فهرست مطالب

Petroleum Science and Technology - Volume:9 Issue: 1, Winter 2019

Journal of Petroleum Science and Technology
Volume:9 Issue: 1, Winter 2019

  • تاریخ انتشار: 1397/12/16
  • تعداد عناوین: 6
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  • Ahmed Zoeir *, Mohammad Simjoo, Jafar Ghajar Pages 3-12
    The routine measurement of direction-dependent reservoir rock properties like permeability often takes place along the axial direction of core samples. As permeability is a tensor property of porous materials, it should be fully described by a tensor matrix or by three main permeabilities in principal directions. Due to compaction, cementation, and other lithification processes, which take place after sedimentation, or later distortion and fractionation of the regional earth’s crust, the axial direction of core samples, may not be always one of the main permeability directions. In this paper, a computational technique to find principal permeability directions from micro-CT images of core samples was developed by us. Moreover, an assumed cube inside the core sample data with dimensions small enough to be able to imaginarily rotate inside the core limits has been chosen by us. Also, connected pore network was extracted from micro-CT data, and permeability was calculated in all space directions. In addition, stepwise rotation process continued until all possible space directions were covered. Then calculated permeabilities from all directions have been compared with each other by us. Afterwards, maximum and minimum values have been found by us. In this paper, two micro-CT datasets, which were taken from the Imperial College website, are used. Finally, the obtained results showed that the direction of maximum permeability within the carbonate core sample is about 30° deviation from the axial core direction. In addition to the main direction, the proposed computational technique can be effectively used to describe the permeability tensor of the reservoir rocks.
    Keywords: Principal Permeability Directions, MATLAB, Image Analyzer App, Micro-CT Image, Rotational Cube Technique
  • Ndubuisi Okereke *, Stephen Udeagbara Pages 13-27

    In pipeline-riser systems, pressure fluctuations which result from the formation of large liquid slugs and gas surges due to operational changes or low mass flow rate from production wells and the profile of pipeline-riser systems often lead to trips at the inlet of the separator; and thereby, the problem causes a a loss of the production.
    In this study, on a sample deep-water oil field off the coast of West Africa is focused. The field lies in water depths greater than 1000 m. Moreover, the wells are connected via a pipeline-riser system to the topside. The slug suppression system (S3) was changed as a control structure on the field case study.
    S3 comprises of a mini separator coupled with dynamically controlled valves at the liquid and gas outlets. This control structure was modeled on OLGA, a one-dimensional, and two-fluid equations based commercial multiphase flow simulation tool. In implementing the S3, it was transformed into a parallel configuration of two proportional-integral (PI) controllers (the separator level and pressure controllers) which controls the total volumetric flow and liquid flow respectively by subsequent opening of the valves at the outlets while stabilizing the riser base pressure. In addition, separator sizing was based on the volume of multiphase fluid at the riser-top. Also, controller-tuning parameters were obtained from parametric studies with pressure and liquid level set point at 20.5 bar and 0.5 m.
    Finally, it is found out that S3 is able to stabilize the riser base pressure and flow rate at the outlet of the mini-separator. Moreover, the comparison of production rates before and after the implementation of the control structure indicated an increase of 12.5% in the production rate.

    Keywords: Severe Slugging, OLGA, Pipeline-Riser, Controller, Proportional-Integral
  • Majid A Abedinzadegan Abdi*_Jing Jing Cai_Kelly Hawboldt Pages 28-43

