scholarly journals Characterization of reservoir sands using 3D seismic attributes in the coastal swamp area of Niger Delta Basin

2021 ◽  
Author(s):  
Oluwatoyin Khadijat Olaleye ◽  
Pius Adekunle Enikanselu ◽  
Michael Ayuk Ayuk
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Seismic Attributes ◽  
Effective Porosity ◽  
High Porosity ◽  
Hydrocarbon Accumulation ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Niger Delta Basin

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.

scholarly journals Application of 3D Seismic Attribute Analyses for Hydrocarbon Prospectivity in Uzot-Field, Onshore Niger Delta Basin, Nigeria

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
U. C. Omoja ◽  
T. N. Obiekezie
Keyword(s):  
Niger Delta ◽  
Hanging Wall ◽  
Average Energy ◽  
Maximum Amplitude ◽  
Seismic Attributes ◽  
Bright Spot ◽  
Maximum Magnitude ◽  
3D Seismic ◽  
Amplitude Maximum ◽  
Niger Delta Basin

3D seismic interpretative study was carried out across the Uzot-field in the western Coastal Swamp Depobelt of the onshore Niger Delta Basin, Nigeria, with the aim to identify possible hydrocarbon leads and prospects away from the drilled zone, utilizing seismic amplitude attributes. The method employed in this study involved systematic picking of faults and mapping of horizons/reservoir tops across seismic volume and extraction of seismic attributes. Structural analysis indicates the presence of down-to-basin footwall and hanging wall faults associated with rollover anticlines and horst-block (back-to-back fault). Generated time and depth structural maps from three reservoir intervals (D3100, D5000, and D9000) revealed the presence of fault dependent closure across the field. Analyses of relevant seismic attributes such as root-mean-square (RMS) amplitude, maximum amplitude, average energy amplitude, average magnitude amplitude, maximum magnitude attribute, and standard deviation amplitude, which were applied on reservoir tops, revealed sections with bright spot anomalies. These amplitude anomalies served as direct hydrocarbon indicators (DHIs), unravelling the presence and possible hydrocarbon prospective zones. In addition, structural top maps show that booming amplitude is seen within the vicinity of fault closures, an indication that these hydrocarbon prospects are structurally controlled. Results from this study have shown that, away from currently producing zone at the central part of the field, additional leads and prospects exist, which could be further evaluated for hydrocarbon production.

scholarly journals Evaluation of seismic attributes for reservoir characterization over Edi field, Niger delta, Nigeria using 3d seismic data

2020 ◽  
Vol 8 (2) ◽  
pp. 168
Author(s):  
Nyeneime O. Etuk ◽  
Mfoniso U. Aka ◽  
Okechukwu A. Agbasi ◽  
Johnson C. Ibuot
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Reservoir Characterization ◽  
Seismic Attributes ◽  
3D Seismic ◽  
Root Mean Square Amplitude ◽  
Phase Gradient ◽  
Major Fault ◽  
Seismic Sections ◽  
3D Seismic Data

Seismic attributes were evaluated over Edi field, offshore Western Niger Delta, Nigeria, via 3D seismic data. Manual mappings of the horizons and faults on the in-lines and cross-lines of the seismic sections were done. Various attributes were calculated and out put on four horizons corresponding to the well markers at different formations within the well were identified. The four horizons identified, which includes: H1, H2, H3 and H4 were mapped and interpreted across the field. The operational agenda was thru picking given faults segments on the in–line of seismic volume. A total of five faults coded as F1, F2, F3, F4 and F5, F1 and F5 were the major fault and were observed as extending through the field. Structural and horizon mappings were used to generate time structure maps. The maps showed the various positions and orientations of the faults. Different attributes which include: root mean square amplitude, instantaneous phase, gradient magnitude and chaos were run on the 3D seismic data. The amplitude and incline magnitude maps indicate direct hydrocarbon on the horizon maps; this is very important in the drilling of wells because it shows areas where hydrocarbons are present in the subsurface. The seismic attributes revealed information, which was not readily apparent in the raw seismic data.   

