This project is a collabrative effort between the Offshore Techonology Research Center, the Texas A&M University Department of Oceanography, The Minerals Management Service and various industrial partners for the purpose of determining the geological and physical oceanographic conditions that govern the formation of mega-furrows along the continental rise in the northwest Gulf of Mexico.
The largest and most recent hydrocarbon finds in the Gulf of Mexico have been discovered along the continental rise at the base of the Sigsbee Escarpment in the Northwest Gulf of Mexico. Drilling on the continental rise south of the Sigsbee Escarpment allows for the recovery of hydrocarbons in Eocene and older deposits without drilling through the thick salt nappe that constitutes the base of the escarpment. Drilling on the continental rise at the base of the escarpment has its advantages as well as some serious problems that are related to the contour currents that sweep along the base of the escarpment as a result of topographic Rossby waves derived from the action of the loop current within the Gulf of Mexico. The recent discovery of mega-furrows on the continental rise at the base of the escarpment indicates that the bottom currents (contour currents) responsible for the furrow formations range up to 100 cm/sec and more. In addition to topographic Rossby waves, density currents associated with the leaching of exposed salt along the escarpment have added an additional parameter to the complex current conditions along the continental rise. This project addresses the question of the nature the currents and the formation of furrows along the base of the Sigsbee Escarpment.
APPROACH:
Understanding the formation of furrows will allow for the broad interpretation of current conditions over vast areas that are prime locations for hydrocarbon production. Seabed furrows have been subsequently found on the continental rise off Africa, Brazil and the East Coast of the United States. Furrows are most likely ubiquitous features to be found along all passive continental rises. In addition to the basic understanding of formation of seabed furrows, the study of furrowing is a study in the basic nature of fine-grained sediment erosion and transport in shallow as well as ultra-deep waters; a point that has not been apparent but was suggested by J.R. Allen and R. Flood over 30 years ago. There are many implications of the affects of currents and furrows on the production of deepwater hydrocarbons, including the following:
1) Extreme topographic relief and strong flow affects the pattern that cuttings and drilling mud might be deposited on the seafloor.
2) Topographic relief and strong flow complicates the design and installation of pipelines.
3) Erosional scour affects stability of pipelines, foundation piles, and seafloor installations.
4) Slope undercutting by erosional scour potentially leads to hazardous slumps and slides.
5) Strong bottom-water flow may produce vortex-induced vibrations that cause fatigue and failure of riser strings, platform tension legs, and anchor cables.The furrow area in the Walker Creek area will be surveyed by high-resolution sub-bottom profiles, side-scan sonar surveys and the determination of high-resolution bathymetry. Five current meter arrays will be placed in and outside the furrows for the period of one year to determine the nature of the flow in, above and around the furrows systems.
DEPLOYMENT OF RESULTS:
The following deliverables will be included in the final report:
1. Seismic / coring cruise summary
- Preliminary sidescan and subbottom data
- Preliminary bathymetric data
- Preliminary non-destructive geotechical data
- Ongoing 3-D seismic data results and interpretations
2. Current meter emplacement cruise summary
- 3-D seismic summary results and interpretations
- Sidescan and subbottom summary results and interpretations
- Bathymetry and furrow morphology results and interpretations
- Preliminary sediment dating results
- Preliminary sediment lithology results
- Summary of previous work, results, and interpretations
ANTICIPATED PROJECT DURATION:
Three years, extending through July 2006.
PROJECT PLAN FOR YEAR 1 (2003-2004):
Deploy TAMU Deep-Tow system to determine structure of mega-furrow field in the Walker Creek-Sigsbee Escarpment area and obtain piston and gravity cores in and around the furrow fields.
CURRENT MEMBER COMPANIES INCLUDE: BHP, BP, RPSEA.
