Showing papers by "China University of Petroleum published in 1999"

Hydrate Formation of CO2-Rich Binary and Quaternary Gas Mixtures in Aqueous Sodium Chloride Solutions

Abstract: Hydrate formation data of CO2-rich mixtures, three binaries (CO2 + CH4, CO2 + C2H6 and CO2 + N2) and one quaternary (CO2 + CH4 + C2H6 + N2), in water and aqueous sodium chloride solutions were measured. The measurements were carried out in a transparent sapphire cell by applying an isothermal pressure search method in the temperature range 264 K to 284 K and the pressure range 0.5 MPa to 5.0 MPa.

Prediction of Gas Hydrate Formation Conditions in Aqueous Solutions Containing Electrolytes and (Electrolytes + Methanol)

Abstract: The prediction of gas hydrate formation conditions in solutions containing single electrolyte and mixed electrolytes and solutions containing both electrolytes and methanol has been performed using the modified Zuo-Gommesen-Guo hydrate model proposed by the authors. The results show that agreement between experimental and calculated values is satisfactory.

Distribution and characterization of C31 sterane from cretaceous sediments and oils, Songliao Basin, China

Abstract: Relatively high abundance of C31 steranes has been identified from cretaceous source rocks and crude oils in the Songliao Basin, China. C31 steranes which occur as ten isomers were tentatively identified as 4, 22, 23, 24-tetrametyhlcholestane based on their retention time and mass spectrum. They bear a lower thermal stability and occur as important components in the immature oils of Chaochang region because they have three-methyl groups in their side chain. The relatively high abundance of C31 steranes in the samples can indicate the source input of some special algae in the brackish and saline environment. Therefore they can be used as very useful bimarkers for organic facies analysis and oil correlation. Their biological source perhaps related to the dinoflagellate such asG. foliaceum andP. foliaceum. The gorgostanol are considered as possible precursors for the putative C314-methyl sterane which formed in the stage of diagenesis.

Research on propagation properties of elastic waves in two-phase anisotropic media

Abstract: With the development of seismic engineering and seismic exploration of energy, the underground media that we study are more and more complicated. Conventional anisotropy theory or two-phase isotropy theory is difficult to describe anisotropic media containing fluid, such as fractures containing gas, shales containing water. Based on Biot theory about two-phase anisotropy, with the use of elastic plane wave equations, we get Christoffel equations. We calculate and analyze the effects of frequency on phase velocity, attenuation, amplitude ratio and polarization direction of elastic waves of two-phase, transversely isotropic media. Results show that frequency affects slow P wave the greatest among the four kinds of waves, i.e., fast P wave, slow P wave, fast S wave and slow S wave. Fluid phase amplitude to solid phase amplitude ratio of fast P wave, fast S wave and slow S wave approaches unit for large dissipation coefficients. Polarization analysis shows that polarization direction of fluid phase displacement is different from, not parallel to or reverse to, that of solid phase displacement in two-phase anisotropic media.

Investigation on intensification of distillation with additives rich in aromatics

Abstract: The effects of the additives rich in aromatics on the intensification of vacuum distillation were investigated with the viscosity measurement, a simulated distillation analyzer, a Kjeldahl vacuum distillation unit and a True Boiling Point distillation unit. The temperature of liquid phase could influence the effects of additives. The hot-stage microscope was adopted to study qualitatively the intensification mechanism of the additives. When the temperature was lower than 320°C, it was found that the additives could help the lighter fractions going out which had been adsorbed by the core and constituted the outer layers of the colloidal particles. Nevertheless, when the temperature was high (above 380°C), the colloidal particles in the atmospheric residue almost disappeared and the distillation yield could not be increased obviously by the additives.

Incidence, reflection and transmission angles in anisotropic media

Abstract: The mathematical description of phenomena related to wave propagation in anisotropic media is considerably more complicated than that for isotropic media. This complexity stems from many physical properties distinguishing the anisotropic from isotropic medium. Therefore, calculating the angles of reflection and transmission for a ray impining on a boundary between two anisotropic media become more complicated in mathematical implication. Snell law in isotropic medium has not been applicable in anisotropic medium, which must be modified. This article presents a new method of calculating the angles of reflection and transmission on a boundary between two anisotropic media, called as the modified Snell law.

Evaluation of ordovician carbonate source rocks in the dagang oilfield, China

Abstract: Ordovician carbonates in the Dagang Oilfield are of wide distribution and have large thickness. Though their organic matter abundance is relatively low, it has reached the standards for carbonate source rock, with most of them being thought to be medium source rocks. These carbonates, whose bio-inputs were mainly of blue bacteria, were deposited in a weakly reducing or weakly oxidizing environment. Their organic maturity is at mature to over-mature phases in most areas, therefore, they should possess geological and geochemical conditions for oil/gas generation and expulsion. Attention should be paid to the Ordovician carbonates in future exploration.

Composition of substituents on pyrrole ring of high-carbon-number geoporphyrins and its dealkylation

Abstract: Geoporphyrins, isolated from source rock, were analyzed on electron ionization mass spectrometry (EIMS) and Tandem mass spectrometry (MS/MS). The spectrum of EIMS shows that the geoporphyrins are mainly composed of two types: DPEP and eito. Most of the porphyrin carbon numbers are greater than C32. The daughter spectra of the molecular ions (C34-36DPEPs) display the loss of methyl and ethyl groups, which indicate there are ethyl and propyl groups in the mother ions. The average condensed structural formulae, derived from the data of the spectra on MS/MS, have clearly shown the composition of the substituents on the porphyrin pyrrole ring, and the regular changes of the substituents reveal the characteristics of the dealkylation of the porphyrins in the geosphere.

Genesis of the massive ordovician dolostones in the Ordos basin, North China : Evidence from inclusions

Abstract: Massive dolostones are well developed and can be classified into fine saccharoidal dolostones and coarse saccharoidal dolostones in the Ordovician of the Ordos Basin, North China. An analysis of the inclusion reveals information for the study of the massive dolostones' genesis. The majority of thin sections show that the inclusions are poorly developed in the host crystals of the fine dolomites, but are well-developed in the pore-filling calcite crystals. The homogenization temperatures of the inclusions range from 49°C to 74°C, and the maximum depth of the inclusion formation calculated from such temperatures is about 172m. Thus the host crystals of the fine saccharoidal dolostones have been formed in shallow burial environments with a depth of about 172m. On the other hand, the inclusions are well -developed in the host crystals of the coarse saccharoidal dolostones. Analytical data of Raman spectra show that, among the inclusions, there is a great deal of methane and other organic material, suggesting that the inclusions must have been formed during the dry gas production stage of the organic material evolution in deep burial environments. The lowest homogenization temperature of the inclusion is 104°C (with pressure correction), and the least depth for the inclusion formation corresponding to such a temperature is about 2600m. Hence, it is believed that the coarse saccharoidal dolostones must have been formed in deep burial environments with hot liquid dolomitization. Therefore, the inclusion analyses bring out the conclusion that there are at least two types of dolomitization in the massive dolostones of the Ordovician of the Ordos basin, one of shallow burial with warm liquid, and the other deep with hot liquid.

Carbon isotopic study of individual n-alkanes in certain modern organisms

Abstract: Simulation experiment was carried out on all kinds of modern organisms significant to oil-gas generation and the C-isotopic values of n-alkanes in different organisms. The distribution characteristics of individual n-alkane isotopes are studied. The experimental results supply important clues in biological provenance of n-alkanes in sedimentary organisms.