Identification of polygonal faulting from legacy 3D seismic data in vintage Gulf of Mexico data using seismic attributes

2021 ◽  
pp. 1-17
Author(s):  
Karen M. Leopoldino Oliveira ◽  
Heather Bedle ◽  
Karelia La Marca Molina
Keyword(s):  
Seismic Data ◽  
Seismic Attributes ◽  
Fault System ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Variable Amplitude ◽  
Attribute Analysis ◽  
Amplitude Data ◽  
3D Seismic Data ◽  
Polygonal Fault

We analyzed a 1991 3D seismic data located offshore Florida and applied seismic attribute analysis to identify geological structures. Initially, the seismic data appears to have a high signal-to-noise-ratio, being of an older vintage of quality, and appears to reveal variable amplitude subparallel horizons. Additional geophysical analysis, including seismic attribute analysis, reveals that the data has excessive denoising, and that the continuous features are actually a network of polygonal faults. The polygonal faults were identified in two tiers using variance, curvature, dip magnitude, and dip azimuth seismic attributes. Inline and crossline sections show continuous reflectors with a noisy appearance, where the polygonal faults are suppressed. In the variance time slices, the polygonal fault system forms a complex network that is not clearly imaged in the seismic amplitude data. The patterns of polygonal fault systems in this legacy dataset are compared to more recently acquired 3D seismic data from Australia and New Zealand. It is relevant to emphasize the importance of seismic attribute analysis to improve accuracy of interpretations, and also to not dismiss older seismic data that has low accurate imaging, as the variable amplitude subparallel horizons might have a geologic origin.

scholarly journals Study on the 3D Sedimentary Characteristics of Sandstone Type Uranium Reservoir Based on 3D Seismic Attribute

Minerals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1096
Author(s):  
Zhangqing Sun ◽  
Yaguang Liu ◽  
Fuxing Han ◽  
Fengjiao Zhang ◽  
Xiyang Ou ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Attributes ◽  
3D Seismic ◽  
Uranium Deposits ◽  
Seismic Attribute ◽  
Sedimentary Characteristics ◽  
Reference Information ◽  
Drilling Data ◽  
The One

It is of great significance to quickly obtain the sedimentary characteristics of sandstone type uranium reservoir for guiding prospecting sandstone type uranium deposits. In order to solve this problem, a method based on the extraction and optimization of 3D seismic attributes is proposed. The target stratum of the uranium reservoir is accurately located by using the gamma and acoustic logging data together. The well seismic calibration for the uranium reservoir is carried out by making full use of the logging and seismic data. The high-density fine horizon tracking is implemented for the top, bottom, and obvious adjacent interfaces of the target stratum. Various seismic attributes along the target interface are extracted using stratigraphic slices. Analyzing the consistency between the results obtained by various seismic attributes and drilling data, the one that can best characterize the sedimentary characteristics of the target uranium reservoir is selected as the optimal seismic attribute. The sedimentary and its evolutionary characteristics of the target uranium reservoir are obtained by extracting the above optimal seismic attribute. A case study shows that we can obtain the 3D sedimentary characteristics of the target uranium reservoir fast and efficiently using the method based on the 3D seismic attribute. They can be used for providing important reference information for the exploration of sandstone type uranium deposits.