COST: The work proposed here will be carried out over a three year period. The current projected cost of participation is $60,000 per year which requires five industrial partners plus support from RPSEA. If the number of participants is less or the RPSEA proposal does not come through we would modify the project for the decreased available funds and direct the research to meet more specific needs of those companies that do participate
PRINCIPAL INVESTIGATOR(S) & OTHERS INVOLVED IN PROJECT:
- William R. Bryant and Niall Slowey, Professors
- Steve DiMarco, Research Scientist
- Dan Bean, Graduate Assistant
Contact Information
To request additional information or membership documents, please contact:
William R. Bryant
Texas A&M University
Oceanography Department
(979) 845-2680
wbryant@ocean.tamu.eduCheck back for:
- Upcoming Project Events
- Photo Gallery
- Project Progress
Date: June 2005Project Title: Deep Sea Furrows JIP
MMS Project: 479 TO Numbers: 73209/35992
PI: William Bryant and Niall Slowey
COTR: S. Buffington & A. Lugo-Fernandez
Estimated Completion Date: May 31, 2007
Project Description:
Significant currents that affect offshore operations and facility designs exist in the deepwater Gulf of Mexico. This project is part of a Joint Industry Program (JIP) formed to carry out an integrated study of the seafloor furrows produced by the flow and the characteristics of the flow itself. We will measure the extent and morphology of the furrows, the sediment properties, and assess the depositional history of the sediments using age-dating and seismic stratigraphic techniques. These results will be compared to the measured current flow regime immediately above the furrows, and relate it to the mechanisms of furrow formation and the climatology of deepwater currents. The resulting information will provide a basis for designing effective deepwater pipelines, risers, and templates (e.g., overbends, spans, and current loads) and a basis for estimating the effects of changes in furrow morphology and deepwater flow over the lifetime of deepwater oil field installations.
Progress:
A research cruise took place in May 2006 to recover the moored current meters from the five locations (see Figure 1). All five moorings were recovered. Each mooring had a vertical array of three current meters and included two CTD. We have begun quick looks and preliminary analysis of the data from the recovered CTDs and current meters. These data are proprietary and to the JIP participants.
Figure 1. Deep Sea Furrows Project - location of current mooring locations
Reports & Publications:None this period.
Date: December, 2005Project Title: Deep Sea Furrows JIP
MMS Project: 479 TO Numbers: 73209/35992
PI: William Bryant and Niall Slowey
COTR: A. Konczvald & A. Lugo-Fernandez
Estimated Completion Date: May 31, 2007
Project Description:
Significant currents that affect offshore operations and facility designs exist in the deepwater Gulf of Mexico. This project is part of a Joint Industry Program (JIP) formed to carry out an integrated study of the seafloor furrows produced by the flow and the characteristics of the flow itself. We will measure the extent and morphology of the furrows, the sediment properties, and assess the depositional history of the sediments using age-dating and seismic stratigraphic techniques. These results will be compared to the measured current flow regime immediately above the furrows, and relate it to the mechanisms of furrow formation and the climatology of deepwater currents. The resulting information will provide a basis for designing effective deepwater pipelines, risers, and templates (e.g., overbends, spans, and current loads) and a basis for estimating the effects of changes in furrow morphology and deepwater flow over the lifetime of deepwater oil field installations.
Progress:
The activities of the past fall included core processing, seismic data analysis and we have started to plan the next cruise to pick up the current meters. As far as core processing, we completed sampling of the two jumbo piston cores at 10 cm intervals for Oxygen isotope analysis (d18O). Due to technical problems with the Oceanography Department’s mass spectrometer the samples have not been analyzed, and we are evaluating the possibility of sending the samples out to be analyzed at another facility. The d18O analysis will in turn allow us to date the sediment, consequently it will help reconstruct the stratigraphy of the region and correlate it with the stratigraphy of nearby regions (e.g. Mad Dog). CRS (constant rate of strain) consolidation tests have been run on one of the gravity cores collected during the last cruise, and a few more are planned.
Regarding seismic data, we converted all subbottom data to segy format in UTM coordinates, to facilitate interpretation with our seismic software. Side-scan mosaic was completed by correcting the position of the imagery with respect to the 3-D multibeam bathymetry. The correction was based on features easily recognizible both in the multibeam bathymetry and in the side-scan images, and the assumption that the multibeam bathymetry position is correct. Side-scan sonar images were then moved until the chosen features overlapped. Finally, Daniel Bean’s dissertation was completed, including final corrections and it is available only to JIP members.
We are now concentrating our efforts to organizing the next research cruise to pick up the current meters. The task is challanging, as ship availability in the Gulf of Mexico is limited, good weather is a constraint for the success of the retrieval, and we need to sail before the end of March to ensure the acoustic releases will have battery power. At this time we are in contact with the new owner of the R/V Gyre (TDI-Brooks) in the attempt to combine our retrievial with one of its next coring cruises in the region (possibly beginning of February). At the same time we are looking into other ships’ availability (e.g. R/V Pelican) and other combination opportunities.
Reports & Publications:
Bean, D. A. (2005) “Past and Present Deepwater Contour-Current Bedforms at the Base of the Sigsbee Escarpment, Northern, Gulf of Mexico”, PhD Dissertation, Texas A&M University, August.
