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research project

By Lee Campbell,2014-11-08 12:13
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research project

    Develop a Drillability Model to

    Predict Drilling Penetration Rate in

    Different Drilling Situations

    Department: Civil & Mining department

    Superviser: Dr. Abbas Taheri

    Name:

    Alireza Sabetzadeh a1643520

    Tong Lu a1636064

    Baixi Zhu a1633713

Table of Contents

    Introduction ............................................................................................................................................. 4

    Drilling and the Importance ................................................................................................................ 4 How to Predict an Accurate Penetration Rate ..................................................................................... 5

    Two Main categories ....................................................................................................................... 5 Literature review ..................................................................................................................................... 6

    Drilling Method .................................................................................................................................. 7

    Where .............................................................................................................................................. 8

    PR is the penetration rate (cm/min) ................................................................................................ 8

    RQD is the rock quality designation (%) ........................................................................................ 8

    BL is the bit load (kg) ..................................................................................................................... 8

    BR is the bit rotation (rpm). ............................................................................................................ 8

    Rotary Drilling ................................................................................................................................ 8

    Percussive Drilling ......................................................................................................................... 9

    Percussive Drilling ......................................................................................... 错误;未定义书签。

    Rotary Blast hole Drills: ................................................................................................................... 9

    Drillability Model ............................................................................................................................... 9

    Factors Affecting .............................................................................................................................. 12

    Operational Variable (Controllable Parameters) ........................................................................... 12

    Drilling Penetration Rate .................................................................................................................. 16

    Specific Energy: ............................................................................................................................ 16

    Resistance to Drilling ................................................................................................................... 17

    Indirect Method to Measure Penetration Rate Index .................................................................... 17

    Pressure loss ................................................................................................................................. 17

    Drilling machine type ................................................................................................................... 18

    Power Transfer ............................................................................................................................. 20

    Impact strength index .................................................................................................................... 22

    Mathematical model of ANN ........................................................................................................ 30

    Review of Literature: ........................................................................................................................ 32 Problem Statement: ............................................................................................................................... 33

    Conclusion ............................................................................................................................................ 34

    Appendix: .............................................................................................................................................. 34

    Appendix 1: Relation between UCS and PR: ................................................................................... 34

     .......................................................................................................................................................... 34

     .......................................................................................................................................................... 34

    Appendix 2: Relation between BTS and PR: .................................................................................... 34 Appendix 3: Young Module and PR: ................................................................................................ 35 Appendix 4: Saturated and Dry Density ........................................................................................... 35 References ............................................................................................................................................. 36

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    Introduction

    Drilling and the Importance

    During the past years, the vital subject in investigation of preliminary mine site was drilling and blasting.Drilling and drillability are categorized between the significant activities in mining site that less accuracy or mistake to do these activities can bear an extensive cost and risk for mining companies(Thuro, 1997a; Yaşar, Ranjith, & Viete, 2011). Therefore, it is

    important to deeply understand the drillability and the main factors that affect it, and looking for those ways and methods to enhance and improve its efficiency.

    Improvement of drilling process is possible in two different ways, which are increase the rate of drilling velocity (Penetration rate) and reduce the bit wear. Study the literature relate to drilling efficiency show the consensus between scholars about the importance of these two factors on the drilling process. For example, Arabjamaloei and Dehkordi (2012) argued that the most important factors in drilling activity are penetration rate. They showed that understanding of how drilling parameters incorporate to make a specific rate of penetration, result to design an optimized method that used all these parameters to have the highest efficiency and lowest cost for drilling company(Aalizad & Rashidinejad, 2012; Arabjamaloei & Karimi Dehkordi, 2012; Basarir, Tutluoglu, & Karpuz, 2014a; Yaşar et al., 2011). In other

    case, Bruland (1998) argued that one of the important factors in rock blasting and tunnelling is penetration rate, he mentioned that PRI has a great influence on both time and cost and also the method and equipment which have to use during mining activity(Basarir, Tutluoglu, & Karpuz, 2014b; Bruland, 2000).

