A New Perspective in Hydro Fracture Evaluation


A New Perspective in Hydro Fracture Evaluation

Authors:

Stefan Goerz, CCI Inc., Edmonton, Alberta Canada
Nicolas Boelhower, CCI Inc.
Justin Taylor, CCI Inc.

Abstract: The pressure sensor and associated guidance software automatically record “real-time” pressure data throughout the length of the HDD crossing. As will be discussed in this paper, this data has been collected and compared to the calculated theoretical drilling fluid pressure within the annulus of the borehole. Results of this analysis show the accepted drilling fluid models used to calculate the annular pressure during drilling generally compare well the data obtained.

Additionally, In this paper as-drilled annular pressure data, in combination with HDD construction inspection reports, are used to determine the date, time, and pressure magnitude of actual hydraulic fracture occurrences in HDD crossings. Through careful evaluation, these occurrences have been isolated within the as-drilled data and compared to the predicted hydraulic fracture pressure calculated by the “Delft” equation using site specific geotechnical parameters. Literature suggests factors of 1/2 and 2/3 multiplied by the overburden height be placed on the value of Rp,max, for clay and sand, respectively. Results of the analysis of as-drilled data show that in most, if not all cases the “Delft” solution overpredicts the actual hydraulic fracture pressure.

Previously, assumptions in the value of Rp,max have not been investigated and compared to actual hydraulic fracture data. Contained within this research, the Rp,max value is modified to determine at what value the Delft equation best predicts the actual hydraulic fracture pressure.

Publication Date: 2019

Presented at:
NASTT’s 2019 No-Dig Show Chicago, Illinois
March 17-21, 2019 | Paper Number: TM1-T2-01


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