Drilling Simulator :
Rock Layer Modelling and Rock Cutting
Movement
Warsidi#1
#
Electrical Engineering Department, School of Electrical and Informatic Engineering,
Bandung Institute of Technology
Bandung, West Java, Inconesia
1warsidi72@yahoo.com
Abstract—Drilling Simulator is one of the oil drilling
process simulation is developed based on the concept of
interaction between the bit with layers of rock that is in the
earth's surface. Drilling Simulator is the representation of
objects in the world of rock layers of 3D graphics.
The aims of this study is explain the patterns of
interaction between the bit and the rock layers that exist
(game object) in the Drilling Simulator. The interaction
pattern that is expected to provide an overview of the
formation pressure distribution (Pformasi), fluid pressure or
the pressure of drilling mud (Pmud), and rate of penetration
(ROP).
Environment development of GUI (graphical user
interface) Drilling Simulator based on 3D modeling and
applying 3D game engine using the unity engine. The main
visual device that is used to describe a 3D model and its
environment is a monitor used to display user interaction
with 3D environmets in Drilling Simulator.
Tests performed included testing the interaction between
the bit and the layers of rock that will provide value to the
rate of penetration (ROP), formation pressure (Pformasi),
and mud drilling pressure (Pmud).
Key words: rate of penetration, user, Drilling Simulator,
cutting.
I. INTRODUCTION
Oil well drilling technology and gas have been
developed in two decades (1950-1970). Each of the
petroleum industry has a goal to be able to explore
and exploit oil fields and gas wells. Oil well drilling
process can be divided into two groups: well drilling
exploration and exploitation drilling. Exploration
drilling aimed to determine the geological structure
of the surface layer of the earth and to determine the
possible discovery of hydrocarbons (petroleum) on
the surface of the earth. Exploitation wells while
drilling acquisition aims to increase the production of
hydrocarbons (petroleum), known as enhanced oil
recovery(EOR) methods[3].
The components of the petroleum drilling consists of
a power system, hoisting system, fluid circulation
system, rotary system, and the model layer of rock
beneath the earth's surface and the movement of
cutting rock drilling results in the earth's surface to
the outer surface of the earth is affected by the
density of rock cutting , the density of drilling mud,
rheology properties of drilling mud, pipeline velocity
(annular) drilling.
Computer simulation is a computer program or
computer network to simulate the abstract models of
a system of particles[7].
According to the Millheim [6] simulator is a device
or equipment that mimics some of the physical
processes or operations at several large degree.
Simulation is not related to equipment and numerical
or mimic the logic in some processes, operations or
phenomena.
Drilling Simulator is a computer program
designed to simulate the physical processes that occur
in petroleum drilling. Realization of drilling and well
engineering simulation created using 3D computer
graphics, real-time simulation and sound effects.
II. BASIC THEORY
Earth composed by three main types of groups of
igneous rocks (igneous rocks), sedimentary rocks
(sedimentary rocks) and metamorphic rocks
(metamorphic
rock).
this
grouping
When drilling a well located at a shallow sedimentary
rock layers of the formation pressure can be assumed
1
as hydrostatic pressure. Hydrostatic pressure is
defined as the weight of the fluid at a certain depth is
defined by equation (II.1).
...(II.1)
P  Po   formasigh
with P the formation terkanan in Pascal (Pa),
 formasi is a mass of rock types in kg/m3, g is in the
earth's gravitational acceleration 9.81 m/s2, h and the
depth of formation (rock layers) from a ref erence
point in meters. By using the assumptions above, the
amount of pressure can be written for drilling fluid
(drilling mud) at a certain depth as in equation (II.2).
...(II.2)
P  Po   mud gh
with P the formation terkanan in Pascal (Pa),
 formasi is a mass of rock types in kg/m3, g is in the
movement speed of cutting rock drilling results are
influenced by these factors:
(1) the density of cutting rock (rock layers),
(2) the density of drilling mud,
(3) drill pipe annular velocity,
(4) angle hole drilling.
Cutting speed of the rock removed from the drilling
bit affects the efficiency and speed of penetration.
Observations about the ability of a numerical study of
the mud to lift the rock cutting depends on the type of
flow, laminar flow or turbulent flow. In the turbulent
flow, the velocity profile is more flat and the reverse
will not happen as shown in Figure II.1 below.
earth's gravitational acceleration 9.81 m/s2, h and the
depth of formation (rock layers) from a ref erence
point in meters.