    Therefore, it can conclude that penetration rate or drilling velocity is one of the most important factors in determining the efficiency of drilling process; however, it is not the only one.

    The other factor which can effect on efficiency of drilling activity is reduction of bit wear (Basarir et al., 2014b; Somerton, 1959; Yarali & Soyer, 2011). For instance Thuro (1997) showed that to achieve the desirable result for a drilling, it is necessary to reduce the bit wear. Moreover, he mentioned that quartes content in the host rock is positively correlated with increase of bit wear(Thuro, 1997a, 1997b). Furthermore, Kahraman et al (2003) after their investigation showed that bit wear is a significant factor to increase efficiency of drilling process and particularly for drilling percussive drilling (Aalizad & Rashidinejad, 2012; S.

    Kahraman et al., 2003). Therefore, it is required to design the tools and methods to reduce the bit wear during drilling activity to increase the efficiency of drilling process. Altogether, it can conclude that the two main factors which can effect on the proficiency of drilling process are penetration rate and bit wear. In this study, it is aimed to focus on penetration rate and how to achieve a formula which can predict it more accurately based on the two vital categories (Controllable Variables and Uncontrollable Variables) which they will explain in detail in literature review.

    How to Predict an Accurate Penetration Rate

    The importance of rock drilling in different mining and petroleum engineering project, because of its high reliability and safety to determine and identify the deep natural resources, causes that it is still used by many engineering project(Basarir et al., 2014b). Moreover,the expensive operational costsin both petroleum and mining project which can be solved by accurate and proper drilling process lead several scholars to consideron both factors and parameters which involved in drilling and can influence on penetration rate. Therefore, today there is a high demand to understand the drilling factors and how to estimate and increase the efficiency of drilling process (Estes, 1971; Lummus, 1970; Moein, Shaabani, & Rezaeian, 2014; Singh, Jain, & Sarkar, 2009).

    As it mentioned in the introduction, drilling performance increase and optimise with two significant factors which are Penetration rate and bit wear(Basarir et al., 2014b). Between these two factors, the most important one is penetration rate and that is why many researchers tried to find the most related factors which can influence on efficiency of penetration rate. Predict an accurate penetration rate which is close to real or actual penetration rate, prevent any dramatic problems and specifically financial problems during the mining activity; therefore, it is important to fully understand all the factors which can effect on penetration rate of drilling process and determine how they effect on it(Yarali & Soyer, 2011).

    Two Main categories

    One of the most important factors to predict the penetration rate is physical, mechanical and petrographic properties of the rock which are all together has vital effect on determining of drilling cost. In this case there are many scholars who consider on different rock properties factor which can be effect on penetration rate. For example, Paone et al (1966) argued that there is significant correlation between the penetration rate and rock properties and particularly uniaxial compressive and tensile strength of the rock(Paone, Bruce, & Virciglio, 1966). In addition, Howarth et al (1986) reported the strong correlation between the

    penetration rate and rock properties such as Dry and saturated density, Saturated p-wave velocity, saturated uniaxial compressive strength and apparent porosity(D. Howarth, W. Adamson, & J. Berndt, 1986). Therefore, from all these academic studies, it can conclude that one of the important categories to estimate the penetration rate is rock mass properties. On the other hand, there are several researchers who considered the operational properties (Drilling equipment and facilities) as the other important categories that can influence on penetration rate(Karpuz, Paşamehmetogˇlu, Dinçer, & Müftüoglu, 1990). For example, Paone

    et al (1966) argue that thrust and rotational speed are the most important equipment factors that can influence on penetration rate(Paone et al., 1966). Moreover, Ersoy and Waller (1995) after their investigation, showed that rate of penetration is significantly correlated with operational properties such as weight on the bit and rotational speed (Ersoy & Waller, 1995). Therefore, the second important category which can effect on rate of penetration is equipment properties.

    Based on the review of all these academic studies, it can conclude that the most relevant categories which effect on penetration rate are rock mass properties ( for instance Uniaxial Compressive Strength and Rock quality Designation) and machine or operational properties (Bit Load and Bit Rotation)(Alvarez Grima & Babuška, 1999; Bruines, 1988).

