Fracture Orientation Determination in Sandhills (McKnight) Field, Crane County, Texas

Cindy Olive

A fracture identification log (FILMAP, Schlumberger) provided an orientation of vertical fracturing in the Sandhills (McKnight) field, Crane County, Texas. During workover operations to deepen an existing well bore to test a lower porosity interval, a 200-ft core was obtained that intersected a fracture plane in several sections of the core. Verification of this fracture having been hydraulically induced (or enhanced through hydraulic stimulation) was established with the discovery of frac-sand grains along the face of the fracture. The 300-ft open-hole section of the original well bore had been fracture stimulated with 30,000 gal of refined oil and 45,000 lb of sand. The fracture identification log was included as a part of the formation evaluation program to ascertain t e orientation of the fracture(s). This tool measures the difference in resistivities along a horizontal plane of the bore hole by detecting fractures that bisect the hole and determines their orientation. Interpretation of the data indicated an east-west fracture, which was concluded to be the basic orientation of the natural fracture system within the northern portion of the Sandhills (McKnight) field. Prior to this physical evidence, the orientation of the fracture system was inferred only by early water breakthrough in an east-west direction within areas of previous waterflooding.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.