DRILLING & MEASUREMENTS
SUGAR LAND
LEARNING CENTER
Drill Bits
SELF - LEARNING PACKAGE
USEFUL PRE-REQUISITES
Knowledge of the Drilling Process.
DRILLING & MEASUREMENTS SUGAR LAND LEARNING CENTER DRILL BITS SELF-LEARNING PACAKAGE
Welcome to Drill Bit Self-Learning Package. This package is design to give you an introductory understanding of Drill Bits.
Introduction to Self-Learning
Self-Learning enables you to learn at your pace, in your time, and in your way. This course book provides the content, structure, and organization of your learning, which would otherwise be managed by an instructor in a class. It also gives you some review questions to help you to confirm your understanding. Below is some information to help you get started.
How To Use This Self-Learning Package
- Try to do the course in a maximum of 2 sessions, close together: (For example: Work session - - Break - - Work session)
- Set yourself up in a suitable learning environment: no noise, no interruptions, and no distractions.
- Use the review questions to confirm that you have understood. They are for your benefit. They are not assessed or marked. If you get an answer wrong, just go back through the material. - It is useful, but not essential for you to have met the pre-course
requirements stated on the course book cover.
Table of Contents
OBJECTIVES... 4
INTRODUCTION... 5
DRILL BIT INDUSRTRY OVERVIEW... 6
- Drill Bit Competitors………..………....…..10
- Drill Bit Market Past & Present………..……...……12
- Drill Bit Competitors: Strengths & Weaknesses……... . ………….13
- Hughes Christensen…………..………..………....13
- Smith Geodiamond………...………..14
- Schlumberger Drill Bits………..……..…………... 15
- Security DBS………..………….. ...…16
- Drill Bit Industry Summary………....…..………… ...…..17
ROLLER CONE BITS ... 19
- Component Parts………..……….19 - Exterior Parts……….…………...……20 - Interior Parts…….……….…………... ………23 - Bearings…………..………..………..23 - Seals……….………...26 - Grease System……….………...…...….…29 - Assembled Components……..……….… .. .……..30 - Cutting Structure.………..………31 - Insert Bits………..………..………..… .31 - Tooth Bits……….... ..34 - Hydraulic Configurations……….………..…………...…...36 - Nozzles…….………..………..……38 - IADC Code…….………..……40 - Schlumberger Nomenclature………..………..43 - Schlumberger Features………..…… . ….………45
- Schlumberger Product Lines……….………54
FIXED CUTTER BITS... 55
- PDC………..………..………. .55
- Natural Diamond & TSP………..……..………… ..…56
FIXED CUTTER BITS... 58
- PDC Components………..………..………. .. .58
- PDC Nozzles ………..………...….. 67
- PDC Designs………..………..……….68
- PDC Cutters ………..………...…69
- Schlumberger PDC Cutter Technology………..………… …..71
- NPI PDC Cutters ………..……….…. ...…75
- TReX Cutters………..………..…………...….76
- Schlumberger Fixed Cutter Product Lines……….……… ..…79
- Schlumberger Fixed Cutter Nomenclature………... ...82
- Schlumberger Fixed Cutter Features………... ....83
DRILL BIT LINKS ON THE SCHLUMBERGER HUB ... 88 Objectives
Upon completion of this Drill Bit Self-Learning Package, you should be able to do the following things:
?? Describe the Drill Bit industry
?? List the 4 major Drill Bit competitors and their strengths & weaknesses
?? Identify the interior components of a roller cone bit
?? Identify the exterior components of a roller cone bit
?? Identify the component parts of a roller cone bit
?? Describe the different roller cone hydraulic configurations
?? Describe the roller cone IADC Code
?? Demonstrate an understanding of Schlumberger’s roller cone
nomenclature
?? List and describe Schlumberger’s roller cone features
?? List Schlumberger’s roller cone product lines
?? Identify the major types of fixed cutter bits
?? Identify the major components of PDC bits
?? Describe Schlumberger’s PDC cutter technology
?? List Schlumberger’s fixed cutter product lines
Introduction
Reed-Hycalog (Schlumberger Drill Bits) is the combination of two strong, technologically advanced leaders in the supply of drill bits and expertise to the petroleum drilling industry. The union of the two companies provides a totally integrated, full-service company dedicated to implementing drill bit solutions on a worldwide basis.
The history behind the two companies is as diverse as the product lines they collectively distribute. Reed Tool Company was formed in 1915 when Clarence E. Reed formed a partnership with J.H. Giesey to manufacture drilling tools. Throughout the years, Reed has designed, manufactured, and sold thousands of different products to make drilling around the world more efficient. Today, Reed focuses its technical resources on developing
premium roller cone drill bits with over 400 different sizes and types of bits in it’s product line.
J.R. Frenchie Mayeaux and Dan Grady in Shreveport, Louisiana formed Hycalog (HYdroCArbon-LOGging) in 1946. This company was later combined with the US operations of Drilling and Service and the Rucker companies. Originally operating as a core bit company, Hycalog has now grown into the leading supplier of PDC and natural diamond drill bits worldwide with the number one market position in most drilling areas. The most recent chapter in this history was the acquisition of Reed-Hycalog (via Camco International) by Schlumberger. Reed-Hycalog is now an integral part of Drilling & Measurements, which is part of Schlumberger’s Reservoir Development Group. In 2001, Reed-Hycalog began the transition of changing the company’s name to Schlumberger Drill Bits.
Schlumberger Drill Bits has four strategically located ISO 9001 certified manufacturing facilities with the most modern CNC manufacturing equipment in order to meet customers requirements. Roller Cone
manufacturing plants are located in Houston, TX and in Singapore. The Fixed Cutter manufacturing plants are located in Houston, TX and in Stonehouse, England. The safety record within these facilities, and in the field, surpasses the industry standard defined by Drill Bits and by
Schlumberger. In addition to ISO 9001, Schlumberger Drill Bits meets the API Q1 standard and the Schlumberger QHSE standards.
Drill Bit Industry Overview
Reservoir development starts with the drill bit. With today’s technology, to drill for oil and gas a drill bit is needed.
Schlumberger (Reed-Hycalog) sells drill bits. There is a major difference between the Drill Bit segment of Schlumberger and all of the other
segments. Drill Bits manufacture and sell tools (bits) that are supported by service. The other Schlumberger segments sells services that are supported by tools. This means that there is a major philosophical difference in the way that Drill Bits sells and conducts business from all of the other
Schlumberger segments. Drill bits are often bought one at a time on the rig site. As they come out of the hole, the performance of the bit is evaluated. The other Schlumberger segments basically sell their services before the well starts and then support it with tools. This is the major difference
between the Drill Bit segment of Schlumberger and all of the other segments of Schlumberger.
There are two major drill bit types: Roller Cone and Fixed Cutter.
Within the roller cones there are two types bits - insert bits and tooth bits.
Roller Cone Bits:
Within the fixed cutters there are two types of bits: PDC bits (Polycrystalline Diamond Compact) and Natural Diamond/Impreg.
