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2	Seismic Method The only method giving complete picture of the whole area Gives by far the best resolution among other geophysical methods (gravity and magnetic) However, the resolution is still limited Maps rock properties related to porosity and permeability, and presence of gas and fluids However, the links may still be non-unique Requires significant logistical effort Relies on extensive data processing and inversion
3	Seismic Reflection Imaging
4	Seismic Impedance
5	Resolution
6	Seismic Displays
7	Types of Seismic Surveys Start with regional 2-D reconnaissance lines Following the initial discovery – detailed 2-D or 3-D Repeated 3-D surveys (“time-lapse”, or 4-D) for monitoring changes in the area during production For best survey planning: In most cases, need to have a good idea about the target Use computerized pre-acquisition modelling Key considerations: For 2-D – lines should be oriented across-strike of the target structures Cost – minimize the number of source points Achieve sufficient multiplicity (“fold”) of coverage Achieve uniformity of coverage of the target horizons “Undershoot” obstacles and survey edges Achieve adequate resolution and fidelity Reduce the acquisition footprint (especially important in 3-D)
8	Planning and surveying
9	Seismic explosive sources on land Gelatin dynamite, ammonium nitrate, pentolite (SEIS-X). Packaged in tins, cardboard or plastic tubes ~5 cm in diameter (0.5-5 kg each). Connected to make desired charges. Detonated using electrical detonators. Best explosives will disintegrate from contact with water when not used.
10	Drilling and Charging
11	Drilling and Charging
12	VibroSeis source Rather than using explosions, acoustic energy can be distributed in time by using a hydraulic vibrator device Usually mounted on a heavy truck Small borehole vibrators, portable vibrators, and >100-ton stationary vibrators also exist. The signal consists of a quasi-monochromatic “sweep” of gradually changing frequency, covering ~20-150 Hz To produce stronger signal, vibrators are able to operate synchronously (vibrate in-phase) in a group The signal sent into the ground is carefully recorded and afterwards “correlated” with the recordings to produce an equivalent of impulsive excitation
13	VibroSeis
14	Marine seismic source - airgun
15	Geophones and Digital Acquisition Systems
16	Line layout and field operations
17	Acquisition and QC
18	Processing
19	Seismic Images 1: Stack
20	Seismic Images 2: Migrated stack
21	Seismic Images 3: Velocity model
22	Seismic Images 4: Pre-stack migration
23	Seismic Images 5: 3-D model
24	Interpretation
25	(Acoustic Impedance) Inversion
26	Seismic Attributes
27	Attributes (some examples for the same “bright spot” section )
28	Amplitude-vs. Offset (AVO) properties
29	Benefits of 3-D Seismic Imaging