Pilot Hole Research Articles

Static Measurements Enhance Saturation and Permeability Interpretation

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202683, “Marrying the Static and Dynamic Worlds: Enhancing Saturation and Permeability Interpretation Using a Combination of Multifrequency Dielectric, Nuclear Magnetic Resonance, and Wireline Formation Testers,” by Hassan Mostafa, Ghassan Al-Jefri, SPE, and Tania Felix Menchaca, SPE, ADNOC, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed. Accurate water saturation evaluation and permeability profiling are crucial factors in determining volumetrics and productivity of multiple, stacked carbonate reservoirs offshore Abu Dhabi and derisking reservoir management. The case study presented in the complete paper illustrates how the integration of static measurements, such as dielectric dispersion and nuclear magnetic resonance (NMR) with dynamic measurements improves understanding of reservoir properties and supports more-accurate reservoir evaluation. Sampling and downhole fluid analysis (DFA) performed by wireline formation tester (WFT) identifies the fluid and rock properties in various flow units. Field Background and Challenges Optimal field development requires accurate estimations of water saturation and permeability. In this greenfield, the hydrocarbon is generally oil (medium to light) with very low asphaltene content. Overall, the reservoir quality is controlled by a combination of depositional environment, sequence stratigraphy, and diagenesis. Some reservoirs have good porosity, but reconciliation of log-based water saturation results with well-test results has been an issue. The objective in this case study was to drill a pilot hole for data gathering in a poorly characterized field location. Phase I included drilling a hole with a 55° deviation to cover all reservoirs for data gathering only, with the openhole reservoir section then being plugged and abandoned. Phase II of the plan was to sidetrack and complete the well as dual water-injector boreholes. In the reservoir section of the pilot borehole, a variety of logs was acquired for evaluation, including both logging-while-drilling and wireline measurements. While drilling, triple- combination data were acquired, consisting of gamma ray, resistivity, and nuclear logs (density neutron) along with resistivity images. The wireline-logging program was carried out in two stages to avoid differential sticking. In the first stage, the WFT was used to acquire 10 pressure points, seven points in the first reservoir and three points in the second. Two DFA stations were also recorded in Zone 1 to confirm whether the oil/water contact was deeper than expected. Logging was conducted using a high-tension wireline cable, which facilitates quicker accessibility to the openhole sections. In the second stage, multiple wireline runs were performed for the formation evaluation of the complete section, followed by the WFT pressure and fluid-sampling run on the drillpipe conveyance. Another critical challenge was to obtain accurate water saturations in the heterogeneous, minor, thin reservoirs, which are bounded by dense layers above and below and cause shoulder-bed effects. The third challenge in this well was to obtain an accurate, continuous, and representative permeability profile for the multiple reservoirs. WFT mini-drillstem test (DST) stations along with NMR logs were used to address this important requirement.

Mechanistic models to predict thrust force and torque in bone drilling: An in-vitro study validated with robot-assisted surgical drilling parameters

Compression plates are widely used in orthopaedic surgeries for internal fixation of fractured femurs. To fix the plate and thus to provide compression to a fracture, the self-tapping bone screws are tightened through predrilled pilot holes of smaller diameter. Preliminary investigation showed that the holes drilled with the inappropriate cutting parameters cause mechanical and thermal damages to the local host bone, which further lead to loosening of internal fixations. In this paper, the mechanistic models to predict the thrust forces and torques during bone drilling were developed, using a 3.20 mm diameter drill bit. As a procedure, the cutting action was investigated at three different regions of the drill point, namely cutting lips, secondary cutting edges and indentation zone. The models employed the analytical approach to account for the drill-bit geometry and cutting parameters, and an empirical approach to account for the material and friction properties. To complete the procedure, calibration experiments were conducted on bovine cortical femurs with two different spindle speeds (1000 and 3000 r/min) and feeds (0.03 and 0.06 mm/rev), and then the specific normal and friction coefficients were determined. The developed mechanistic models were validated with different ranges of parameters (500–3500 r/min speeds, and 0.02–0.07 mm/rev feeds) those commonly involved in manual and robot-assisted surgery. The validation study revealed that the thrust forces predicted using the mechanistic models showed a maximum error of only 5.80%. However, the torques predicted from the mechanistic model found with more error than the thrust forces. The predominant reasons for this under-prediction might because of the extrapolation used to determine the specific cutting pressures, slip-line field applied to the indentation zone instead of compressive fracture, and chip clogging involved during the bone drilling as demonstrated in earlier studies. Despite the deviations, the developed mechanistic models satisfactorily follow the trends of the thrust forces and torques experienced during bone drilling. The outcomes can be used to practice the bone drilling procedure and monitor the effect of process parameters on thrust forces and torques in the in-silico environment before performing actual surgery.