    Literature review

    By the explanation of the materials in introduction parts, now in this part (Literature review), it is

    aimed to deeply explain about:

    ; Drilling method

    ; Diamond

    ; Percussive

    ; Rotary

    ; Drillability Model

    ; Specific Energy

    ; Resistance to Drilling

    ; Bit Wear Index (BWI)

    ; Cutter Life Index (CLI)

    ; Brittleness Model

    ; Factor Affecting

    ; Rock Properties

     Apparent Porosity

     Uniaxial Compressive Strength

     Rock Quality Designation

     Tensile Strength of the Rock

     Density

     Young Module

     S- Wave Velocity

     P- Wave Velocity

     Schmidt Hammer

     Shore Hardness

     Abrasiveness

    ; Machine Properties

     Hole Diameter

     Hole Length

     Pressure

     Feed

     Percussion

     Speed

     Shape

     Thrust

     Blow Frequency

    ; Review of Recent Studies

    ; Summary of all Studies

    For all the above categories it is tried to explain them briefly and express in what matter they

    can influence on penetration rate. Moreover, it is tried to mention exactly the result of

    previous study, whether they support or ignore that particular factor.

    Drilling Method

    Drilling is one of the significant and essential activities in both mining and petroleum activities. It is used in both exploration and excavation stage and plays prominent role in both. The importance of drilling will become more when it is realized that almost all activities such as machinery selection directly or indirectly dependent to the result of drilling. Therefore, it is important to use the most accurate method which is applicable with the characteristics of the Mine region or among other characteristics.In this part, it is tried to explain the mostly used drilling method and their merits and drawbacks.

    Drilling method is much depends on the drilling machine type, and which can be classified by three main categories and they are as follows:

    ; Diamond

    ; Percussive

    ; Rotary

    Each methodhas different sub categories and influence on drill rate. For instance, auger drilling is done with a helical screw which is driven into the ground with rotation which is cheap and fast. However, air core drilling is more costly and slower than percussion rotary air blast drilling. (McCann,

Quigley, Zamora, & Slater, 1995)Drilling method can be divided by three main measurediamond

    drillingrotary drilling and Percussive Drilling.

    Diamond Drilling

    Diamond drilling is one of the most desirable drilling technologies which are widely used in mineral exploration, and the impact of drilling has been widely used in open pit mines, quarries and construction sites. In mining engineering, diamond drilling is dominantly used for mineral exploration and gathering geotechnical information (Boffo, Pocock, Karakus, & Xu, 2012)

    Practice has proved that diamond drilling has many advantages over other drilling methods; it has a high drilling efficiency, good quality drilling fewer wells accidents, less steel consumption, low cost and wide application range of features(Park, Beal, Kim, Kwon, & Lantrip, 2011). Park et.al(2011)

    point that diamond drilling unrestricted aperture, a minimum of 28mm, maximum up to 30mm, the depth of hole is more than 4000m. Therefore, it is widely used in metal and non-metal geological exploration, coal, oil, etc., but also for the oil, gas, mining and other underground works holes. Tang et al.,(2014) think diamond drilling boreholes inclination unrestricted, it can not only drill vertical holes, inclined holes can drill horizontal holes and Yang hole, so it can be widely used for tunnelling and mining engineering drilling blast holes and trenches recourse mine exploration drilling holes in the body. Applications of multiple linear and nonlinear regression analysis using the statistical software package SPSS 20 made the following permeability prediction model: (J. Tang et

    al., 2014)

    ;?=?.???×?????;?+?.???×?????~,??.?????????:??.???????

    +?.???

    Where

    PR is the penetration rate (cm/min)

    RQD is the rock quality designation (%)

    BL is the bit load (kg)

    BR is the bit rotation (rpm).

