Integrating Microseismic Monitoring With Well Completions, Reservoir Behavior, and Rock Mechanics

Abstract

Microseismic monitoring has proved to be a valuable technology for assessing and optimizing hydraulic fracturing in a host of tight sand and gas shale reservoirs. Parameters such as fracture length, height, azimuth, and asymmetry are readily identified, but this technology can also be useful for understanding staging effectiveness, stimulated volume, complexity and network growth, natural fractures, stress azimuth and changes in that azimuth, fault interactions, and reservoir behavior as a result of the treatment. Various published data sets are examined to show how both quantitative and qualitative information about the fracturing behavior, completion effectiveness, and reservoir behavior can be usefully extracted from the microseismic data. Examples will include both vertical and horizontal wells, relatively planar and network fracture systems, various staging and diversion techniques, and faulted and naturally fractured reservoir response.

Mechanical Factors Controlling the Development of Orthogonal and Nested Fracture Network Geometries

“…For instance, recent studies on the low permeable layers of the Whitby Mudstone Formation and Cleveland Ironstone Formation (Cleveland basin, Yorkshire, UK) (Emery 2016;Imber et al 2014), argued that the observed orthogonal and nested fracture networks were created by pore fluid overpressures. Furthermore, micro seismicity and core data from the low permeability reservoirs found evidence of open parallel and orthogonal fracture networks being present within the subsurface (Fisher et al 2005;Gale et al 2010;Warpinski 2009). The observed fracture networks were believed to be created by fluid overpressures prolonging for a relatively long time, resulting in effective tensile stress and the development of closely spaced orthogonal fracture networks (Fisher et al 2005;Warpinski et al 2014;Warpinski 2009).…”

“…Furthermore, micro seismicity and core data from the low permeability reservoirs found evidence of open parallel and orthogonal fracture networks being present within the subsurface (Fisher et al 2005;Gale et al 2010;Warpinski 2009). The observed fracture networks were believed to be created by fluid overpressures prolonging for a relatively long time, resulting in effective tensile stress and the development of closely spaced orthogonal fracture networks (Fisher et al 2005;Warpinski et al 2014;Warpinski 2009). These studies also argued that the stimulation, effective permeability and resulting production was significantly enhanced by the presence of the natural fractures.…”

A Comparison of Hydraulic Fracture Modeling With Downhole and Surface Microseismic Data in a Stacked Fluvial Pay System

“…The microseismic events occur as formation rocks break, and the events signals are potentially strongest at the tips of the fractures. Therefore, microseismicity fracture mapping provides fracture dimensions in terms of "created fracture length" (Warpinski, 2009). In addition to the total fracture length acquired in this mapping process, the microseismic data can also be used to build a calibrated model to help compute effective fracture length based on the measured total fracture length (Warpinski, 2009).…”

Extracting low signal-to-noise ratio events with the Hough transform from sparse array data

“…The monitoring of microseismic events in the reservoirs and mines is used to provide information on hydraulic fracturing, changes in the local stress field, imaging, and for seismic hazard analysis (Chambers et al, 2010;Maxwell et al, 2010). The detection of such events can be difficult in cases in which background noise levels are high due to anthropogenic activity, leading to misleading results (Ge, 2005;Warpinski, 2009). Therefore, low-S/N event detection is desirable.…”