Factors that influence the ROP[1] is the type of bit, the
characteristics of the formation (rock layers), the
properties of drilling fluid (drilling mud), bit
operating conditions (heavy bit and bit rotational
speed), use of dental bits, and bits of hydraulic
pressure. In drilling with tricone bit, there are four
factors that affect the drilling process, the
mathematics can be expressed by equation (II.3).
…(II.3)
ROP  f (WOB , N , C, Q) [5]
With ROP the rate of penetration, WOB is the
weight on bit, N rotation speed is in bits, C is a bit
high gear, and Q the volume of air flow is used.
Rock drilling capability means ROP is given to the
rocks
by
the
drilling
bit.
In 1971 Bauer[5] formulated on the ROP as expressed
by equation (II.4).
 WOB  N 
…(II.4)
ROP  61  28 . log S c 


 D  300 
with S c is uniaxial compressive strength (UCS) in
MPa, D is bit diameter in meter.
In 1994, equation (II.4) is modified by Bauer into
equation (II.5).
ROP  5.7105 RF  28 log0.145S c WN …(II.5)
with RF the penetration factor of the rock.
Table II.1 The penetration factor of the rock ( RF )
No
1.
2.
3.
Rock Name
limestone
shale
sandstone
UCS(MPa)
RF
220
25
50
61
200
200
Cutting rock drilling is the result of the drilling
process is performed bit. The magnitude of the
Figure II.1 Differences in laminar flow and turbulent
flow[4]
In laminar flow, rise and fall of rock cutting
advanced by Pigott by applying Stokes law, as in
equation (II.6) and equation (II.7) below[4].
148 d c2  s   m 
vls 
...(II.6)

Equation (II.6) for cutting a spherical rock. As for the
cutting flat shaped stones according to equation (II.7)
57 .5d c2  s   m 
vls 
…(II.7)

With vls the maximum slip velocity (terminal) of
rock cutting on the laminar flow (ft / min), d c the
rock cutting diameter (in), is the density of mud and
rock cutting is the density (lb / gal), the sludge
viscosity (cp), 148 and 57.5 is the constant
dimensional coefficient including grit (cutting a flat
rock about 40% faster than the ball-shaped rock
cutting).
Turbulent velocity obtained from the equation
changes Rittinger. William and Bruce have used
equation (II.8) and equation (II.9) below [4].
d    m 
…(II.8)
vc  170 c s
m
Equation (II.8) for cutting a spherical, while equation
(II.9) for cutting flat shaped rocks.
t
d c  s   m 
…(II.9)
vc  133 c
dc
m
2
With vc the cutting slip velocity in turbulent flow
(ft/min), and
tc
the ratio of the thickness and
dc
diameter rock cutting.The value v c must be corrected
for the influence of the wall, or rock cutting itself
from an annular region. This is achieved by the
empirical expression as in equation (II.10) below.
vc
vts 
…(II.10)
d
1 c
da
with vts the cutting slip velocity on turbulent flow
(ft/min) and d a the hydraulic diameter anullus.
Annulus diameter ( d a ) can be expressed by equation
(II.11).
d a  d lub ang  d pipa
…(II.11)
with the borehole diameter in meters and the
diameter of the drill pipe being used.
Reynolds number is a number that is used to
check the type of fluid flow, laminar flow, turbulent
flow or transitional flow between laminar flow and
turbulent flow. Reynolds number is expressed by
equation (II.12) below. [4]
928 vd
Re 
...(II.12)

with Re the Reynolds number,  is the density of the
fluid (lb / gal), v is the average velocity of flow (ft /
s), d is the diameter of the pipe (in),  is the fluid
viscosity(cp).
With the following conditions:
(1) if <2000, then the type of flow is laminar flow,
(2) if> 4000, then the type of flow is turbulent flow,
(3) if 2000 << 4000, then the type of flow is a flow
transition between laminar flow to turbulent flow.
III. DESIGN AND ANALYSIS
A. Specifications
To analyze and design the system behavior
Drilling Simulator, based on system specifications
are as follows:
1. user can select and use the menu on the Drilling
Simulator;
2. user can menentukkan magnitude of the density of
drilling mud (rho_mud), the magnitude of the
rotational speed (RPM);
3. user can menngganti bit;
4. the interaction between the bit with a layer of rock
that is expressed by the magnitude of ROP;
5. game object created, such as the pipe model, the
model layer of rock, rig models, models of rolling
cutter bits, drill collar and models.
