scholarly journals Fault interpretation uncertainties using seismic data, and the effects on fault seal analysis: a case study from the Horda Platform, with implications for CO<sub>2</sub> storage

Solid Earth ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 1259-1286
Author(s):  
Emma A. H. Michie ◽  
Mark J. Mulrooney ◽  
Alvar Braathen
Keyword(s):  
Fluid Flow ◽  
Seismic Data ◽  
Growth Models ◽  
Fault Analysis ◽  
Surface Generation ◽  
Co2 Injection ◽  
Line Spacing ◽  
Fault Growth ◽  
Fault Interpretation

Abstract. Significant uncertainties occur through varying methodologies when interpreting faults using seismic data. These uncertainties are carried through to the interpretation of how faults may act as baffles or barriers, or increase fluid flow. How fault segments are picked when interpreting structures, i.e. which seismic line orientation, bin spacing and line spacing are specified, as well as what surface generation algorithm is used, will dictate how rugose the surface is and hence will impact any further interpretation such as fault seal or fault growth models. We can observe that an optimum spacing for fault interpretation for this case study is set at approximately 100 m, both for accuracy of analysis but also for considering time invested. It appears that any additional detail through interpretation with a line spacing of ≤ 50 m adds complexity associated with sensitivities by the individual interpreter. Further, the locations of all seismic-scale fault segmentation identified on throw–distance plots using the finest line spacing are also observed when 100 m line spacing is used. Hence, interpreting at a finer scale may not necessarily improve the subsurface model and any related analysis but in fact lead to the production of very rough surfaces, which impacts any further fault analysis. Interpreting on spacing greater than 100 m often leads to overly smoothed fault surfaces that miss details that could be crucial, both for fault seal as well as for fault growth models. Uncertainty in seismic interpretation methodology will follow through to fault seal analysis, specifically for analysis of whether in situ stresses combined with increased pressure through CO2 injection will act to reactivate the faults, leading to up-fault fluid flow. We have shown that changing picking strategies alter the interpreted stability of the fault, where picking with an increased line spacing has shown to increase the overall fault stability. Picking strategy has shown to have a minor, although potentially crucial, impact on the predicted shale gouge ratio.

scholarly journals Fault Interpretation Uncertainties using Seismic Data, and the Effects on Fault Seal Analysis: A Case Study from the Horda Platform, with Implications for CO<sub>2</sub> storage

2021 ◽  
Author(s):  
Emma A. H. Michie ◽  
Mark J. Mulrooney ◽  
Alvar Braathen
Keyword(s):  
Fluid Flow ◽  
Seismic Data ◽  
Growth Models ◽  
Fault Analysis ◽  
Surface Generation ◽  
Co2 Injection ◽  
Line Spacing ◽  
Fault Growth ◽  
Fault Interpretation

Abstract. Significant uncertainties occur through varying methodologies when interpreting faults using seismic data. These uncertainties are carried through to the interpretation of how faults may act as baffles/barriers or increase fluid flow. How fault segments are picked when interpreting structures, i.e. what seismic line spacing is specified, as well as what surface generation algorithm is used, will dictate how detailed the surface is, and hence will impact any further interpretation such as fault seal or fault growth models. We can observe that an optimum spacing for fault interpretation for this case study is set at approximately 100 m. It appears that any additional detail through interpretation with a line spacing of ≤ 50 m adds complexity associated with sensitivities by the individual interpreter. Further, the location of all fault segmentation identified on Throw-Distance plots using the finest line spacing are also observed when 100 m line spacing is used. Hence, interpreting at a finer scale may not necessarily improve the subsurface model and any related analysis, but in fact lead to the production of very rough surfaces, which impacts any further fault analysis. Interpreting on spacing greater than 100 m often leads to overly smoothed fault surfaces that miss details that could be crucial, both for fault seal as well as for fault growth models. Uncertainty in seismic interpretation methodology will follow through to fault seal analysis, specifically for analysis of whether in situ stresses combined with increased pressure through CO2 injection will act to reactivate the faults, leading to up-fault fluid flow/seep. We have shown that changing picking strategies alter the interpreted stability of the fault, where picking with an increased line spacing has shown to increase the overall fault stability. Picking strategy has shown to have minor, although potentially crucial, impact on the predicted Shale Gouge Ratio.