PDC Bit Natural Diamond / Impreg Bit
Customer’s Expectations
In order to sell drill bits, specific customer’s expectations must be met. There are several things that the customer might expect from a drill bit when they buy it:
- they may expect the bit to drill an entire interval
- they may expect the bit to drill the interval faster than on previous wells
- they may want the bit to drill it at the lowest cost-per-foot - they may want a good dull condition from the drill bit once it comes out of the hole
- they may be interested in directional accuracy
Which one of these customer’s expectations are the most important? From a drill bit aspect, bit cost-per-foot is going to be the best measure of performance. But, the customer is not always interested in cost-per-foot. Sometimes they are interested in making sure they can drill the interval in a specific amount of time irregardless of how much it costs them. Sometimes they have to drill the interval at a certain ROP (Rate Of Penetration) in order to meet the criteria that they have for a specific well. Another situation that customers might need is to have a good dull condition. This is important because sometimes customers rerun bits on multiple wells. Sometimes directional accuracy is the most important for a customer. This is extremely important if you are drilling horizontal or directional wells anywhere in the world. The directional accuracy could be far more important than how much it cost for the bit, or how much it cost to drill a specific interval of the well. If the customer cannot hit their targets, then they are not going to get the reservoir development that they expect. There could be some other things that customers expect out of bits; for example, hours. There are some customers in parts of the United States that if the bit does not drill a certain amount of hours then their expectations have not been met.
So which one is most important? The answer is it depends. It depends on what that specific customer's expectations are out of the drill bit. It is the responsibility of the Drill Bit Engineers and Specialist to find out what are the customers' expectations. Once the customer’s expectations are
identified, the proper bit to meet the proper application can be selected.
Drill Bit Sales
Drill bits are sold in a variety of different ways. One of the ways drill bits are sold is at the rig site. In this situation bits are loaded up in the back of a pickup truck and an Engineer or Specialist, in a geographically assigned area, will go out into the field and sell the bits at the drilling rigs. Contact is made with the people that are buying the bits. Then a decision is made on what bits are going to meet that customer's expectations on that specific
Another way drill bits are sold is in the office. They are sold to operating companies, to drilling engineers, and to purchasing departments. Typically it is better not to sell bits to purchasing departments because they are only interested in price. Drill bits are not a commodity. They are a “performance tool”.
Drill bits are also sold directly to directional drillers and drilling contractors. There are a lot of wells that are drilled, especially in the US and Canada, on a footage basis. Footage means that a drilling contractor has agreed with an oil company that they will drill a specific depth of a well for a certain price. In this case the contractors are responsible for purchasing the bits. The drill bits will be sold directly to the drilling contractor as opposed to the oil company. There are some situations where directional drillers are responsible for buying the bits. Directional companies will turnkey a directional well, or a section of a well. Being part of Drilling &
Measurements, Schlumberger Drill Bits will need to take advantage of this situation when D & M has the directional job and is buying the bits.
Drill bits are also sold by tender to national oil companies. Basically what this means is that a national oil company will put out a bid for bits.
Sometimes this is for a 6-month supply, a year supply, or some other period of time that they will designate. All of the major drill bit companies get to bid on the tender. The bits are typically bought from whomever provides them with the lowest price.
Another way drill bits are sold is by supply contracts to major oil companies. This is typically driven by management consultants and purchasing
managers. When this happens the companies are trying to reduce their costs over a period of time by buying bits in bulk from one or more of the major drill bit suppliers. Many of the major oil companies do have some kind of supply contracts with one or more of the drill bit companies.
Drill Bit Competitors
There are 4 major drill bit competitors that control approximately 92% of the $1 billion dollar worldwide drill bit market.
First is Hughes Christensen. Hughes Christensen is owned by Baker Hughes International. They are the #1 drill bit company in the world with
approximately 30% market share. Hughes is the roller cone portion of the business and Christensen is the fixed cutter portion of the business.
Second is Smith Geodiamond. Smith GeoDiamond is owned by Smith International. They are the #2 drill bit company in the world with
approximately 27% market share. Smith is the roller cone portion of the business and Geodiamond is the fixed cutter portion of the business. Third is Reed-Hycalog which in 2001 were changing the name to
Schlumberger Drill Bits. Reed-Hycalog is owned by Schlumberger and is part of Drilling & Measurements. They are the #3 drill bit company in the world with approximately 20% market share. Reed is the roller cone portion of the business and Hycalog is the fixed cutter portion of the business.
Fourth is Security DBS. Security DBS is owned by Halliburton. They are the #4 drill bit company in the world with approximately 15% market share. Security is the roller cone portion of the business and DBS is the fixed cutter portion of the business.
There are several other drill bit competitors around the world that
collectively have approximately 8% market share. There are RBI, Varel, Walker-Macdonald and TSK which are all roller cone companies. There are also many regional and local PDC companies located around the world. The drill bit market is basically split out into the 2 major bit types - roller cone and fixed cutter. The roller cone is approximately 60% or $600 million, and the fixed cutter is about 40% or $400 million.
Drill Bit Market – Past and Present
To understand the drill bit market, it is necessary to look at the market in the past and then where it is today.
Past Drill Bit Market
On the vertical axis is penetration rate, and on the horizontal axis is formation compressive strength.
The chart shows the PDC, the tooth, the insert, and the impreg / natural diamond bits. As indicated, there is very little overlap between the PDC, the tooth bits, the insert bits, and the diamond / impreg. If a customer wanted to drill in a specific area it would be pretty easy to identify what type of bit they were going to need to run for the particular formation. Based on how fast they wanted to drill it, and the compressive strength of the rock, it would dictate which one of the four bit types would actually be used in that
particular application.
Formation Compressive Strength
Penetration Rate
PDC Tooth Insert Impreg & N.D.Today the bit market has changed quite a bit.
Present Drill Bit Market
On the vertical axis is penetration rate, and on the horizontal axis is formation compressive strength.
With the evolution of PDC cutter technology, the evolution of tooth bits and of insert bits, and the improvements to the impreg and natural diamond bits, there is now quite a bit of overlap in the present bit market. If a customer wanted to drill in a specific formation, a decision would have to be made on which drill bit type would be the best to use. This was one of the major reasons why all 4 of the major roller cone drill bit companies and the major fixed cutter drill bit companies combined as one instead of operating as two separate companies.
Formation Compressive Strength
Penetration Rate
PDC Tooth Insert Impreg & N.D.Drill Bit Competitors – Strength & Weaknesses Hughes Christensen
The first strength of Hughes Christensen is that they were the first in Bit Optimization Service. Basically they were the first ones to put a drill bit engineer in a customer’s office, at no charge, to do all of the analytical and business requirements for the customer’s drill bit needs. In some cases they were given a bit contract to provide a certain number of bits. Hughes was first in this Bit Optimization service. Smith and Security quickly followed and Schlumberger Drill Bits were the last ones to offer that service.
The second strength of Hughes Christensen is volume economics. They build twice as many bits as Schlumberger Drill Bits. Their volume
economics allow them to have a lower cost per bit because they can absorb the overhead from their factories over a greater number of products.
The third strength of Hughes Christensen is market strategy. They have done an excellent job over the years of marketing their product. Every innovation, every new feature, and every good performance are published in many of the oil & gas publications.
