Abstract

Accumulation and flow in hydrocarbon reservoirs are strongly influenced by fracture systems. The geologic factors that control fracturing are an essential prerequisite to understand the origin and distribution of fractures. This paper describes a methodology based on structural data from 40 outcrops in the Sierra de Chiapas, southeastern Mexico. We analyzed the orientation, apertures, and spacing of 3900 fractures obtained from 83 scan lines. In addition, 71 oriented samples were collected for petrographic analyses. The cumulative fracture apertures were analyzed using log-log plots in which power-law distributions are shown at different scales. By studying the values of fracture aperture, we were able to analyze their relationships with geological variables. To do this, we performed multivariate analyses. The results indicate that the degree of dolomitization is the most important variable. Structural position and depositional environment also have some significant control on fracture density. This knowledge can be applied in the subsurface where fracture data are scarce. The results of this study have been taken as a guide in the characterization of fractures in several reservoirs of Mexico.