INTEGRATED INTERPRETATION OF BOREHOLE MICROSEISMIC DATA FROM HYDRAULIC FRACTURING STIMULATION TREATMENTS

Abstract

Sequence stratigraphic principles provide means to interpret the geological framework and likelihood of finding hydrocarbon–bearing rocks. In this work, I show that they can also be used to predict and better interpret the microseismic response associated with a hydraulic fracturing stimulation treatment. In order to test my hypothesis, first I recognize the presence in the subsurface of brittle-ductile couplets, based on a sequence stratigraphic framework provided by gamma ray stacking patterns. Then, I use my geological model to better interpret the microseismic response recorded during a single stage fracture stimulation treatment monitored from three strategically located observation wells. I analyzed and compared hydraulic fracturing results inferred by individual processing of microseismic data acquired from horizontal and vertical sensor arrays, as well as the results from simultaneously processing the signals recorded by all three sensors. At the end, I show how the triple array simultaneous solution provides the most useful data set to interpret the stimulation treatment based on the good fit between the microseismic events locations obtained under this approach and the theoretical expectation from the aforementioned sequence stratigraphic framework. Additionally, this document summarizes significant findings obtained while working on my dissertation. I discovered that despite its widespread use, there are several issues associated with the implementation of microseismic technology, which may lead to erroneous interpretations of the treatment results. In this publication, I discuss several examples of common pitfalls, including poor data recording, velocity model artifacts, processing constraints and display limitations. These findings underscore the importance of the interpreter’s role in ensuring a high quality outcome from a microseismic hydraulic fracturing evaluation. Moreover, I demonstrate that microseismic data can also serve to identify subsurface geological features such as faults and natural fractures zones through the use of magnitude vs. distance plots. The results from this dissertation not only improve current hydraulic fracturing microseismic interpretation workflows, but they also translate into significant costs savings associated with more efficient hydrocarbon developing campaigns.