The final major strength of Hughes Christensen is name recognition. Hughes was the first roller cone drill bit company. They are very well known throughout the industry. They have good competitive products. Hughes Christensen does have several weaknesses. First, they have an arrogant sales staff. This attitude has cost them some business in the past. Their second major weakness is sometimes they are slow to respond. Since they have such large volumes of product they cannot always get their bits out to the market in as a timely manner as they would like to. Also the actual drill bit market is not predictable. So if activity increases faster than planned, sometimes Hughes Christensen can be a little slow to get their products out to the market place.
Smith Geodiamond
The first strength of Smith Geodiamond is they have autonomy, which allows them to focus. Since they are not owned by one of the major oil service companies, they can spend more of their time focused specifically on the drill bit segment.
The second strength of Smith Geodiamond is that they were second in the market with Bit Optimization Service. Soon after Hughes Christensen, they started putting their engineers in the offices to help make bit selections. The third strength of Smith Geodiamond is that they market new technology very well. Any time they come up with what new products or features, they have brochures coming out, they have covers on the major oil publications, and they do an excellent job of marketing their product.
The third strength of Smith Geodiamond is the fact they acquired
experienced personnel. A few years ago, Smith decided that they wanted to go full force into building fixed cutter bits and becoming a dominant force in the fixed cutter market. They decided to go after the #1 fixed cutter
company in the world at that time - Hycalog. They hired Hycalog’s
President, their Vice- Presidents, their design engineers, and they selected and hired the specific Hycalog salesmen that they wanted for specific geographical areas. Instead of developing their company and their
personnel, they went out and bought them from Hycalog. This is one of the things that contributed to Hycalog falling from the #1 fixed cutter company in the world to #3, and has allowed Smit h Geodiamond to become a viable fixed cutter competitor.
The final major strength for Smith Geodiamond is customer relations. They spend a lot of money, time, and resources on making sure they take care of their customers. They give away jackets, shirts, cups, hats, etc. They also take their customers on expensive trips. They are the drill bit company that are the most committed to spending money on customer relations.
Smith Geodiamond does have several weaknesses. The first weakness is a lack of corporate structure. They are not owned by of one of the major
Smith Geodiamond
The second weakness of Smith Geodiamond is the lack of access to related drilling technologies. Schlumberger Drill Bits has Drilling & Measurements with the PowerDrive and PowerPak systems. Hughes Christensen has Baker Inteq with the AutoTrack system. Security DBS has Sperry Sun with the GeoPilot system. The lack of access to related drilling technologies does put Smith Geodiamond at a disadvantage.
The final weakness of Smith Geodiamond is that they have limited
packaging opportunities. If you are not owned by one of the major service companies, it is very difficult to package all the services in order to provide the drilling solutions that the customers may need.
Schlumberger Drill Bits (Reed-Hycalog)
The first strength of Schlumberger Drill Bits is the differentiated
technologies. There are many developments that have been patented that differentiates Schlumberger from their competitors.
The second strength of Schlumberger Drill Bits is fixed cutter market recognition. A few years ago Hycalog was the #1 fixed cutter company in the world. They are still recognized in several markets as being the #1 fixed cutter company.
The third major strength of Schlumberger Drill Bits is the Schlumberger resources. Financial, technical, and personnel resources are now available. Schlumberger Drill Bits also have several weaknesses. First was the
company’s focus on margin. While this may not be a bad strategy, if you are going to try to gain market share, margins may not be the primary focus. Currently under D & M, the focus is on market share first.
The second weakness of Schlumberger Drill Bits is late to service delivery. It sometimes takes a lot longer to get products to the market place than it did for the competitors.
To become the #1 drill bit company in the world, it will require better customer response and getting products on time to the market as quickly as possible.
The last major weakness of Schlumberger Drill Bits is struggling to reorganize. There have been 3 reorganizations in the last 4 years. First, Schlumberger acquired Camco International. This made Reed and Hycalog part of Schlumberger. Second, was the reorganization of Reed Tool
Company and Hycalog to combine to form one company, Reed-Hycalog. Finally, in January 2001, Reed-Hycalog reorganized into Drilling &
Measurements. Almost any company would have had difficulty surviving three reorganizations in four years.
Security DBS
The first strength of Security DBS is their synergy with Sperry Sun. This gives them access to related drilling technologies and packaging
opportunities.
The second strength of Security DBS is the modernization of their
manufacturing plant. Within the last two years they renovated their roller cone manufacturing plant. They put in new machinery and new technology to improve the speed and efficiency of building their roller cone bits.
The third strength of Security DBS is that they were right behind Hughes and Smith with Bit Optimization Service.
The last strength of Security DBS is their fixed cutter technology. In their fixed cutter bits, they have some excellent products and some excellent cutter technology.
Security DBS also has several weaknesses. The first weakness is their roller cone technology. Most of their roller cone bits are not competitive with Hughes, Smith, and Schlumberger. However, they do make a few good products, especially in their bigger bits that have performed well in the Gulf of Mexico and in other offshore applications.
The final weakness of Security DBS is that they tend to operate as 2 separate companies. Since they have such a strong fixed cutter side and such a weak roller cone side, most of the focus is on fixed cutter bits. Even though they are one company, they tend to operate as two. This prevents them from being a fully unified company.
Drill Bit Industry – Summary
Drill bits have unique technologies. There are different drilling demands. Almost anywhere in the world that drilling is done the drill bit application will be different. For example, in multiple places in the United States there will be different formations and different drilling applications.
Drill bits have unique design concepts. There is a lot of design work that goes into fixed cutter and roller cone bits. There are materials issues, bearings, elastomers, grease, moving parts, and cutter development.
Drill bits have manufacturing issues. One of the reasons why there are only 4 major drill bit companies that control approximately 92% of the worldwide market, is because roller cone manufacturing is a very capital-intense and complicated business. Not everybody can easily get into the roller cone manufacturing business. That is one of the reasons for the major oilfield service companies such as Schlumberger, Baker, and Halliburton aligning themselves with an established drill bit company. It would be very difficult for someone to start up a new roller cone company.
Finally, patents are what are unique to drill bit technologies. There are many patents that are filed on drill bits that never get into bits. It is a very
competitive market with only 4 major competitors in the market place. All of the drill bit companies are actively trying to patent everything they can to prevent the competitors from copying their designs or taking advantage of some of the concepts and innovations that have been developed.
Drill Bit Industry
Drill Bit Industry
Review Questions
Review Questions
•
List the major Drill Bit types
•
List the 4 major Drill Bit competitors and their
market shares
•
List Schlumberger Drill Bits’ strengths & weaknesses
•
Describe the Schlumberger Drill Bit plan for market share
growth
•
List 4 Schlumberger Drill Bit Roller Cone differentiations
•
List 4 Schlumberger Drill Bit Fixed Cutter differentiations
Roller Cone Bits – Component Parts
There are two types of roller cone bits. There are tooth bits and there are insert bits. Sometimes roller cone bits are referred to as rock bits. Under tooth bits, these bits are sometimes referred to as steel tooth bits or mill tooth bits. On the insert side, these bits are sometimes referred to as carbide bits or button bits.
