Structural lead and prospect delineation

Exploring for Oil and Gas Traps
Series	Treatise in Petroleum Geology
Part	Predicting the occurrence of oil and gas traps
Chapter	Exploring for structural traps
Author	R.A. Nelson, T.L. Patton, S. Serra
Link	Web page
Store	AAPG Store

Prospect identification

A structural lead becomes a prospect once we determine that the major components of the hydrocarbon system have sufficient probabilities of success in contributing to an economic accumulation of hydrocarbons in the structure. In the table below are examples of some structural technical issues to consider when assessing the petroleum system relative to a structural lead. Many companies use a mixture of these issues to assess exploration risk, employing various numerical approaches.

Element	Factors Defining the Structural Prospect
Trap	Trap integrity (certainty of dip closure; integrity of the closure throughout the evolution of the structure) Area/volume under closure (present closure; structural closure during migration)
Seal	Integrity of seals (continuity and integrity of top seal; integrity and capacity of fault seals)
Reservoir	Storage capacity (structural degradation or enhancement effects) Deliverability (structurally induced enhancement or degradation of permeability) Anisotropy (flow anisotropy due to faults, folds, or fracture facies variability) Heterogeneity (local enhancement or degradation; fault isolation or compartmentalization) Pressures (structurally induced overpressures)
Source facies	Maturation (structural overburden considerations; tectonic subsidence and uplift effects considered)
Expulsion/ migration	Structural pathways (charge areas have been in effective communication with prospects) Structural gathering areas (sufficient volumes of migrating hydrocarbons captured and diverted into appropriate pathways) Timing (structural pathways effective throughout generation/migration event)

Assessing technical issues

The following data sources and techniques can help us assess some of these technical issues:

• Outcrop studies (interpretive analogs)
• Structure section balancing (structural geometry)
• Palinspastic restoration (migration pathways; paleostructure)
• Dipmeter and FMS analysis (structural geometry)
• Detailed seismic, 2-D and 3-D (structural geometry)
• Modeling studies (seismic; theoretical; physical; interpretive analogs)
• Hydrocarbon migration pathway analysis
• Fault-seal studies (trap integrity)
• Core analysis (fracture potential)
• Mechanical testing of rock (fracture potential)
• Petrofabric analysis
• Fracture analysis
• Curvature analysis (fracture potential)
• Mechanical testing (fracture potential)
• Special seismic processing and velocity analysis (e.g., prestack migration; amplitude vs. offset)

When a lead becomes a prospect

Once we determine that the risk in drilling for hydrocarbons on the structural anomaly is acceptable, the lead qualifies as a prospect. The next problem confronting the explorationist is picking an appropriate location on the prospect.

See also

• Structural exploration workflow
• Tectonic setting
• Structural domains
• Structural fairway prospectivity
• Structural exploration:location selection
• Structural exploration: thrust belt example

External links

find literature about Structural lead and prospect delineation

• Original content in Datapages
• Find the book in the AAPG Store