How Chosen Seismic Fault Picking Strategy Influences Subsequent Fault Analyses: A Case Study from the Horda Platform, with Implications for CO2 storage

2021 ◽  
Author(s):  
Emma Michie ◽  
Mark Mulrooney ◽  
Alvar Braathen
Keyword(s):  
Fluid Flow ◽  
Co2 Storage ◽  
Fault Analysis ◽  
Surface Generation ◽  
Storage Site ◽  
Seismic Line ◽  
Fault Stability ◽  
Line Spacing ◽  
Fault Growth

&lt;p&gt;Significant uncertainties occur through varying methodologies when interpreting faults using seismic data.&amp;#160; These uncertainties are carried through to the interpretation of how faults may act as baffles/barriers or increase fluid flow.&amp;#160; Seismic line spacing chosen by the interpreter when picking fault segments, as well as the chosen surface generation algorithm used, will dictate how detailed or smoothed the surface is, and hence will impact any further interpretation such as fault seal, fault stability and fault growth analyses.&lt;/p&gt;&lt;p&gt;This contribution is a case study showing how picking strategies influence analysis of a bounding fault in terms of CO&lt;sub&gt;2&lt;/sub&gt; storage assessment.&amp;#160; This example utilizes data from the Smeaheia potential storage site within the Horda Platform, 20 km East of Troll East.&amp;#160; This is a fault bound prospect, known as the Alpha prospect, and hence the bounding fault is required to have a high seal potential and low chance of reactivation upon CO&lt;sub&gt;2&lt;/sub&gt; injection.&lt;/p&gt;&lt;p&gt;We can observe that an optimum spacing for fault interpretation for this case study is set at approximately 100 m.&amp;#160; It appears that any additional detail through interpretation with a line spacing of &amp;#8804;50 m simply adds further complexities, associated with sensitivities by the individual interpreter.&amp;#160; Hence, interpreting at a finer scale may not necessarily improve the subsurface model and any related analysis, but in fact lead to the production of highly irregular surfaces, which impacts any further fault analysis.&amp;#160; Interpreting on spacing greater than 100 m often leads to overly smoothed fault surfaces that miss details that could be crucial, both for fault seal / stability as well as for fault growth models.&lt;/p&gt;&lt;p&gt;Uncertainty associated with the chosen seismic interpretation methodology will follow through to subsequent fault seal analysis, such as analysis of whether in situ stresses, combined with increased pore pressure through CO&lt;sub&gt;2&lt;/sub&gt; injection, will act to reactivate the faults, leading to up-fault fluid flow / seep.&amp;#160; We have shown that changing picking strategies significantly alters the interpreted stability of the fault, where picking with an increased line spacing has shown to increase the overall fault stability, and picking using every line leads to the interpretation of a critically stressed fault.&amp;#160; Alternatively, it is important to note that differences in picking strategy show little influence on the overall predicted fault membrane seal (i.e. shale gouge ratio) of the fault, used when interpreting the fault seal capacity for a fault bound CO&lt;sub&gt;2&lt;/sub&gt; storage site.&lt;/p&gt;

Fluid flow impact on slope failure from 3D seismic data: a case study in the Storegga Slide

2005 ◽  
Vol 17 (1) ◽  
pp. 109-122 ◽  
Author(s):  
Stefan Bunz ◽  
Jurgen Mienert ◽  
Petter Bryn ◽  
Kjell Berg
Keyword(s):  
Fluid Flow ◽  
Seismic Data ◽  
Slope Failure ◽  
3D Seismic ◽  
Storegga Slide ◽  
3D Seismic Data

scholarly journals Evaluation of the reservoir architectural elements in deepwater turbidites of Niger Delta – a case study from the “AFUN” Field

2021 ◽  
Vol 51 (1) ◽  
pp. 83-108
Author(s):  
Yemisi C. AJISAFE
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Architectural Elements ◽  
Structural Style ◽  
Reverse Faulting ◽  
Thrust Zone ◽  
Detailed Interpretation ◽  
Fault Interpretation

3D post-stack time migrated seismic data and a suite of composite well log data from six wells drilled within the “AFUN” field Niger delta were used to effect a detailed interpretation of the field. This was with a view to delineating architectural elements that control reservoir quality of a deepwater turbidite reservoir. The data analyses were done using the Petrel software. LAS file of logs were imported into the Petrel software as well as SEG.Y. seismic data. Fault interpretation and horizon mapping were based on the well-seismic tie from the generated seismogram. Time and depth structure maps were created. Thirty faults which include growth faults, reverse faults, collapsed crest structure and as well as faults that are synthetic and antithetic to the growth faults were mapped. The growth faults are believed to act as pathways for the updip movement of hydrocarbon from the Akata Formation to Agbada Formation. The structural interpretation showed that the area has been subjected to compressional deformation which resulted in reverse faulting system in toe thrust zone influenced by shale diapirs. The maps revealed contour closures that belong to an anticlinal structure which is forming traps in the reservoirs. The structures are faulted North-South trending rollover anticlines. It has also been shown that the distribution and type of architectural elements i.e. fractures within the fan system have major impact upon the reservoir distribution, continuity and connectivity of sand/shale bodies. The study concluded that structural style and facies architecture are the two fundamental elements that defined the reservoir heterogeneity of the “AFUN” Field.