Review of Recent Drilling Projects in Unconventional Geothermal Resources at Campi Flegrei Caldera, Cornubian Batholith, and Williston Sedimentary Basin

Unconventional geothermal resource development can contribute to increase power generation from renewable energy sources in countries without conventional hydrothermal reservoirs, which are usually associated with magmatic activity and extensional faulting, as well as to expand the generation in those regions where conventional resources are already used. Three recent drilling experiences focused on the characterization of unconventional resources are described and compared: the Campi Flegrei Deep Drilling Project (CFDDP) in Italy, the United Downs Deep Geothermal Power (UDDGP) project in the United Kingdom, and the DEEP Earth Energy Production in Canada. The main aspects of each project are described (geology, drilling, data collection, communication strategies) and compared to discuss challenges encountered at the tree sites considered, including a scientific drilling project (CFDDP) and two industrial ones (UDDGP and DEEP). The first project, at the first stage of pilot hole, although not reaching deep supercritical targets, showed extremely high, very rare thermal gradients even at shallow depths. Although each project has its own history, as well as social and economic context, the lessons learned at each drilling site can be used to further facilitate geothermal energy development.

Construction optimization of PBA of Subway station tunnel excavation and its cross section in loess area

This paper takes the project of Hejiaying Station of Xi’an Subway Line 2 as the background for the study. The dynamic numerical simulation of the construction process of the station by the PBA method is carried out using the 3D finite element method. The changes of surface settlement, vault settlement, headroom convergence and structural stresses are studied up to the intersection of the guide tunnel and large section duct. The research results show that: the construction of the upper guide hole of the station has a small effect on the deformation and internal force of the initial support structure of the duct. The construction of the lower pilot hole will increase the deformation and internal force of the initial support structure of the duct, especially the construction of the lower 2 pilot holes and the lower 3 pilot holes will lead to a significant increase in the deformation and internal force of the initial support structure of the duct. Therefore, it is necessary to make a 10m reservation for the lower guide hole of the main line, and to grout the cross section of the lower guide hole to ensure the safe construction of the cross section.

New drilling method for damage reduction of CFRP/Ti stacks drilling

In order to reduce the damage during drilling of CFRP/titanium alloy (Ti) stacks, a machining method of pilot hole with liquid nitrogen cooling (P_hole+LN) was proposed, and the underlying mechanisms of the new method were studied. In this paper, four kinds of drilling conditions were compared, such as P_hole+LN, pilot hole, liquid nitrogen cooling, and traditional dry drilling. The P_hole+LN condition produced the smallest thrust force in CFRP and Ti layer, formed discontinuous titanium alloy chips, and could effectively reduce the interface damage. Therefore, the method of P_hole+LN is suitable for drilling CFRP/Ti stacks.

Оценка эффективности применения электронных инициирующих устройств «ИСКРА-Т» по условиям дробления и сейсмического действия торцевых взрывов

The paper justifies the optimal delay time in non-synchronous fan blasting with the most optimal delay time between the holes being 15 ms. Experiments were conducted to assess the breaking conditions and seismic effects of face blasts in the underground conditions of the Rasvumchorrsky mine using the Iskra-T electronic initiating systems with delay times of 10, 15 and 20 ms. With the delay times of 10 and 15 ms there is no clear segregation of the blast stages and interference of compression waves, created by consecutively blasted charges, takes place, while their joint interaction leads to insignificant increase of the seismic effects on the mine workings. According to the results of ore drawing monitoring, the number of boulders with the above delay times did not exceed 10 pieces for the whole blasted volume for each round. With the delay time of 20 ms a clear segregation of the blast stages was obtained with the minimum number of 7 boulders per blast. In order to ensure acceptable rock mass fragmentation quality and reduce the seismic effect of blasting on the mine workings, as well as to preserve the pilot holes drilled, it is advisable to use reverse initiation with non-synchronized fan blasting with the delay time of 20 ms between the holes.

