Rock property- and seismic-attribute analysis of a chert reservoir in the Devonian Thirty-one Formation, west Texas, U.S.A.

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. B151-B158 ◽  
Author(s):  
Dongjun (Taller) Fu ◽  
E. Charlotte Sullivan ◽  
Kurt J. Marfurt
Keyword(s):  
Rock Physics ◽  
Wave Impedance ◽  
Seismic Inversion ◽  
P Wave ◽  
Seismic Attribute ◽  
West Texas ◽  
Attribute Analysis ◽  
Bedded Chert ◽  
Petrophysical Logs ◽  
Tripolitic Chert

In west Texas, fractured-chert reservoirs of Devonian age have produced more than 700 million barrels of oil. About the same amount of mobile petroleum remains in place. These reservoirs are characterized by microporosity; they are heterogeneous and compartmented, which results in recovery of less than 30% of the oil in place. In this case study the objective was to use cores, petrophysical logs, rock physics, and seismic attributes to characterize porosity and field-scale fractures. The relations among porosity, velocity, and impedance were explored and also reactions among production, impedance, and lineaments observed in 3D attribute volumes. Laboratory core data show that Gassmann’s fluid-substitution equation works well for microporous tripolitic chert. Also, laboratry measurements show excellent linear correlation between P-wave impedance and porosity. Volumetric calculations of reflector curvature and seismic inversion of acoustic impedance were combined to infer distribution of lithofacies and fractures and to predict porosity. Statistical relations were established between P-wave velocity and porosity measured from cores, between P-wave impedance and producing zones, and between initial production rates and seismic “fracture lineaments.” The strong quantitative correlation between thick-bedded chert lithofacies and seismic impedance was used to map the reservoir. A qualitative inverse relation between the first [Formula: see text] of production and curvature lineaments was documented.

Convolutional neural network for seismic impedance inversion

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. R869-R880 ◽  
Author(s):  
Vishal Das ◽  
Ahinoam Pollack ◽  
Uri Wollner ◽  
Tapan Mukerji
Keyword(s):  
Rock Physics ◽  
Normal Incidence ◽  
Wave Impedance ◽  
Training Data ◽  
P Wave ◽  
Computation Method ◽  
Elastic Model ◽  
Spatial Correlations ◽  
Data Set ◽  
Earth Models

We have addressed the geophysical problem of obtaining an elastic model of the subsurface from recorded normal-incidence seismic data using convolutional neural networks (CNNs). We train the network on synthetic full-waveform seismograms generated using Kennett’s reflectivity method on earth models that were created under rock-physics modeling constraints. We use an approximate Bayesian computation method to estimate the posterior distribution corresponding to the CNN prediction and to quantify the uncertainty related to the predictions. In addition, we test the robustness of the network in predicting impedances of previously unobserved earth models when the input to the network consisted of seismograms generated using: (1) earth models with different spatial correlations (i.e. variograms), (2) earth models with different facies proportions, (3) earth models with different underlying rock-physics relations, and (4) source-wavelet phase and frequency different than in the training data. Results indicate that the predictions of the trained network are susceptible to facies proportions, the rock-physics model, and source-wavelet parameters used in the training data set. Finally, we apply CNN inversion on the Volve field data set from offshore Norway. P-wave impedance [Formula: see text] inverted for the Volve data set using CNN showed a strong correlation (82%) with the [Formula: see text] log at a well.

scholarly journals Microcrack Porosity Estimation Based on Rock Physics Templates: A Case Study in Sichuan Basin, China

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7225
Author(s):  
Chuantong Ruan ◽  
Jing Ba ◽  
José M. Carcione ◽  
Tiansheng Chen ◽  
Runfa He
Keyword(s):  
Sichuan Basin ◽  
Rock Physics ◽  
Wave Impedance ◽  
Gas Production ◽  
P Wave ◽  
Gas Reservoirs ◽  
Tight Sandstone ◽  
Amplitude Variation With Offset ◽  
Xujiahe Formation ◽  
Seismic Properties

Low porosity-permeability structures and microcracks, where gas is produced, are the main characteristics of tight sandstone gas reservoirs in the Sichuan Basin, China. In this work, an analysis of amplitude variation with offset (AVO) is performed. Based on the experimental and log data, sensitivity analysis is performed to sort out the rock physics attributes sensitive to microcrack and total porosities. The Biot–Rayleigh poroelasticity theory describes the complexity of the rock and yields the seismic properties, such as Poisson’s ratio and P-wave impedance, which are used to build rock-physics templates calibrated with ultrasonic data at varying effective pressures. The templates are then applied to seismic data of the Xujiahe formation to estimate the total and microcrack porosities, indicating that the results are consistent with actual gas production reports.

