Learn about the common challenges and solutions for reducing drill bit MSE, a measure of drilling efficiency, penetration rate, and bit life.

Bits perform best when they maintain effective contact with the formation. Any BHA or drillstring vibration modes present (axial, lateral or torsional) will compromise effective bit to formation contact, leading to premature bit cutting structure damage. Hence, very important to know, and be operating far enough away from, any drillstring/BHA resonant frequencies in order to keep the bit drilling smoothly and prevent premature failure.

What are the common challenges and solutions for reducing drill bit mechanical specific energy?

Drill bit mechanical specific energy (MSE) is a measure of how efficiently a drill bit breaks the rock formation. It is calculated by dividing the total energy applied to the bit by the volume of rock removed. A high MSE indicates that the bit is facing more resistance and friction, which can lead to poor drilling performance, bit wear, and formation damage. Reducing MSE can improve drilling efficiency, penetration rate, and bit life. In this article, you will learn about some of the common challenges and solutions for reducing drill bit MSE.

1 Challenge 1: Bit design and selection

One of the main factors that affect MSE is the bit design and selection. Different types of bits have different characteristics and capabilities for drilling different formations. For example, roller cone bits are more suitable for soft to medium formations, while polycrystalline diamond compact (PDC) bits are more effective for hard and abrasive formations. Choosing the wrong bit type or size can result in high MSE and low rate of penetration (ROP). Therefore, it is important to select the optimal bit for the formation, based on the bit geometry, cutting structure, hydraulics, and wear resistance.

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Akram Miriyev

Senior Wells Engineer at WellPerform
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More complete version of MSE computation also includes hydraulic energy we transmit to bit. Selecting nozzle sizes and hence resulting hydraulic horsepower per area also affect MSE levels we measure.

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2 Solution 1: Bit optimization and evaluation

In order to reduce MSE, it is necessary to optimize and evaluate the bit performance and suitability for the formation. This can be accomplished by utilizing various methods and tools, such as bit optimization software that can design and select the best bit based on drilling parameters, objectives, and constraints. Additionally, bit sensors and data can monitor and measure the bit performance and condition. Bit testing and analysis can then evaluate the bit performance and efficiency post-drilling by examining the bit condition, wear pattern, and cutting analysis; this can help identify causes of high MSE and improve future bit design and selection.

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Akram Miriyev

Senior Wells Engineer at WellPerform
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Especially overlaying depth based MSE curves from offset wells helps to compare two different bit types and helps to improve future bit selection process.

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3 Challenge 2: Formation heterogeneity and variability

Another factor that affects MSE is the formation heterogeneity and variability. This refers to the changes and differences in the formation properties, such as the hardness, strength, porosity, permeability, and stress. These changes can create variations in the rock cutting behavior and resistance, which can result in high MSE and low ROP. For example, drilling through a hard and abrasive formation can cause more bit wear and damage, while drilling through a soft and sticky formation can cause more bit balling and plugging.

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Ken Marks

Strategic Account Manager at Baker Hughes Drilling Fluids (Retired)
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In my experience the drilling fluid composition type and flow dynamics will make a huge difference in performance. Bit design for certain types of formations along with chemical composition of the drilling fluid will make a difference. It is not just the mechanical properties of the bit that determine the best performance the drilling fluid of choice needs to be considered for best results as wells as flow dynamics and chemical properties such as adding lubricants. Evaluating the results from past wells drilled for best bit selection and drilling fluid characteristics for the best results will determine your best performance.

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4 Solution 2: Formation characterization and modeling

To reduce MSE, you need to characterize and model the formation properties and behavior. This can be accomplished by utilizing various methods and tools, such as formation evaluation, geomechanical modeling, and real-time drilling optimization. Formation evaluation can help you obtain and analyze the formation data, such as the lithology, mineralogy, fluid content, and pressure. This data can be used to understand the formation characteristics and challenges, as well as plan the drilling strategy accordingly. Geomechanical modeling can help create and simulate the formation stress and strain based on the formation data and drilling parameters. This model can help predict and manage the formation response and stability while optimizing the drilling parameters and bit selection. Real-time drilling optimization can assist in monitoring and controlling the drilling operation based on real-time formation data and feedback. This can help adjust the drilling parameters and bit performance while avoiding or mitigating any formation problems or hazards.

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5 Challenge 3: Drilling parameters and practices

A third factor that affects MSE is the drilling parameters and practices. These include the factors that influence the drilling operation, such as the weight on bit (WOB), rotational speed (RPM), flow rate, mud properties, and directional drilling. These parameters and practices can affect the bit-rock interaction and efficiency, which can result in high MSE and low ROP. For example, applying too much or too little WOB can cause overloading or underloading of the bit, which can reduce the bit penetration and increase the bit wear.

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6 Solution 3: Drilling optimization and automation

To reduce MSE, you should optimize and automate the drilling parameters and practices by using various methods and tools. Drilling optimization software can help you calculate the optimal parameters, analyze the drilling performance, and optimize the efficiency based on MSE and ROP data. Drilling automation systems can help you control and regulate the parameters based on real-time data and feedback, as well as execute and maintain the optimal parameters. Drilling best practices provide guidelines for improving quality and safety, as well as avoiding errors or risks like bit whirl, stick-slip, vibration or borehole instability.

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7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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Brian Tarr

Retired Aug 2018 after 41 year major oil & gas companies career in Well Engineering.
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Bits perform best when they maintain effective contact with the formation. Any BHA or drillstring vibration modes present (axial, lateral or torsional) will compromise effective bit to formation contact, leading to premature bit cutting structure damage. Hence, very important to know, and be operating far enough away from, any drillstring/BHA resonant frequencies in order to keep the bit drilling smoothly and prevent premature failure.

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Akram Miriyev

Senior Wells Engineer at WellPerform
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If there is UR exist in BHA then careful evaluation of bit MSE requires downhole weight on bit, torque on bit sensors to asess performance of bit. In such cases only certain part of the surface energy expenditure utilized by the bit and rest by the UR.

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Wilfredo Honores

Human ingenuity at both ends of AI | Inspect. Adapt. Transform.
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A high MSE may also influence the elasticity of the BHA, overcoming stabilization, and even if drilling with a DHM, deflecting the hole in an unexpected direction.

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Jordan Davidson

You got to be a friend to have a friend.
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I would think they should mention a holistic approach in a good BHA design. A variety of components allow for each BHA to be tailored to the well and expected geology to maximize the runtime of your bit and the entire assembly. From Collars to shock subs, BHA design can accomplish a lot.

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What are the common challenges and solutions for reducing drill bit mechanical specific energy?

1

2

3

4

5

6

7

1 Challenge 1: Bit design and selection

2 Solution 1: Bit optimization and evaluation

3 Challenge 2: Formation heterogeneity and variability

4 Solution 2: Formation characterization and modeling

5 Challenge 3: Drilling parameters and practices

6 Solution 3: Drilling optimization and automation

7 Here’s what else to consider

Drilling Engineering

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What are the common challenges and solutions for reducing drill bit mechanical specific energy?

1

2

3

4

5

6

7

1 Challenge 1: Bit design and selection

2 Solution 1: Bit optimization and evaluation

3 Challenge 2: Formation heterogeneity and variability

4 Solution 2: Formation characterization and modeling

5 Challenge 3: Drilling parameters and practices

6 Solution 3: Drilling optimization and automation

7 Here’s what else to consider

Drilling Engineering

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