Radiation exposure associated with percutaneous fluoroscopically guided lag screw fixation for sacroiliac luxation in dogs.

To determine radiation exposure to surgical personnel and to evaluate the accuracy of a modified percutaneous lag screw fixation technique for sacroiliac luxation (SIL) under fluoroscopic guidance in dogs. Cadaveric experimental study. Seventeen beagle cadavers with iatrogenic SIL. Seventeen beagles with iatrogenic SIL underwent reduction and stabilization with 3.5-mm screws. Hypodermic needles (14 gauge) and fluoroscopy were used to orient two Kirschner wires for temporary stabilization and to guide drilling of glide and pilot holes using cannulated drill bits. Duration of surgery and radiation exposure were recorded. Postoperative computed tomographic evaluation of screw position and angulation was performed. Average time for fixation was 15.85 minutes (range, 6.37-33.5). Cumulative radiation doses of 0.4 mrem for the dominant arm of the assistant and 0 mrem for the primary surgeon were recorded. The mean dorsoventral and craniocaudal screw angles were 0.68° ± 3.4° (range - 5.4° to 9.5°) and 1.9° ± 3.2° (range - 4.3° to 9.1°), respectively. Sixteen of the 17 dogs had 100% sacral screw purchase, with the remaining case achieving 93.4% purchase. Fluoroscopy-assisted percutaneous placement of 3.5-mm cortical screws in lag fashion performed with 14-gauge needles in conjunction with Kirschner wires and cannulated drill bits yielded repeatable accurate screw placement with low levels of ionizing radiation exposure to the surgical team. The described technique may be a viable method for minimally invasive osteosynthesis fixation of SIL with low levels of radiation exposure to the surgical team. These results provide evidence to support further evaluation of radiation exposure in clinical cases and can aid in study design and sample size determination.

Forming a Flanged Hole When Quenching Press-Hardened Steel for Mechanical Fastening

The recent stringent regulations on vehicle safety and reducing CO2 emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques employed in automotive production lines is significantly difficult because of the surface coating layers and the additives within. This difficulty in post-processing, attributed to its high strength, also limits the mechanical fastening of PHS components. Therefore, this study aims to develop a process for forming a structure enabling mechanical fastening by sequentially applying piercing and hole-flanging operations during the hot stamping process. Our experimental apparatus was designed to perform the hole-flanging operation after the piercing operation within a single stroke at a specific temperature during the quenching process of PHS. At high temperatures of 440 °C or higher, the hole-flanging process was conducted in a direction opposite to that of the piercing operation for creating the pilot hole. An extruded collar with a height of 8.0 mm and a diameter of 17.5 mm was achieved, which is hole expansion ratio(HER) of 82.5%.

Workshop report: Exploring deep oceanic crust off Hawai`i

Abstract. For more than half a century, exploring a complete sequence of the oceanic crust from the seafloor through the Mohorovičić discontinuity (Moho) and into the uppermost mantle has been one of the most challenging missions of scientific ocean drilling. Such a scientific and technological achievement would provide humankind with profound insights into the largest realm of our planet and expand our fundamental understanding of Earth's deep interior and its geodynamic behavior. The formation of new oceanic crust at mid-ocean ridges and its subsequent aging over millions of years, leading to subduction, arc volcanism, and recycling of some components into the mantle, comprise the dominant geological cycle of matter and energy on Earth. Although previous scientific ocean drilling has cored some drill holes into old (> 110 Ma) and young (< 20 Ma) ocean crust, our sampling remains relatively shallow (< 2 km into intact crust) and unrepresentative of average oceanic crust. To date, no hole penetrates more than 100 m into intact average-aged oceanic crust that records the long-term history of seawater–basalt exchange (60 to 90 Myr). In addition, the nature, extent, and evolution of the deep subseafloor biosphere within oceanic crust remains poorly unknown. To address these fundamentally significant scientific issues, an international workshop “Exploring Deep Oceanic Crust off Hawai`i” brought together 106 scientists and engineers from 16 countries that represented the entire spectrum of disciplines, including petrologists, geophysicists, geochemists, microbiologists, geodynamic modelers, and drilling/logging engineers. The aim of the workshop was to develop a full International Ocean Discovery Program (IODP) proposal to drill a 2.5 km deep hole into oceanic crust on the North Arch off Hawai`i with the drilling research vessel Chikyu. This drill hole would provide samples down to cumulate gabbros of mature (∼ 80 Ma) oceanic crust formed at a half spreading rate of ∼ 3.5 cm a−1. A Moho reflection has been observed at ∼ 5.5 km below the seafloor at this site, and the workshop concluded that the proposed 2.5 km deep scientific drilling on the North Arch off Hawai`i would provide an essential “pilot hole” to inform the design of future mantle drilling.

