Modeling for Drilling Bits Interaction in
Drilling Simulator
Musabikhin#1
#
Department of Electrical Engineering, School of Electrical Engineering and Informatics,
Bandung Institute of Technology
Bandung, West Java, Indonesia
1mbikhin@yahoo.co.id
Abstract - Drilling Simulator is a computer application that
was developed to describe the behavior and the process of
drilling oil wells carried out in the field.
This study aims to make design patterns of interaction between
the drill bits with the rock formations in accordance with the
suggested mathematical model.
Designing the interaction model of the destruction of the rock
formation using a different equation for soft to medium rock
formations, and for the hard rock formations. While the
interaction using the equation denudation bits added to the
estimated age of bits after bits are used at certain depths.
Performed on the data manipulation interaction model so
obtained rate of penetration (ROP) in meters/hour, and the
drilling depth as its output. In the interaction model was also
conducted manipulation denudation bits, so we get bits
denudation rate.
The test results obtained describe the magnitude and speed of
deforestation bits ROP models with field data, test results with
the help of MATLAB software. Some quantities can still be
derived from the interaction of other support systems are more
complex. This condition can be used as a basis for further
development of the simulator.
Keywords: drilling simulator, rock formations, bits, rate of
penetration, rate of deforestation bits.
I.
INTRODUCTION
Based on this background, the research was conducted
with the aim to design and implement interacting modeling
bits with a layer of rock at the drilling simulator, the system
development methodology in general through a needs
analysis and review of literature, design, and
implementation and testing.
II. BASIS OF THEORY
Computer simulation or a computational model is a
computer program, or computer network, which tries to
simulate an abstract model of a particular system.
Simulation can be used to explore and gain new insights
related to the understanding of a system that occurs [9].
Petroleum is a fossil fuel formed in the process of
millions of years ago. Petroleum required to fuel the
engine, motor vehicles, household fuels, as well as raw
materials in chemical industry. To get the oil to do the
exploration and exploitation of oil resources both onshore
or offshore.
A. Bits Classification
The process of drilling the wells drilling include some
important parts such as drilling rig, hoisting system,
circulating system, rotary system, well control system,
monitoring well system.
The process of drilling is one of the important steps
made in the petroleum industry, in addition to the
exploitation stage. This process is costly, and a relatively
long time, so it is lost if this process fails to do well.
In the rotary system are an important component of the
so-called drilling bits or drill bits. There are 2 types of
rotary drilling bits, as follows.
In studying the process of drilling needed to describe
the process of media that can be designed in a simple and
can be applied quickly, and describes all phases of the
drilling process. Drilling Simulator is offered as a medium
that can describe the drilling process.
1. Roller-cone bits[4] or rolling cutter bits[1].
Commonly used in drilling various types of formations,
from the softest to the loudest, with a milled tooth type bits
are commonly used in soft formations, and tungsten carbide
inserts bits (TCI) which is used in a wider formations,
including the formation of the loudest and highly abrasive
formations.
2. Fixed-cutter bits[4] or drag bits[1].
Used in the drilling of the various types of formations at
various depths. Drilling by drag bits are cutting the ground
from the bottom of the borehole as a farmer plowing a field
to make a water channel. Include polycrystalline diamond
(PCD), impregnated bits and diamond bits.
To classify the bits from many manufacturers, the
International Association of Drilling Contractors (IADC)
made good on the classification of rolling cutter bits and
drag bits on. IADC makes the classification of rolling cutter
bits by using a combination of three digit numbers, with the
classification as detailed in the following table.
Table 1. Type of bits in IADC standard.
Digit
1
1
2
3
4
5
6
7
8
Digit
2
1
2
3
4
Digit
3
1
2
3
Type
of bits
Steel
tooth
bits
4
5
6
7
TCI
3. Gauge wear level.
Gauge wear levels are also identified with the same
gauge as tooth wear with the code G1 to G8.
III. ANALISIS DAN PERANCANGAN INTERAKSI
A. System Specifications
Specification of a system built in the design of this
study was to build a simulator application that is one of the
media evaluation drilling activities in order to get the
calculation of the performance of the system economically
and efficiently. Here is a system and sub systems of drilling
simulator applications.
Information
Soft
medium
hard
Soft
Soft-medium
medium
hard
Very hard
B. Destruction Stone Mechanism
Interaction bits of rock formations causing the
destruction of the formation so that the resulting hole with a
certain depth. On the other hand these interactions also lead
to the erosion of the teeth bits.
1.
2.
3.
4.
5.
2. Bearing wear level.
Bearing wear levels are also identified with the same
bearing as tooth wear with the code B1 to B8.