The Application of Seismic Attribute in the Prediction of Inner Front Facies Sands

2012 ◽  
Vol 616-618 ◽  
pp. 705-709
Author(s):  
Kai Chun Yu ◽  
Yan Zhu ◽  
Yan Meng
Keyword(s):  
Comparative Analysis ◽  
Seismic Data ◽  
Prediction Accuracy ◽  
Seismic Attributes ◽  
Small River ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Well Spacing ◽  
Reservoir Description ◽  
3D Seismic Data

The south of Daqing placanticline is mainly front facies reservoir which is chiefly the smooth, direct, narrow and small river. The size of the river is small and the reservoir thickness is mainly 1.0m-1.2m.The prediction accuracy of the interwell sandbody is only up to 60~70% under the condition of existing well network and well spacing, causing the relatively worse development effect. In order to raise the prediction accuracy of the interwell sandbody, it proposes the thinking of identifying the boundary and orientation of the inner front facies by means of the combination of wells and seismos of 3D seismic data. After the comparative analysis of the wells and the seismos, it determines the seismic attributes which can reflect the sandstone and identify mudstone preferablely, and proposes the method of reservoir description by means of the combination of wells and seismos which makes the prediction accuracy of the interwell sandbody reach to 80.77%.

Estimation of effective porosity using geostatistics and multiattribute transforms: A case study

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 352-372 ◽  
Author(s):  
A. G. Pramanik ◽  
V. Singh ◽  
Rajiv Vig ◽  
A. K. Srivastava ◽  
D. N. Tiwary
Keyword(s):  
Seismic Data ◽  
Acoustic Impedance ◽  
Reservoir Characterization ◽  
Middle Eocene ◽  
Seismic Attributes ◽  
Effective Porosity ◽  
3D Seismic ◽  
Porosity Distribution ◽  
Porosity Logs ◽  
3D Seismic Data

The middle Eocene Kalol Formation in the north Cambay Basin of India is producing hydrocarbons in commercial quantity from a series of thin clastic reservoirs. These reservoirs are sandwiched between coal and shale layers, and are discrete in nature. The Kalol Formation has been divided into eleven units (K‐I to K‐XI) from top to bottom. Multipay sands of the K‐IX unit 2–8 m thick are the main hydrocarbon producers in the study area. Apart from their discrete nature, these sands exhibit lithological variation, which affects the porosity distribution. Low‐porosity zones are found devoid of hydrocarbons. In the available 3D seismic data, these sands are not resolved and generate a composite detectable seismic response, making reservoir characterization through seismic attributes impossible. After proper well‐to‐seismic tie, the major stratigraphic markers were tracked in the 3D seismic data volume for structural mapping and carrying out attribute analysis. The 3D seismic volume was inverted to obtain an acoustic impedance volume using a model‐based inversion algorithm, improving the vertical resolution and resolving the K‐IX pay sands. For better reservoir characterization, effective porosity distribution was estimated through different available techniques taking the K‐IX upper sand as an example. Various sample‐based seismic attributes, the impedance volume, and effective porosity logs were used as inputs for this purpose. These techniques are map‐based geostatistical methods using the acoustic impedance volume, stepwise multilinear regression, probabilistic neural networks (PNN) using multiattribute transforms, and a new technique that incorporates both geostatistics and multiattribute transforms (either linear or nonlinear). This paper is an attempt to compare different available techniques for porosity estimation. On comparison, it is found that the PNN‐based approach using ten sample‐based attributes showed highest crosscorrelation (0.9508) between actual and predicted effective porosity logs at eight wells in the study area. After validation, the predicted effective porosity maps for the K‐IX upper sand are generated using different techniques, and a comparison among them is made. The predicted effective porosity map obtained from PNN‐based model provides more meaningful information about the K‐IX upper sand reservoir. In order to give priority to the actual effective porosity values at wells, the predicted effective porosity map obtained from PNN‐based model for the K‐IX upper sand was combined with actual effective porosity values using co‐kriging geostatistical technique. This final map provides geologically more realistic predicted effective porosity distribution and helps in understanding the subsurface image. The implication of this work in exploration and development of hydrocarbons in the study area is discussed.