A Novel Approach for a better exploitation of a 3D seismic on a development field 

2021 ◽  
Author(s):  
Nasrine Medjdouba ◽  
Zahia Benaissa ◽  
Sabiha Annou
Keyword(s):  
Reservoir Characterization ◽  
Seismic Analysis ◽  
Lower Triassic ◽  
Seismic Inversion ◽  
Reservoir Properties ◽  
Seismic Attribute ◽  
Amplitude Inversion ◽  
Well Location ◽  
Attribute Analysis ◽  
Novel Approach

<p>The main hydrocarbon-bearing reservoirover the study area is the lower Triassic Argilo-Gréseux reservoir. The Triassic sand is deposited as fluvial channels and overbank sands with a thickness ranging from 10 to 20 m, lying unconformably on the Paleozoic formations. Lateral and vertical distribution of the sand bodies is challenging which makes their mapping very difficult andnearly impossible with conventional seismic analysis. </p><p>In order to better define the optimum drilling targets, the seismic attribute analysis and reservoir characterization process were performed targeting suchthin reservoir level, analysis of available two seismic vintages of PSTM cubes as well as post and pre stack inversion results were carried out.The combination of various attributes analysis (RMS amplitude, Spectral decomposition, variance, etc.) along with seismic inversion results has helped to clearly identify the channelized feature and its delineation on various horizon slices and geobodies, the results were reviewed and calibrated with reservoir properties at well location and showed remarkable correlation.</p><p>Ten development wells have been successfully drilledbased on the seismic analysis study, confirming the efficiency of seismic attribute analysis to predicted channel body geometry.</p><p>Keywords: Channel, Attributes, Amplitude, Inversion, Fluvial reservoir.</p>

Temperature, differential-pressure and porosity inversion for ultra-deep carbonate reservoirs based on 3D rock physics templates

Geophysics ◽  
2021 ◽  
pp. 1-54
Author(s):  
Yijun Wei ◽  
Jing Ba ◽  
José M. Carcione ◽  
Li-Yun Fu ◽  
Mengqiang Pang ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Rock Physics ◽  
Wave Impedance ◽  
Tectonic Stress ◽  
Differential Pressure ◽  
Carbonate Reservoirs ◽  
Hydrocarbon Exploration ◽  
P Wave ◽  
High Porosity ◽  
Temperature Differential

Ultra-deep carbonate reservoirs have high temperatures and pressures, complex pressure/tectonic stress settings and pore structures. These conditions make their seismic detection and characterization difficult, particularly if the signal-to-noise ratio is low, as it is the case in most situations. Moreover, the high risk of deep-drilling exploration makes it impractical to carry out normal logging operations. We propose a temperature-differential pressure-porosity (TPP) rock-physics model based on the Biot-Rayleigh poroelasticity theory to describe the wave response of the reservoir. A preliminary analysis shows that temperature, pressure and porosity are well correlated with wave velocity and attenuation. On the basis of this theory, we built 3D rock-physics templates that account for the effects of TPP on the P-wave impedance, VP/ VS ratio and attenuation. The templates are calibrated with laboratory, well-log and seismic data of the S area (Shuntuoguole uplift, Tarim Basin, Xinjiang, China). Then, the template is used to obtain the properties of the reservoir at seismic frequencies. The predicted results are consistent with the field reports, high temperature, low differential pressure and high porosity, indicating high production rates. The methodology will be useful for the hydrocarbon exploration in ultra-deep carbonate reservoirs.

Research of Imaging and Inversion of Seismic Attribute

2013 ◽  
Vol 774-776 ◽  
pp. 1591-1598
Author(s):  
Xiao San Hu ◽  
Guang Xun Chen ◽  
Pan Ke Qin
Keyword(s):  
Poisson Ratio ◽  
Seismic Profile ◽  
Wave Impedance ◽  
Seismic Inversion ◽  
Geological Model ◽  
Seismic Attribute ◽  
Inversion Result ◽  
And Inversion ◽  
Oil Gas

In order to improve the accuracy of inversion and quality of imaging of seismic attribute in some targeted area, a new inversion solution is proposed in this paper. By introducing instantaneous seismic inversion and hybrid inversion, the new solution can establish the geological model commendably and thus can finely depict the detailed characteristics of the structure of the stratum. Empirical results show that interpreters can obtain more precise inversion result and clearer seismic profile when adopt this new inversion solution. Hybrid inversion can deduce more reliable wave impedance, Poisson ratio, elasticity value and other important parameters, which is meaningful to the identification of oil, gas, or gas hydrate.

