DHIs exploration can be very challenging and can result in...

DHIs exploration can be very challenging and can result in failed wells. Some possible reasons for failure may be:

• Problem in differentiating the wells with gas buildups and wells with low-saturation gas (fizz gas), which are considered dry holes. These are principally costly due to their locations and lack of infrastructure.
  • Dry holes are often interpreted as false positives; which are often found in tight reservoirs and thick wet sands.
  • Low-saturation gas phenomenon is often related to a break in a reservoir seal and is due to residual gas that assemble a high amplitude effect similar to a commercial saturation.^[12]
• Flat reflections may be caused by unusual lithologic variations rather than fluid contacts.
• Rocks with low impedance could be mistaken for hydrocarbons, such as coal beds, low density shale, ash, mud volcano, etc.
• Polarity of the data could be incorrect, causing a bright amplitude in a high impedance zone. ^[2]
• Superposition of seismic reflections and tuning effects.
• Signal contamination due to noise.

See https://wiki.seg.org/wiki/Direct_hydrocarbon_indicators or google the DHI consortium.

Dr Mello has seen the volcanic ash as risk in Namibia. Another risk is that the turbidites did not have high enough velocities when it was formed to get cleaner sands for the reservoir.
1st part
https://lnkd.in/ezsbAMVd
2nd part
https://lnkd.in/epfxjy5q
3rd part
https://lnkd.in/eFSccCVH