Acoustic Emission Interpretation for Estimating Hydraulic Fracture Extent: Laboratory and Field Studies

Abstract

It is useful to map hydraulic fractures in order to improve the rate of success of such operations and to optimize the pattern of stimulated wells. The proposed method can be used during a minifracturing or prefracturing operation and necessitates a downhole 3D acoustic detector clamped in the well. A few to a few dozen cubic meters of gel are injected during fracturing phases, and the acoustic activity is recorded after every injection. Then signals containing apparent P and S waves are analyzed to determine the directions and distances of the emitting sources. A number of arrivals cannot be interpreted easily, in particular those corresponding to refractions along the casing.Three field examples corresponding to a vertical, a deviated and a slant well are given. Knowing the P and S wave velocities in the different layers and a careful choice of the tool position are essential to the success of the method.

Induced Microseismicity: Short Overview, State of the Art and Feedback on Source Rock Production

“…For that, wireline acoustic sondes equipped with a 3C-sensor were first adapted or designed to collect the information downhole more precisely, in an observation well located close to the injector well or even in the injector well itself [20]. Fig.…”

“…The tool was lowered-down through the tubing into the stimulated well, just below the perforations and was oriented using surface calibration shots. As suggested by laboratory studies performed in a parallel research project [1,20], a series of re-injections into the created fracture was performed to acquire more microseismic events, and thus to increase the reliability of fracture mapping. Each re-injection reopened the recently-created fracture of which the closure was associated with an important induced seismicity.…”

Active and Passive Acoustic Imaging Inside a Large-Scale Polyaxial Hydraulic Fracture Test

“…Uncertainties in predicting the actual hydraulic fracture geometry by numerical models prompted numerous field fracture monitoring experiments (e.g., Sadra et al 1988;Vinegar et al 1992;Sleefe et al 1993;Block et al 1994). An objective of these experiments is to compare the numerically computed hydraulic fracture geometry with geometry mapped using geophysical methods.…”

Injection-induced Microseismicity in Colorado Shales

“…Among different techniques investigated to detect fracture propagation during fluid injection operations in rock masses, monitoring and analysis of microseismic activity associated with fluid percolation has been proved to be the most reliable technique. This method has been in use over the last two decades in geothermal applications (e.g., ALBRIGHT and PEARSON, 1980;PEARSON, 1981;CASH et al, 1983;NIITSUMA et al, 1985;MURPHY and FEHLER, 1986;TALEBI and CORNET, 1987;HOUSE, 1987) as well as oil and gas applications (e.g., POWER et al, 1976;THORNE and MORRIS, 1988;SARDA et al, 1988;TALEBI et al, 1991;DEFLANDRE and DUBESSET, 1992). Because of technical limitations and the cost of the application of this technique at large depths, many authors have been limited to the use of only one borehole for sensor installation and sometimes even only one three-component sensor.…”