Feasibility Study of Controlled-Source Electromagnetic Method for Monitoring Low-Enthalpy Geothermal Reservoirs

Tracking temperature changes by measuring the resulting resistivity changes inside low-enthalpy reservoirs is crucial to avoid early thermal breakthroughs and maintain sustainable energy production. The controlled-source electromagnetic method (CSEM) allows for the estimation of sub-surface resistivity. However, it has not yet been proven that...

Towards an open-source landscape for 3-D CSEM modelling

Large-scale modelling of 3-D controlled-source electromagnetic (CSEM) surveys used to be feasible only for large companies and research consortia. This has changed over the last few years, and today there exists a selection of different open-source codes available to everyone. Using four different codes in the Python ecosystem, we perform...

Fast Fourier transform of electromagnetic data for computationally expensive kernels

3-D controlled-source electromagnetic data are often computed directly in the domain of interest, either in the frequency domain or in the time domain. Computing it in one domain and transforming it via a Fourier transform to the other domain is a viable alternative. It requires the evaluation of many responses in the computational domain if...

Land time-lapse CSEM: Collecting, modeling and inversion of CSEM data for a steam-injected oil field

Geophysical methods are widely used for hydrocarbon exploration and time-lapse measurements. One method that can be applied in place of or in addition to the routinely used seismic method, is the Controlled-Source ElectroMagnetic (CSEM) method. The work described in this thesis explores various aspects to improve the land CSEM method for...

CSEM component analysis: Analysing the contribution of different components to the HED response in a typical 1D VTI medium

A MATLAB program was built around 1D closed form representations of the radial electrical field in a vertical transverse isotropic (VTI) medium driven by an horizontal electric dipole (HED) in the transverse magnetic (TM) and transverse electric (TE) mode published in Andréis and MacGregor (2008). It is able to compute the contribution of the...

Sensitivity of the near-surface vertical electric field land Controlled-Source Electromagnetic monitoring

We investigate potential benefits of measuring the vertical electric field component in addition to the routinely measured horizontal electric field components in onshore time-lapse controlled-source electromagnetics. Synthetic electromagnetic data based on a model of the Schoonebeek onshore oil field are used. We confirm that the vertical...

Probing the solution space of an EM inversion problem with a genetic algorithm

In an inversion for the subsurface conductivity distribution using frequency-domain Controlled-Source Electromagnetic data, various amounts of horizontal components may be included. We investigate which combination of components are best suited to invert for a vertical transverse isotropic (VTI) subsurface. We do this by probing the...

Enhancing Land Controlled-Source Electromagnetic Surveys using Vertical Electric Field Measurements

Nowadays, marine Controlled Source ElectroMagnetic surveys are commonly used for oil exploration whereas similar surveys on land are still a rarity. In recent years theoretical studies have shown that using a horizontal source and vertical receivers on land will result in lower noise levels measured by the receivers. In order to test this, a...

Fast Frequency and Time Domain Integral Equation Modelling for Marine CSEM Applications

In this study we developed algorithms for fast frequency and time domain integral equation modelling for marine controlled-source electromagnetic (CSEM) applications. Solutions of integral equations for CSEM applications in a three-layered earth with an assumed reservoirs is examined using the conjugate gradient fast Fourier transformation (CG...

Controlled-Source Electromagnetics for Reservoir Monitoring on Land

The main goal of exploration geophysics is to obtain information about the subsurface that is not directly available from surface geological observations. The results are primarily used for finding potential reservoirs that contain commercial quantities of hydrocarbons. A number of possible geophysical methods exists these days to achieve such a...

CSEM modeling of a VTI layered medium with the effective anisotropic medium

The numerical modeling with the diffusive controlled source electromagnetic (CSEM) method has been used to validate the published results of Ellis et al. (2010a) by first investigating the validity of effective medium theory for both horizontally layered isotropic and vertically transverse isotropic (VTI) layered earth. Ellis et al. (2010a) used...

Synthetic aperture controlled source electromagnetics

Controlled?source electromagnetics (CSEM) has been used as a de?risking tool in the hydrocarbon exploration industry. Although there have been successful applications of CSEM, this technique is still not widely used in the industry because the limited types of hydrocarbon reservoirs CSEM can detect. In this paper, we apply the concept of...

Inversion of multi-transient EM data from anisotropic media

Forward modelling demonstrates that resistivity anisotropy has a huge effect on Multi-Transient ElectroMagnetic step and impulse responses. The earth is never isotropic – even a stack of isotropic layers behaves anisotropically – and there is a great need to ccount for resistivity anisotropy in order to delineate the true target depth and target...