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Enhancing Cement and Rock Mechanical Properties Assessment

IP.com Disclosure Number: IPCOM000236987D
Publication Date: 2014-May-23
Document File: 6 page(s) / 248K

Publishing Venue

The IP.com Prior Art Database

Abstract

Post fracture and post fatigue analysis can be improved by increasing measurement accuracy. Using an array of sensors to measure the same process point, each specified to measure a specified range that best suits the individual sensor’s accuracy, will improve overall assessment accuracy. Process isolation for each sensor will prevent sensor failure. The oil/gas industry knowledge base for rock mechanics and cementing material analysis can be improved using this method.

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  Enhancing Cement and Rock Mechanical Properties Assessment

Abstract

Post fracture and post fatigue analysis can be improved by increasing measurement accuracy. Using an array of sensors to measure the same process point, each specified to measure a specified range that best suits the individual sensor's accuracy, will improve overall assessment accuracy. Process isolation for each sensor will prevent sensor failure. The oil/gas industry knowledge base for rock mechanics and

Introduction

Fatigue and/or failure testing is a very common analysis that directly or indirectly affects most industries. These testing procedures are typically accomplished by monitoring one sensor that is capable of measuring the full range of the expected failure point. The overall variable change determines the peak performance. In the oil/gas industry, peak performance is not the only aspect of the test that is relevant. For example, many post pressure peak behavior characteristics are important throughout rock/cement When performing assessments to determine mechanical and geological properties for rock or cement samples, accuracy is lost for post-fracture/failure analysis. The limitation for these tests is the sensor accuracy at lower pressures. Pressure sensor accuracy is based on a percentage of the maximum sustainable pressure that the sensor was designed to measure. A sensor capable of measuring high pressure has a larger error than a sensor rated for a lower pressure at the same accuracy percentage.

This document introduces a method for using multiple sensors of varying ranges to attain the most accurate measurements before, during, and after a fracture or failure without compromising the pressure

Description

Typical oil/gas industry fracture testing, or cement material failure testing, will measure the changes in applied force to determine mechanical properties of a sample. Generally, for rock mechanics research and cement testing for wellbore applications, this testing is performed using only one pressure sensor that is rated for more than the peak pressure expected throughout the test. Unfortunately, using only one pressure sensor with such a high rating inherently presents greater error in the measurements. This is For example, if a sensor is rated for 20,000 psi with 0.1% accuracy, then the measurement has ±20 psi error, while a 100 psi rated sensor with 0.1% accuracy will narrow that margin of error to only ±0.1 psi. For a 15,000 psi measurement, ±20 psi error is not detrimental, however, the lower the pressure drops after a fracture, the less usable a measurement with ±20 psi error becomes. Adding sensors with gradually smaller pressure ratings would allow the user or the acquisition software the ability to choose the most appropriate measurement as pressure changes. Nevertheless, most sensors can handle only small amounts of pressure in excess of their rated maximum before they become physically damaged. For example, a 100 psi range sen...