查看更多>>摘要：In this work, we applied a Bayesian time-lapse (4D) seismic inversion to a deep-water heavy oil field located in the Campos Basin (Brazil). In this procedure, the differences of seismic amplitudes of baseline and repeated surveys are the input to calculate the changes in acoustic impedances. To ensure the quality of the results, the parametrization of the inversion was performed by analyzing the anomalies resolution and signal-to-noise ratio with different values of input parameters, and the estimates are crosschecked with the results of a petroelastic modeling applied to the dynamic model. Results show a relevant improvement in the vertical resolution of estimated acoustic impedances in comparison to the amplitude data in a thin reservoir (with thickness ranging from 15 to 45 m). This improvement was possible because of the high-quality of acquired seismic amplitudes (permanent reservoir monitoring) and because of the data variability that is controlled in the Bayesian 4D inversion algorithm. The high resolution of Bayesian inverted results enabled a more detailed vertical zoning of the reservoir, revealing important geological features, such as channels in the main interval and below the reservoir's base, and improved the understanding of the fluid movement over time, enabling the analysis of the injection efficiency and by-passed oil zones as well as the aquifer movement. This information is important to update the static model, by improving the definition of geological features, and to calibrate dynamic models, in the future, by adding the inverted acoustic impedance maps into the data assimilation procedure.
查看更多>>摘要：Superparamagnetic Iron Oxide Nanoparticles (SPION) exhibit relatively low toxicity and cost, while their chemical versatility provides an interesting class of materials for the development of nanofluids for advanced oil recovery. In this article, we present a comprehensive characterization of SPION modified with the disodium 4,5dihydroxy-1,3-benzenedisulfonate (HBS) anionic ligand, forming a coating capable of improving the colloidal stability of the nanofluid, even in brine containing up to 22,000 ppm of sodium chloride. Fourier-transform infrared spectroscopy (FTIR) and x-ray photoelectron spectrometry (XPS) data demonstrated the chemical modification of the surface of the particles by the HBS ligand, through the linking of the catechol group, expose the sulfonate groups on the surface of the SPION-HBS. The anionic groups modify the surface charge distribution of the nanoparticles, shifting the isoelectric point of the nanoparticles from pH 6.3 (SPION) to less than pH 2 (SPION-HBS). This fact affords greater stability, supporting the drastic conditions of enhanced oil recovery (EOR) application. The interfacial properties of these particles were also investigated, revealing a slight reduction in the interfacial tension (IFT) of the nanofluid/oil, and small changes in the contact angle (CA) measured as a decane droplet on a glass surface. Despite the slight reduction in IFT and CA, spontaneous imbibition experiments showed a dramatic improvement in oil production in the nanofluid group, reaching a relative value of 2.75 times greater than in the control, at the end of the 5-month trial. The higher oil production achieved with the SPIONHBS nanofluid can be attributed to a more efficient change in wettability, reflecting the role of electrostatic interactions between the sulfonate groups at the particle surface and the porous surface of limestone rock. Since there was no surfactant in the composition of the nanofluid, the observed effects can only be attributed to the influence of the nanoparticles in the EOR process.
查看更多>>摘要：In recent years, the hybrid thermal-solvent process has been widely applied to improve the recovery performance of steam injection processes in heavy oil reservoirs. In this paper, the method of Molecular Dynamics (MD) simulation is employed to illuminate the asphaltenes adsorption behavior in the thermal-solvent recovery process. Three different solvent molecules (CO2, C3H8, and nC(4)H(10)) and SARA (Saturates, Aromatics, Resins, Asphaltenes) simulated heavy oil model are constructed as the basic simulation model. A series of MD simulations at different temperature conditions are performed. Results show that for the SARA model, the asphaltene molecules can interact with the silica by a T-shape stacking, finally forming the asphaltene dense aggregates as a basic heavy oil occurrence state. The steric hindrance effect of other SARA components can also contribute to this configuration. Temperature significantly affects the adsorption configuration of asphaltenes by disassembling the dense core and loosening the structure of the aggregates. For the SARA model in three solvent atmospheres, the increasing temperature can benefit the extraction of light components. CO2 can only extract saturates, while nC(4)H(10) and C3H8 can simultaneously extract the saturates and aromatics. Besides, asphaltenes re-precipitation behavior can be observed in the 393 K CO2 atmosphere. Both nC(4)H(10) and C3H8 have mutual solubility with the heavy oil system. No apparent precipitation of asphaltenes occurs in the above two atmospheres. Comparing the performance of extraction capability and diffusion capability in all MD simulations, the nC(4)H(10) can both extract light oil components and control the asphaltenes precipitation. It further reveals that nC(4)H(10) can recover heavy oil more efficiently at a microcosm level. Among the three different solvents, nC(4)H(10) is the optimal solvent for hybrid thermal-solvent processes in heavy oil reservoirs.
