ISO/TC 67/SC 7/WG 10 - Foundations

This document provides requirements and guidelines for marine geophysical investigations. It is applicable to operators/end users, contractors and public and regulatory authorities concerned with marine site investigations for offshore structures for petroleum and natural gas industries. This document provides requirements, specifications, and guidance for: a) objectives, planning, and quality management; b) positioning; c) seafloor mapping, including instrumentation and acquisition parameters, acquisition methods, and deliverables; d) sub-seafloor mapping, including seismic instrumentation and acquisition parameters, and non-seismic-reflection methods; e) reporting; f) data integration, interpretation, and investigation of geohazards. This document is applicable to investigation of the seafloor and the sub-seafloor, from shallow coastal waters to water depths of 3 000 m and more. It provides guidance for the integration of the results from marine soil investigations and marine geophysical investigations with other relevant datasets. NOTE 1 The depth of interest for sub-seafloor mapping depends on the objectives of the investigation. For offshore construction, the depths of investigation are typically in the range 1 m below seafloor to 200 m below seafloor. Some methods for sub-seafloor mapping can also achieve much greater investigation depths, for example for assessing geohazards for hydrocarbon well drilling. There is a fundamental difference between seafloor mapping and sub-seafloor mapping: seafloor signal resolution can be specified, while sub-seafloor signal resolution and penetration cannot. This document therefore contains requirements for the use of certain techniques for certain types of seafloor mapping and sub-seafloor mapping (similarly, requirements are given for certain aspects of data processing). If other techniques can be shown to obtain the same information, with the same or better resolution and accuracy, then those techniques may be used. Mapping of pre-drilling well-site geohazards beneath the seafloor is part of the scope of this document. NOTE 2 This implies depths of investigation that are typically 200 m below the first pressure-containment casing string or 1 000 m below the seafloor, whichever is greatest. Mapping of pre-drilling well-site geohazards is therefore the deepest type of investigation covered by this document. In this document, positioning information relates only to the positioning of survey platforms, sources and receivers. The processes used to determine positions of seafloor and sub-seafloor data points are not covered in this document. Guidance only is given in this document for the use of marine shear waves (A.8.3.3), marine surface waves (A.8.3.4), electrical resistivity imaging (A.8.3.5) and electromagnetic imaging (A.8.3.6).

ISO 19901-4:2016 contains provisions for those aspects of geoscience and foundation engineering that are applicable to a broad range of offshore structures, rather than to a particular structure type. Such aspects are: - site and soil characterization; - identification of hazards; - design and installation of shallow foundations supported by the seabed; - design and installation of pile foundations; - soil-structure interaction for auxiliary structures, e.g. subsea production systems, risers and flowlines (guidance given in A.10); - design of anchors for the stationkeeping systems of floating structures (guidance given in A.11). Particular requirements for marine soil investigations are detailed in ISO 19901‑8. Aspects of soil mechanics and foundation engineering that apply equally to offshore and onshore structures are not addressed. The user of this part of ISO 19901 is expected to be familiar with such aspects. ISO 19901‑4 outlines methods developed primarily for the design of shallow foundations with an embedded length (L) to diameter (D) ratio L/D 10 (Clause 8). This part of ISO 19901 does not apply to intermediate foundations with 1

ISO 19901-8:2014 specifies requirements, and provides recommendations and guidelines for marine soil investigations regarding: a) objectives, planning and execution of marine soil investigations; b) deployment of investigation equipment; c) drilling and logging; d) in situ testing; e) sampling; f) laboratory testing; and g) reporting. Rock materials are only covered by ISO 19901-8:2014 to the extent that ordinary marine soil investigation tools can be used, e.g. for chalk, calcareous soils, cemented soils or similar soft rock. ISO 19901-8:2014 is intended for clients, soil investigation contractors, designers, installation contractors, geotechnical laboratories and public and regulatory authorities concerned with marine soil investigations for any type of offshore and nearshore structures, or geohazard assessment studies, for petroleum and natural gas industries.

ISO 19901-4:2003 contains requirements and recommendations for those aspects of geoscience and foundation engineering that are applicable to a broad range of offshore structures, rather than to a particular structure type. Such aspects are site characterization, soil and rock characterization, and design and installation of foundations supported by the seabed (shallow foundations) and the identification of hazards. Aspects of soil mechanics and foundation engineering that apply equally to offshore and onshore structures are not addressed. The user of this part of ISO 19901-4:2003 is expected to be familiar with such aspects.