Date: June 2005
Project Title: Deep Sea Furrows JIP
MMS Project: 479 TO Numbers: 73209/35992
PI: William Bryant and Niall Slowey
COTR: Andrew Konczvald & A. Lugo-Fernandez
Estimated Completion Date: September 2006
Project Description: Significant currents that affect offshore operations and facility designs exist in the deepwater Gulf of Mexico. This project is part of a Joint Industry Program (JIP) formed to carry out an integrated study of the seafloor furrows produced by the flow and the characteristics of the flow itself. We will measure the extent and morphology of the furrows, the sediment properties, and assess the depositional history of the sediments using age-dating and seismic stratigraphic techniques. These results will be compared to the measured current flow regime immediately above the furrows, and relate it to the mechanisms of furrow formation and the climatology of deepwater currents. The resulting information will provide a basis for designing effective deepwater pipelines, risers, and templates (e.g., over-bends, spans, and current loads) and a basis for estimating the effects of changes in furrow morphology and deepwater flow over the lifetime of deepwater oil field installations.
Progress: We have completed processing approximately all of the geophysical data sets from the May 2004 research cruise. The completion of the processing has allowed us to create a mosaic of the side-scan overlaid on the bathymetry determined from 3-D seismic data provided by WesternGeco. We have also created a web-based project for viewing all of the processed seismic data on the private JIP participant’s website. The April “R/V Geyer 2005 Cruise” to deploy five moorings each consisting of three Acoustic current meters and three conductivity, pressure and temperature sensors was a complete success. All five moorings were deployed, four of them being positioned within 50 meters of their respective planned sites, and a fifth (M5) positioned at a site 1500 meters from the position originally planned but within the same seabed feature originally planned. The current meter arrays will remain in place for a period of one year. All of the 10 large diameter gravity cores recovered on the April 2005 cruise have been logged with a multi-sensor core logging device. Shear strength measurements and C14, O16 andO18 age dating of the gravity cores and the two long (18 meter) piston cores recovered for by TDI Brooks Inc. is now in progress.
Reports & Publications: Detailed project results are proprietary
Date: December, 2004
Project Title: Deep Sea Furrows JIP
MMS Project: 479 TO Numbers: 73209/35992
PI: William Bryant and Niall Slowey
COTR: Julie McNeil
Estimated Completion Date: September 30, 2006
Project Description: Significant currents that affect offshore operations and facility designs exist in the deepwater Gulf of Mexico. This project is part of a Joint Industry Program (JIP) formed to carry out an integrated study of the seafloor furrows produced by the flow and the characteristics of the flow itself. We will measure the extent and morphology of the furrows, the sediment properties, and assess the depositional history of the sediments using age-dating and seismic stratigraphic techniques. These results will be compared to the measured current flow regime immediately above the furrows, and relate it to the mechanisms of furrow formation and the climatology of deepwater currents. The resulting information will provide a basis for designing effective deepwater pipelines, risers, and templates (e.g., overbends, spans, and current loads) and a basis for estimating the effects of changes in furrow morphology and deepwater flow over the lifetime of deepwater oil field installations.
Progress: We have completed processing approximately 75% of the geophysical data set from the May 2004 research cruise. The remaining 25% will require additional processing. The completion of a majority of the processing has allowed us to create a mosaic of the side-scan overlaid on the bathymetry determined from 3-D seismic data provided by WesternGeco. We have also created a web-based project for viewing all of the processed seismic data on the private JIP participants website(http://deeptow.tamu.edu/jip_private/).
In addition to processing and compiling the seismic data, we have begun analysis of the two jumbo piston cores, 17 meters in length, collected by TDI Brooks Inc. The initial processing involved logging the cores via the GeoTek Multi-Sensor Core Logger (MSCL). This MSCL provides non-destructive bulk density, porosity and velocity measurements at 1 cm over the full length of the sediment core. Shear strength measurements at 4 cm intervals have been completed. The data will be used to compare the sediment characteristics with the seismic data. Preliminary indications are that we have sampled at least one regional marker bed with the cores that will later be dated to provide a time stratigraphic framework for the region. September 2004, marked the end of the RPSEA funded portion of the Mega-Furrows JIP. We have compiled a Final Report summarizing the first year of the JIP for RPSEA and all JIP participants.