Rotary Drilling

    Status quo and development trend in the 21st century, rotary drilling oil and gas industry will continue to be the main drilling. Rotary drilling is divided into turntable rotary drilling, downhole drilling and two different ways both composite rotary drilling and so on. Turntable rotary drilling in the entire drillstring rotation motion, while driving drill rotary drilling ; downhole drilling downhole drill motor rotor is driven rotary drilling drill, rotary drill string and the whole cannot rotate; composite rotary drilling is in using downhole drill while rotating turntable start drilling.(N. Tang, Wang, Huo, & CHENG, 2012)

    Research and Practice has proved that each rotary drilling method have their different characteristics and advantages and disadvantages of drilling. Among them, the composite rotary drilling methods to some extent, the advantages of both rotary drilling and downhole drilling, either continuous control trajectory and reduce tripping times, while improving ROP is a more efficient and controllable drilling

    methods, future drilling system dynamics approach to deal with this in-depth research and testing.(N. Tang et al., 2012)

    Percussive Drilling

    Impact drilling campaign is using the kinetic energy of an impact shock cone effect, crushing rock drilling to achieve a drilling method. Therefore, dynamic impact cone movement with pneumatic, hydraulic and gravitymethods(Lundberg & Okrouhlik, 2006). LundbergandCollet (2010) argue that the following describes the impact of drilling under gravity. The impact of general use crank rocker mechanism rig or hoist rope suspended from the lower end to improve drill to a certain height and then fall under gravity, have an impact on the bottom crushed rock. Drilling efficiency depends on the weight of the drill, stroke and punch times(Wiercigroch, Wojewoda, & Krivtsov, 2005). Due to the falling speed drill and the time limit by gravity, in the mud stroke of 1 m, the pumping is generally 40 to 50 times, to improve stroke have reduced red times, whereas you have to be reduced to improve the pumping stroke, This limits the impact of drilling to further improve the efficiency of drilling, so in addition to drilling in the weathered bedrock and gravel layer, in general, lower than the normal drilling efficiency rotary drilling. Impact drill cuttings by pumping drum fish take rock samples, or samples taken with a hit into the sand sampler to understand the formation. Since the rotary drilling did not like handling drill pipe from under sampling, so the efficiency of not less than rotary drilling. With the impact of the drilling the depth of hole increases gradually reduced drilling efficiency, while useful impact drill deep hole drilling records, but generally used for drilling deep wells within 300 meters(Rabia, 1985).

    Rotary Blast hole Drills:

    One of the drilling widely used methods is rotary drills. The advantageous of this method for

    over burden removal makes it one of the most widely used methods in all over the world. For

    example, in Turkey, this method is used by different open mining sites which they have a total

    ?annual drilling length of more than ?.?????meter(S Kahraman, Balcı, Yazıcı, & Bilgin,

    2000).

    Drillability Model

    Brittleness

    As rock drillability is defined as the penetration rate of a drill bit into the rock, there are certain comprehensive parameters that may contain several other basic rock mass factors can be regard as the principal factors in predicting the penetration rate.

    Yarali et.al (2011) suggested that brittleness is one of those significant rock mass mechanical properties especially in the prediction of rotary drilling method. Furthermore, specific correlation between brittleness factor and DRI(Drilling rate index) which is usually used to describe bore hole drillability has been carried out though some basic mathematical analysis.

    Evans and Pomeroy (1966) theoretically analyzed that the energy of a cutter pick is inversely proportional to brittleness. Another potential correlation between coal mine drilling process and the brittleness factor is suggested by Singh (1986). Kahraman and Altindag (2004) correlated fracture prediction with different brittleness with the help of certain experimental data. Many researchers‟

    work indicate the potential impact from brittleness towards the drillability index

    Figure 2. Correlation between DRI and brittleness (Altindag, 2004)

The classical definition of brittleness “when the internal cohesion of rocks is broken, the rocks are

    said to be brittle” can be manipulated in the latest unit B which is usually generated from the formula:

    ???4= ??

    Where Wr stands for reversible energy and Wt for total energy from stress-stain curve. The potential trend measured by Yarali et.al (2011) is illustrated in Figure 2. Conclusion from other researchers‟ work that DRI has an inverse proportion correlation with brittleness can be made.

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