The roller cone bits are basically made up of the 3 major things. There are: 1) lugs, 2) cutters, and 3) component parts.
To make a roller cone bit there will be 3 lugs per bit. All 3 lugs will be
exactly the same. There will also be 3 cutters per bit. All 3 cutters will have different cutting structures. Finally there will be a variety of component parts.
Lugs Cutters Component Parts
To make 1 roller cone bit, it takes: - 3 lugs
- 3 cutters
- 3 sets of component parts. The cutters are attached to the lugs. Then the 3 lug and cutter assemblies are welded together to make a drill bit.
Roller Cone Exterior Parts
In this diagram, the first area to identify is the API pin. The purpose of the pin is to connect the bit to the drill string and to allow fluid to get through into the body of the bit and out through the nozzles.
Next is the bit body. This is all the exterior part of the bit that is not the cutter. So it includes all 3 of the lugs, the nozzle pods, and the areas that are on the shirttail.
The next area is the lug. As mentioned before, it takes 3 lugs to make up 1 bit. So the lug is the area of the bit where the shirttail is located and the bit body that goes down to the pin. It is the part of the bit that holds on the cutter.
There are 3 cutters on each bit. There is Cutter #1, Cutter #2, and Cutter #3. Each one of these 3 cutters will have a different cutting structure design. The way to identify the 3 cutters is Cutter # 1 will have the insert or tooth
Pin
Nozzle, Pod & Socket Cutter #3 Shirttail Heel Row Gage Row Cutter #1 Cutter #2 Inner Row Lug Bit Body Bit Bowl Nose
Once the Cutter #1 is identified, count the cutters in a clockwise manner to find Cutter #2 and Cutter #3. The reason these cutter numbers are important is when dull grading the bits, the location of the dulling characteristics will be identified by the cutter numbers. When identifying whether the
bearings/seals are effective or have failed, the cutter numbers are used if all 3 of the cutters do not have the same grading.
The nose of the bit is the area of inserts or teeth that is the closest to the center of the middle of the bit. The inner row would be all of the rows that are not the gauge. The gauge row is the row of inserts that are the furthest on the outside of the cutting structure. The heel row are small, tungsten carbide or diamond inserts that are put on the back face of the cutter. The shirttail is the area of the lug where the grease reservoir cap, the hard metal that is applied to protect the shirttail, the cone retention loading hole, and the grease-loading hole is located. This is an important part of the bit because it will identify some of the areas that will need to be protected. Shirttail protection features that are added to the bits will be discussed later.
Pin
Nozzle, Pod & Socket Cutter #3 Shirttail Heel Row Gage Row Cutter #1 Cutter #2 Inner Row Lug Bit Body Bit Bowl Nose
Then there is the nozzle pod and socket. This is the where the nozzles is located. There is an O-ring and a snap ring that holds the nozzles in. This whole assembly area where the nozzle goes in is called the nozzle pod and nozzle socket.
Finally there is the bit bowl. This is all of the blank space, the void space that is inside, the interior of the bit beneath the cutters, and inside of the nozzle pod and nozzle sockets. In the bit bowl is where there may be drilled cuttings. A lot of flow has to get through there in order to keep the bit clean. This is also where your center jet would be installed if a center jet were to be added to any bit.
Now that the external parts of the roller cone drill bit have been reviewed, it is time to take a look at what is on the inside. The focus will be on the bearings and seals. These are one of the most critic al parts of a roller cone drill bit. If the bearings and seals fail prematurely, your bit life will be limited.
Pin
Nozzle, Pod & Socket Cutter #3 Shirttail Heel Row Gage Row Cutter #1 Cutter #2 Inner Row Lug Bit Body Bit Bowl Nose
Roller Cone Interior Parts Bearings
In roller cone bits, there are generally 4 major bearings.
There is the main bearing, the retention bearing, the thrust bearing, and the pin bearing.
The main bearing, the thrust bearing, and the pin bearing are all load-bearing surfaces. The function of the retention bearing is to attach the cutter to the lug. However, through testing, and looking at the bits that have been cut down for dull analysis, the retention bearings also do take some load.
• Retention Bearing
• Thrust Bearing
• Pin Bearing
• Main Bearing
There are 2 major types of main bearings in a roller cone bit. There are roller bearings and there are friction/journal bearings.
Roller bearings are long cylinders that roll in tracks or grooves that have been cut in the lug. Typically roller bearing bits will have two rows of roller bearings, or three rows for the larger bits. They roll freely between the cutter and the journal.
The friction or journal bearing bits have a bushing that rotates between the lug and cutter. Schlumberger Drill Bits have a floating bushing that rotates freely between the cutter and the lug. In the past these bearings were called friction bearing. Today, most people in the drill bit industry call them journal bearings.
There are two types of retention bearings. There are ball bearings and there are threaded rings.
On most all drill bits, the cones or cutters are held onto the lug using ball bearings. This is not a unique feature to Schlumberger. Ball bearings are used by all 4 major drill bit competitors as their cone retention bearings. Ball bearings roll in the track and keep the cutter from falling off of the lug. The threaded ring, however, is a unique and patented feature that can only be used by Schlumberger Drill Bits. It is attached by the threads in the cutter shell and the corresponding threads located on the threaded ring. The threaded ring rides in a groove on the lug, and allows the cutter to be attached to the lug. A retention tool holds the threaded ring in place while the cutter is screwed on. Once the cutter is on, the retention tool is taken out, and a peening tool is inserted. The peening tool will peen or deface the threads on the cutter to prevent the cutter from backing off. The advantages of having a threaded ring retention bearing over a ball bearing is:
- the threaded ring will help reduce the lost cone rate by two-thirds - it becomes an integral part of the cutter, so it allows the cutter to have more freedom and be better tolerant of cutter movement
- it has surface contact as opposed to point loading of the balls bearings
With ball bearings there is point loading that can cause spalling,
Spalling is little particles of metal that have flaked off of the lug surface. This makes the surface uneven and no longer will run smoothly. This affects the bearing performance. As soon as the bearing performance is negatively affected, then the bit life will be limited.
Seals
At Schlumberger there are 4 major types of seals that are used. The first is an O-ring seal. Years ago the O-ring seal was patented by Hughes and was not allowed to be used by any of the other major bit companies. What Hughes actually patented was the amount of squeeze on the O-ring to seal the bit to keep the drilling fluids out and keep the bearing grease in.
Reed-Hycalog decided to use a HNBR radial seal to counteract the patent Hughes had on the O-ring. The HNBR radial seal is a patented feature that only Schlumberger uses. Smith and Security decided that they would go ahead and use the O-ring even though Hughes had a patent. Then several years later there were lawsuits. Hughes was paid hundreds of millions of dollars by Smith and Security for violation of their patent. The O-ring
O-Ring and HNBR Radial HNBR Texturized HNBR Ribbed Texturized
The O-ring seal is used in Schlumberger’s 4-3/4" and smaller inch diameter bits. All of the bits larger than 4 3/4, use the HNBR radial seal. The radial seal provides several advantages. It runs cooler, it is recessed and is better protected, and it is more tolerant of cutter movement. A radial seal is flat and has more surface contact.
