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Introducing The Hole Cleaning Pillars Series

Efficient hole cleaning is an important aspect of successful drilling operations. Whether you’re drilling for oil, gas, or geothermal energy, a clean hole is an essential building block of reliable drilling performance, minimizing risk and ultimately reducing NPT.  The objective of this series of videos is to demonstrate the influence of the three critical parameters on hole cleaning efficiency in a high angle wellbore.

1. Flow Rate

We all know that flow rate is important for hole cleaning. The first instalment of our new flow loop videos demonstrates the effects of three rates of annular velocity on cuttings transportation across in-gauge and over-gauge holes.

2. Rotation

How important is drill pipe rotary speed for effective hole cleaning? This second instalment explains in detail how rotary speed influences high angle hole cleaning.

3. Rheology

What role does drilling fluid rheology play in hole cleaning? This final instalment explains in detail how low-end drilling fluid rheology influences high angle hole cleaning.

The Making Of The Hole Cleaning Video Series

This project was carried out at Robert Gordon University, School of Engineering. The flow loop was modified; changing the diameter, internal pipe position, and length. A test matrix was then performed varying flow rate, rotational speed, rheology, test section angle, and internal geometry. This resulted in 98 tests with different configurations. The most relevant videos were selected to produce the hole cleaning pillars series.

“This series illustrates the downhole interaction between cuttings, fluid, drill string and wellbore geometry in horizontal and high angle wells – highlighting the key parameters in hole cleaning systems”.

Matias Garza – Merlin Drilling Engineer

The flow loop test sections are 3-meters long and include an internal pipe which rotates up to 150rpm and that is positioned eccentrically on the low side. The dimension relationship represents an equivalent configuration of a 5” drill pipe on an 8 ½” hole scaled 1:1.6.

Two extra sections were used to show the impact of the wellbore geometry, one being enlarged and the other restricted in the internal diameter. Also, two different sets of fluids were used in this test, showing the effect of low and high rheology values.

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