Integrating potential field data with seismic, geochemistry and structural geology Prepared for: Finding Petroleum
Contents Historical issues Non-integration Present day, integration Seismic planning Mapping structural geology Magnetic data Geochemical integration Hyperspectral imaging Conclusions
Overview Seismic s little brother Airborne surveying has had significant success in frontier exploration. Integration of all datasets key.
Historically Gravity response d1 d1 d2 d1 d2 d2 d4 d5 d3 d3 d3 Correct model? Gravity data seen as a regional tool Generally limited experience within oil companies Non-uniqueness therefore uncertainty?
Why so Underused? We acquired grav and mag but haven t done much with it. I don t understand how it s useful to my exploration? Sounds great, but we re on an exploration timeline no time to figure out how it really works!
Time for a better Understanding We need to effectively become part of the exploration team to deliver results alongside and integrated with the exploration program. Geophysical models rather than geological Data that is not explained is misunderstood and useless
Not integrated Geophysical 2D model Depth estimate calculations
Present day Modern acquisition techniques allow very high resolution datasets Cover large areas quickly and cheaply Ideal for frontier exploration areas such as Africa The data is not the problem 1 2 3 FTG data courtesy of Bell Geospace Magnetic image courtesy of SRK Consulting 2011 12km
calc50kmhp Used correctly mgals 4.00 0.00 Calculated gravity response -4.00-2 50 100 150 200 222 calc50kmhp Depth (km) Geological 2D model Gravity data Depth to basement surface
Integration with seismic data Gravity and magnetics often a pre-cursor to seismic acquisition. Particularly in Africa, with large frontier areas. Logistical and security issues of establishing a large seismic crew in country. Arguably assisting in the seismic planning from a cost/logistics point of view is as important as any subsequent detailed geological results Typical airborne gravity and magnetic survey could have the cost equivalent of 70km of 2D land seismic.
Seismic planning Typical 2D seismic survey planning without gravity and magnetics as a tool The same seismic line km s located more efficiently based on prior airborne surveying
FINAL_Tz (m) FINAL_Tz_10kmres FINAL_Tz_25kmres (m) Seismic integration and structural geology 6.0 1.2 2.0 0.0 0.6 0.0-6.0 0.0-12.0-0.6-2.0-2 50 100
Mapping structural geology Surface geology Gravity data with surface faulting overlaid Gravity derived fault mapping
Mapping structural geology Description Major thrust Symbol Major offset Anticline Syncline Minor thrust Minor offset
Geochemical data Surface geochemical can indicate a working system, but little indication of size and extent Potential fields can indicate large basinal areas, but no direct indication of a hydrocarbon producing system Gravity and Magnetics Seismic Geochemical Integrated model In frontier areas the establishment of a working system is key for companies to assist with exploration funding, farm-ins, CPR s etc.
510000 21 15' 520000 21 30' 530000 21 45' 540000 550000 560000 22 00' 570000 580000 22 15' 590000 600000 22 30' 610000 22 45' 620000 5480000 5450000 5420000 5420000 49 00' 5430000 49 00' 5430000 5440000 5440000 5450000 49 15' 49 15' 5460000 5460000 5470000 5470000 49 30' 5480000 Gravity derived depth structure and surface seeps 510000 520000 21 15' 530000 540000 21 30' 550000 560000 21 45' 570000 22 00' 580000 590000 22 15' 600000 610000 22 30' 620000 22 45' 5000 0 (m WGS 84
Hyperspectral imaging Hyperspectral imaging has been used routinely in environmental and mineral studies. Used to map different materials at the surface of the Earth based on their spectral characteristics.
Hyperspectral imaging Studies have been completed on its use in onshore oil seep detection (Ellis). By combining gravity, magnetics, hyperspectral in a single aircraft a multidisciplinary survey can be flown. Other airborne oil sniffer technologies in development. Image courtesy of Northrop Grumman
Conclusions Data nowadays is very high resolution. Integration with other datasets is key. Producing geological models and deliverables are critical to the exploration process. Not just gravity: magnetics, hyperspectral, geochemical all add extra information.
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