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Usage of Finite Element Analysis to Produce Trends of "Build Rate vs. Weight on Bit" to Improve Well Planning, While-Drilling Operations, Tool Design, and Post Job Analysis

IP.com Disclosure Number: IPCOM000245221D
Publication Date: 2016-Feb-18
Document File: 2 page(s) / 10K

Publishing Venue

The IP.com Prior Art Database

Abstract

Downhole motors are used for directional drilling. Many design parameters such as AKO angle and stabilization type have documentation to show their effect on the build rate. However, weight on bit and its effect on the downhole geometry is often not considered. A 'Build Rate' vs 'Weight on Bit' chart, based on FEA calculations with different motor configurations, is proposed to demonstrate these effects. By utilizing such a chart, significant improvements are possible to tool design, wellbore planning, and in field operational corrections.

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Title:

Usage of Finite Element Analysis to Produce Trends of "Build Rate vs. Weight on Bit" to Improve Well Planning, While-Drilling Operations, Tool Design, and Post Job Analysis

Abstract:

Downhole motors are used for directional drilling. Many design parameters such as AKO angle and stabilization type have documentation to show their effect on the build rate. However, weight on bit and its effect on the downhole geometry is often not considered. A 'Build Rate' vs 'Weight on Bit' chart, based on FEA calculations with different motor configurations, is proposed to demonstrate these effects. By utilizing such a chart, significant improvements are possible to tool design, wellbore planning, and in field operational corrections.

Description:

It is common to use downhole motors for directional drilling. The amount of deflection or build up rate (BUR) during drilling is controlled by changing various parameters of the motor, both before and during operation. To aid in this process, operational aids are often provided with the motor. Commonly documented parameters and their effects on the build rate include: AKO angle, stabilization type, and bit size (hole size). All of these factors affect the transfer of applied weight and eventual translation to side force at the bit, and hence the build up rate results. However, the effect of the weight on bit is often not documented or not known. If it is considered, it is only generically described and does not account for changing tool geometries downhole.

A 'Build Rate' vs 'Weight on Bit' chart is proposed. The configuration of the motor and weight are analyzed with an FEA model. Through these FEA results, a different downhole geometry is observed. Then these FEA results are used to produce build results for each configuration and weight combination. An example chart of `Build Rate vs `Weight on Bit' for changing AKO angles is attached. However, other motor properties may include, but are not limited to, bit size, stabilization placement, stabilization size, component gemetry, and material choices. The same process can be used for any downhole tool intended for directional drilling.

Traditionally BUR information has been obtained in a mostly, if not entirely, geometric way. Three points of contact are assumed on the tool assembly, and these three points are used to define a circle. The curvature of t...