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.

scholarly journals A Parallel Stochastic Framework for Reservoir Characterization and History Matching

2011 ◽  
Vol 2011 ◽  
pp. 1-19 ◽  
Author(s):  
Sunil G. Thomas ◽  
Hector M. Klie ◽  
Adolfo A. Rodriguez ◽  
Mary F. Wheeler
Keyword(s):  
Porous Media ◽  
Spatial Distribution ◽  
Multiphase Flow ◽  
History Matching ◽  
Reservoir Characterization ◽  
Well Log ◽  
Species Transport ◽  
Medium Permeability ◽  
Stochastic Framework ◽  
Sensor Information

The spatial distribution of parameters that characterize the subsurface is never known to any reasonable level of accuracy required to solve the governing PDEs of multiphase flow or species transport through porous media. This paper presents a numerically cheap, yet efficient, accurate and parallel framework to estimate reservoir parameters, for example, medium permeability, using sensor information from measurements of the solution variables such as phase pressures, phase concentrations, fluxes, and seismic and well log data. Numerical results are presented to demonstrate the method.

Seismic reservoir characterization of Utica-Point Pleasant shale with efforts at fracability evaluation — Part 2: A case study

2018 ◽  
Vol 6 (2) ◽  
pp. T325-T336 ◽  
Author(s):  
Ritesh Kumar Sharma ◽  
Satinder Chopra ◽  
James Keay ◽  
Hossein Nemati ◽  
Larry Lines
Keyword(s):  
Seismic Data ◽  
Reservoir Characterization ◽  
Low Frequency ◽  
Rock Physics ◽  
Well Log ◽  
X Ray Diffraction ◽  
Impedance Inversion ◽  
Seismic Reservoir ◽  
Petrophysical Modeling

The Utica Formation in eastern Ohio possesses all the prerequisites for being a successful unconventional play. Attempts at seismic reservoir characterization of the Utica Formation have been discussed in part 1, in which, after providing the geologic background of the area of study, the preconditioning of prestack seismic data, well-log correlation, and building of robust low-frequency models for prestack simultaneous impedance inversion were explained. All these efforts were aimed at identification of sweet spots in the Utica Formation in terms of organic richness as well as brittleness. We elaborate on some aspects of that exercise, such as the challenges we faced in the determination of the total organic carbon (TOC) volume and computation of brittleness indices based on mineralogical and geomechanical considerations. The prediction of TOC in the Utica play using a methodology, in which limited seismic as well as well-log data are available, is demonstrated first. Thereafter, knowing the nonexistence of the universally accepted indicator of brittleness, mechanical along with mineralogical attempts to extract the brittleness information for the Utica play are discussed. Although an attempt is made to determine brittleness from mechanical rock-physics parameters (Young’s modulus and Poisson’s ratio) derived from seismic data, the available X-ray diffraction data and regional petrophysical modeling make it possible to determine the brittleness index based on mineralogical data and thereafter be derived from seismic data.

scholarly journals Rock Physics Formula and RMS Stacking Velocity Calculation to Assist Acoustic Impedance Inversion that Constrain Well Data

2020 ◽  
Vol 5 (2) ◽  
pp. 68-72
Author(s):  
Handoyo ◽  
Mochammad Puput Erlangga ◽  
Paul Young
Keyword(s):  
Acoustic Impedance ◽  
Rock Physics ◽  
Well Log ◽  
Initial Model ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion ◽  
The Matrix ◽  
Using Data ◽  
Well Data ◽  
Interval Velocities

This research ilustrate the generation of acoustic impedance inversion in the absence of well log using stacking velocity input in Salawati Basin, Papua, Indonesia using data obtained from seismic lines and stacking velocity section. Initial acoustic impedance modelswere first before the inversion process and were created by spreading the value of well log data to the all seismic CDP. The calculated acoustic impedance logs from standard sonic and density logs were used to build the initial model of acoustic impedance.First, the stacking velocities was first interpolated on a grid that has the same size as the seismic data using by means of Polynomial algorithm. This was closely followed by the conversion of the stacking velocities to interval velocities using Dix’s equation. The matrix densities were estimated by simple rock physics approach i.e. Gardner’s equation as a velocity function. The initial model of acoustic impedance was calculated by multiplying the densities section and interval velocities section. The resulting initial model of acoustic impedance was inverted to obtain the best of acoustic impedance section based on reflectivity.

