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Frenkel M.A.,EMGS
PIERS 2010 Cambridge - Progress in Electromagnetics Research Symposium, Proceedings | Year: 2010

The marine Controlled-Source Electromagnetic (CSEM) method has been evolving into a subsurface resistivity imaging tool for increasingly complex geological settings. The measured EM field needs to be inverted to obtain accurate formation resistivity volumes. This information can be used to find reservoirs and determine hydrocarbon saturations. An important step in the resistivity interpretation process is the inclusion of constraints to guide inversion and reduce its non-uniqueness. In this paper, we use 2.5D and 3D synthetic models to investigate the accuracy of the subsurface resistivity reconstruction using additional information about the target body's position. We show that application of seed-type initial models leads to a significantly improved inversion-based CSEM resistivity interpretation.


Baltar D.,EMGS | Roth F.,EMGS
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

Net rock volume is the main uncertainty affecting the evaluation of recoverable reserves for prospect risk analysis. We present a Monte Carlo method for estimating a net rock volume probability distribution from an anisotropic 3D CSEM inversion result. Given a CSEM favourable exploration setting, the method can significantly reduce the uncertainty in net rock volume, especially for stratigraphic traps. The method relies on the sensitivity of CSEM to the volume of resistive rock and on the transverse resistance equivalence principle for relating the low resolution inversion result to possible reservoir scenarios at the well log scale. We demonstrate the performance of the method using unconstrained inversion results from a full-azimuth 3D CSEM survey over a known oil field. No prior information in terms of well data or field geometry was assumed to simulate an exploration case. The uncertainty associated with the resulting net rock volume probability distribution as measured by the P10/P90 ratio is less than 6, which is considered low by common industry practice. The actual net rock volume defined by the reservoir top and the oilwater contact coincides with the 60th percentile of the distribution, i.e. the predicted range of possible net rock volumes is very reasonable.


Hite D.A.,EMGS | Solevag L.P.,EMGS
Proceedings of the Annual Offshore Technology Conference | Year: 2015

It's been over a decade since the first CSEM acquisitions were done along 2D lines in relatively open water. Today's CSEM acquisitions cover hundreds of square kilometers in true 3D fashion using receivers and towing systems purpose-designed for ease of handling, accuracy of deployment and efficiency in towing. Making use of these advancements, EMGS has been able to acquire data closer than ever before to existing infrastructure in a safe and reliable manner. This paper covers the acquisition of a portion of the multi-client survey Daybreak Phase III around the Perdido installation over the Great White field in the Alaminos Canyon protraction area of the U.S. Gulf of Mexico. The survey covers approximately 46 OCS Blocks in water depths from 1700-3000m. The survey was acquired by the vessel EM Leader during the month of June, 2014 and consisted of 130 receiver drops and 702 tow kms. In order to acquire the survey, EMGS contacted Shell, the operator of Perdido, and requested permission to conduct operations around the facility. Shell agreed and provided the following stipulations which were to be complied with at all times: When the planned tow line crosses a pipeline location, the CSEM source must be raised from its nominal towing depth of 30m to 100m at a point 250m away from the pipeline No gear or the survey vessel could come within 1.5 NM of the facility The survey area bathymetry and infrastructure are showin in Figure 1. Copyright © (2015) by the Offshore Technology Conference All rights reserved.


Fanavoll S.,EMGS | Gabrielsen P.T.,EMGS
76th EAGE Conference and Exhibition 2014, Workshops | Year: 2014

After more than ten years of acquisition of EM data, it is widely accepted that the technology has a significant potential for improving exploration efficiency. However, despite the fact that there is a convincing track record of EM results correlating with well results and some oil companies incorporating EM technology into their workflows, adoption of the technology in the industry overall has not come a long way. This paper discuss some of the challenges faced by the petroleum industry in the interpretation of EM data, as well as necessary improvements of the technolgy in order to enhance the value of incorporating EM data into decision workflows. the current use ofEM is illustrated by two examples, one unsuccessful and one successful.


Hesthammer J.,Rocksource | Stefatos A.,Rocksource | Boulaenko M.,Rocksource | Fanavoll S.,EMGS | Danielsen J.,EMGS
Leading Edge (Tulsa, OK) | Year: 2010

During the past several years, we have seen an increasing focus on the use of CSEM technology for hydrocarbon exploration in marine environments and, recently, a number of success stories have been published. The technology has been demonstrated to aid both detection and delineation of hydrocarbon-filled reservoirs. © 2010 Society of Exploration Geophysicists.

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