Small scale reflection seismology
CMP gather
3D seismic reflection
The goal is a 3D image of structure (data cube)
Visualization (slice & dice) 3-D image Visualization (slice & dice) Volume construction of salt dome image
Typical Geometry for 3D Acquisition
Acquisition Animation Courtesy of PetroSkills Marine Acquisition Animation (Bin Gathering) Courtesy of PetroSkills
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition
Marine 3D Acquisition Traces in Each Bin 16 14 12 10 8 6 4 2
Marine 3D Acquisition Mid- Points
Marine 3D Acquisition Mid- Points Inline Crossline Stacked Trace
Seismic Interpretation Integration of seismic data with other constraints on the geology well logs outcrop patterns known stratigraphy, faults, etc Important to remember what seismology provides: imaging of interfaces between beds of different velocity detailed constraints on the geometry of these interfaces What seismology does not provide: unique identification of rock type usually does not provide direct imaging of petroleum, gas, water, etc Thus: seismic data is much more useful along with other constraints on geology providing identification of the interfaces.
Caliper – measures borehole size Lithology Logs – differentiate sands Overview of Key Logs Caliper – measures borehole size Lithology Logs – differentiate sands Porosity Logs – porosity & fluid types Sonic Logs – relate well to seismic Resistivity Logs – Identify HC zones SLIDE 3 We will briefly look at these 5 classes of key logs Courtesy of ExxonMobil L 4 - Well Log Data
Porosity Logs Shale Density porosity (solid black line) Neutron Porosity Density porosity (solid black line) measure the bulk (average) density of the formation (rock & fluids) Neutron porosity (dashed red line) measures the hydrogen content Shale Deflections to the left = more porous Deflections to the right = less porous Dashed red left of Solid black black = Shale Dashed red right of Solid black = Gas Sand Dashed red over Solid black = Wet Sand or Oil Sand SLIDE 7 This slide introduces two porosity logs Density porosity (solid black line) measure the bulk (average) density of the formation (rock & fluids) Neutron porosity (dashed red line) measures the hydrogen content For both logs, Deflections to the left = more porous Deflections to the right = less porous The way we interpret these logs is to draw them together (in the same track) If the dashed red line is to the LEFT of the solid black line = Shale If the dashed red line is to the RIGHT of the solid black line = Gas Sand If the dashed red approximately overlies the solid black line = Wet Sand or Oil Sand Gas Gas Oil or H2O Courtesy of ExxonMobil L 4 - Well Log Data