Paper: Detection of Natural Fractures From A Drillstem Test

The presence and magnitude of natural fractures in a potentially productive zone may have a significant effect on the completion of that zone. Their existence may dominate the pore space of the rocks and control the production rate. In addition, the method and materials required to stimulate this heterogeneous system may require special attention. This paper discusses the detection of fractures from the pressure buildup behavior of a drillstem test, and how this behavior may be distinguished from unconnected layered zones and flow capacity discontinuities. A quantitative analysis making this distinction is demonstrated by a Horner plot, square root of time plot, and Gringarten curve fit. The magnitude of the fractures may he estimated.