--> ABSTRACT: Percent Trap Fill and Its Implications , by Bishop, Richard S.; #90142 (2012)
[First Hit]

Datapages, Inc.Print this page

Percent Trap Fill and Its Implications

Previous HitBishopTop, Richard S.*1
(1) Consultant, Houston, TX.

Observations of hundreds fields in many different types of basins and source rocks shows that traps are full to either a leak point or spill point. Percent fill, however, cannot be determined for many types of traps even after development. Specifically, this is true for traps with few wells and complex geometries and/or complex stratigraphies. In general, percent fill can be determined only in densely drilled, geometrically simple structural traps. The implication clearly is that if the large, simple traps are full, there was sufficient hydrocarbon generated to fill the complex ones as well.

There are many implications derived from this observation including the following:

1. Maximum field size is determined by maximum trap capacity, not source rock yield

2. Different tectonic settings have different maximum field sizes

3. Trap risking can be based on number and type of hydrocarbon boundaries as well as seal quality

4. The occurrence of both free gas and oil in a single reservoir requires leakage or the gas would displace the oil

5. The widespread occurrence of oils saturated with gas indicates selective leakage of gas from these traps.

6. Spill from downdip traps may reduce risk in updip traps

7. Regional top seals can produce more traps filled to spill and thus larger field sizes than vertically leaking hydrocarbon systems. The caution, however is that many widespread, thick top seals may also leak vertically.

These observations and implications also illustrate many mysteries about how hydrocarbons can enter traps. Awareness of such examples can lead to different exploration strategies if we realize and accept what can happen, even though we cannot explain it.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California