Continuous Scratch Testing on Core Allows Effective Calibration of Log-Derived Mechanical Properties for Use in Sanding Prediction Evaluation
Roberto Suárez-Rivera, SPE, TerraTek Inc., Jørn Stenebråten,
TerraTek Inc., Fabrice Dagrain, Faculté Polytechnique de Mons
This paper waspresented at the SPE/ISRM Rock
Mechanics Conference held in Irving, Texas, 20-23 October 2002.
Copyright
2002, Society of Petroleum Engineers Inc.
Abstract
This paper discusses the use of continuous scratch testing for evaluation
of rock heterogeneity and effective correction and calibration of mechanical
properties predictions using wire line logging. Understanding the vertical
variability of rock properties (strength and moduli) along the reservoir
thickness is of primordial importance for sanding prediction analysis.
Logging measurements (GR, Sonic, Density and Porosity) are traditionally
used to identify troublesome intervals, to select sections for laboratory
testing and for extrapolating laboratory data to untested reservoir
sections. However, depending on the scale of the reservoir heterogeneity,
the log measurements, by providing integrated values over their window
of vertical resolution, can considerably underestimate the strong reservoir
sections and overestimate the weak reservoir sections. This leads to
misrepresentation of critical weak layers with high potential for sanding
and potentially to large errors in the completion strategy with costly
long-term consequences. Corrections are thus necessary and are traditionally
based on simple unconfined compression (UCS) tests conducted sparsely
or at high density, varying from operator to operator. This paper presents
a method for log-correction based on continuous core scratching in
the laboratory and shows that the methodology is effective in evaluating
changes in properties with high accuracy and a resolution of at least
1 cm.
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