查看更多>>摘要：Limestone caprock permeability and damage characteristics have a significant impact on the tightness and stability of salt cavern gas storage. To investigate the gas sealing capacity of limestone as caprock for a gas reservoir at different burial depths, triaxial compression coupled with permeability tests of limestone subjected to different confining pressures and temperatures were carried out using the improved MTS 815 test machine. After the tests, X-ray micro-computed tomography (mu CT) is used to perform CT scanning of the limestone sample after seepage failure to estimate the rock meso-damage. The experimental results depicted that: (1) At the confining pressures of 10 MPa, 20 MPa and 30 MPa, the final permeability increases with the increase of temperature, while at the confining pressures of 40 MPa, the evolution of the final permeability is opposite. (2) The pore radius of limestone is concentrated in the range of 0-200 mu m, and the pore with a radius greater than 1200 mu m is the main permeability channel with the greatest contribution. The final permeability is positively correlated with porosity. (3) The fractal dimension decreases with the increase of confining pressure, and some areas of rock do not have fractal characteristics when the confining pressure reaches 40 MPa. Permeability after rock damage is positively correlated with the fractal dimension and the maximum pore diameter and negatively correlated with the tortuous fractal dimension, according to the fractal permeability model. These experimental results and analyses provide scholars and engineers with a thorough understanding of cap rock tightness in the construction of deep-earth gas storage reservoirs.
查看更多>>摘要：As most of the oil fields gradually come to the middle and late exploitation period, the crude oil production becomes more complex, stable and water cut is also very high. This has brought challenges to oil-water separation in onshore and offshore production trains especially for the demulsification and dehydration of crude oil. In particularly, the pre-separation efficiency of conventional three-phase separators installed at the front position of the crude oil processing systems are severely affected. In this paper, we explored the demulsification performance of W/O emulsion in an electric field-enhanced separator with insulated electrode assembly inside by static demulsification experiment and dynamic demulsification experiment separately. Focused beam reflectance measurement (FBRM) was used to make real-time online measurements of water droplet sizes in the emulsion. The average water droplet diameters, distribution of droplets within certain size and water content in oil outlet of the separator are set as indicators for evaluating the dehydration performance. The effect of electric voltage, frequency, water content and inlet flowrate on the demulsification performance were both investigated. Experimental results showed that the high frequency AC electric field with insulated electrode can promote the growth of small water droplets and thus contribute to the demulsification. The dehydration performance is deteriorated drastically with the increase of inlet water content or flowrate. The electrical field parameters such as electrical voltage and frequency both have obvious effect on the diameter distribution of dispersed water droplets and water contents at oil outlet of the separator. For certain inlet water content 20% and inlet flowrate 0.3 m3/h, the optimal electrical voltage is 5 kV and frequency is 3 kHz. The research results can provide guidance for the optimization and performance improvement of the electric field-enhanced separator.
查看更多>>摘要：Molecular markers have a strong ability to maintain their own structure. The side chain fracture, isomerization and aromatization show regular response characteristics for the organic matter evolution process, which can measure oil maturity and identify oil cracking degree. In this research, 43 crude oil samples were collected for geochemical investigation in the Dongpu Depression from Bohai Bay Basin of North China. By the gas chromatography (GC) experiments of saturated hydrocarbon and aromatic hydrocarbon, a variety of molecular marker parameters were selected for quantitative evaluation of crude oil maturity and cracking rate, including pristane isomerization index (PIR), C-29 sterane parameters, monoaromatic sterane, rearranged sterane (20 S/(20 S + 20 R)), hopane (Ts/(Tm + Ts)), methyl phenanthrene ratio (MPR), Methyl phenanthrene index (MPI), alkyl naphthalene, and alkyl dibenzothiophenes (DBTs). Thus, the crude oil cracking rate in the different regions of Dongpu Depression were calculated quantitatively. The results show that the increase of temperature, the pressure (<40Mpa) and thermochemical sulfate reduction (TSR) action promotes crude oil cracking, whereas the pressure (>40 MPa) generally inhibits the crude oil cracking. In addition, well Wei 20 does not experience prominent thermal history temperature and burial history pressure, but its oil cracking rate is higher than the average cracking rate curve value, suggesting other factors also have an important impact on crude oil cracking, which needs to be further discussed.
查看更多>>摘要：This paper focuses on research progress of molecular simulation in oil displacement system. Through summarizing relevant literature in recent years, various applications of molecular simulation in tertiary oil recovery technology are reviewed. The main content is molecular simulation research on the interfacial properties of oil/ water systems involving surfactants, polymers, foams, and nanoparticles. It is hoped that starting from the simulation system, through the research and analysis of molecular aggregation behavior at the oil/water interface, the feasibility conditions can be provided for the experimental system, and relevant theoretical guidance can be provided for design of new oil displacement agent for tertiary oil recovery.
