Initial Ensemble Design Scheme for Effective Characterization of Three-Dimensional Channel Gas Reservoirs With an Aquifer

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Sungil Kim ◽  
Hyungsik Jung ◽  
Kyungbook Lee ◽  
Jonggeun Choe
Keyword(s):  
Reservoir Characterization ◽  
Three Dimensional ◽  
Grid System ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Design Scheme ◽  
Initial Ensemble ◽  
The Mean ◽  
Grid Points

Reservoir characterization is a process of making models, which reliably predict reservoir behaviors. Ensemble Kalman filter (EnKF) is one of the fine methods for reservoir characterization with many advantages. However, it is hard to get trustworthy results in discrete grid system ensuring preservation of channel properties. There have been many schemes such as discrete cosine transform (DCT) and preservation of facies ratio (PFR) for improvement of channel reservoirs characterization. These schemes are mostly applied to 2D cases, but cannot present satisfactory results in 3D channel gas reservoirs with an aquifer because of complex production behaviors and high uncertainty of them. For a complicated 3D channel reservoir, we need reliable initial ensemble members to reduce uncertainty and stably characterize reservoir models due to the assumption of EnKF, which regards the mean of ensemble as true. In this study, initial ensemble design scheme is suggested for EnKF. The reference 3D channel gas reservoir system has 200 × 200 × 5 grid system (250 × 250 × 100 ft for x, y, and z, respectively), 15% porosity, and two facies of 100 md sand and 1 md shale. As the first step, it samples initial ensemble members, which show similar water production behaviors with the reference. Then, grid points are randomly selected for high and low 5% from the mean of sampled members. As a final step, initial ensemble members are remade using the selected data, which are assumed as additional known data. This proposed method reliably characterizes 3D channel reservoirs with an aquifer.

scholarly journals Nanometer Scale Tomographic Investigation of Fine Scale Precipitates in a CuFeNi Granular System by Three-Dimensional Field Ion Microscopy

2012 ◽  
Vol 18 (5) ◽  
pp. 1129-1134 ◽  
Author(s):  
Sophie Cazottes ◽  
François Vurpillot ◽  
Abdeslem Fnidiki ◽  
Dany Lemarchand ◽  
Marcello Baricco ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Precise Determination ◽  
Atomic Scale ◽  
Granular System ◽  
Field Ion Microscopy ◽  
Mean Diameter ◽  
The Matrix ◽  
The Mean ◽  
Ion Microscopy

AbstractThe microstructure of Cu80Fe10Ni10 (at. %) granular ribbons was investigated by means of three-dimensional field ion microscopy (3D FIM). This ribbon is composed of magnetic precipitates embedded in a nonmagnetic matrix. The magnetic precipitates have a diameter smaller than 5 nm in the as-spun state and are coherent with the matrix. No accurate characterization of such a microstructure has been performed so far. A tomographic characterization of the microstructure of melt spun and annealed Cu80Fe10Ni10 ribbon was achieved with 3D FIM at the atomic scale. A precise determination of the size distribution, number density, and distance between the precipitates was carried out. The mean diameter for the precipitates is 4 nm in the as-spun state. After 2 h at 350°C, there is an increase of the size of the precipitates, while after 2 h at 400°C the mean diameter of the precipitates decreases. Those data were used as inputs in models that describe the magnetic and magnetoresistive properties of this alloy.

scholarly journals Evaluation of the Percolation Sensitivity of Loose Sandstone Using Digital Core Technology

2018 ◽  
Vol 11 (1) ◽  
pp. 84-97
Author(s):  
Jin Pang ◽  
Junnan Li ◽  
Jie Liang ◽  
XiaoLu Wang ◽  
Mingqing Kui
Keyword(s):  
Effective Stress ◽  
Three Dimensional ◽  
Reservoir Rock ◽  
Formation Water ◽  
Pore Throat ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
The Core ◽  
Core Technology ◽  
Digital Core