The next seal used by Schlumberger is a HNBR texturized seal. HNBR stands for Hydrogenated Nitrile Butadiene Rubber. It is obvious why this seal is just called HNBR. The HNBR texturized seal was the seal that was developed for Schlumberger’s motor bit product line. This seal has a series of Xs cut into the inside surface of the seal. The purpose of these Xs is to trap grease in all of the little small pockets, as shown in this picture.
By trapping the grease into these little pockets, it allows the seal to run cooler. Typically motor bits are running at higher RPM (Revolutions Per Minute) so running cooler is important to extending bit life.
The HNBR ribbed textured seal is a brand new seal that was recently developed to be put into
Schlumberger’s new “Titan” bits. It is an upgrade from the HNBR texturized seal in that it has a rib in the middle that helps keep the grease on both sides of the seal. As shown in this picture, once the grease gets into the little pockets, it gets trapped and allows the seal to run cooler. A cool running seal is critical when running at high rotary speeds on motor bits.
HNBR
Texturized
Seal
From this diagram, the bearing terms can be identified. Starting on the right-hand side of the picture an insert bit cutter is shown. The ball race is where the ball bearings roll and allow the cutter to move around the lug. Moving from the right side of the diagram into the middle of the cutter is the cutter bore. The cutter bore has the internal bearing surfaces that match up with the corresponding parts on the lug. There is also a groove in which the seal is recessed. Moving on into the center part of the diagram is the thrust washer. The thrust washer is a washer that is silver-plated. The silver is used as a dry lubricant so as the thrust washer heats up, takes loads, becomes hot, and develops friction; the silver will melt and form a lubricant. Next there is the floating bushing. This is a copper beryllium bushing that is also silver-plated for dry lubricant. Next is the HNBR radial seal. This could be a texturized radial seal, a ribbed texturized radial seal, or an O-ring. This shows the order in which component parts and the cutter fit on the lug. Moving over to the journal part of the lug is the thrust pin bearing and the pilot/friction pin bearing. Next there is the main bearing surface, the ball bearing groove, the seal land, and the back face of the cutter. The ball retention plug is used to secure the cutter once it is connected to the lug. The ball bearings are loaded through this ball-loading hole on the backsid e of the journal. After the proper number of balls are loaded, the retaining plug is inserted and is welded with what is called a frogeye weld.
Insert Cutter Cutter Bore Floating Bushing Radial Seal Ball Bearing Ball Retaining Plug Thrust Washer Seal Land Snag
Main Bearing Pilot Pin (Friction Pin)
Shirttail
Seal Groove
Ball Race (Bearing Race)
Grease System
On sealed bearing roller cone bits there is a grease system. This diagram shows Schlumberger Drill Bits’ greasing system. The grease reservoir is where the extra grease for the bearings is located. The grease is pumped from the grease reservoir through a grease passage holes into all of the bearing surfaces. To ensure that grease gets to all the bearing surfaces, grease is painted on every bearing surface before the bit is assembled. A grease-compensating diaphragm is used. If too much pressure builds up in the reservoir or bearing system, the grease can vent or release through the diaphragm so it does not burst the seal. Once the seal is damaged or fails, the drilling fluid will flow in, compromise the bearing system, and will limit the bearing life. On top of the diaphragm is a reservoir cap that is held in place with a snap ring. A hex nut is screwed in with an Allen wrench that closes off the grease-loading hole.
Grease Reservoir Grease Loading Hole Plug Snap Ring Reservoir Cap Grease Passage Holes Diaphragm Threaded Ring Access Hole Plug
Assembled Interior Components
Earlier the ball-loading hole for a ball bearing retention system was discussed. If the bit has a threaded ring, the threaded ring access hole is where the tool to hold the threaded ring still is located. It also serves as the access hole for the peening tool used to deface the threads on the cutter side of the threaded ring assembly. A threaded ring access hole plug is then inserted and sealed off with a frogeye weld.
This diagram shows a view of the cutter assembled to the journal on the lug. Starting on the left side is the borehole wall. Moving inward from the left side of the picture are the heel row inserts that are in contact with the
borehole wall. Next are gauge row inserts. This diagram shows how much of the insert is actually in the cutter and how much of the insert is protruding out from the cutter shell. On the top of the picture is the radial seal and the groove where the radial seal is recessed. Next is the main bearing - in this case a journal bearing. On the bottom of the picture are the inner row inserts. Finally there is the thrust bearing, thrust washer, and the pin
Hole Wall Gauge Row Radial Seal Thrust Bearing Retention Bearing Heel Row Inner Row Cutter Lug Main Bearing Pin Bearing Hole Wall Gauge Row Radial Seal Thrust Bearing Retention Bearing Heel Row Inner Row Cutter Lug Main Bearing Pin Bearing
Cutting Structure – Insert Bits
The cutting structure is also important for the life of a drill bit. If the cutting structure fails the bit is finished. If the cutting structure wears out, the
inserts break, or the cutting structure gets damaged, the bit will have to be pulled out of the hole because it will no longer be able drill the formations economically. Sometimes the cutting structure of a bit is called the “cone” or the “cutter”. These two terms can be used interchangeably.
Starting on the right side of this diagram is the cone pro file. The cone profile identifies how aggressive the bit is going to be in terms of cutting formation. A more rounded cone profile would be for a more aggressive bit. A flatter cone profile will be used for a slower drilling, more durable cutting structure type bit, typically used in harder formations. Beginning on the right side of the picture and moving inward, the first insert is the spear point or the spade. This is also the nose insert. When identifying the nose insert on the cutter, this is the insert that is closest to the center of the middle of the bit.
Spear Point (Spade)
Heel Face (Gage Face)l
Heel Row “Cone”
or “Cutter”
Cone Shell Gage Row Interlock Row
Cone Groove Inner Rows Outer Rows Back Face Insert Pad Cone Profile Seal Flange “Teeth”
Next are the insert pads. The insert pads are created as a result of the designed cone grooves. Since the bit has 3 cutters, each with a different cutting structure, the cutting elements have to intermesh with each other. The cone grooves are machined into the cutter to allow the inserts to intermesh. Another reason for the insert pad is to support the insert. If the insert is not protected, and the proper amount of the insert is not in the cutter shell, the insert will not be properly supported and will break.
Next are the inner row inserts. These are all the inserts that are not the gauge row inserts and not the nose row inserts. The remaining row of inserts are called the interlock row. An interlock row means that part of the interlock insert is intersecting the line of the gauge row inserts. This does not mean that these inserts are on top of each other. It just means that they intersect the line of the gauge row inserts. Finally there is the heel row. The heel row inserts are on the back face of the cutter.
Spear Point (Spade)
Heel Face (Gage Face)l
Heel Row “Cone”
or “Cutter”
Cone Shell Gage Row Interlock Row
Cone Groove Inner Rows Outer Rows Back Face Insert Pad Cone Profile Seal Flange “Teeth”
This picture gives a few examples of insert shapes by formation.