    In this paper, a system for efficient removal of carbon dioxide by hollow fiber membranes is proposed. The system is compact, and it is very useful for application in the offshore energy industries. In particular, it is used to removing CO2 from the exhaust of power generation facilities on offshore platforms.
    The proposed dual membrane contactor contains two types of membranes (polypropylene membrane and silicone rubber membrane); moreover, the dual membrane contactor was designed and constructed for gas absorption processes. The module performance was evaluated based on permeation flux experiments. The experimental results were compared with the predictions from a numerical model developed in our previous studies. Furthermore, the mass transfer resistance in the fabricated module was investigated using resistance-in-series model. It is proposed that the computational techniques be used to develop design techniques in these kinds of complex systems. In addition, experimental methodologies have been used for the design and optimization of cross-flow hollow fiber membrane modules to absorb or desorb the gas. However, the experiments can be expensive and time consuming.
    Numerical simulations used in conjunction with experiments can decrease the number of required experiments, thus reduce the required costs and time. In this work, a new modelling approach using computational fluid dynamics (CFD) is proposed to improve modelling flow within cross-flow membrane modules, and subsequently as a design means for such modules. In the CFD model, the fiber bundle is modeled as a porous medium to capture flow characteristics through the fiber bundle.
    Also, mass transfer equations in the fiber and shell sides are coupled and solved using an iteration algorithm by taking consideration of the influence of flow behavior of both gas phase and liquid phase. In parallel, experimental study was also carried out to validate the results of computational modeling.
    The CFD modeling results correlated well with the experimental data obtained from a lab scale cross-flow membrane module with uniform distributed fibers. The developed model was then used to examine the performance of modules with more complex geometries such as baffled modules and modules containing unevenly distributed fiber bundles. Finally, it was demonstrated that the CFD simulation is a promising approach in developing and optimizing cross-flow membrane module.
    Keywords: Foam flooding, Low permeability, Heterogeneities
  • Zhi yuan Liu, Qian shen Ding *, Bing Zhao, De Li, Nan Li Pages 44-55
    The onshore oil and natural gas industries of China have started a large-scale development when crude oil reserves have been difficult to recover. The stratum fracture modification is an indispensable measure to efficiently develop oil and gas fields. Hydraulic fracturing is the most important reservoir stimulation technique, but it is still faced with various problems such as the failure to fracture the target reservoir, long fracturing duration, and short efficient length of the fracture. High Energy Gas Fracturing (HEGF) can easily break down the high-fracture-pressure oil reservoir and generate multiple fractures free of in-situ stress. Moreover, HEGF entails no large-scale devices, and this method is strongly adaptable to the environment without causing environmental pollution. After combining the two technologies (HEGF and the other), then they can complement each other with their strengths. That is, both of them decrease the fracture initiation pressure of (or caused by) hydraulic fracturing on the one hand, and to extend, gather, and support multiple radial fractures of gas fracturing on the other hand. Thus, a fracture zone with a large radius is finally formed, and the percolating resistance of the fluid is significantly decreased.
    Moreover, in this study, a dynamic model related to the drainage flow of the perforated holes in a gas well, fluid pressure distribution in the fracture, fluid seepage on the fracture wall, fracture initiation criterion, and fracture propagation velocity during the HEGF process has been presented. Consequently, a gas/liquid/solid coupling fracture dynamic propagation model during the HEGF process can be built to provide a theoretical basis for the accurate simulation of the fracture form changes during this process.
    Keywords: High Energy Gas Fracturing, Fracture Dynamic Propagation, Coupling Simulation
  • Mohammad Latifi *, Lorenzo Ferrante, Cedric Briens, Franco Berruti Pages 56-72

    A fluidized bed reactor that is operating in the bubbling regime has been developed for the conversion of bio-oils to syngas.
    The reactor consists of a 7.6 cm I.D. (or internal diameter) bed, with an expanded freeboard. The volume of the reactor can be adjusted to vary the gas residence time. This reactor has been used to carry out either thermal or catalytic cracking for reforming bio-oils.
    A gas-atomized injector has been specially developed to feed a bio-oil, which may be viscous and contaminated with small ash and char particles. Besides, the gas-atomized nozzle allows it to remain cool until coming in contact with the fluidized particles inside the bed.
    This article presents the product yields and compositions obtained by thermally cracking the bio-oil at various temperatures and gas residence times. The bed temperature was varied from 500 to 700 °C. Moreover, the vapor residence time ranged from 7.8 to 27.6 seconds.
    Also, the effect of particle size and mass of bed was investigated. Finally, based on this study, the conversion of bio-oil to gas increased with an increase in temperature and residence time
    Keywords: Bio-Oil, Syngas, Hydrogen, Fluidized Bed Reactor, Thermal Cracking
  • Lin Sun, Daibo Li *, Fanqi Zhao, Xiao Zhang, Di Wang, Ximing Tang Pages 73-80
    Foam flooding (or injection of foam) is a common technology to enhance oil recovery. Although the effects of permeability on foam flooding were well studied in many laboratory experiments, little research has been focused on the specificity of low permeability. In this paper, a series of constant-quality nitrogen foam flow experiments were conducted to investigate the effects of permeability on the foam performance and oil displacement efficiency. Moreover, the results indicated that foam can be generated in low permeability porous media. With uniform experimental conditions, the higher permeability core has a bigger recovery amplification and greater decreasing range of water cut decline. Furthermore, the effect of microscopic heterogeneities of low permeability reservoir on foam displacement is considered. Moreover, experimental comparative analysis with different microscopic heterogeneity cores showed that, in low permeability condition, homogeneous porous media has a better prospects of oil-displacement. Finally, in this work, the results of the permeability effects on the foam performance and oil displacement efficiency exemplify a potential to apply the technology to low permeability reservoir.
    Keywords: Foam flooding, Low permeability, Heterogeneities