scholarly journals Application of the Acoustic Impedance (AI) Seismic Inversion and Multi-Attribute Method for Reservoir Characterization in Bonaparte Basin

2021 ◽  
Vol 4 (1) ◽  
pp. 8-20
Author(s):  
Maurin Puspitasari ◽  
Ambran Hartono ◽  
Egie Wijaksono ◽  
Tati Zera
Keyword(s):  
Acoustic Impedance ◽  
Stepwise Regression ◽  
Reservoir Characterization ◽  
Seismic Inversion ◽  
Impedance Method ◽  
Linear Regression Method ◽  
Seismic Method ◽  
Impedance Inversion ◽  
Southwest Part ◽  
Acoustic Impedance Method

Research on the application of the acoustic impedance (AI) seismic inversion and multi-attribute method was conducted with the aim to characterize the reservoir in the Bonaparte Basin. The modeling which used in the acoustic impedance inversion seismic method is model-based. Meanwhile, the multi-attribute seismic method used log porosity that appliying the linear regression method and using the stepwise regression technique. Based on the result of the sensitivity analysis and analysis using the seismic inversion acoustic impedance method, the sandstone reservoir zone that has the prospect of hydrocarbons containing gas is located in the Northeast-Southwest part of the study area which in WCB-1, WCB-3 and WCB-4 well with the acoustic impedance values are in the range of 4,800 - 13,000 (m / s) * (g / cc), and the porosity values generated from the analysis using the multi-attribute seismic method are in the range of 5 - 16% in WCB-1 and WCB-4, 2 - 10% on WCB-3.

scholarly journals Improved neural network model of assessment for interpretation of miocene lithofacies in the Vukovar formation, Northern Croatia / Izboljšani nevronsko-mrežni model za oceno interpretacije miocenskega litofaciesa v Vukovarski formaciji v severni Hrvaški

2018 ◽  
Vol 65 (3) ◽  
pp. 145-156
Author(s):  
Varenina Andrija ◽  
Malvić Tomislav ◽  
Mate Režić
Keyword(s):  
Neural Networks ◽  
Oil And Gas ◽  
Neural Model ◽  
Oil Reservoir ◽  
Well Log ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Lithological Composition ◽  
Northern Croatia ◽  
The City

Abstract The Ladislavci Field (oil and gas reservoirs) is located 40 km from the city of Osijek, Croatia. The oil reservoir is in structural-stratigraphic trap and Miocene rocks of the Vukovar formation (informally named as El, F1a and F1b). The shallower gas reservoir is of Pliocene age, i.e. part of the Osijek sandstones (informally named as B). The oil reservoirs consist of limestones, breccias and conglomerates, and gas is accumulated in sandstones. Using neural networks, it was possible to interpret applicability of neural algorithm in well log analyses, and using neural model, it was possible to predict reservoir without or with small number of log data. Neural networks are trained on the data from two wells (A and B), collected from the interval starting with border of Sarmatian/ Lower Pannonian (EL marker Rs7) to the well’s bottom. The inputs were data from spontaneous potential (SP) and resistivity (R16 and R64) logs. They were used for neural training and validation as well as for final prediction of lithological composition in the analysed field. The multilayer perceptron (MLP) network had been selected as the most appropriate.