Damage free drilling of carbon fibre reinforced composites – a review

ABSTRACT Carbon fibre reinforced plastic materials (CFRPs) have a wide range of industrial applications like automobile, aerospace, biomedical, defence, and sports industries because of extraordinary multidimensional properties. Mechanical drilling is a most widely used common secondary machining process for composite laminates. Drilling induced delamination at hole-entry and hole-exit of a drilled hole is frequently occurred due to anisotropic and non-homogeneous structure of a material mechanics. Delamination can be smothered by employing tool design optimisation, upgraded drilling strategies and improving drilling methods. In this paper, various drilling conditions towards damage free drilling of CFRPs are reviewed. The above drilling conditions are categorised under adhesive layer, cryogenic cooling, minimum quantity lubrication (MQL), pilot hole, reverse air suctioning, spring-damper mechanism, support plate mechanism, variable feed strategy, etc. These strategies are extensively reviewed with reference to drill bit geometry, drilling techniques and drilling methods to uncover the significance of drilling conditions and its importance on drilled quality. This common review on various drilling conditions for delamination-free drilling can be referenced as not only a widespread summary from literature survey available till the date but also help researchers to explore new possible ways to achieve delamination-free drilling for composite materials in upcoming years.

Torque Requirements and the Influence of Pilot Holes on Orthodontic Miniscrew Microdamage

This study aimed to quantify the microdamage to cortical bone of different thickness and the maximum insertion torque during orthodontic miniscrew implant (OMI) placement with and without a pilot hole. Forty-five porcine bone specimens were prepared with thicknesses of 1.5, 2 and 2.5 mm. Ten bone specimens per thickness had a pilot hole drilled prior to the insertion of an OMI, and the remaining 15 bone specimens had an OMI without a pilot hole inserted. Sequential staining was used to identify damage caused by bone preparation and surface microdamage from OMI insertion and confocal laser microscopy images were used to quantify damage characteristics. Of the five damage characteristics, only one decreased when a pilot hole was used for all bone specimens (p = 0.025), while two increased as cortical bone thickness increased (p = 0.0064, p = 0.0003). There was no evidence that maximum insertion torque differed according to pilot hole status (p = 0.1144) and increased as cortical bone thickness increased (p = 0.0001). The presence of a pilot hole had minimal effect on microdamage characteristics and no effect on maximum insertion torque. As cortical bone thickness increased, an increase in microdamage and in maximum insertion torque was observed.

Tool geometry analysis for plunge milling of lead-free CuZn-alloys

Plunge milling is a critical process step in mass manufacturing of rectangular shapes in electrical connector components. These shapes are manufactured by drilling a pilot hole and subsequent plunge milling with a radial offset (pitch) one or more times. The plunged cavity serves as guidance for the final broaching cut. In light of new legislative initiatives, the electronics industry is forced to use lead-free Cu-Zn-Alloys for mass manufacturing of these connectors. The plunging tool is deflected due to the higher cutting forces experienced in machining of lead-free CuZn-alloys in comparison to alloys with lead. This results in an offset of the milled cavity and negatively impacts tool guidance in the subsequent broaching process. Therefore, the geometric tolerances cannot be met. In this paper, the effect of tool geometry and cutting parameters on the workpiece geometry in plunge milling is investigated. The effect of the microstructure of the work-piece materials CuZn37, CuZn42 and CuZn21Si3P on the tool deflection and cutting force components is examined. The tools used vary regarding the design of the corner in terms of the corner chamfer and the inner shaft thickness. Friction between chips in the tools inner flutes and the cavity walls reduced workpiece accuracy. Improvements were achieved by reducing the width of the cutting corner chamfers, using large inner flutes and applying low cutting parameters.

Evaluation of Cortical Bone Microdamage and Primary Stability of Orthodontic Miniscrew Using a Human Bone Analogue.

