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Nondestructive Core-Strength Tester Uses Steel Ball To Evaluate Hardness

This paper presents results from a nondestructive core-strength-index tester that is less destructive than the Schmidt hammer and less intrusive, easier, faster, and less expensive than the core scratch tester. The portable hardness-index tester measures and compares the impact and rebound velocities of a small steel ball after its collision with a rock surface to determine rock hardness, which, in turn, reflects the relative strength of the rock.

Theory and Application of the Index Tester

The index tester (Fig. 1) is a hand-held, electronic, battery operated, spring-loaded device that provides an indirect method to predict rock strength. The Leeb hardness unit is calculated by comparing the impact (Vi) and rebound (Vr) velocities of a small steel ball after its collision with a rock surface (Fig. 2). The impact body rebounds faster from harder rocks than from softer ones, resulting in a higher energy quotient, which, in turn, reflects the relative strength of the rock. Features of the index tester include a liquid-crystal display of the results, internal data storage, and a connection for download of data for future analysis and reporting.

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 158326, “Nondestructive Strength-Index Testing Applications for Sand Failure Evaluation,” by Gillian Daniels, SPE, Colin McPhee, SPE, Philip McCurdy, SPE, and Yelitza Sorrentino, SPE, Senergy, prepared for the 2012 SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, 22–24 October. The paper has not been peer reviewed.
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Nondestructive Core-Strength Tester Uses Steel Ball To Evaluate Hardness

01 October 2013

Volume: 65 | Issue: 10

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