A predictive anisotropic rock-physics model for estimating elastic rock properties of unconventional shale reservoirs

2019 ◽  
Vol 38 (5) ◽  
pp. 358-365 ◽  
Author(s):  
Colin M. Sayers ◽  
Sagnik Dasgupta
Keyword(s):  
Accurate Determination ◽  
Rock Physics ◽  
Seismic Inversion ◽  
P Wave ◽  
Rock Properties ◽  
Anisotropic Rock ◽  
Rock Classification ◽  
Shale Reservoirs ◽  
Physics Model ◽  
Rock Physics Model

This paper presents a predictive rock-physics model for unconventional shale reservoirs based on an extended Maxwell scheme. This model accounts for intrinsic anisotropy of rock matrix and heterogeneities and shape-induced anisotropy arising because the dimensions of kerogen inclusions and pores are larger parallel to the bedding plane than perpendicular to this plane. The model relates the results of seismic amplitude variation with offset inversion, such as P- and S-impedance, to the composition of the rock and enables identification of rock classes such as calcareous, argillaceous, siliceous, and mixed shales. This allows the choice of locations with the best potential for economic production of hydrocarbons. While this can be done using well data, prestack inversion of seismic P-wave data allows identification of the best locations before the wells are drilled. The results clearly show the ambiguity in rock classification obtained using poststack inversion of P-wave seismic data and demonstrate the need for prestack seismic inversion. The model provides estimates of formation anisotropy, as required for accurate determination of P- and S-impedance, and shows that anisotropy is a function not only of clay content but also other components of the rock as well as the aspect ratio of kerogen and pores. Estimates of minimum horizontal stress based on the model demonstrate the need to identify rock class and estimate anisotropy to determine the location of any stress barriers that may inhibit hydraulic fracture growth.

Quantitative application of post-stack inversion of organic-rich shale based on rock physics linear relationship and 3D seismic data, Perth Basin, Western Australia

2014 ◽  
Vol 54 (2) ◽  
pp. 532
Author(s):  
Yazeed Altowairqi ◽  
Reza Rezaee ◽  
Milovan Urosevic
Keyword(s):  
Shale Gas ◽  
Seismic Data ◽  
Rock Physics ◽  
Seismic Inversion ◽  
3D Seismic ◽  
Physical Relationship ◽  
Seismic Properties ◽  
Attribute Analysis ◽  
Exploration And Production ◽  
Compressional Velocity

Unconventional resources such as shale gas have been an extremely important exploration and production target. To understand the seismic responses of the shale gas plays, the use of rock physical relationship is important, which is constrained with geology and formation-evaluation analysis. Since organic-rich shale seismic properties remains poorly understood, seismic inversion can be used to identify the organic-rich shale from barren shale. This approach helps identify and map spatial distributions and of the organic rich shales. This study shows the acoustic impedance (AI), which is the product of compressional velocity and density, decreases nonlinearly with increasing total organic carbon (TOC) content. TOC is obtained using Roc-Eval pyrolysis for more than 120 core shale samples for the Perth Basin. By converting the AI data to TOC precent on the seismic data, we therefore can map lateral distribution, thickness, and variation in TOC profile. This extended abstract presents a case study of the northern Perth Basin 3D seismic with application of different approaches of seismic inversion and multi-attribute analysis with the rock physical relationships.

Seismic reprocessing and interpretation of a fractured-basement play: Texas Panhandle

2017 ◽  
Vol 5 (3) ◽  
pp. SK179-SK187 ◽  
Author(s):  
Thang Ha ◽  
Kurt Marfurt
Keyword(s):  
Horizontal Stress ◽  
Wave Impedance ◽  
Azimuthal Anisotropy ◽  
Oil Field ◽  
P Wave ◽  
Coherent Noise ◽  
Seismic Attribute ◽  
Gas Field ◽  
Direction Parallel ◽  
Head Waves

The Panhandle-Hugoton field, of Texas, Oklahoma, and Kansas, is a giant oil field and is the largest conventional gas field in North America. Most hydrocarbon production in this field comes from the Wichita Uplift area, where the basement is the most shallow. Although the field has been extensively produced, many local hydrocarbon accumulations have not been fully exploited. Recent drilling activity in the survey indicates that some wells produce directly from basement fractures, suggesting a new play type for the area. Because the target is shallow, the seismic data are heavily contaminated by coherent noise, such as ground roll and head waves, creating challenges for seismic processing. To improve the seismic interpretation, we carefully reprocessed the field gathers resulting in improved correlation within the sedimentary and the basement sections. Correlating well control to seismic attribute volumes indicates that a fractured basement gives rise to lower P-wave impedance and strong amplitude versus azimuth anomalies. The azimuthal anisotropy is strongest in a direction parallel to the regional maximum horizontal stress, suggesting that these fractures are open. Coherence anomalies indicate a rugose basement surface, whereas curvature shows two lineament sets, consistent with the weathering and fractured exposure of basement in the Wichita Mountains to the southeast.

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