Overview
Hydraulic fracture stimulations are critical for the development of
unconventional reservoirs, and the growing interest in shale reservoirs
has resulted in the rapid expansion of microseismic fracture imaging.
During high-pressure fluid injections of a hydraulic fracture treatment,
microseismic emissions occur as cracks form and interact with
pre-existing fractures. Images of the microseismic locations can be used
to interpret hydraulic fracture geometries, including the direction,
dimensions, and complexity resulting from networks of fractures in
different orientations. The course will provide an overview of
microseismic theory and practical application: from acquisition and
survey design, processing through to interpretation. The emphasis will
be on practical issues associated with acquisition of high-quality
microseismic data, including potential pitfalls and quality control
steps. Actual case studies will be used to demonstrate engineering
benefits and improved production through the use of microseismic.
Summary
The following topics will be addressed in the course:
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Introduction and History of Microseismic Monitoring:
A review of the history of microseismic applications, including
mining-induced seismicity, reservoir monitoring, and hydraulic
fracturing for the stimulation of geothermal and oil and gas reservoirs.
Practical application to engineering problems is stressed, including
environmental concerns associated with the contamination of shallow
aquifers and induced seismicity.
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Hydraulic Fracturing Basics:
A tutorial of fracture mechanics theory, field operations and
equipment, diagnostic technologies, and factors that influence hydraulic
fracture growth. The review describes engineering challenges associated
with designing an effective hydraulic fracture treatment ,and provides a
context for practical application of microseismic imaging through the
remainder of the course.
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Acquisition and Pre-Survey Design:
Various microseismic monitoring configurations are described, including
vertical, horizontal and multi-well downhole, surface, and shallow
buried arrays. Pros and cons of each configuration are described along
with acquisition system specifications and the impact on microseismic
data quality. Essentials of survey design for both surface and downhole
monitoring are given, along with criteria for designing an optimal
monitoring system.
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Basic Processing for Microseismic Locations:
Basis processing of microseismicity involves estimating the hypocentral
location of the microseismic sources along with uncertainty estimates. A
standard processing workflow is described, including velocity model
construction and calibration. Standard location algorithms are
described, with a focus on practical quality control. The impact of
acquisition geometry on the resulting microseismic image is described.
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Geomechanics of Microseismic Deformation:
Microseismic source characterization, including source strength
estimates using magnitude scales and focal mechanisms, are presented.
The relationship between deformations associated with the observed
microseismic sources and the underlying hydraulic fracture are reviewed
to provide context to interpret microseismic source characterization.
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Interpretation of Microseismic Fracture Images:
Assessment of sensitivity, resolution, and confidence of microseismic
images is reviewed. Workflows are described to remove potential biases
and improve the accuracy of the microseismic events. Assessment of
fracture direction, dimensions, complexity and stimulated volume from
microseismic is described with a focus on interpretational pitfalls.
Integration with other information is stressed to provide geologic and
geomechanical interpretation frameworks.
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Engineering Applications of Microseismic Imaging:
Presentation of case studies demonstrating various aspects of improving
engineering designs for hydraulic fracture stimulations, well
completions and field development. Various engineering design issues are
discussed along with case study examples describing the use of
microseismic data to improve the engineering design. The value of
information considerations are described along with improving the
economic viability of unconventional developments using microseismic
imaging to increase productivity and reduce well, completion, and
stimulation costs and designs using microseismic data.
Course Objectives
Students will gain an understanding of the theoretical and practical
aspects of microseismicity, including how to use data to improve
engineering design of hydraulic fractures, as well as:
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Basics of hydraulic fracture operations
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Geomechanical processes that generate microseismicity, and how it relates to the hydraulic fracture growth
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Issues associated with high-quality microseismic data
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Common processing pitfalls and quality control approaches to processing workflows
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Identifying and accounting for potential monitoring biases
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Interpretation of microseismic images
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Application of microseismic data to fracture engineering challenges
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Monitoring-induced seismicity
Who should attend
The course is intended for geophysicists, engineers and geologists.
The emphasis is on practical application and, as such, only basic
prerequisite knowledge is assumed. The course would be most relevant to
those currently involved with, or considering development of,
unconventional reservoirs and particularly shales.