Includes destruction of the basic bits [1]:
wedging
scraping and grinding
erosion by fluid jet action
percussion or crushing
torsion or twisting
C. Selection and Evaluation of Bits
Bits that have been used can be selected and evaluated
by three categories[1].
1.
Tooth wear levels.
Identified with the level of T1 to T8 as shown in Figure
1 shows the calculated reduction in the use jagged bits
eighths. Eg bit with T4 means the use of achieve 4/8 or 0.5.
Figure 1. Tooth wear level.
Drilling Simulator
Formation
Simulation
Bits
Simulation
Fluid
Simulation
Figure 2. Drilling application system simulator.
In order to produce a good application and system
specifications, first made a list of requirements that need to
be met by this application. Needs basis determined by
reference to the following.
 Usability
Functionally, namely to support the process of drilling
in the field, these simulations must be able to provide
additional information about the activity in the hole drilling
bits for the user.

The user experience
This simulator is expected to provide a special
experience for the user when to use it as a medium of
learning, or performance evaluation in the field. With
interactivity on simulation capability is expected to meet
those needs.
Under field conditions, requirements in the design of
mathematical models to simulate the situation. It takes
manipulation variable, and constant variables to get a
response variable. The terms of the required related to these
variables is as follows.
1. Data of rock formations to be explored.
Data on the rock formations are distinguished 3 kinds of
soil layers based on the uniaxial compressive strength
(UCS), and the value of factor of rock (RF), namely
a. layer of soft soil, in the form of shale rock with UCS 70
MPa, and RF 135.
C. Reference Model on the Interaction of Mathematics
and Rock Bits
b. soil medium, a limestone rock with UCS 125 MPa, and
RF 100.
Influence on the destruction of rock bits are usually
expressed in terms of penetration rate, rate of penetration
(ROP), drilling rate or other terms relating to the progress
of drilling. Some researchers try to connect the penetration
rate with some rock properties are easily measured.
c. hard rock, a sandstone rock with UCS 200 MPa, and RF
80.
2. Type the required bits.
Bits are used according to the rock formations to be
explored is the rolling cutter bits specified in the standard
specification IADC code, namely the type 4-1-2, 5-1-2, and
6-1-2.
3. Rotational speed of bits.
Rotational speed of bits can be set between 0 to 150
rpm.
4. Bits weight.
Bits weight, or bits on weight (BOW) is set on two
alternative input for 4x103 lb / in and 6x103 lb / in or equal
to 71.43 kg / mm and 107.15 kg / mm.
5. Rate of tooth wear (average age of the jagged bits).
Age of bits expressed in units of time (hours) according to
the type bits are used in certain rock layers.
6. Penetration rate or Rate of Penetration (ROP) which is
an average penetration of bits of the formation.
ROP obtained from equation Calder and Workman for
drilling in soft and medium layer, and the similarities Bauer
on the hard layer.
B. Flow Chart of Drilling Simulator Model
Bits groove interaction model can be described as in
Figure 3 below.
Bauer equation
Bauer modify equation penetration rate (ROP) as
follows
𝑊
𝑁
𝑑
300
𝑃 = (61 − 28𝑙𝑜𝑔𝑆𝑐 ) ( ) (
)
… (1)
with
𝑃 = Penetration rate (ft/hr)
𝑁 = rotation speed (RPM)
𝑆𝑐 = UCS (uniaxial compressive strength) in 1000 lb/in2
𝑊 = bits weight in 1000 lb.
𝑑 = bits diameter (in)
Above equation can describe good results when drilling
conducted on the hard rock, but it will happen aberration
results when used in the drilling of rocks with a small value
of UCS
2.
Calder and Workman equation
𝑃 = 5,7𝑥10−5 (𝑅𝐹 − 28 log(0,145 𝑆𝑐 ))𝑊𝑁
… (2)
with
𝑃 = penetration rate (m/hr)
𝑅𝐹 = rock penetration factor
𝑆𝑐 = UCS (MPa)
𝑊 = bits weight (kg/mm)
N = rotation speed bits (RPM)
Mulai
Input: t,
BOW, RPM,
tipe bits
T
ROP Calder
Workman
D. Destruction Testing of Rock
Y
ROP Bauer
Input data in accordance with the needs analysis, ROP
obtained on three different rock layers as follows.
Hitung kedalaman
pengeboran
T
1.
Calder dan Workman[3] recommends penetration rate
equations in a layer of rock with low UCS values as follows
7. Constants associated with the drilling.
Apakah lapisan
batuan keras?
In the interaction model used estimates of drilling
simulator ROP measurements using multiple equations as
follows.
Apakah penggundulan
bits > 6/8?
Y
Selesai
Figure 3. Flowchart model.
Table 2. ROP in several layers of rock conditions.