Cases of Generalized Low-frequency Shadows of Tight Gas Reservoirs

2021 ◽  
pp. 1-40
Author(s):  
Renhai Pu ◽  
Qiang Han ◽  
Pengye Xu
Keyword(s):  
Ordos Basin ◽  
Low Frequency ◽  
Energy Difference ◽  
Dominant Frequency ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Tight Gas Reservoir ◽  
Gas Layer ◽  
Gas Bearing

The phenomenon that frequency decreases and amplitude increases near the bottom of a gas layer on a seismic profile is called a low-frequency shadow, but this phenomenon may not occur in all gas reservoirs. When the tight gas reservoir is thick enough, spectral decomposition data after Fourier transform will show the characteristics similar to those of low-frequency shadows. We call it a generalized low-frequency shadows. Compared with dominant frequency of non-gas-bearing zone spectral, the dominant frequency of a gas zone moves toward the low end of the frequency range and the low-frequency amplitude increases accordingly. By analyzing known gas reservoirs such as the Sulige and Yanchang tight sandstones in the Ordos Basin and tight carbonate rocks in the Tarim Basin, we can see that, with the visual dominant seismic frequency close to 30 Hz, the peak frequency of the gas-bearing tight sandstones and tight dolomite reservoirs will move from about 30 Hz to about 10–15 Hz. There is a certain correlation between the drop of the dominant frequency of a tight gas reservoir, the attenuation energy difference, and the thickness and productivity of the gas layer. Several cases show that nearly all tight gas layers thicker than 15 m exhibit attenuation characteristics of the generalized low-frequency shadows.

Rock Property Cross-Plot Analysis and Post-Stack Acoustic Impedance Inversion for Optimal Reservoir Characterization in Aplha Field, Onshore Niger Delta Basin

2021 ◽  
Author(s):  
George-Best Azuoko ◽  
Amobi Ekwe ◽  
Amulu Emmanuel ◽  
Ayatu Usman ◽  
Eluwa Ndidiamaka ◽  
...  
Keyword(s):  
Acoustic Impedance ◽  
Reservoir Characterization ◽  
Water Saturation ◽  
Seismic Inversion ◽  
Hydrocarbon Reservoirs ◽  
Event Time ◽  
Plot Analysis ◽  
Impedance Inversion ◽  
Acoustic Impedance Inversion ◽  
Niger Delta Basin

Abstract In the quest to recover by-passed hydrocarbons, extend the life of mature fields, increase hydrocarbon reserves and satiate the increasing global demand for energy, the need for robust reservoir characterization using acoustic impedance inversion continues to grow. In this study, petrophysical parameters were evaluated for two sand intervals RX2 and RX5. Detailed cross-plot analysis of robust petrophysical properties, (density, water Saturation, Lambda-rho and Mu-rho and Porosity) facilitated fluid and lithology discrimination. Well to seismic correlations and acoustic-Impedance model-based, 3-D seismic inversion was done using Hampson Russell software, while petrophysical attribute slices and event-time structure maps were extracted at two horizons - H1 and H2. Results show that RX2 is 100ft thick in Well A, ranging from 5860ft to 5960ft, and 141ft thick in Well B, ranging from 5794ft to 5935ft. Interval RX5, 71ft thick, ranges from 6447ft to 6518ft in Well A, and 88ft thick in Well B, ranging from 6447ft to 6535ft. These intervals had average densities of 2.20g/cc for RX2 and 2.23g/cc for RX5 in Well A. In well B, density values are 1.95g/cc in RX2 and 2.06g/cc for RX5. Average porosities of 25.5% and 27.5% in RX2 and RX5 respectively for Well A; 29% and 19% in RX2 and RX5 respectively for Well B were observed. Respectively, average water and hydrocarbon saturation values of 0.31Swand 0.69Shfor Well A; 0.51Swand 0.49Shfor Well B, was recorded in both intervals. From the results, the thicknesses of RX2 and RX5 conform to the standard thickness of hydrocarbon reservoirs in the study area. Furthermore, the discrimination of the reservoir contents into fluid and lithology by the cross plots, and the observations in the attribute slices indicate that the selected intervals RX2 and RX5 are viable conventional hydrocarbon reservoirs.

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