Ronald J. Staskowski1,
Cynthia K. Dacre1,
John R. Everett1
(1) Earth Satellite Corporation, Rockville, MD
Abstract: Fracture density as a guide to petroleum exploration and development
In areas as diverse as Western New York, Central Texas, the Powder River Basin, and Central China, there is a strong correlation between high density fractures mapped from remotely sensed data and hydrocarbon production. Where accumulation is related to fracture porosity and permeability (eg. Texas and China) the relationship is anticipated. However, in areas with other structural and stratigraphic traps, the relationship also persists.
Faulting and fracturing influence the location of channels and offshore bars; differential compaction over buried sand or carbonate bodies may produce higher fracture density. Alteration related to vertical migration of hydrocarbons along fractures may make the fractures more obvious. Vertical fractures may constitute critical pathways for fluid migration from generating source beds to reservoirs. Thus, traps are preferentially charged in the vicinity of fractures. Some of these fractures may be the product of the overpressuring of source beds during generation and expulsion.
Both density and orientation of fractures are important factors. Areas of high fracture density are the most attractive, and wells that encounter relatively openstanding fractures (those parallel to maximum principal compressive stress in most areas) are the most prolific.
Digital technology allows one to rapidly digitize fractures, compute and map fracture density, and analyze fracture orientation.
The approach is useful for identifying new exploration targets, extending producing trends, choosing optimal location for development wells, and selecting the orientation of horizontal well bores. Fracture analysis is relatively inexpensive and, like all other tools, is best used in concert with sound geologic thinking and other conventional tools and techniques.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana