 (Freon TF) as the titration solvent. Since CFC-113 will not be available in the future, several other solvents have been examined. Isopropanol and pure hydrocarbons show promise as suitable replacements.     

3-Nitramino-6-hydroxy-1,2,4,5-tetrazine and its alkaline earth metal salts: an effective strategy to balance energy density and safety of energetic compounds

ABSTRACT

3-Nitramino-6-hydroxy-1,2,4,5-tetrazine (NHTZ) and its alkaline earth metal salts (Mg²⁺(1), Ca²⁺(2), Sr²⁺(3), Ba²⁺(4)) were prepared via 3,6-dinitramino-1,2,4,5-tetrazine for the first time. The electrostatic potentials and HOMO-LUMO orbitals of them were computed to better understand the electronic structure of NHTZ. Structures of the four alkaline earth metal salts were confirmed by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Structural analysis revealed that all compounds have differently dimensional structures, increasing with the radius of metal atoms. Compounds 3 and 4 can be classified as coordination polymers due to their structural features. As the only 3D polymeric structure in this series, compound 4 possesses the highest density and best thermal stability in these compounds. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurement shows the excellent thermal stability of these salts, with the thermal decomposition temperatures of 291.1°C (1), 294.1°C (2), 294.9°C (3) and 324.7°C (4). Heat of formation and sensitivity of the four salts were investigated, which suggest 4 as a potential heat-resistant energetic compound instructions for authors.     

Effect of different molecular weight amphiphilic polymers on emulsifying behavior

Abstract

Amphiphilic polymers applied in oil fields are polymer mixtures with different molecular weight. Stability of O/W emulsion prepared by amphiphilic polymers with different molecular weight was studied by stability analyzer. The difference in stability was clarified according to the external phase and interfacial properties. Results showed that PI(micro-molecular polymer) formed a tighter network structure in solution which exhibit higher viscoelasticity and more resistant to shear; and was more favorable to the emulsion stability than PII(macro-molecular polymer) due to higher surface activity. This work provides references for the molecular weight distribution optimization of amphiphilic polymer.     

Water-in-Crude Oil Emulsion Stability Investigation

Abstract

The water-in-crude oil emulsion has great importance in the oil industry. The stability of water-in-crude oil emulsion is investigated over a wide range of parameters. These parameters are water concentration (10–50%), surfactant concentration (0.1–1%), mixing speed (500–2, 000 rpm), salt concentration (0–5%), polymer concentration (0–1, 000 ppm), and temperature (13–40^○C). The physical properties of water-in-crude oil emulsion in terms of density, viscosity, and interfacial tension are measured by Pycnometer, Ostwald viscometer, and spinning drop tensiometer, respectively. The stability of water-in-crude oil emulsion is studied for each case in details. This investigation shows that the presence of the emulsifying agent is necessary for stable emulsion, and stability gradually decreases with water concentration. The presence of 5% NaCl or 1, 000 ppm of Alcoflood polymer provides 100% stable emulsion. Emulsion stability reduces with temperature. Impeller type has a strong effect on the emulsion stability. S-curved blade impeller provides 100% stable emulsion for more than 2 days.     

Eutectic system of ammonium nitrate with 15 wt% potassium nitrate/ethylenediamine dinitrate/diethylenetriamine trinitrate

Abstract

The phase diagram was determined for the ternary system diethylenetriamine trinitrate/ethylenediamine dinitrate/ammonium nitrate with 15 wt% potassium nitrate (DETN/EDD/AK₁₅). The eutectic mixture (DEAK), containing 40, 35, and 25 wt% AK₁₅, DETN, and EDD respectively, was subjected to small-scale sensitivity and performance tests. The measured P_CJ (223 kbar) from a 4.13-cm-diam, unconfined rate-stick test of the DEAK system agrees with Kamlet-Short-Method (KSM) data calculated at the same pressed density [97.7% of theoretical maximum density (TMD)].

A rate-stick test of EAK at the same charge diameter and pressed density failed, indicating that the addition of the DETN component to the EAK system has reduced the critical diameter of EAK.     