Naseer, Muhammad TayyabNaseem, ShaziaShah, Muhammad Ali
19页
查看更多>>摘要：Fluvial channels (FC) and point bars sandstone (PDs) sedimentary fills form primary brilliant stratigraphic petroleum systems within the transgressive system tract (TST). They are developed during the rapid rise and subsequent standstill of sea-level, which fills the reservoirs with FC and PD. These petroleum systems are ultra thin-bedded (UTB) due to the very small vertical thickness of TST within the complete depositional sequences. Hence, they create hurdles in the prediction of lithology and porosity for these stratigraphic traps. The continuous wavelet transform (CWT) is the only sub-surface seismic imaging tool of spectral decomposition that can resolve the thin-beds of petroleum-bearing stratigraphic traps. This method removes the tuning effects of ambiguous lithology and fluids that masks the reservoir zones, and hence, generates false bright spots. This method decomposes the conventional seismic data into its constituent frequency components without fixing the vertical time window for the stratigraphic systems. These frequency components are further used for the prediction of lithology and porosity for resolving sub-surface depositional systems. Therefore, the CWT has delineated the fluvial sandstone facies, fractures connectivity, and architecture of the fluvial depositional system during the sea-level fluctuations. The 48-Hz has imaged the regional standstill of sea level, which have accumulated the porous sedimentary facies of coarse-grained FC andPDs. A very local sea-level rise was imaged in the eastern to the central part of this petroleum system. This sea-level fluctuation has implicated that there were minor cycles of transgressive sea-level, which has developed a pure stratigraphic play. The trace envelope attribute experienced a poor correlation coefficient with R-2>0.2. The 48-Hz CWT experienced a correlation coefficient of R-2>0.91 for FC and PDs. The conventional inverted reservoir simulation has imaged the low frequency variance inside similar to 15-31% porous zones of FC and PDs. The 48-Hz volume has imaged the laterally continuous and hydrocarbon-bearing reservoirs with >25% porosity. 48-Hz CWT model also has imaged the coarse-grained FC of aggradational meandering channel stream, which were implicated to develop during standstill of sea-level. These sandstone lenses were enclosed at the top by progradational shale facies of the highstand system tract (HST) and bottom and lateral by the shales of the TST. This workflow serves as an analogue within the SE-Asian sedimentary Basins and similar worldwide geological basins.
查看更多>>摘要：The fatigue damage of subsea wellhead has become one of the important issues in deepwater oil and gas industry. Current research on the fatigue damage evaluation of the subsea wellhead is based on the recommended practices (DNVGL-RP-0142, 2015; DNVGL-RP-E104, 2018), where the influence of the temperature and pressure is ignored. This paper presents the fatigue damage of the subsea wellhead under the condition that the temperature and pressure is considered. Firstly, the analysis model of the temperature and pressure is established. Then, the influence of the temperature and pressure are considered in the local response analysis based on the recommended practices. In addition, the interaction between the conductor and soil is evaluated by the Goodman element model and the P -y model in the local response analysis. Finally, the accumulated fatigue damage of the subsea wellhead is obtained according to the S-N curve recommended by DNVGL (DNVGL-RP-C203 (2016)). On this basis, the influence of the temperature, pressure, top of cement (TOC), contact surface model on the fatigue damage of the subsea wellhead is discussed in detail. Analysis results show that both the temperature and pressure have effect on the fatigue damage of the subsea wellhead. The ranking of the influence strength is temperature and pressure (TP), pressure (P) and temperature(T). The fatigue damage of the subsea wellhead would be underestimated if the temperature or pressure is neglected. This study has guiding significance for fatigue damage evaluation of the subsea wellhead and safe operation of deepwater drilling.
查看更多>>摘要：H(2 )geo-storage has been suggested as a key technology with which large quantities of H(2 )can be stored and withdrawn again rapidly. One option which is currently explored is H(2 )storage in sedimentary geologic for-mations which are geographically widespread and potentially provide large storage space. The mechanism which keeps the buoyant H(2 )in the subsurface is structural trapping where a caprock prevents the H(2 )from rising by capillary forces. It is therefore important to assess how much H(2 )can be stored via structural trapping under given geo-thermal conditions. This structural trapping capacity is thus assessed here, and it is demonstrated that an optimum storage depth for H(2 )exists at a depth of 1100 m, at which a maximum amount of H(2 )can be stored. This work therefore aids in the industrial-scale implementation of a hydrogen economy.
NSTL
Elsevier