Orthodontic miniscrews have gained popularity; however, they have some drawbacks, including screw loosening that results from bone resorption caused by excess microdamage created during screw insertion. Pilot hole preparation through the cortical bone is considered beneficial to avoid such microdamage, while an overly large pilot hole impairs primary stability. Hence, we used a human bone analogue to evaluate the microdamage and primary stability to estimate the optimal pilot hole size that would minimize the screw loosening risk. Ti6Al4V orthodontic miniscrews and 1.0-mm-thick synthetic cortical bone pieces were prepared. Various compressive loads were applied in indentation tests to test pieces’ surfaces, and the microdamaged areas were confirmed as stress-whitening zones. Screw insertion tests were performed in which a miniscrew was inserted into the test pieces’ pilot hole with a diameter of 0.7–1.2 mm in 0.1-mm intervals, and the stress-whitening area was measured. The insertion and removal torque were also measured to evaluate primary stability. The stress-whitening areas of the 1.0–1.2 mm pilot hole diameter groups were significantly smaller than those of the other groups (p < 0.05), whereas the 0.9 and 1.0 mm pilot hole diameter groups showed higher primary stability than other groups. In conclusion, the bone analogue could be utilized to evaluate microdamage in cortical bones and the primary stability of miniscrews.

Deep ice-core drilling to 800 m at Dome A in East Antarctica

AbstractA deep ice core was drilled at Dome A, Antarctic Plateau, East Antarctica, which started with the installation of a casing in January 2012 and reached 800.8 m in January 2017. To date, a total of 337 successful ice-core drilling runs have been conducted, including 118 runs to drill the pilot hole. The total drilling time was 52 days, of which eight days were required for drilling down and reaming the pilot hole, and 44 days for deep ice coring. The average penetration depths of individual runs were 1 and 3.1 m for the pilot hole drilling and deep ice coring, respectively. The quality of the ice cores was imperfect in the brittle zone (650−800 m). Some of the troubles encountered are discussed for reference, such as armoured cable knotting, screws falling into the hole bottom, and damaged parts, among others.

Research on the Construction Technology for the Reconstruction of Existing Retaining Piles under the Condition of the New and Old Foundation Pits in Close Proximity

In view of the development of the city and the development and utilization of underground space, the new building foundation pit is close to the existing foundation pit. In view of this problem, a common reconstruction technology of existing retaining piles under the condition that the new and old foundation pits are adjacent to each other is proposed. The main construction process includes: primary selection of common pile section, design change, bored pile inspection, construction of steel pipe pile with pilot hole, depth judgment of new and old foundation pit, construction of locking anchor rod, foundation pit construction, monitoring and acceptance, etc. The reconstruction and reuse technology of the existing foundation pit supporting pile has been applied in a foundation pit in Zhuhai, which proves that it is safe and reliable, saves the construction period, reduces the construction difficulty, and improves the construction efficiency, which can provide reference for similar projects.

Thread-stripping test procedures leading to factors of safety data for friction-drilled holes in thin-section aluminium alloy

Friction drilling is a hole-making process suitable for thin sections of ductile metal. A rotating tool is plunged into the workpiece to form the pilot hole. The hole is then threaded in a follow-up process. A bushing forms on the exit side of the hole, which allows for longer engagement lengths in threaded assemblies. For comparison purposes, four combinations of threaded-hole processes were applied to 1.5 mm-section, 6082-T6 aluminium alloy. The processes involved were friction and twist drilling followed by thread forming or cutting. Vickers hardness and microstructural analyses were used to assess the condition of the material. An in-house test method was developed to measure the axial load–deflection response. Progressive failure occurred by thread stripping. Friction drilling followed by thread forming gave peak loads 35% higher than conventionally drilled and tapped holes. Also, hardness increased from 111HV in the parent metal to 125HV (with an increase in hardness to depths of 0.5 mm) due to work hardening. Evidence of precipitate dissolution was negligible which suggests that the friction drilling process operated below the solvus temperature. A novel approach for determining reliably-based, thread-stripping Factors of Safety (FoS) is presented. FoS in the range 3.61 to 4.38 gave a reliability of 95% to 99.9% against thread stripping in friction-drilled, thread formed joints.