Heat Transfer Processes in Double-emulsion Systems

Abstract

The authors present a theoretical analysis of the heat transfer processes problem for globules and liquid membrane in a double-emulsion system. Volume-averaging transport equations are derived for globules, membrane, and continuous phase, which results in the three-equation average model to determine the temperatures in globules, membrane, and external phase with heat source diffusion and convection effects. With these equations, two average models were derived: (a) the two-equation model, where globules and membrane are characterized by a single temperature and thermodynamic nonequilibrium with the external phase; and (b) one equation model (thermodynamic equilibrium) where the double-emulsion system (globules, liquid membrane, and external phase) has a single temperature. The terms in the mathematical model responsible of the thermodynamic nonequilibrium effects were established.     

A Study on the Thickness of a Cutting Bed Monitor and Control in an Extended Reach Well

Abstract

Based on solid–liquid flow mechanics, considering the interaction between layers, the slip between solid and liquid phase, and the effect of drillpipe rotation, a dynamic three-layer cutting transport model was developed. By orthogonal experiment regression, a formula for calculating the thickness of the cutting bed was developed that is suitable for field application. The dynamic thickness of the cutting bed can be predicted by measured equivalent circulating density (ECD). Research has shown that the field equipment cannot attain the capability to keep the borehole clean, and when the thickness of the cutting bed exceeds 10%, a flushing method must be used to keep the borehole clean.     

Crystal chemistry study on nitrobenzenes Part 2. hydregen bonding,stability and density

Abstract

In crystal structures of nitrobenzenes, intramolecular hydrogen bonding increases the molecule's stability, planarity and packing coefficient. The head-to-tail pattern of intermolecular hydrogen bonding favours the antiparallel packing of the molecular assemblies and close packing. The geometry of the C-H linkage alpha to the NO₂ group is discussed in connecting to the molecular stability. The relation between the crystal density and hydrogen bonding is discussed.     

Diffusion and Convection With Chemical Reaction in a Three-Phase System

Abstract

The authors present a general theoretical analysis of the diffusion problem including chemical reaction for globules and liquid membrane in a 3-phase system. Volume-averaging transport equations are derived for globules and membrane with chemical reaction in both phases and for the continuous phase with diffusion and convection effects. With these equations, a one-concentration model to double emulsion system (globules and membrane) was derived, and for this the principle of local mass equilibrium was applied.     

IN-SITU REDUCTION OF A METHANOL SYNTHESIS CATALYST IN A THREE-PHASE SLURRY REACTOR

ABSTRACT

A new method for the reduction of metal oxide catalysts has been developed, for the reduction of the CuO - ZnO - A1203 catalyst for liquid phase methanol synthesis. The reducing agent is a 5% hydrogen in nitrogen mixture and the operation is carried out at 446.09 KPa. This method makes it possible to reduce finely crushed catalyst (-100 + 120 mesh) in a three phase slurry reactor. This method offers several advantages over methods in which the catalyst is reduced in a gas-solid contact mode and then slurried for use. The catalyst has been shown to be very effectively reduced and reaches its full production capacity after reduction.     

Stability of Water-in-Crude Oil Emulsions: Effect of Oil Aromaticity,Resins to Asphaltene Ratio,and pH of Water

Abstract

The formation of tight water-in-oil emulsions during production and transport of crude oils is a great problem challenging the petroleum industry. Tremendous research works are directed to understanding the mechanism of formation, stabilization, and controlling of oil field emulsions. This article presents experimental results of some of the factors controlling the formation and stabilization of water-in-crude oil emulsions. In this study, asphaltenes and resins separated from emulsion samples collected from Burgan oil field in Kuwait have been used to study emulsion stability. Model oils of resin to asphaltene ratio of 5:1 and toluene-heptane mixtures have been used to study the effect of oil aromaticity on emulsion stability. Results indicate that at low toluene content (below 20%) or high content (above 40%) less stable emulsions are formed. At a threshold value of 30% toluene, a very tight model oil emulsion is formed. The effect of resins to asphaltene (R/A) ratio on stability of model oil has also been investigated. Results reported in this paper show that as the R/A increases the emulsions become less stable. The effect of pH on stability of model oil emulsion made of 50/50 heptane-toluene mixture having R/A ratio of 5:1 have been studied. Experimental results revealed that as the pH of the aqueous phase of model oil increased from 2 to 10, the emulsion became less stable. At high pH, the asphaltene particles are subjected to complete ionization leading to destruction of the water-oil interface and eventually breakdown of the emulsion.     