Common-azimuth seismic data fault analysis using residual UNet

2020 ◽  
Vol 8 (3) ◽  
pp. SM25-SM37 ◽  
Author(s):  
Naihao Liu ◽  
Tao He ◽  
Yajun Tian ◽  
Bangyu Wu ◽  
Jinghuai Gao ◽  
...  
Keyword(s):  
Seismic Data ◽  
Field Data ◽  
Synthetic Data ◽  
Detection Algorithm ◽  
Fault Analysis ◽  
Seismic Structure ◽  
Validation Data ◽  
Seismic Fault ◽  
Key Steps ◽  
Fault Interpretation

Seismic fault interpretation is one of the key steps for seismic structure interpretation, which is a time-consuming task and strongly depends on the experience of the interpreter. Aiming to automate fault interpretation, we have considered it as an image segmentation issue and adopt a solution using a residual UNet (ResUNet), which introduces residual units to UNet. Using the ResUNet model, we develop a fault-versus-azimuth analysis based on offset vector tile data, which, as common-azimuth seismic data, provide more detailed and useful information for interpreting seismic faults. To avoid manual efforts for picking training labels and the inaccuracy introduced by different interpreters, we use synthetic seismic data with a random number of faults with different locations and throws as the training and validation data sets. ResUNet is finally trained using only synthetic data and tested on field data. Field data applications show that the proposed fault-detection algorithm using ResUNet can predict seismic faults more accurately than coherence- and UNet-based approaches. Moreover, geologic fault interpretation results computed using common-azimuth data exhibit higher lateral resolution than those computed using poststack seismic data.

scholarly journals The role of pre-existing jointing on damage zone evolution and faulting style of thin competent layers in mechanically stratified sequences: a case study from the Limestone Coal Formation at Spireslack Surface Coal Mine

2020 ◽  
Author(s):  
Billy J. Andrews ◽  
Zoe K. Shipton ◽  
Richard Lord ◽  
Lucy McKay
Keyword(s):  
Fluid Flow ◽  
Internal Structure ◽  
Coal Mine ◽  
Damage Zone ◽  
Fault Rock ◽  
Surface Coal Mine ◽  
Fracture Mapping ◽  
Fault Growth

Abstract. Fault and fracture networks play an important role in sub-surface fluid flow and can act to enhance, retard or compartmentalise groundwater flow. In multi-layered sequences, the internal structure and growth of faults is not only controlled by fault throw, but also the mechanical properties of lithologies cut by the fault. This paper uses geological fieldwork, combined with fault and fracture mapping, to investigate the internal structure and fault development of the mechanically stratified Limestone Coal Formation and surrounding lithologies exposed at Spireslack Surface Coal Mine. We find that the development of fault rock, and complexity of a fault zone is dependent on: a) whether a fault is self-juxtaposed or cuts multiple lithologies; b) the presence and behaviour of shale, which can lead to significant bed-rotation and the formation of fault-core lenses; and c) whether pre-existing weakness (e.g. joints) are present at the time of faulting. Pre-existing joint networks in the McDonald Limestone, and cleats in the McDonald Coal, influenced both fault growth and fluid flow within these lithologies.

PROCESSING AND IMAGING OF MARINE SEISMIC DATA FROM THE JEQUITINHONHA BASIN (BAHIA, BRAZIL)

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Lourenildo W.B. Leite ◽  
J. Mann ◽  
Wildney W.S. Vieira
Keyword(s):  
Seismic Data ◽  
Sedimentary Basins ◽  
Study Results ◽  
Marine Seismic ◽  
Present Case Study

ABSTRACT. The present case study results from a consistent processing and imaging of marine seismic data from a set collected over sedimentary basins of the East Brazilian Atlantic. Our general aim is... RESUMO. O presente artigo resulta de um processamento e imageamento consistentes de dados sísmicos marinhos de levantamento realizado em bacias sedimentares do Atlântico do Nordeste...

Sign in / Sign up

Export Citation Format

Share Document