Implementing a CSEM Survey Around Existing Infrastructure - The Perdido Installation, Gulf of Mexico

Abstract

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 pipelineNo gear or the survey vessel could come within 1.5 NM of the facility The survey area bathymetry and infrastructure are showin in .

CSEM in Proximity of Subsea Infrastructure - A Reservoir Sensitivity Study

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In mature hydrocarbon basins the seabed might have extensive subsea infrastructure and Hite et al (2015) describe how a Controlled Source ElectroMagnetic (CSEM) survey was designed to follow strict safety requirements around the Perdido installation in the Gulf of Mexico. The imaging results presented are reconstructing the known Frio pay zone and in this paper we conduct a generic synthetic study to look at the degree of reservoir sensitivity loss where obstructions prohibit optimal hardware positioning and demonstrate why exclusion zones is not detrimental to reservoir illumination.

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