THERMAL STABILITY ANALYSIS OF THE LIQUID PHASE METHANOL SYNTHESIS REACTOR

ABSTRACT

The effect of addition of an inert liquid phase on the rate of heat generation in the catalytic synthesis of methanol from syngas has been studied. Gas compositions typical of product gases from Lurgi and Koppers-Totzek gasifiers, represented by H₂-rich and CO-rich syngas respectively, were used to experimentally verify the “slope” and “dynamic” critria in a three-phase fixed bed recycle reactor. The liquid medium, witco-40 oil, has been effective in controlling the rate of heat generation and in preventing catalyst overheating, signifying that the liquid phase synthesis is thermally far more stable than the vapor phase synthesis. The experimental thermal stability study provides crucial and valuable information in commercializing the liquid phase methanol synthesis process. The current approach of thermal stability analysis does not require any a priori assumption or predetermined reaction kinetics.     

Analysis of the Mechanical Stability of Boreholes Drilled in Sedimentary Rocks

Abstract

This article presents the method and results of wellbore stability analysis for three common reservoir lithologies consisting of a consolidated sandstone, a shaly sandstone, and a limestone formation. The effect of stress anisotropy on the mechanical stability of wellbores is evaluated while varying the inclination angle from 0 to 90°, for both the Mohr–Coulomb and the Drucker–Prager failure criteria. The selected failure criterion, and the in-situ rock stress regime are found to have significant effects on the safe drilling fluid density required to maintain wellbore integrity. According to some field examples, the Drucker–Prager failure criterion appears to systematically mimic rock conditions more realistically than the Mohr–Coulomb failure criterion. The simulated consolidated sandstone formation is found more stable with lesser drilling fluid density, at any inclination angle, than the simulated shaly sandstone formation. The simulated limestone formation is even more stable than the consolidated sandstone at all inclination angles since it requires lighter fluid density to prevent wellbore collapse. For all these rock types, the higher the deviation angle (from vertical), the higher the drilling fluid density needed for maintaining wellbore integrity. For the depth and rock conditions simulated, both consolidated and shaly sands are unstable in a strike-slip stress regime, but stable in an extensional stress regime. The simulated limestone formation was found stable in both stress regimes. However, in an extensional stress regime, the limestone formation required lighter fluid density to maintain wellbore integrity than in a strike-slip stress regime. This article introduces the theory of using a practically-oriented model to assess the mechanical stability of a wellbore in a linearly-elastic stress field. The model can be used to determine the range of mechanically stable well inclinations for a given formation, and to suggest drilling-fluid density programs tailored to efficient and safe drilling.     

A New Synthetic Route for 3,3′-Bis(fluorodinitromethyl)difurazanyl Ether (FOF-13) and Its Energetic Properties

A new protocol for preparation of 3,3-bis(fluorodinitromethyl)difurazanyl ether (FOF-13) was developed. It involves (i) nitration of 3,3’-bis(chlorohydroxyminomethyl)difurazanyl ether with N₂O₅/MeCN to give 3,3-bis(chlorodinitromethyl)difurazanyl ether (4), (ii) reduction of 4 with KI/MeOH to obtain potassium salt of 3,3’-bis(dinitromethyl)difurazanyl ether (6) and (iii) fluorination of 6 with XeF₂ in anhydrous acetonitrile to form the desired FOF-13. FOF-13 was fully characterized by IR, ¹³C NMR, ¹⁹F NMR, and elemental analysis. FOF-13 exhibits excellent physicochemical and detonation properties, such as high density (1.91 g cm^?3), good thermal stability, reasonable impact sensitivity (14 J) and friction sensitivity (64%), high measured detonation velocity (8497 m s^?1 at 1.69 g cm^?3). Furthermore, the precursors 4 and 6 were developed for the first time.     

Modified vacuum thermal stability test apparatus for energetic materials

Abstract

An apparatus, hereinafter named the modified vacuum thermal stability (MVTS) test apparatus, that replaces the mercury manometric method used to determine the vacuum thermal stability of energetic materials is described. The volume calibrated MVTS system provides continuous pressure/time data for the duration of the test via a computerized data acquisition system. Total gas volume (reduced to STP) is computed from the pressure data. Subsequent gas chromatographic analysis of the evolved gaseous mixture further provides identification and individual volumes of the components. Water/solvent volume is obtained by difference (V_p — V_{Calibrated Gases GC}).