Schlumberger has over 100 different insert shapes and types that are used on their roller cone drill bits. As illustrated, the inserts get shorter and more rounded when going from soft formations to harder formations. The first insert on the chart has a sharp tip and a lot of protrusion. The straight lines that go across the picture indicate the protrusion. Everything below that line represents the part of the insert that is buried in the cutter shell. Everything above that line represents the part of the insert that is protruding from the cutter shell and makes contact with the formation. The first insert has quite a long protrusion and the insert shape is quite sharp. Looking at the very last insert in this picture, that insert is much shorter and has a much rounder shape. Selecting the right insert for the right bit is most important to provid e you the best bit performance in any given application.
Cutting Structure – Tooth Bits
Mill tooth bits have their tooth shape milled out of steel. Once the teeth are milled, a hard metal is welded to each tooth to make the tooth more durable. There are 4 basic types of hard metal that are used on Schlumberger’s mill tooth bits.
Duraclad Hardmetal
Armorclad Hardmetal
First there is the standard Duraclad hard metal. This is a tungsten carbide matrix composite. The hard metal is welded onto the teeth in a manual process. Duraclad has a lot of porosity. It is a durable product but is typically use this in Schlumberger’s non-premium tooth bits.
The next type of hard metal is called Armorclad. This is much more dense and much less porous type of material. It has a much higher concentrated mix of tungsten carbide pellets. Armorclad is typically use this in the premium mill tooth bits such as EHT, MHT, and the SL - Slim Line bits. Armorclad II is a new hardmetal that has just been introduced. This is a premium hard metal that is an upgrade from Armorclad. This hardmetal will
Finally there is the “built-in” hard metal – PMC (Powdered Metal Cutter). Schlumberger has as patented process of using powdered metal to make a tooth cutter. Because of the patent protection, Schlumberger is the only drill bit company that can use this “built-in” hard metal. The PMC product technology has been in development for more than 12 years. In 2001 the first PMC products will be going standard. The first product lines will be FMJ (Full Metal Jacket) and CMC (Composite Matrix Cutter).
PMC “Built-In” Hardmetal
PMC is a “built-in” hardmetal that is built using a mold. This hard metal is more durable, more abrasive-resistant, and provides a lot longer life for the tooth. PMC will also allow more flexibility in designing tooth shapes. For Schlumberger Drill Bits, the PMC process for making tooth bits may
become the way tooth bits are made in the future. It will be more economical to manufacture once the process is fully developed. All of Schlumberger’s competitors use welded hard metal on their tooth bits.
Hydraulic Configurations
Hydraulics are very important for a drill bit. The primary purposes of hydraulics for the drill bit are to keep the bit cool and to get the cuttings off the bottom of the hole and up the annulus. There are 3 basic Schlumberger hydraulics configurations: Conventional, Mudpick, and Mudpick II.
First is conventional hydraulics. This means that the drilling fluid comes out of the nozzle and goes straight to the bottom of the hole. There is no tooth cleaning and the fluid cleans the rock between the cutting zones. There is stagnant flow at the cutting zone where the inserts or teeth are in contact with the bottom of the hole. There is no cleaning where the cutters are
actually in contact with the formation. All of the competitors use some form of conventional hydraulics.
In the late 1970s, early 1980s, Reed started developing improved hydraulics. The objective was to find a way, given the same set of hydraulic conditions, that ROP could be improve by changing the direction of the hydraulic flow.
Mudpick II
Mudpick II
Mudpick
Mudpick
Conventional
Conventional
With Mudpick hydraulics, as you can see in this picture, the position of the nozzle is re-directed so that now the flow is cleaning the gauge row and interlock row inserts. The rock is being cleaned at the leading edge of the cutting zone. The stagnant flow has been shifted to the trailing side of the cutter. Now there is better cleaning on the bottom of the hole. With Mudpick there was an increase in rate of penetration given the same set of hydraulic conditions. Without changing nozzle diameter, the flow rates, and any of the variables for hydraulics, ROP was improved by changing to Mudpick hydraulics. We use Mudpick hydraulics on all of the
Schlumberger product lines, except those that use the Mudpick II hydraulics. In the early 1990s, almost ten years after the development of Mudpick,
Mudpick II hydraulics was introduced. Mudpick II cleans the gauge row and inner row of teeth. It cleans the rock at the cutting zone right at the corner as the inserts are coming around to make contact with the formation. It cleans the cuttings from the bottom of the hole and removes the stagnant flow completely from the cutting zone. The stagnant flow is shifted outside the area where the inserts are in contact with the formation. Mudpick II has shown that ROP was increases an average of 20% - 22% over the offset bit runs. Mudpick and Mudpick II hydraulics are patented features of
Schlumberger. None of the other drill bit companies can use these hydraulic configurations.
Mudpick II
Mudpick II
Mudpick
Mudpick
Conventional
Conventional
Competition has developed various types of hydraulic configurations to combat Mudpick and Mudpick II hydraulics. Because of the improvements in ROP, the competitors will continue to try to meet or exceed
Schlumberger’s performance.
Schlumberger builds bits with both Mudpick and Mudpick II hydraulics. The reason for this is because there are both advantages and disadvantages to Mudpick II. Mudpick II will increase ROP, but it is limited to only the soft and soft-to-medium formations. The harder the formations become, the less effective the Mudpick II hydraulics. Also, because of the angle of the nozzle and the flow, there have been some cases of abnormal erosion in the gauge and interlock row insert where the fluid is hitting the cutting structure at high rates of speed. There has also been some backwash on the shirttail as a result of the Mudpick II configuration. Whether Mudpick or Mudpick II is the right hydraulic configuration for a specific bit will be determined by the application, the hydraulic conditions, and satisfying the customer's needs.
Schlumberger’s Roller Cone Nozzles
Schlumberger has a variety of different types of roller cone nozzles. The chart bellows shows the 2 basic types of Schlumberger nozzles: shrouded nozzle and standard nozzle.
