20
THURSDAY 15TH MARCH For full conference programme and abstracts, visit the Oceanology website.
HYDROGRAPHY AND GEOPHYSICS
CHAIRED BY: ANDY HILL, MARINE GEOHAZARD TECHNICAL AUTHORITY, BP EXPLORATION LOCATION: SOUTH GALLERY, ROOMS 7/8
AM SESSION
09:15 Introduction Andy Hill, BP
09:30– 10:00
The OGP Guidelines for Conduct of Marine Drilling Hazard Surveys
Palle Jensen , Maersk Oil After assuming custodianship of the former UKOOA document “Guidelines For The Conduct of Mobile Drilling Rig Site Surveys” OGP published a completely revised and updated version as the new “Guidelines for the conduct of offshore drilling hazard site surveys” in 2011 with the objective of providing an up to date industry guideline for oilfield good practice for the conduct of geophysical and hydrographic site surveys of proposed offshore drilling locations and the use of exploration 3D seismic data to enhance, or to replace, acquisition of a site survey. The presentation will focus on the most significant updates and the most important recommendations of the guideline.
10:00– 10:30
Recent Problems related to the identification of Shallow Gas
Dag Lundqvist, Statoil The presentation is divided into three parts with the main topic focused on how to avoid geohazard incidents in future wells. 1. Identification of Geohazards Shallow Gas has traditionally been predicted and identified by the use of High Resolution (HR) 2D seismic data. Identification of features like reflection amplitude anomalies, phase-reversal, gas chimneys etc. have all been relatively easy and quick to identify and map. However during recent years Statoil has experienced a number of cases where free shallow gas has caused serious incidents during drilling without leaving any seismic features to identify. Similarly a large number of very clear gas indicators have proven not to be gas filled at all. 2. Statistics Going through the records of wells drilled in the period 1986-2009 showed that results have been more, or less, the same over the years. The following categories were compared: 1. Gas predicted but not shown during drilling 2. Gas not predicted but shown during drilling 3. Gas predicted and shown during drilling 4. Gas not predicted and not shown during drilling Problems with such statistics are demonstrated by the complete lack of any wells in category (3). The reason for this is that when gas is predicted, the well is very often moved and, even if it isn’t, the countermeasures are such that it makes the identification of possible gas more or less impossible. 3. Mass-Prediction In addition, the presentation deals with the problem that the geophysical data acquired during a site survey very often are not linked to geology. Many of the produced maps are created automatically by seismic interpretation software and are not always thought through properly. A better understanding of the local geology is the key to the identification of potential shallow gas traps. The industry needs to allow time to carry out a proper shallow geological interpretation if incidents are to be avoided in the future.”
Break and Exhibition
11:00– 11:30
Limitations in HR2D Seismic: not understood then and not understood now
Karen Ware, RPS Energy In the site survey industry the requirement for HR2D seismic data has been in place for many years. However there is a great lack of understanding of the value and reliability of 2D seismic data. This is particularly relevant in deep water, where the use of HR2D seismic can often result in false positive and false negative identification of hazards. It is important not to view temporal (vertical) resolution of HR2D data in isolation without consideration of the impact of spatial resolution, errors and limitations of the data set. In comparison 3D seismic data, although lower in temporal (vertical) resolution, has vastly improved spatial resolution and should remain more accurate in terms of amplitudes and positioning. It’s post processing footprint is significantly smaller than that of 2DHR seismic data. It therefore has much higher data integrity and accuracy. Spatial resolution is much greater value for the types of hazards seen in deep water. HR2D seismic should only be acquired with an understanding of the limitations and with a specific goal in mind, to believe the data without checking the integrity of the data and interpretation can be dangerous.
Programmes may be subject to change.
16:00– 16:30
Chairmen: Andy Hill, BP and Ken Games, Gardline
11:30– 12:00
Application of New and Emerging Technologies for the improvement of Marine Site Investigations
Alistair Robertshaw, BP The presentation is about the application of new seismic technologies in marine site investigation and discuss considerations required to successfully harness them for improved Geohazard assessment.
The technologies considered include broadband acquisition systems, ocean bottom seismic, converted waves, AVO analysis and full waveform inversion.
12:00– 12:30
12:30- 14:00
14:00– 14:30
Discussion Lunch & Exhibition PM SESSION Chairmen: Andy Hill, BP and Richard Salisbury, Fugro
Improved Geohazards Identification, Well Trajectory Selection and Drilling Performance through High Definition Seismic
Oyvind Ruden, Shell A/S Norske Shell together with CGGVeritas have developed a high-definition (HiDef) seismic processing workflow using conventional 3D seismic streamer data, with results that offer a dramatic improvement in shallow subsurface imaging. This can lead to improved geohazard identification as well as optimising drilling safety and performance through real time monitoring of bit position whilst drilling. This presentation will describe the benefits of HiDef seismic data over conventional 3D seismic and 2D site survey seismic.
14:30– 15:00
Multi-streamer Short Offset High Resolution 3D seismic acquisition
Peter Sack, Sound Oceanics A system is developed using common off-the-shelf tools to acquire high resolution seismic data in 3D. Particular attention is paid to the utilization of the navigation sensors within the system to provide a precise positioning solution. The system proves to be robust in both field operations and in data integrity. The system is used on a survey in the North Sea and the results show the added value of this technique.
15:00– 15:30
15:30– 16:00
Break and Exhibition
Integrated Site Investigations – Deep-water KGD6, Offshore India: Approach, Learning and Benefits
Rajesh A Vaidya, Reliance Industries • One of the largest deepwater gas field development in the world & first in India • Subsea Tie-in to Onshore gas handling facility • Highly complex and large infrastructure facilities such as : 18 subsea wells, 6 Subsea Manifolds, 1 DWPLEM, 1 CRP, 350 km of Offshore Pipelines (Deep, Mid, Shallow water & River section), 150 km of Umbilicals, Over 200 subsea connections, 45 PLETs, 56 Jumpers, 31 Tie-in Spools, 29 Anchor boxes, 4 GDUs
• Development Concept: - Full Subsea Production System with Onshore Processing and a Control and Riser Platform
Identification and Characterization of Geohazards and Geotechnical Challenges in the Mad Dog Area, Gulf of Mexico,
Richard Weiland, BP The Mad Dog field and proposed expansion of the development facilties are located in a geologically complex setting that straddles the Sigsbee Escarpment. Several field acquisition programs, plus numerous laboratory and office-based studies have been undertaken to collect the data needed to better delineate and quantify the timing and rates of the principle geohazards and geotechnical challenges, in particular geologically active faults and slope instability, that could potentially impact the proposed new facilities.
16:30– 17:00
Session Summary and Open Discussion 17:00 Close
Conference programme sponsored by:
...COUNT ON FUGRO
www.fugro.com
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