Downhole microseismic monitoring: processing, algorithms and error analysis
Date
2014-04-09
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Abstract
Basic microseismic data processing for hypocentre location estimates is a pre-requisite to
extracting information about the stimulated reservoir volume as well as understanding the
geomechanics of the fracturing process. The primary objective of this thesis is to investigate
the basic processing of microseismic data acquired with receivers in a single observation well,
with emphasis on the evaluation and parameter selection of processing algorithms and the
associated hypocentre location error analysis. This thesis is made up of five independent
studies.
The first study discusses the development of a MATLAB based microseismic data processing
package (Calgary microseismic processing system; CaMPS). This software is used to process
the microseismic data from a hydraulic fracture treatment in western Canada. For reference,
the results are compared with those obtained independently by a microseismic services company.
The second study examines several single-trace event-detection and arrival-time picking algorithms
for microseismic data. A dynamic threshold criterion for event detection and a
hybrid, arrival-time picking approach are proposed. The performance of these algorithms is
evaluated using synthetic and real microseismic data.
The third study describes an iterative cross-correlation based workflow to refine the initial
arrival-time picks. This workflow is compared with other single-trace and multi-trace techniques.
The proposed workflow provides an arrival-time accuracy of ±0.5 − 1ms for both
synthetic and real microseismic data examples considered in this study.
The fourth study examines hypocentre location uncertainty and errors due to inaccurate
velocity model. The Monte Carlo uncertainty analysis suggests that the velocity errors have
a greater impact on hypocentre locations than arrival-time pick errors. The hypocentre location
errors resulting from the model calibration process are also discussed, in particular the use of single vs. multiple calibration shots, a priori information, and first vs. direct arrival
times.
The fifth study discusses the remaining hypocentre location errors after anisotropic model
calibration. The behaviour of hypocentre location is discussed when a 1-D layered, isotropic
and homogeneous model is used to locate hypocentres from anisotropic and heterogeneous
subsurface. The results emphasize the use of a detailed model with anisotropy and lithological
or structural variations for improving hypocentre location accuracy.
Description
Keywords
Geophysics
Citation
Akram, J. (2014). Downhole microseismic monitoring: processing, algorithms and error analysis (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25742