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Anyang, South Korea

Jung S.,Korea National Oil Corporation | Choe J.,Seoul National University
Energy Sources, Part A: Recovery, Utilization and Environmental Effects | Year: 2010

Oil reserves can be estimated by numerical simulations in a waterflooded production system. For accurate reserves estimations, reservoir models should be calibrated by production history data with optimization schemes, which typically ensure better matches on the production data and permeability distribution. More reliable estimations with uncertainty could be conducted through stochastic estimations after history matching. The developed ensemble Kalman filter history matching technique can overcome the non-uniqueness problem and efficiently estimate oil reserves for decision-making with uncertainties.

Lee J.O.,Korea Atomic Energy Research Institute | Kang I.M.,Korea National Oil Corporation | Cho W.J.,Korea Atomic Energy Research Institute
Applied Clay Science | Year: 2010

Hydrothermal tests were conducted to investigate smectite alteration and its influence on the barrier properties of a smectite clay for a repository. Examinations of the X-ray diffraction patterns of the starting material and reacted samples and the silica release rate in the solution revealed that the smectite was transformed into randomly interstratified illite-smectite by a smectite-to-illite conversion when it was hydrothermally treated under a potassium concentration of 0.5 M, maintaining a 1 g/20 ml of solid sample-to-solution ratio. Temperature was observed to be a key factor controlling the conversion reaction. The smectite alteration affected the barrier properties of smectite clay for a repository: when the temperature increased, the percentage of the expandable smectite layers in the randomly interstratified illite-smectite decreased, the layer charge was more negative, and the cation exchange capacity and the sorption capacity for the cesium and nickel ions were reduced. © 2008 Elsevier B.V. All rights reserved.

Jeong W.,Seoul National University | Lee H.-Y.,Korea National Oil Corporation | Min D.-J.,Seoul National University
Geophysical Journal International | Year: 2012

To interpret subsurface structures properly, elastic wave propagation must be considered. Because elastic media are described by more parameters than acoustic media, elastic waveform inversion is more likely to be affected by local minima than acoustic waveform inversion. In a conventional elastic waveform inversion, P- and S-wave velocities are properly recovered, whereas density is difficult to reconstruct. For this reason, most elastic full-waveform inversion studies assume that density is fixed. Although several algorithms have been developed that attempt to describe density properly, their results are still not satisfactory. In this study, we propose a two-stage elastic waveform inversion strategy to recover density properly. The Lamé constants are first recovered while holding density fixed. While the Lamé constants and density are not correct under this assumption, the velocities obtained using these incorrect Lamé constants and constant density may be reliable. In the second stage, we simultaneously update density and Lamé constants using the wave equations expressed through velocities and density. While density is updated following the conventional method, the Lamé constants are updated using the gradient obtained by applying the chain rule. Among several parameter-selection strategies tested, only this strategy gives reliable solutions for both velocities and density. Our elastic full waveform inversion algorithm is based on the finite-element method and the backpropagation technique in the frequency domain. We demonstrate our inversion strategy for the modified Marmousi-2 model and the SEG/EAGE salt model. Numerical examples show that this new inversion strategy enhances density inversion results. © 2012 The Authors Geophysical Journal International © 2012 RAS.

Han W.S.,University of Wisconsin - Milwaukee | Kim K.-Y.,Korea Institute of Geoscience and Mineral Resources | Park E.,Kyungpook National University | McPherson B.J.,University of Utah | And 2 more authors.
Transport in Porous Media | Year: 2012

We evaluated the thermal processes with numerical simulation models that include processes of solid NaCl precipitation, buoyancy-driven multiphase SCCO 2 migration, and potential non-isothermal effects. Simulation results suggest that these processes-solid NaCl precipitation, buoyancy effects, JT cooling, water vaporization, and exothermic SCCO 2 reactions-are strongly coupled and dynamic. In addition, we performed sensitivity studies to determine how geologic (heat capacity, brine concentration, porosity, the magnitude and anisotropy of permeability, and capillary pressure) and operational (injection rate and injected SCCO 2 temperature) parameters may affect these induced thermal disturbances. Overall, a fundamental understanding of potential thermal processes investigated through this research will be beneficial in the collection and analysis of temperature signals collectively measured from monitoring wells. © 2012 Springer Science+Business Media B.V.

Yang B.,Korea National Oil Corporation
Society of Petroleum Engineers - Unconventional Resources Technology Conference, URTeC 2015 | Year: 2015

The main structural features affecting the Mesozoic sequences of the Gulf rim are a series of interior salt basins extending from south Texas to Alabama. These basins formed during the rifting stage of the formation of the Gulf of Mexico. The early Oxfordian Smackover Formation, characterized by organic-rich, carbonate source rock intervals, represents the initial phase of the Late Jurassic marine transgression in the Gulf of Mexico Basin, where a density-stratified shallow sea was developed. It is predominantly composed of carbonates and calcareous shales and can easily be correlated by its lithology for considerable distances along its depositional strike. Over most of the Gulf coast, it can be subdivided into two distinct units. The Lower Smackover Formation (Brown Dense) is composed of dark-colored, organic-rich carbonate mudstone and dense argillaceous limestone deposited in a low-energy setting, while the Upper Smackover Formation is typically composed of coarser, grain-supported, porous carbonates formed in a high-energy shallow-water environment. Oil and gas resources have been produced from the more porous upper unit on which most geologic works have mainly focused. The Brown Dense has been, however, less studied, although it could become a viable resource play with the utilization of modern drilling techniques. Recently collected 450-ft (ca. 137 m) thick core and full-suite well logs have been studied to delineate geologic features, the results of which would be significant impact on exploration programs. The detailed geologic studies have revealed that 1) the Brown Dense interval comprises the multi-stacked cyclic succession, having the coarsening-upward trend, in which the basal part is dominated with organic-rich deposits, grading upward into algal laminite-like deposits, 2) each coarsening-upward succession (interpreted as parasequence), sharply demarcated by flooding surface, would be deposited during a regression period, 3) the porosity-permeability trend is characterized by organic-rich deposits that have relatively high effective porosity (average > 3%) and permeability (up to 5 μD), respectively 4) the presence of framboidal pyrites is mostly associated with organic-rich layers, where relatively high porosity is evident, 5) porosity is mainly comprised of the shelter type with some amounts of interparticle and intraparticle pores, and 6) cementation might be severe throughout the entire interval, but it would be limited within the organic layers. Copyright 2015, Unconventional Resources Technology Conference.

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