Specification of requirements modeling and its
interaction with the rock layers on the simulator
drilling bits as follows.
(1) The simulator can model the layers of rock
drilling in the oil drilling area consists of
sandstone rock layer model, the model layer of
shale, limestone layer models that have a
variable such as density of rock (rho_rock),
depth (h), pressure (P_formation), the fluid
pressure or drilling mud (P_mud) and data
robustness rock (K_batuan),
(2) Drilling Simulator to show an association
between ROP bit values to the model layer of
rock being drilled (ROP depends on the layer of
rock).
(3) Drilling Simulator can display the value of the
formation pressure (Pfor), drilling mud pressure,
depth, time of drilling, the value of WOB on the
panel are available.
Specification modeling of rock layers and their
interaction with the system bit Drilling Simulator as
follows.
(1) Model rock layer in the form of a 3D model
with a thick layer of rock layers of the model
includes some sandstone, limestone rock layer
model, and model layers of shale rock.
(2) Model rock layer contains the physical data
such as density of rock (rho_sandstone = 2650
kg/m3), rho_limestone = 2710 kg/m3, and
rho_shale = 2500 kg/m3), depth of bedrock (h),
rock hardness (usandstone = 10000000 Pa, Pa
ulimestone = 250000000, and ushale = 2000000
Pa) and rock penetration factor (Rfsandstone =
200, Rflimestone = 61, and Rfshale = 200).
(3) Model rock layer affect the bit value of ROP,
the ROP is calculated using equation (II.7).
ROP  5.7105 RF  28 log0.145S c WN
(4) Model rock layer determines the pressure of the
rock formations (Pfor) and the drilling fluid
pressure (pmud). Pressure value formations
(rock layers) can be calculated using equation
(II.1) while the value of the drilling mud
pressure can be calculated using equation (II.2).
P  Po   formasigh
P  Po   mud gh
Specification modeling the movement of rock cutting
bits from the bottom to the surface of the Earth
Simulator in Drilling system as follows.
(1) Cutting rock is modeled as a 3D model in a
spherical shape with a size that matches the size
of rocks in the drill.
3
(2) The process of breaking rock layers depends on
the UCS and RF rocks (depending on the value
of ROP) of each layer of rock being drilled.
(3) The model of rock cutting speed can be
determined by determining the Reynolds
number as in equation (II.13).
(4) Speed of rock cutting bits from the bottom up to
the surface of the earth can ditentukkan by using
equation (II.8) for laminar flow model and
equation (II.10) to model the turbulent flow.
Figure III.2 Model layer of limestone rock
B. Analysis
To realize the system specifications that will be
designed in this study required supporting
components.
(1) Software for modeling and 3D animation
Required to create 3D models such as models of
rock layers, drilling rig models, model pipe,
drill colar models, models of blow out preventer
(BOP) and the model bit.
(2) Software for the creation and graphic design
Required to make a rock texture, texture
pipeline.
(3) Software for the game engine used
Drilling is required to make the system
simulator.
C. Design
Modeling of rock layers include three-dimensional
modeling and object modeling physically. Model
rock layer that covers the model layer is made of rock
shale, sandstone rock layer models, and models of
limestone rock layers with different layer thickness
variation.
Figure III.2 Model layer of sandstone rock
Modeling the interaction between the model and bit
of rock layers can be illustrated by Figure III.4
below.
Picture III.4 model the interaction between the
models with a bit of rock layers
Design use case diagram for Drilling Simulator as
shown in Figure III.5.
<<include>>
play
<<include>>
<<include>>
tutorial
Or physical modeling involving data for layers of
rock shale, sandstone, and limestone that includes a
data density of the rock consists of shale density
(rho_shale), the density of the sandstone
(rho_sandstone), and the density of limestone
(rho_limestone) as in Figure III.1, Figure III.2 and
Figure III.3 below.
scene viewdrillmovement
<<include>>
scenetutorial
<<include>>
help
<<include>>
scene help
<<include>>
<<include>>
about
scene about
exit
Figure III.5 Use case drilling simulator
To determine the relationship between rock layers
with ROP may be illustrated by the following
algorithm below.