STANDARD TYPE SHROUDED TYPE STANDARD TYPE SHROUDED TYPE BIT SIZE RANGE 3-3/4” – 5-1/2” 5-7/8” – 6-3/4” 7-7/8” – 9” 9-1/2” – 18-1/2” 20” – 26” STANDARD TYPE AAK AK CK DK EK SHROUDED TYPE AACK ACK CCK DCK ECK NOZZLES AVAILABILITY SIZE (32ND) TFA in² 0.0498 0.0629 0.07710 0.09311 0.11012 0.13013 0.15014 0.17315 0.19616 0.24918 0.30720 0.37122 0.44224 0.60128 STANDARD TYPE AAK ? ? ? ? ? ? ? ? ? ? ? AK ? ? ? ? ? ? ? ? ? ? ? CK ? ? ? ? ? ? ? ? ? ? ? ? ? DK ? ? ? ? ? ? ? ? ? ? ? ? ? ? EK ? ? ? ? ? ? ? ? ? ? ? ? ? ? SHROUDED TYPE AACK ? ? ? ? ? ? ACK ? ? ? ? ? ? ? ? CCK ? ? ? ? ? ? ? ? ? ? ? DCK ? ? ? ? ? ? ? ? ? ? ? ECK ? ? ? ? ? ? ? ? ? ? ? N STANDARD TYPE SHROUDED TYPE NOZZLES AVAILABILTY BIT SIZE RANGE 3-3/4” – 5-1/2” 5-7/8” – 6-3/4” 7-7/8” – 9” 9-1/2” – 18-1/2” 20” – 26” STANDARD TYPE AAK AK CK DK EK SHROUDED TYPE AACK ACK CCK DCK ECK NOZZLES AVAILABILITY SIZE (32ND) TFA in² 0.0498 0.0629 0.07710 0.09311 0.11012 0.13013 0.15014 0.17315 0.19616 0.24918 0.30720 0.37122 0.44224 0.60128 STANDARD TYPE AAK ? ? ? ? ? ? ? ? ? ? ? AK ? ? ? ? ? ? ? ? ? ? ? CK ? ? ? ? ? ? ? ? ? ? ? ? ? DK ? ? ? ? ? ? ? ? ? ? ? ? ? ? EK ? ? ? ? ? ? ? ? ? ? ? ? ? ? SHROUDED TYPE AACK ? ? ? ? ? ? ACK ? ? ? ? ? ? ? ? CCK ? ? ? ? ? ? ? ? ? ? ? DCK ? ? ? ? ? ? ? ? ? ? ? ECK ? ? ? ? ? ? ? ? ? ? ? N STANDARD TYPE SHROUDED TYPE BIT SIZE RANGE 3-3/4” – 5-1/2” 5-7/8” – 6-3/4” 7-7/8” – 9” 9-1/2” – 18-1/2” 20” – 26” STANDARD TYPE AAK AK CK DK EK SHROUDED TYPE AACK ACK CCK DCK ECK NOZZLES AVAILABILITY SIZE (32ND) TFA in² 0.0498 0.0629 0.07710 0.09311 0.11012 0.13013 0.15014 0.17315 0.19616 0.24918 0.30720 0.37122 0.44224 0.60128 STANDARD TYPE AAK ? ? ? ? ? ? ? ? ? ? ? AK ? ? ? ? ? ? ? ? ? ? ? CK ? ? ? ? ? ? ? ? ? ? ? ? ? DK ? ? ? ? ? ? ? ? ? ? ? ? ? ? EK ? ? ? ? ? ? ? ? ? ? ? ? ? ? SHROUDED TYPE AACK ? ? ? ? ? ? ACK ? ? ? ? ? ? ? ? CCK ? ? ? ? ? ? ? ? ? ? ? DCK ? ? ? ? ? ? ? ? ? ? ? ECK ? ? ? ? ? ? ? ? ? ? ? N STANDARD TYPE SHROUDED TYPE NOZZLES AVAILABILTY
The standard type nozzle has got a flat surface on the top and the snap ring, which is what holds the nozzle in the bit. On the shrouded type nozzle, the snap ring is covered by a recessed groove. The purpose for shrouded nozzles is for use with highly abrasive fluids or if there are highly abrasive formations. The shroud protects the snap ring. All nozzles are measured in 32nds of an inch in terms of the diameter. In the picture on the previous page there is a 14 stenciled on top of the nozzle above the center hole. This means that this nozzle is a 14/32nd nozzle.
Hughes Christensen also used the same types of roller cone nozzles as Schlumberger. In fact the nozzles are interchangeable. Smith Geodiamond uses a screw type nozzle. Security DBS uses a nozzle that is held in by a nail. The Smith and Security roller cone nozzles are not interchangeable with Schlumberger.
Roller Cone Components
Roller Cone Components
Review Questions
Review Questions
• Identify the exterior components of a roller cone bit • Identify all of the interior components of a roller cone bit • List the 2 Schlumberger Drill Bit main bearing types
• List the 2 Schlumberger Drill Bit cone retention bearings • List the 3 Schlumberger Drill Bit seals
• List the 3 Schlumberger Drill Bit hydraulic configurations
JOURNAL & ROLLER BALLS THREATED CONVENTIONAL MUDPICK MUDPICK II
Roller Cone IADC Code
The IADC code, which stands for International Association of Drilling Contractors, was developed for roller cone bits in 1992. There is an IADC / SPE Paper 23937, that details this IADC roller cone bit classification
system. In the IADC roller cone classification system the numbers are divided up into formation, series / types, and cutting elements. Within soft or hard formations, there will be a series and type. If the first two numbers of the IADC code are 11 through 34 the cutting element will be mill tooth. If the first two numbers of the IADC code are 41 to 84 the cutting element will be a tungsten carbide insert bit.
The second digit of the IADC code tells the hardness of the bit within the series. So a 11 would be the softest of the mill tooth bits. A 12 would be the next hardest, and 13 would be the hardest. On inserts, for example, there may be a 41, 42, 43, 44, 45, etc. So within the series, the harder the bit, the higher the second number will be.
IADC Cutting Structure Code
IADC Cutting Structure Code
11-to
34-Soft
to
Hard
Mill
Tooth
Formation
Series / Type
Soft
to
Hard
41-to
84-Tungsten
Carbide
Insert
Cutting
Element
The IADC roller cone classification code basically looks like this:
If you look at this diagram, there are two examples. There is a 417 and a 115M. The first number represents the series. The 4 means it is an insert bit. The 1 means it is a mill tooth bit. The second number represents the type within that series. The third number in the IADC code represents the bearing and gauge package. Most of the time there will be three numbers in the IADC code. Occasionally, in the fourth position, there will be a letter. This letter represents special features. It is not used very often but
sometimes the drill bit manufacturer wants to indicate that this bit has some kind of special feature.
There are 7 different types of bearing and gauge configurations in the IADC code. They are:
1. Standard roller 2. Roller air cooled
3. Roller with gauge protection 4. Sealed roller
5. Sealed roller and gauge protection 6. Friction/Journal bearing
7. Friction/Journal bearing and gauge protection
The codes that are used the most often are IADC code numbers 1, 5, 6, and
4
1
7
Series Type Bearing
Gage
Special Features
1
1
5
M
IADC
IADC
Roller Cone
Roller Cone
Classification
There are several letters used in IADC to represent these special features. They are not used very often. Most of the time the bit manufacturer will choose to identify the special feature in their nomenclature as opposed to the IADC code. Below is a list of these special features:
A = air application B = special bearing /seal C = center jet
D = deviation control E = extended jets
G = gauge or body protection
H = horizontal or steering application J = jet deflection
L = lug pads
M = motor application
S = standard steel tooth model T = a two-cone bit
W = enhanced cutting structure
X = predominantly chisel tooth inserts Y = conical tooth insert
Z = other shaped insert
The M letter is used most often to designate a bit is designed for motor application.
The IADC code for roller cone bits has several uses. It is a good starting place when trying to compare roller cone bits on offset bit records. In order to determine what bit is going to be run in a specific application, bit
performance has to be evaluated. By looking at offset bit records, the IADC code of the offset bits can be identified. Why would the IADC code be only a starting place? If a customer says, “I need a 12-1/4” IADC code 517,” sure, which one do they want? Within the industry there are probably 60+ 12 ¼” 517 type bits. The IADC code gives a general indication of what kind of cutting structure is needed. The features, or combination of features, will then be selected for the specific application.
Schlumberger Drill Bits – Roller Cone Nomenclature
Below is an example of two of Schlumberger’s roller cone bits: a 12-1/4” EHP51HDLK and a 17-1/2 EMS13GC.
