Applicability of 1D and 2.5D marine controlled source electromagnetic modelling. (27th February 2013)

• Record Type: Journal Article
• Authors: Tehrani, Ali Moradi; Slob, Evert
• Is Part Of: Geophysical prospecting. Volume 61:(2013:Jun.)supplement s1
• Page Start: 602
• Page End: 613
• Publication Date: 2013-02-27
• Subjects: CSEM modelling -- Reservoir model; Prospecting -- Geophysical methods -- Periodicals; 622.15
• DOI: 10.1111/1365-2478.12019
• Languages: English
• ISSNs: 0016-8025

Abstract

ABSTRACT: We present two‐and‐a‐half dimensional (2.5D) and three‐dimensional (3D) integral equation modelling of the marine controlled source electromagnetic method. We implement 2.5D modelling using a point source and a two‐dimensional reservoir and compare the results with point source responses from one‐dimensional and three‐dimensional reservoir models. These methods are based on an electric field domain integral equation formulation. We show how the 2.5D method performs in terms of both accuracy and computing speed with different configurations. We compare the results from 1D, 2.5D and 3D modelling, for a symmetrically placed reservoir and the in‐line acquisition configuration, as a function of different reservoir sizes in the cross‐line direction, thickness and for different frequencies and depths. Depending on the model's parameters 2.5D modelling can be considered as an accurate and fast method for marine controlled source electromagnetic acquisition optimization and interpretation. If the thickness of the reservoir is less than one fifth of the skin depth of the embedding and if the depth of the reservoir is two or more times the skin depth of the embedding, the largest amplitude difference between two‐dimensional and three‐dimensional reservoirs is less than 10% when the source is above the centre of the reservoir. In this paper we discuss supporting examples with different configurations, where the 2.5D results lead to an optimistic detection estimate. Phase differences between 2.5D and 3D modelling are even smaller and the 2.5D solution can be used to assess the ability to detect the reservoir with a given acquisition configuration.