Figure III.1 Model layer of shale rock
Start
if any collision between bit with layer
rock model then
Cek collision.gameObject.layer == 9
then
Rock layer is ”shale”
Count formation pressure
Pfor = Po+rho_shale*g*h
Count ROP;
else
4
Cek collision.gameObject.layer == 10
maka
Rock layer is ”sandstone”
Count formation pressure
Pfor = Po+rho_shale*g*h
Count ROP;
else
Cek collision.gameObject.layer == 10
maka
Rock layer is ”limestone”
Count formation pressure
Pfor = Po+rho_shale*g*h
Count ROP;
Finish
Figure III.6 image panel on the drilling simulator
models
E. Implementation
In the implementation phase dilakukkan following
steps:
1. Implementation of the model into the engine
2. Program Code Implementation (coding)
This stage is the implementation phase of the
program code (coding) to build the interaction
between the user with a Drilling Simulator and the
interaction between the bit with the model of rock
layers.
a. Program code for the interactions between the bits
of rock layers to the model include:
• display the slider to adjust the rotation speed,
• Print a magnitude of ROP,
• display the time of drilling,
• show the type of rock layers,
• display the depth of drilling (bit),
• displaying rock formation pressure,
• displays pressure drilling fluid (mud),
• display the WOB.
b. Program code for collision detection.
c. Program code for loading sound.
3. Object into the implementation stage of the game
engine:
a. makes modeling in 3D Max;
b. export the model into a format *. FBX;
c. import the model into the engine;
d. add a mesh collider (for collision detection);
e. add script (coding) for each behavior designed.
F. Testing
The following is the initial view Drilling Simulator
using the game engine Unity 3.4.
Figure III.5 The initial view of drilling simulator
Testing is done to the parameters of the design and
implementation can be measured very well. Here is a
table mapping functionality in modeling the
movement of rock layers and rock cutting.
III.7 picture below is a display parameter Drilling
Simulator run time.
Figure III.7 Image display parameters of drilling
simulator
Table IV.1 The test results
Spesification
Rock
model
Implementation
+ Test
Output
layer
Yes
The influence of
rock type on the
pressure rock
formations and the
ROP
Rock
cutting
movement
model
No
View the movement
of rock particles
from the bottom bit
to the surface (not
available)
Model
rock
layer can accept
input from user
No
-
Rig model
yes
Rig display
Pipe model
yes
Pipe display
Drill Collar
model
yes
DrillCollar
display
5
IV. CONCLUSIONS AND SUGGESTIONS
A. Conclusions
The conclusion to be drawn from this study are as
follows.
(1) The design and implementation of the model can
provide a layer of rock stones lithologi.
(2) For this type of rock layers of different models
will give different values of ROP.
(3) The more models of rock layers, the more varied
the value of ROP bit and the movement of rock
cutting.
Evolution Fourth, Brooks/Cole, forth edition,
Belmont, 2006.
[8] Prassl, Wolfgang F., Drilling Engineering,
Departement of Petroleum Engineering, Curtin
University of Technology.
B. Suggestions
Some suggestions that may be applied further on the
results of this study are as follows.
(1) Make the model more layers of rock.
(2) Drilling Simulator created a 3D model of the
movement are not yet cutting rock, resulting in
the development can then use the particle method
for modeling the movement of the cutting system
of the lower bits of rock to the surface of the
earth.
(3) The parts of Drilling Simulator is yet to be made
can be developed further as a model the flow of
drilling mud (drilling fluid models) and models of
petroleum reservoirs.
REFERENCES
[1] Bourgoyne Jr, Adam T, Millheim, Keith K,
Chenevert, Martin E., dan Young Jr, F.S.,
Applied Drilling Engineering, SPE, Richardson,
TX, 1991
[2] Bruno, Michael, Han, Gang, and Honeger,
Claudia, Advanced Simulation Technology for
Combined Percussion and Rotary Drilling and
Cutting Transport. Terralog Technologies, USA,
2005.
[3] Darley,H.C.H, Gray,George R, Composition and
Properties of Drilling and Completion Fluids,
Gulf Publishing Company, fifth edition, Houston,
1988.
[4] Gatlin, Carl, Petroleum Engineering Drilling and
Well Completions, Prentice Hall Inc, Englewood
Cliffs,N.J, 2006.
[5] Gokhale,B.V, Rotary Drilling and Blasting in
Large Surface Mines, CRC Press. London, 2011.
[6] Jose Gregorio Salas Safe, Drilling Optimization
Using Drilling Simulator, Texas A&M
University, Texas, 2004.
[7] Monroe, James S., Wicander, Reed, The
Changing Earth Exploring Geology and
6