The first set of numbers, the 12-1/4 and the 17-1/2, represent the size in inches. The size is also indicated in metric on Schlumberger’s box labels for those that work in the metric system.
The next set of prefixes in Schlumberger’s nomenclature represent the product line. In this case, EHP, Enhanced High Performance, and EMS, Enhanced Motor Series, are the product lines for these particular bits. The Schlumberger product lines will be discussed later.
The next two numbers are the first two numbers of the bit’s IADC code. Schlumberger Drill Bits is the only company that uses the first two numbers of the IADC code, to identify their cutting structure. All the rest of the competitors use different sets of nomenclature and different sets of numbers to identify their bit types. In the top example, the 12-1/4" EHP51, the 51 indicates that the first two numbers of the IADC code for this bit is a 517. In the bottom example, the 17-1/2" EMS13, the IADC code for this bit is 135. So the first two numbers of the IADC code is represented in our nomenclature as 13. In 2001, Schlumberger launched three product lines which do not use the first 2 numbers of the IADC code in it’s nomenclature. The numbers used in the FMJ, DJ, and DR product lines are not associated with the IADC code.
12 ¼”
EHP
51
H
DLK
Size Size17 ½”
EMS
13 G C
Product Product Line Line IADC IADC Cutting Cutting Structure Structure Added Added Features Features Design Design Variant VariantThe next letter, if there is one, would represent the design variant. There are three different design variants frequently used by Schlumberger. They are designated by A, H, and X. Below are the design variants:
A = Chisel-Shaped Inserts. The application for this would be an aggressive insert shape typically for soft to medium formations. The downside to using the A variant is that an insert shape that is sharp chisel may not be durable enough. If the insert is not durable enough, the bit life could be limited.
H = Chisel-Shaped Inserts in IADC code 41 to 51 with 3° cutter skew. Typically insert bits in 41 to 51 range have 5° cutter skew. The application for the H designate is that it is a durable skew angle for any application where you need more durability. A 5° skew is for a more aggressive bit but it is less durable. A 3° skew is a little less aggressive but it is more durable. Durability could be needed in situations like running high RPM
(Revolutions Per Minute), a directional situation, motor bit runs, or any time there are streaky formations. The downside is that the more durable the bit, the slower the ROP. So a little bit of ROP is sacrificed in order to get durability. Schlumberger also builds bits that have faster ROP. So it depends on the customer's expectations, the application, and the objective for that bit run.
X = is a special cutting structure that might vary from type to type. When an X is in the suffix of Schlumberger’s nomenclature, the special cutting structure will be different from a normal bit. The applications for this type bit are formations such as medium-hard carbonates that suit an aggressive gauge design but does not lead to gauge breakage. The downside is that if you put a little longer gauge row inserts in for aggressive gauge design, there could be a tendency for the inserts to break.
Schlumberger Drill Bits has several options for added features.
With the example of the 12-1/4", DLK stands for diamond lug pad and K shirttail protection, and in the case of the 17-1/2" EMS13, G stands for gage protection on the bit and C stands for center jet.
Schlumberger Drill Bits – Roller Cone Features
Below are the Schlumberger Drill Bits roller cone features:
C = Center Jets. There are 2 types of center jets. There is a single-port
center jet that is installed in the center of the bit to provide hydraulic fluid to the inner row and nose area. There is also a port center jet. The three-port center jet is fixed and is installed in the factory. For the single-three-port center jet, it is interchangeable and can be installed or changed
in the field.
There are several benefits to running center jets. They reduce bit balling and help keep the nose and inner rows of the cutting structure clean. The major disadvantage of center jets is that they can reduce the outer cutter cleaning. If a bit has three nozzles, and then a center jet is added, there will be less fluid exiting out of the 3 outside nozzles.
C - Center Jet
F - Flame Spray cutter shell coating
G - Heel Row Inserts on tooth bits
JA - Jet Air Drilling
K - Shirttail Inserts
KP - Shirttail Inserts - Premium Coverage
KPR - Shirttail Inserts Raised - Premium Coverage
L - Lug Stabilizing Pad
M - Mudpick II Hydraulics on HP Bits
T - GageGuard - shorter inserts in between the gauge row Inserts
Another disadvantage is the center jet can aggravate the nose area. With high flow rates through your center jet, there can be nose cone erosion in the center of the bit. The applications for center jets are basically in bits 12-1/4" and larger. It is available in 7-7/8" and larger, and on occasion, a center jet has been installed in a bit smaller than 7-7/8". Typically center jets are used in medium to very soft, very sticky, gumbo type formations, or where
cleaning around the center of the bit is most important. Generally, no more than 18% of the TFA (Total Flow Area) should be going through the center jet. If the center jet is more than 18% TFA, the outside nozzles could be starved for fluid and will not keep the gauge row of inserts cleaned.
D = Diamond PDC-coated inserts. PDC stands for Polycrystalline Diamond
Compact. The purpose of using PDC-coated inserts is to eliminate thermal fatigue and to eliminate abrasive wear. Almost any of the cutting structure or shirttail inserts can be replaced with the diamond PDC-coated inserts. In the Schlumberger nomenclature, it is very simple to identify what features have diamond PDC-coated inserts and which ones do not. When looking at the suffixes of Schlumberger nomenclature, everything to the right side of the D represents diamond PDC-coated inserts. Everything to the left side of the D represents non-diamond PDC-coated inserts. The competition uses the D repetitive when they indicate their diamond coated inserts.
The benefits of PDC-coated inserts, the D feature, are that it does eliminate abrasive wear and thermal fatigue. There are some downsides, however. It is costly. Some of the PDC-coated inserts could cost $25, $50, or $100 per insert. The application must be right for using these inserts because it does increase the cost of the bit. Another downside is it will not solve fracture due to overload. If the inserts are breaking due to overload, using diamond
The applications for the D feature would be any application where abrasive cutting structure wear or thermal fatigue limits bit life. It can also be used in directional applications where there would be excessive wear on the gauge row inserts. The diamond PDC-coated insert would be a good solution to that gauge wear problem.
F = Flame Spray. This is a tungsten carbide coating that is applied to the
finished cutter in a high-velocity oxygen-fuel environment. After the inserts are pressed into the cutter, the cutters are sent to an outside vendor for the Flame Spray to be applied. For Flame Spray, the steel cutter shell surface is bombarded with tungsten carbide pellets at high velocity and they are
embedded into the cutter shell.
The benefits of Flame Spray are that it reduces cutter shell erosion and eliminates cone wear. The downside is that the coating may flake due to differences in modulus of elasticity between the tungsten carbide pellets and the steel. The best applications for flame spray is directional, or any
application where there is off-center rotation, gyration, or cutter wear limits bit life due to erosion. Sometimes this happens with poor solids control or high solids in the mud. Flame spraying has to be done in the before the bit is assembled. It is not something that can be done in the field. It has to be requested while the bits are being built. If there is a very abrasive formation, the abrasive formation will erode the steel. The problem with cutter shell erosion is that when the cutter shell is eroded, there is no longer support for the inserts. Once the inserts fall out, the bit will not drill at an adequate ROP. The bit will have to pull out of the hole and be replaced.
