Application of 3D marine CSEM finite-element forward modeling to hydrocarbon exploration in the Flemish Pass Basin offshore Newfoundland, Canada

Dunham, Michael W.; Ansari, Seyedmasoud; Farquharson, Colin G.

doi:10.1190/segam2016-13779957.1

Cited by 4 publications

(3 citation statements)

References 10 publications

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“…Unstructured grids have long been exercised in various fields such as engineering and applied mathematics; however, this feature has only recently been used in the EM geophysical field, as exemplified by the use of FE method code in marine EM surveys (e.g., [3,[32][33][34]). This feature can realistically replicate the complexities of geological structures [19].…”

Section: Introductionmentioning

confidence: 93%

“…This survey was very important to hydrocarbon exploration due to its capability of providing information of the subsurface. According to [19], seismic data interpretation provides good resolution of the subsurface structures underneath the seabed; however, it has deficiencies. It is said that seismic surveys are unable to distinguish the fluid content inside the reservoirs, whether brine (conductive seawater) or hydrocarbon.…”

Section: Introductionmentioning

confidence: 99%

“…Constable and Srnka [14] stated that the economic challenges (e.g., related to drilling) increase as the hydrocarbon exploration moves to deeper offshore environments. Thus, any additional data that can be obtained or collected will be advantageous to the exploration if there is a potential to de-risk a given expectation [19].…”

Section: Introductionmentioning

confidence: 99%

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Gaussian Process Methodology for Multi-Frequency Marine Controlled-Source Electromagnetic Profile Estimation in Isotropic Medium

et al. 2019

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The marine controlled-source electromagnetic (CSEM) technique is an application of electromagnetic (EM) waves to image the electrical resistivity of the subsurface underneath the seabed. The modeling of marine CSEM is a crucial and time-consuming task due to the complexity of its mathematical equations. Hence, high computational cost is incurred to solve the linear systems, especially for high-dimensional models. Addressing these problems, we propose Gaussian process (GP) calibrated with computer experiment outputs to estimate multi-frequency marine CSEM profiles at various hydrocarbon depths. This methodology utilizes prior information to provide beneficial EM profiles with uncertainty quantification in terms of variance (95% confidence interval). In this paper, prior marine CSEM information was generated through Computer Simulation Technology (CST) software at various observed hydrocarbon depths (250–2750 m with an increment of 250 m each) and different transmission frequencies (0.125, 0.25, and 0.5 Hz). A two-dimensional (2D) forward GP model was developed for every frequency by utilizing the marine CSEM information. From the results, the uncertainty measurement showed that the estimates were close to the mean. For model validation, the calculated root mean square error (RMSE) and coefficient of variation (CV) proved in good agreement between the computer output and the estimated EM profile at unobserved hydrocarbon depths.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Gaussian Process Methodology for Multi-Frequency Marine Controlled-Source Electromagnetic Profile Estimation in Isotropic Medium

et al. 2019

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Trial-and-error modeling of ground-airborne electromagnetic data in the Yishu Faulting Basin, China

Zhang,

Farquharson,

Lin

2024

GEOPHYSICS

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Trial-and-error modeling may provide some level of interpretation of the subsurface while sacrificing certainty, and certainty it is a viable alternative for precise three-dimensional (3D) interpretation of real ground-airborne frequency-domain electromagnetic (GAFEM) data. Therefore, a semiautomatic trial-and-error modeling approach has been presented in this study. We first developed a 3D GAFEM forward modeling code. Its accuracy was demonstrated using a 3D synthetic model with a topography and a tilted anomalous body. An initial model was established based on known geological constraints. The code was repeated, and the parameters of the model were renewed semi-automatically based on a predefined geometry-resistivity combination list. The model that could achieve the minimum error between the computed response and collected GAFEM data was selected as the final model. We applied the proposed semi-automatic trial-and-error modeling approach to a geothermal resource survey in the Yishu Faulting Basin, China. The purpose of this survey was to interpret the resistivity structure of the subsurface and evaluate the potential development of geothermal resources in the survey area. The final model obtained by trial-and-error modeling, which was constrained by known geological information and subsurface geoelectric structures inferred from 2D models inverted by the CSAMT and MT data measured at the same location, indicated the existence of geothermal resources. This indication was supported by drilling results from a well site located on the survey line. A comparative analysis was also conducted between the model obtained by trial-and-error modeling and the models obtained by 3D inversion of the GAFEM dataset. The apparent resistivity was calculated using the same data. The results have shown that different approaches can achieve similar subsurface geometries and resistivity distributions for faulting basin structures.

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Gaussian Processes for Hydrocarbon Depth Estimation in Forward Modeling of Seabed Logging

Aris

Daud

Dass

et al. 2019

JEEG

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Seabed logging (SBL) is an application of the marine controlled-source electromagnetic (CSEM) technique to discover offshore hydrocarbon reservoirs underneath the seabed. This application is based on electrical resistivity contrast between hydrocarbon and its surroundings. In this paper, simulation and forward modeling were performed to estimate the hydrocarbon depths in one-dimensional (1-D) SBL data. 1-D data, consisted offset distance (input) and magnitude of electric field (output), were acquired from SBL models developed using computer simulation technology (CST) software. The computer simulated outputs were observed at various depths of hydrocarbon reservoir (250 m–2,750 m with an increment of 250 m) with frequency of 0.125 Hz. Gaussian processes (GP) was employed in the forward modeling by utilizing prior information which is electric field (E-field) at all observed inputs to provide E-field profile at unobserved/untried inputs with uncertainty quantification in terms of variance. The concept was extended for two-dimensional (2-D) model. All observations of E-field were then investigated with the 2-D forward GP model. Root mean square error (RMSE) and coefficient of variation (CV) were utilized to compare the acquired and modeled data at random untried hydrocarbon depths at 400 m, 950 m, 1,450 m, 2,100 m and 2,600 m. Small RMSE and CV values have indicated that developed model can fit well the SBL data at untried hydrocarbon depths. The measured variances of the untried inputs revealed that the data points (true values) were very close to the estimated values, which was 0.003 (in average). RMSEs obtained were very small as an average of 0.049, and CVs found as very reliable percentages, an average of 0.914%, which implied well fitting of the GP model. Hence, the 2-D forward GP model is believed to be capable of predicting unobserved hydrocarbon depths.

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Application of 3D marine CSEM finite-element forward modeling to hydrocarbon exploration in the Flemish Pass Basin offshore Newfoundland, Canada

Cited by 4 publications

References 10 publications

Gaussian Process Methodology for Multi-Frequency Marine Controlled-Source Electromagnetic Profile Estimation in Isotropic Medium

Gaussian Process Methodology for Multi-Frequency Marine Controlled-Source Electromagnetic Profile Estimation in Isotropic Medium

Trial-and-error modeling of ground-airborne electromagnetic data in the Yishu Faulting Basin, China

Gaussian Processes for Hydrocarbon Depth Estimation in Forward Modeling of Seabed Logging

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