Analysis of Surface Lineaments and Fractures for Hydrocarbon Exploration and Production Optimization in the Mid-Continent Region
Authors: Guo Genliang , George Stephen A. , Lindsey Rhonda P. 
Published: December 2007

A large number of surface lineaments, surface fractures, gravity and magnetic lineaments, and Precambrian basement faults have been collected and digitized throughout the Mid-Continent region. Geological and mathematical analyses were performed on the orientations of these surface and subsurface linear features. A computer software was developed and used in the orientation analysis to generate rose diagrams. A trapping mechanism is proposed for the formation of subsurface oil and gas reservoirs in the Mid-Continent region.

It is observed that the surface lineaments and fractures are extremely consistent in orientation with the gravity and magnetic lineaments and the basement faults in the Mid-Continent region. They all consist of two major sets trending northeast and northwest, representing, therefore, the basic structural grains of the region. Also observed is a strong association both in orientation and position between the surface linear features and the subsurface oil and gas reservoirs in various parts of the region. Therefore, it is concluded that the systematic fault systems at the basement in the Mid-Continent region have probably been reactivated many times and have propagated upward all the way to the surface. They may have acted as the loci for the development of other geological structures, including oil and gas traps.

The observations and the trapping mechanism presented in this paper may provide important guidance for locating additional oil and gas reservoirs in these mature provinces. Furthermore, the surface and subsurface linear features collected in this paper can potentially be used in optimizing horizontal well drilling and secondary oil recovery operations in the Mid-Continent region.

Introduction

The validity of using surface lineament and fracture analysis for oil and gas exploration and production optimization hinges on whether lineaments and fractures observed at the surface can be projected into the subsurface, and whether surface fracture anomalies, if properly identified, are indicative of geological features in the subsurface. Many field observations and engineering analyses have concluded that at least surface lineament and fracture orientations are very consistent with those in the subsurface, and subsurface structures are generally aligned with the locations of surface fracture or curvilinear anomalies.

Field studies in the Colorado Plateau, Wyoming, and New York indicate, by observing sedimentary systems exposed in succession on deep canyon walls, that the systematic fracture patterns observed in earlier rocks are essentially repeated within each of the younger sedimentary systems all the way to the surface. When viewed over a large region, the areal pattern of folds in central Wyoming is remarkably regular. The regional fold pattern compares favorably with a fracture pattern of similar extent.

The consistency in orientation between surface and subsurface fractures was also observed by comparing various aerial-photograph analyses and production monitoring of petroleum reservoirs. A photogeological study of the North Burbank unit in Osage and Kay Counties, Oklahoma, showed that the orientation of the primary fracture set mapped from aerial photos is approximately parallel to the direction of early water breakthrough of the waterflooding operations in the field. The congruence of fracture orientations from well logging with those of surface fractures from aerial photo mapping was also observed in the Midland Basin area after analyzing data from eight reservoirs. correlation between subsurface hydraulic-fracture azimuths and surface fracture orientations was observed in Appalachian areas.

Based on these observations, researchers have proposed that regional fracture patterns are first established in basement and/or deep subsurface rocks due to large-scale tectonic activities.