Precise Depth and Subsidence Measurements During Deepwater OBN Surveys

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2019Precise depth and subsidence measurements during deepwater OBN surveysAuthors: Paul HatchellHugo RuizAudun LibakBrad NolanRemy AgersborgPaul HatchellShell International Exploration and Production Inc., and OCTIO Gravitude ASSearch for more papers by this author, Hugo RuizShell International Exploration and Production Inc., and OCTIO Gravitude ASSearch for more papers by this author, Audun LibakShell International Exploration and Production Inc., and OCTIO Gravitude ASSearch for more papers by this author, Brad NolanShell International Exploration and Production Inc., and OCTIO Gravitude ASSearch for more papers by this author, and Remy AgersborgShell International Exploration and Production Inc., and OCTIO Gravitude ASSearch for more papers by this authorhttps://doi.org/10.1190/segam2019-3214533.1 SectionsSupplemental MaterialAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail AbstractA common problem in deepwater node surveys is the lack of accurate information on the depths of nodes deployed at the seafloor. Tides, rapidly changing water properties, pressure sensor drift and calibration errors limit the accuracy of depth measurements performed during the operations. Depth uncertainties at the level of a few meters are not uncommon.Previous work on gravity-subsidence surveys that were carried out on the Norwegian continental shelf using permanent concrete monuments have produced depth repeatability at the mm level that enable the measurement of small subsidence rates over years.In this paper, we introduce the principles of gravity-subsidence surveys into an OBN operation with the goal of accurately determining relative node depths and developing the capability to measure long-term subsidence between repeat OBN surveys. We applied this technique on a node survey acquired in ∼2500 m water depth and demonstrated an average relative depth accuracy of 4 cm. We also carried out a set of base-line measurements on fixed seafloor frames that can be used to deliver cm-level accuracy in subsidence measurement during future surveys. This experience demonstrates the concept of introducing the well-proven survey method for depth determinations into OBN campaigns.Presentation Date: Wednesday, September 18, 2019Session Start Time: 1:50 PMPresentation Time: 2:40 PMLocation: 221APresentation Type: OralKeywords: ocean-bottom node, acquisition, 3D, 4D, deepwaterPermalink: https://doi.org/10.1190/segam2019-3214533.1FiguresReferencesRelatedDetailsCited byUnlocking seismic monitoring of stiff reservoirs with 4D OBN: a case study from Brazil pre-saltDenis Kiyashchenko, Wai-Fan Wong, Dalila Cherief, Dan Clarke, Yuting Duan, and Paul Hatchell30 September 2020 SEG Technical Program Expanded Abstracts 2019ISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2019 Pages: 5407 publication data© 2019 Published in electronic format with permission by the Society of Exploration GeophysicistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 10 Aug 2019 CITATION INFORMATION Paul Hatchell, Hugo Ruiz, Audun Libak, Brad Nolan, and Remy Agersborg, (2019), "Precise depth and subsidence measurements during deepwater OBN surveys," SEG Technical Program Expanded Abstracts : 162-166. https://doi.org/10.1190/segam2019-3214533.1 Plain-Language Summary Keywordsocean-bottom nodeacquisition3D4DdeepwaterPDF DownloadLoading ...