Reports & Publications: Detailed project results are proprietary
Date: June 2004Project Name: Mega-Furrows JIP
Project Number: 479 Task Order: 73209
Principal Investigators: Dr. William Bryant, Dr. Niall Slowey
Estimated Completion Date: July 1, 2006
Project Description:
Significant currents that affect offshore operations and facility designs exist in the deepwater Gulf of Mexico. This project is part of a Joint Industry Program (JIP) formed to carry out an integrated study of the seafloor furrows produced by the flow and the characteristics of the flow itself. We will measure the extent and morphology of the furrows, the sediment properties, and assess the depositional history of the sediments using age-dating and seismic stratigraphic techniques. These results will be compared to the measured current flow regime immediately above the furrows, and relate it to the mechanisms of furrow formation and the climatology of deepwater currents. The resulting information will provide a basis for designing effective deepwater pipelines, risers, and templates (e.g., overbends, spans, and current loads) and a basis for estimating the effects of changes in furrow morphology and deepwater flow over the lifetime of deepwater oil field installations.
Progress:
The first cruise of the Mega-Furrows JIP took place between May 1st and May 10th 2004. All efforts prior to the cruise were focused on cruise planning and equipment preparation. The total equipment preparation time for this cruise was high due to the attempt to integrate a Simrad multibeam bathymetry system with the TAMU Deep Towed sidescan and subbottom system. The primary goal of the cruise was to complete the initial seismic survey of the Green Knoll region using the TAMU Deep Tow system. Additional coring was to be performed on a time available basis. The following are the primary objectives of the seismic survey:
• Characterize furrow/contour current bedform types
• Quantitatively characterize bedform morphologies
• Determine the bedform spatial distributions
• Examine relation between large scale morphologic features and flow patterns
• Assess potential coring locations
• Assess potential current meter placement
• Analyze furrow morphologies within the context of current flow with a furrow
The expected survey time was 4.5 days at a speed of 3.5 knots, yielding an expected total of 375 nautical miles. The actual survey time was closer to 4 days at 2.5 knots yielding a total of 200 nautical miles of survey distance. The final survey cruise track is shown in Figure 1. Several factors affected the total acquired line mileage. Weather and equipment downtime led to initial delays, while USBL considerations and the cable to depth ratios led to a decrease in average survey speed.Overall, the cruise was a success despite the decrease in total line miles from the original plan. It is important to note that despite the changes to the planned survey, it will still be possible to address each of the above objectives via the acquired data set. Furthermore, as is typical of the TAMU Deep Tow surveys, the high-resolution data has already yielded some unexpected and important results. The regional nature of at least two regionally persistent reflectors and the location of an outcrop for both bode well for developing a time bounded stratigraphic framework for the region. Connection of reflectors in the survey area with previous work in the Atlantis prospect will further refine the stratigraphy. Data from the USBL system and comparison to the 3D seismic bathymetry indicate that the calculated towfish position is already close and can be further fine-tuned to provide excellent data for positioning cores and current meters on the next JIP cruise. Over the coming weeks we will fully process and analyze the data we have collected to develop a detailed understanding of the region as we also look to fit it within a more global framework.
Figure 1. Cruise track from the May 2004 Mega-Furrows JIP seismic cruise (blue line).
Reports & Publications:
Internal reports only.
Date: December, 18, 2003Project Name: Deep Sea Furrows: Physical Characteristics, Mechanisms of Formation and Associated Environmental Processes – Joint Industry Project
TEES Project Number: 32558-60120 MMS Task Order: 73209 MMS Project Number: 479
Principal Investigators: William Bryant and Niall Slowey
Estimated Completion Date: September 30, 2006
Project Description:
Significant currents that affect offshore operations and facility designs exist in the deepwater Gulf of Mexico. This project is part of a Joint Industry Program (JIP) formed to carry out an integrated study of the seafloor furrows produced by the flow and the characteristics of the flow itself. We will measure the extent and morphology of the furrows, the sediment properties, and assess the depositional history of the sediments using age-dating and seismic stratigraphic techniques. These results will be compared to the measured current flow regime immediately above the furrows, and relate it to the mechanisms of furrow formation and the climatology of deepwater currents. The resulting information will provide a basis for designing effective deepwater pipelines, risers, and templates (e.g., overbends, spans, and current loads) and a basis for estimating the effects of changes in furrow morphology and deepwater flow over the lifetime of deepwater oil field installations.
Progress:
A high-resolution geophysical cruise is tentatively scheduled for March 2004. TAMU's Deep-Tow will be employed to obtain high-resolution sub bottom profiles, side scan sonagrams and high-resolution multibeam bathymetry of the furrow fields in the area south of Green Knoll. Records will be obtained in water depths ranging from 2500 to 3300 meters. Eight meter sediment cores will also be recovered at the base of the Sigsbee Escarpment and in the furrows. Later in the year, five current meter arrays will be deployed within the furrow field south of Green Knoll.
MMS, BP and RPSEA have joined the JIP, and contract negotiations are in progress with BHP.