Background:The integrity of the extracted core in loose sandstone gas reservoirs is poor, and because hydration and collapse easily occur, it is difficult to evaluate the sensitivity characteristics accurately by the traditional core flooding experiments.Objectives:We instead investigate the stress sensitivity and water sensitivity of the formation water soaking time using digital core technology.Methods:We take the core of a loose sandstone gas reservoir as a research object and begin by scanning the core samples with a CT scanner. A three-dimensional image of the core can be obtained, the digital information extracted, the pore structure of the porous media mapped directly to the network, and a digital core established using the principles of fractal geometry. The three-dimensional pore network model can also be extracted. Next, we can compare and correct the results calculated by the model based on the real core experimental results, and an objective and effective digital core model can be obtained.Results and Conclusion:Finally, we can calculate the different effective stress, pore throat parameters (pore throat radius, shape factor, coordination number, pore-throat ratio) and relative permeability of different formation water injury times. The research results demonstrate that in sandstone gas reservoir development, as the effective stress continuously increases, the rock pore-throat parameters continue to decrease, and the permeability of the reservoir rock ultimately declines by more than 43.2%. Clay minerals will expand after the edge and bottom water intrude into the reservoir and soak it for a long time: the pore throat is significantly narrowed within 30 days, while after 30 days more, the pore throat undergoes any only slight further changes, and the final permeability decline of the reservoir rock is up to 5.7%. The research results provide important basic petrophysical data for the development of loose sandstone gas reservoirs which, in turn, provide a scientific basis for formulating a reasonable gas production rate in a gas reservoir.

THE GEOMETRICAL CHARACTERIZATION OF NEURAL ACTIVITY DISPLAYS A SENSITIVITY TO CONVULSANTS

1991 ◽  
Vol 01 (01) ◽  
pp. 253-259 ◽  
Author(s):  
I. D. ZIMMERMAN ◽  
P. E. RAPP ◽  
A. I. MEES
Keyword(s):  
Interspike Interval ◽  
Three Dimensional ◽  
Interval Data ◽  
Time Intervals ◽  
Geometrical Characterization ◽  
Single Nerve ◽  
Before And After ◽  
The Mean ◽  
Standard Techniques

Direct application of a drop of penicillin to the brain's surface can elicit brain electrical activity similar to that seen in some forms of epilepsy. The procedure has therefore become one of the standard techniques in the experimental investigation of epilepsy. The time intervals between action potentials, called the interspike intervals, were measured from single nerve cells in the cerebral cortex of the rat before and after local administration of penicillin. The resulting interspike interval data were examined by elementary statistical procedures and by embedding the data in two- and three-dimensional spaces. The mean interspike interval did not change significantly in response to penicillin. In contrast, the geometrical characterization displayed a dramatic sensitivity to the drug.

JOINT IMPEDANCE INVERSION AND SPECTRAL DECOMPOSITION FOR DEEPWATER GAS RESERVOIR CHARACTERIZATION: A CASE STUDY IN SOUTH CHINA SEA

2020 ◽  
pp. 1-74
Author(s):  
Yaneng Luo ◽  
Mengqi Jiang ◽  
Kun Xiang ◽  
Yadi Yang ◽  
Handong Huang
Keyword(s):  
Spatial Distribution ◽  
Acoustic Impedance ◽  
Spectral Decomposition ◽  
Reservoir Characterization ◽  
Well Log ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Absorption Effect ◽  
Impedance Inversion ◽  
Gas Bearing

Gas reservoir characterization is one of the frontiers in seismic exploration. Acoustic impedance, one of the most effective seismic attributes, aims to describe the spatial distribution of rock properties. However, using acoustic impedance only is insufficient to describe gas-bearing layers accurately, in the case of rapid lithologic changes and complex geology in the deepwater area. The reflection seismograms show an absorption effect when seismic waves propagate through gas-bearing layers. The absorption effect can be used as an additional attribute to help gas reservoir characterization. Therefore, a new attribute is proposed for gas reservoir characterization in this study, which integrates the results of acoustic impedance and absorption coefficient. We estimate the acoustic impedance model by employing poststack impedance inversion and then we calculate probability distribution functions. Functions are classified into gas-bearing and non-gas layers. We discuss an absorption coefficient and obtain it from the spectrum gradient, where the gradient is calculated by spectral decomposition using the matching pursuit method. We apply the new attribute to characterize the spatial distribution and thickness of deepwater gas reservoirs in the Pearl River Mouth Basin. Well-log and geologic information show that the study area has an enrichment of gas reservoirs. Field data application shows the explicit distribution of the gas reservoir and in accordance with the well-log information, which indicates that the proposed attribute can improve gas reservoir characterization.

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