Characterization of a fracture zone using seismic attributes at the In Salah CO2 storage project

2015 ◽  
Vol 3 (2) ◽  
pp. SM37-SM46 ◽  
Author(s):  
Rui Zhang ◽  
Donald Vasco ◽  
Thomas M. Daley ◽  
William Harbert
Keyword(s):  
Carbon Dioxide ◽  
Fracture Zone ◽  
Seismic Data ◽  
Co2 Storage ◽  
Seismic Attributes ◽  
3D Seismic ◽  
Lower Velocity ◽  
Surface Uplift ◽  
3D Seismic Data

The In Salah carbon dioxide storage project in Algeria has injected more than 3 million tons of carbon dioxide into a water-filled tight-sand formation. During injection, interferometric synthetic aperture radar (InSAR) reveals a double-lobed pattern of up to a 20-mm surface uplift above the horizontal leg of an injection well. Interpretation of 3D seismic data reveals the presence of a subtle linear push-down feature located along the InSAR determined surface depression between the two lobes, which we interpreted to have to be caused by anomalously lower velocity from the fracture zone and the presence of [Formula: see text] displacing brine in this feature. To enhance the seismic interpretation, we calculated many poststack seismic attributes, including positive and negative curvatures as well as ant track, from the 3D seismic data. The maximum positive curvature attributes and ant track found the clearest linear features, with two parallel trends, which agreed well with the ant-track volume and the InSAR observations of the depression zone. The seismic attributes provided a plausible characterization of the fracture zone extent, including height, width, and length (80, 350, and 3500 m, respectively), providing important information for further study of fracture behavior due to the [Formula: see text] injection at In Salah. We interpreted the pattern of depression between two surface-deformation lobes as caused by the opening of a subvertical fracture or damage zone at depth above the injection interval, which allowed injected [Formula: see text] to migrate upward. Our analysis corroborated previous interpretation of surface uplift as due to the injection of [Formula: see text] in this well.

NEW SEISMIC METHODS AND POTENTIAL FORTHE REGION

2000 ◽  
Vol 40 (1) ◽  
pp. 326 ◽  
Author(s):  
S.B. Reymond
Keyword(s):  
Seismic Data ◽  
Seismic Attributes ◽  
3D Seismic ◽  
Data Types ◽  
Seismic Attribute ◽  
Single Class ◽  
Polynomial Coefficients ◽  
Seismic Methods ◽  
Exploration And Production ◽  
New Interpretation

New seismic data types and new interpretation tools are rapidly changing and expanding the applicability of seismic methods. In Australia, the hydrocarbon and mining industries are both using an increased proportion of 3D seismic data to improve lateral predictability and to reduce exploration and production risks and costs. New techniques and workflows described below are expected to come into more common usage over the next five years.3D reservoir characterisation workflows integrate all reservoir data types including well log measurements, seismic data, reservoir models and simulations. Within the domain of seismic data, complementary data types, such as 3D, 4D, 4C, AVO and down-hole seismic, need to be synthesised into a single optimum reservoir representation. One way of producing such results is by using seismic classification which is based on a set of geostatistical and neural network algorithms to produce a single class map or cube mapping reservoir parameters with an uncertainty estimate associated with each trace and sample location.Seismic classification is applied to two types of seismic data: attribute grids and 3D seismic attribute cubes. Seismic classification provides a tool for generalised inversion of seismic data for lithofacies, faults and fluids (DHI, Direct Hydrocarbon Indicators). At the acquisition and processing stages of seismic data, the same classification algorithms are used to assess data quality to quantify and improve seismic data quality.Recent developments in seismic attributes have shown that additional reservoir characterisation information is obtained by decomposing the seismic trace into a set of polynomial coefficients. Such seismic attributes are computed both on the seismic trace and on a synthetic trace computed along the borehole trajectory in order to calibrate the seismic attribute by measured reservoir parameters.An increasing number of 3D attribute cubes or transforms of the raw seismic volume are used by geophysicists to better capture lateral changes in seismic response. The potential and pitfalls of 3D attribute cubes are illustrated with reference to Australasian examples.Increasing interest is also being shown in fault and fracture mapping bom seismic data with applications in both the mining and hydrocarbon industries. Fault mapping and automated extraction can both be based on structural seismic attribute grids and cubes.

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