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High Resolution Geophysical Surveys

May 25, 2010 By admin

High resolution drilling hazard surveys are critical for relatively shallow water shelf settings because  gas pockets can be stable within a few hundred ft beneath the seafloor and 3-D seismic data often poorly image this section.

These surveys typically have a grid of high resolution 2-D data that have five times the resolution of conventional deep-looking seismic data.

Seafloor features are imaged with side-scan sonar that are processed to mosaics that are analyzed much like areal photographs.

Multibeam echosounders provide high resolution bathymetric information as well as soil properies from co-located, subsampled backscatter.

Subbottom profilers are used to image the topmost soils in order to assess foundation zone conditions.

Magnetometer are towed to detect ferrous objects such as oil and gas infrastructure, piplines or wellheads,  or metallic debris.

In West Africa and the Americas, AOA Geophysics provide survey services in collaboration with TDI Brooks International, headquartered in College Station, Texas.  http://www.tdi-bi.com/

In Southeast Asia, AOA Geophysics provide interpretation, consulting services, and acquisition support  through Ocean Technologies Geomatics Sdn Bhd based in Kuala Lumpur, Malaysia.

contact Dan McConnell +1 713 532-2624
Email Dan

(image courtesy TDI Brooks Intl., and AOA Geophysics Inc.)

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Deepwater Geohazard Assessments

May 24, 2010 By admin

AOA Geophysics are recognized experts in deepwater geohazard assessments.  Our technical roots come from the mid 1990′s when the techniques and methodology for identifying and assessing hazards and constraints  in the deepwater were developed by the super-major oil companies and key geohazard and geotechnical contractors.  Steep slopes, irregular topography, variable soils, protected deepwater benthic communities, seafloor vents, active faulting, overpressured sands, gas pockets, and gas hydrates, can all pose hazards or constrain the well design or development plan.

  • At the Exploration and Pre-Development Stage-  we typically use conventional 3-D seismic data.  Although lacking vertical resolution for foundation zone studies, the lateral resolution is extremely useful in initial site characterizations and is adequate to define exploration hazards for most deepwater drilling situations.  Shallow gas, sand mapping, fault mapping, and gas hydrate identification can be accomplished with good-quality conventional 3-D seismic data.

These assessments are used by oil and gas exploration companies to plan their drilling operations and casing plans.  These same assessments generally have a dual purpose for getting authorization to drill from government permitting authorities (such as the US Bureau of Ocean Energy Management) or for rig insurance.

High resolution geophysical data acquired from an AUV (Autonomous Underwater Vehicle) are used for the pre-development deepwater development survey.   These are simply the shallow water high resolution tools flown close to the deepwater seabed- multibeam echosounder, side-scan sonar, and subbottom profiler.  From these data, soils characterization, erosion assessments, fault displacement assessments are made.

Whether the project is a rank wildcat well or a field development, AOA delivers high quality geohazard assessments that you can plan by- on time and on budget.

For deepwater geohazard assessments, pipeline routing, and field layout planning:
contact Dan McConnell +1 713 532-2624
Email Dan

(image courtesy Mariner Energy Inc.)

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Offshore Site Investigation

May 23, 2010 By admin

Safe Drilling – No Surprises.   It is critical that accurate and comprehensive site investigations be part of every exploration well and development.  The data have to be good and the interpretation of those data sound.

Exploration wells require a careful interpretion and assessment of hazards and constraints prior to drilling. There should be no surprises.  An ideal well in the tophole section will have no unforseen conditions.  AOA geoscientists have the knowledge and experience to identify hazards and constraints to the drilling team and communicate the findings and recommendations for internal, permitting, and insurance purposes.

Offshore developments require a careful integration of known conditions from the discovery wells and foundation and soil conditions in order to provide the information required to plan and construct the field layout.  This is true whether the water depth is 70 ft or 7,000 ft.

AOA work primarily as a consultant  but we also provide contractor support.  AOA specialize in wellsite assessments, pipeline routing surveys, archeological assessments, sand surveys, geochemical, and marine seep hunting surveys.

Data integration.  We firmly believe that data acquired for separate purposes can be integrated early within the exploration-development life-cycle at great value to the client.  Integrating knowledge of site conditions will help guide, focus, and optimize further high-resolution geophysical and geotechnical investigations required in advance of a field development.

The marine geoscientists and geological engineers at AOA are broadly skilled-  whether acquiring and  processing high resolution data offshore or interpreting 3-D seismic data in the office.
For marine survey and consulting, contact Dan McConnell +1 713-532-2624
Email Dan

For geotechnical survey and consulting, contact Adrian Digby +1 713-532-2624
Email Adrian

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Borehole Geophysics – Wireline Logging

May 22, 2010 By admin

Offshore Borehole Logging

The shallow section offshore from mud line to the surface casing shoe, often placed at around 800’/250m, can be the section of a well with the least detailed geologic information. This section is the location of a number of geohazards with the potential for well loss or delay in completion. These geohazards include unexpected overpressures, gas hydrates, shallow gas, and variable physical soil properties due to presence of faulting or mass transport deposits.

Geotechnical boreholes are drilled to investigate these issues.  Employing wireline logging, such as is always done for target reservoir identification and definition , can also greatly aid the understanding of shallow section properties.

Specialized slimline tools with the ability to log both in the casing and below the bit are now available. AOA’s VP Adrian Digby was the originator of the concept of shallow section logging offshore and is a leading proponent of the interpretation of the geophysical data obtainable from boreholes in the shallow section and integration with the traditional geotechnical data required for safe field development.

Onshore Well Logging

AOA provides design advice, QA/QC and data interpretation of borehole logging programs for a number of uses onshore. These uses including: geotechnical investigations for civil engineering projects, mining, water and geothermal energy developments plus new and exciting developments including carbon dioxide sequestration and deep waste disposal.

Contact Adrian Digby +1 713-532-2624
Email Adrian

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