Effect of laser parameters on sequential laser beam micromachining and micro electro-discharge machining

Laser beam micromachining (LBMM) and micro electro-discharge machining (μEDM) based sequential micromachining technique, LBMM-μEDM, has drawn significant research attention to utilize the advantages of both methods, i.e., LBMM and μEDM. In this process, a pilot hole is machined by the LBMM, and subsequently finishing operation of the hole is carried out by the μEDM. This paper presents an experimental investigation on the stainless steel (type SS304) to observe the effects of laser input parameters (namely, laser power, scanning speed, and pulse frequency) on the performance of the finishing technique, that is, the μEDM in this case. The scope of the work is limited to 1-D machining, i.e., drilling microholes. It was found that laser input parameters mainly scanning speed and power influenced the output performance of μEDM significantly. Our study suggests that if an increased scanning speed at a lower laser power is used for the pilot hole drilling by the LBMM process, it could result in significantly slower μEDM machining time. On the contrary, if the higher laser power is used with even the highest scanning speed for the pilot hole drilling, then μEDM processing time was faster than the previous case. Similarly, μEDM time was also quicker for LBMMed pilot holes machined at low laser power and slow scanning speed. Our study confirms that LBMM-μEDM-based sequential machining technique reduces the machining time, tool wear, and instability (in terms of short circuit count) by a margin of 2.5 x, 9 x, and 40 x, respectively, in contrast to the pure μEDM process without compromising the quality of the holes.

On the effect of pilot holes on the mechanical behaviour of flow-drill screw joints. Experimental tests and mesoscale numerical simulations

This research work investigated in detail the mechanical performance of a flow-drill screw connection of two aluminium plates with and without pilot holes. An extensive experimental campaign involving material and joint tests under different loading modes is presented. These tests are supported by numerical models. Detailed solid-element models provided meaningful information about the local deformation mechanisms of the tested configurations, and allowed to identify the reason behind the early screw failure observed in some of the experimental joint tests. Moreover, several geometrical features of the connection were found to be relevant for the mesoscopic model, so their influence was assessed. The combination of experiments and simulations provided robust and meaningful understanding of the connections.

St1 Deep Heat Project: Geothermal energy to the district heating network in Espoo

St1 Deep Heat Project with its two deep wells extending to 6.2 - 6.4 km depth is the world’s deepest industrial geothermal energy project. The aim is to build an EGS (enhanced geothermal system) at the depth of about 5 - 6 km. The project is a pilot aiming at exploring the technical and economic feasibility of geothermal energy in the crystalline rock conditions of Finland for production of thermal power to a district heating network. Due to the demands of the district heating, the aim is to produce hot fluid at about 100°C and re-inject it to the formation at 50°C. The 100°C goal requires to drill to about 6 km depth. The drill site is located in Espoo, next to the Fortum district heating plant on the Aalto University campus. So far (2020) the project has drilled a 2 km deep completely cored pilot hole (OTN-1), and two deep wells OTN-2 to 6.2 km and OTN-3 to 6.4 km. Hydraulic conductivity has been enhanced by hydraulic stimulation in both deep wells in 2018 and 2020. The extreme depth level sets significant challenges for drilling and hydraulic stimulation, as well as controlling of induced seismicity. At present, the project proceeds with the installation of production pumps in OTN-2 and OTN-3, and first test cross-hole pumpings are expected to start in January 2021. In the presentation we provide an insight to the project and its major achievements and challenges.

Empirical Performance Prediction for Raise Boring Machines Based on Rock Properties, Pilot Hole Drilling Data and Raise Inclination

The basic aim of this study is to develop empirical models for predicting performances of pilot hole drilling and reaming for raise boring operations using rock properties and pilot hole drilling operational parameters for classified raise inclinations [vertical (90°) and inclined (70°)] that could be used in feasibility and operational stages of a project. Field study includes collecting performance and operational parameters including rotational speeds, tricone bit and reamer head torques, weight on bit (pushing force), net reaming thrust (pulling) force, unit penetration rate, and field-specific energy. Totally 21 different rocks are sampled in eight different sites to define physical and mechanical properties. The empirical models developed by performing multi-variable regression analyses for the vertical and inclined reaming and pilot hole drilling data groups indicate that static elasticity modulus, dynamic elasticity modulus, uniaxial compressive strength, Brazilian tensile strength, and rock quality designation are the most important intact rock and rock mass properties affecting performances of the vertical and inclined reaming and pilot hole drilling. This study should be continued to develop more generalized and reliable prediction models, especially by adding different reamer head diameters and raise inclinations to the database as predictive parameters.