MAPPING INFLUENCE OF GEOLOGIC DISCONTINUITIES ON HYDRAULIC FRACTURE PROPAGATION

Understanding the created fracture geometry is key to the effectiveness of any stimulation program. Technology has progressed to the point where microseismic monitoring of hydraulic fractures can provide extensive diagnostic information on fracture development and geometry. Critical elements of a monitoring system include the receivers, the telemetry system and processing of the vast amount of acquired data.

Geology is a fundamental element in the design of a stimulation program and the interpretation of its results. Rock properties govern the type of fluids to be injected in the formation as well as the pumping schedule. Rock layering controls the location of the monitoring device, guides the depth at which perforations should be located, and rules how hydrocarbons flow within the formation. Despite these facts, the impact geology may have on the stimulation results is often overlooked as it is often assumed that stimulated fractures have a symmetric planar geometry.

We present the results of hydraulic fracture stimulations in various geological environments that have been monitored using microseismic data. We illustrate with these case-studies that in some rare cases, simple radial and planar fracture system (often mislabeled penny shape-like fracture) may be generated as predicted using simple modeling techniques. However, in most cases the final fracture system geometry is asymmetric and largely governed by geologic discontinuities such as joints, faults, and bedding planes. These geologic discontinuities significantly affect the overall geometry of the hydraulic fracture system. This may end the fracture system’s development, increase fluid leakoff, hinder proppant transport, or even create a complex fracture network. Ultimately, such factors impact well productivity.