Type
of
formation
W/d
(kg/mm)
N (rpm)
ROP (m/hr)
Shale
71.43
80
34.79
100
Limestone
80
Sandstone
80
107,15
80
80
Testing the influence of the length of the serrations of
the denudation rate relative to the results of testing bits in
the range of values 0.1 to 0.5 (the jagged bits long)
produces the graph shown in Figure 5 below.
8,13
65,24
31,65
100
Sandstone
26,37
52,19
100
Limestone
E. Destruction of Bits
6,50
100
Shale
43,49
21.10
100
From the graph Figure 4 above, can be interpreted to
mean that the value of ROP decreases exponentially
increasing in line with UCS. This means that the rocks have
high compressiv longer be penetrated and destroyed by the
bits of rock that is more than soft.
80
39,56
9,75
100
12,19
If we assume the thickness of each layer of rock is 40
m, the drilling time required are listed in Table 3 below
Figure 5. Charts the influence of jagged bits long
Table 3. Time of drilling at a depth of 40m.
Type of
rock
Shale
ROP (m/jam)
34.79
43,49
Limestone
21.10
Sandstone
6,50
Shale
52,19
26,37
8,13
65,24
Limestone
31,65
Sandstone
9,75
39,56
12,19
Drilling time
(jam)
1,15
0,92
1,90
1,52
6,15
4,92
0,77
0,61
1,26
1,01
4,10
3,28
Penetration rate (ROP) on the type of formation is very
different depending on the specific value of the uniaxial
compressive rock strength (UCS), which influences the
magnitude of the ROP UCS can be described on a graph as
in Figure 4 below.
Figure 4. Charts the influence of UCS on ROP.
From Figure 5 it can be concluded that the rate of
deforestation relative bits decreases with the initial length
jagged bits. The longer the initial size of the jagged bits, the
smaller the relative speed of the denudation bits.
Testing the influence of weight bits of bits denudation
rate relative to the results of testing on a range of values 1
through 9 produces the graph shown in Figure 6 below
Figure 6. Charts the influence of weight per-diameter bits.
Testing the influence of rotation speed to the speed of
deforestation bits bits represented by the test results relative
to the range of values of 70 rpm to 120 rpm produces a
graph as shown in Figure 7 below.
Figure 7. Charts the influence of rotation speed bits.
From the test results on the mathematical model, it
shows the same results with the simulation on the
simulator, and together with the results of field data with
the same conditions.
IV. CONCLUSIONS AND RECOMMENDATIONS
A. Conclusion
1. The simulator can model the destruction of rocks by a
mathematical model equations Calder and Workman on
a rock with low UCS, and Bauer equations on a high
rock with UCS.
2. Interaction also leads to bits of rock bits that are
affected by desertification have long jagged bits at first,
bits weight, round bits.
B. Suggestion
1. Test patterns of interaction with rock bits can be closer
to real conditions in the field, if there is data drilling
results are more specific and detailed. So it takes the
actual data that can only be obtained from the drilling
field.
2. Applications can be further related to the setting pipe,
drill colar, and the connection that exists in the drill
stem, and other parameters related to drilling, so that the
simulator generates a more complex and closer to the
actual conditions.
REFERENSI
[1]
Bourgoyne, Adam T. Jr, Applied Drilling Engineering, Society of
Petroleum Engineers Richardson, TX, 1991
[2]
Darley, H.C.H, Gray George R., Composition and Properties of
Drilling and Completion Fluids, Fifth Edition, Gulf Publishing
Company, Houston, 1988.
[3]
Gokhale, Bhalchandra V., Rotary Drilling and Blasting in Large
Surface Mines, Taylor & Francis Group, London, UK, 2011.
[4]
Lake, Larry W., Petroleum Engineering Handbook, Society of
Petroleum Engineers USA, 2006.
[5]
Lyons, William C., Standard handbook of petroleum and natural
gas engineering, Gulf Publishing Company, Houston, Texas ,1996.
[6]
Lyons, William C., Working Guide to Drilling Equipment and
Operations, Gulf Publishing, Burlington, 2010.
[7]
Moore, Preston L, Driling Practice Manual, Penn Well Publishing
Company, Second edition, Oklahoma, 1986.
[8]
Prassl Wolfgang F. Drilling Engineering, Departement of
Petroleum Engineering, Curtin University of Technology.
[9]
Robinson Stewart, Simulation: The Practise of Model Development
and Use, John Wiley & Sons Ltd, West Sussex, 2004.
[10] Selley Richard C., Elements of Petroleum Geology, Academic Press
An Imprint of Elsevier, Second Edition, California, 1998.
[11] Sridadi, Bambang, Pemodelan dan Simulasi Sistem. Teori, Aplikasi,
dan Contoh Program dalam Bahasa C, Informatika Bandung, 2009.