Rotary Drilling Methods Research Articles

Analysis of Potential Use of Freezing Boreholes Drilled for an Underground Mine Shaft as Borehole Heat Exchangers for Heat and/or Cooling Applications

Borehole engineering encompasses the part of mining that involves the process of drilling boreholes and their utilization (e.g., for research, exploration, exploitation, and injection purposes). According to legal regulations, mining pits must be closed after their use, and this applies to pits in the form of boreholes as well. The Laboratory of Geoenergetics at AGH University of Krakow is involved in adapting old, exploited and already closed boreholes for energetic purposes. This includes geothermal applications, as well as energy storage in rock formations and boreholes. Geoenergetics is a relatively new concept that combines geothermal energy with energy storage in rock formations (including boreholes). One type of analysed borehole is a freezing borehole. They are used, for example, in drilling mining shafts that are in the vicinity of aquifers and are drilled using the rotary drilling method with a reverse circulation of drilling mud, or in peat bogs. For borehole heat exchangers based on freezing boreholes for long-term mathematical modelling, several heating scenarios were considered with several thermal loads. The maximum average power obtained after one year of usage of four boreholes with variable temperatures was 11 kW. With the usage of 10 boreholes the power reached over 27 kW. The heat-carrying temperature was assumed to be 22 °C during early summer (June and July) and 2 °C during the rest of the year. When considering stable exploitation during a 10-year period with four boreholes with the same temperatures, a heating power of over 12 kW was obtained, as well as a power of over 28 kW when considering using 10 boreholes. The maximum amount of heat obtained during the 10-year period using 10 boreholes was over 8.8 thousand GJ. Once they have fulfilled their function, these boreholes lose their technological significance. In the paper, the concept is outlined, and the results of the analysis are described using the numerical program BoHEx.

A modeling of the inertia properties of a drill string section as a continual bent rotating rod

The article considers the problem of determining the moment of inertia of the bent rotating section of the drill string. The tasks of such a plan are of paramount importance for the dynamic analysis of drill strings in rotary and rotaryturbine drilling methods. Presented are the exact and approximate analytical dependences for determining the moment of inertia of the bent section of the drill string, depending on the geometric parameters of its deflection. Given the scientific and practical interest in the use of pipes made of non-traditional materials, the moments of inertia for bent sections of steel, titanium, aluminum and fiberglass drill pipes are calculated. The nature of the change in the moment of inertia of sections of drill pipes of different diameters depending on the length of the half-wave and the magnitude of the maximum deflection is established. Keywords: drill string; rod; moment of inertia; deflection boom; deflection half-wave length.

Field test of a Combined Thermo-Mechanical Drilling technology. Mode II: Flame-assisted rotary drilling

To enhance the drilling performance in deep hard rocks and reduce overall drilling efforts, this work proposes a Combined Thermo-Mechanical Drilling (CTMD) technology. This technology employs a heat source (e.g., a flame jet) and includes two main drilling modes: (I) thermal spallation drilling, investigated in the companion paper and (II) flame-assisted rotary drilling, investigated here as a field test. The CTMD technology is expected to reduce drilling efforts, especially in hard rocks, enhancing the rock penetration rate and increasing the bit lifetime, all of which reduces the drilling costs. The present work investigates Mode II (flame-assisted rotary drilling) of the CTMD technology by implementing the concept in an existing drilling rig and testing the technology under relevant process conditions. This contribution studies the underlying rock removal mechanism of CTMD and demonstrates its drilling performance, compared to conventional rotary drilling methods. Acoustic emission monitoring, and analysis of the collected drill cuttings provide multiple evidences for thermal-cracking-enhanced rock removal during the flame-assisted rotary drilling. This removal mechanism appears to represent an optimal compromise to minimize rock fragmentation and cutting transport efforts during drilling, compared to a less efficient mechanical scraping of the hard granite rock, observed during the standalone-mechanical drill test. The drilling performance, in terms of removal and wear rates, are evaluated for the flame-assisted rotary drilling. This shows that the proposed drilling approach is capable of enhancing the removal process in hard granite rock, by a factor of 2.5, compared to standalone-mechanical drilling. The implementation of this drilling approach into a conventional drilling system shows that integration of thermal assistance to conventional rotary drilling requires marginal technical efforts. Additionally, this technology can profit from established knowledge in conventional mechanical drilling, facilitating its implementation to improve drilling performance in hard rocks. Hence, this study demonstrates that the Combined Thermo-Mechanical Drilling method is feasible and concludes that this technology constitutes a promising approach to improve the drilling process, thereby increasing the viability of accessing deep geo-resources in hard rocks.

Comprehensive optimization of process parameters in rotary ultrasonic drilling of CFRP aimed at minimizing delamination

Delamination damage is one of the main problems in drilling of carbon fiber reinforced plastics (CFRP) laminates. In recent years, rotary ultrasonic drilling, a brand new machining process that results in better machining quality, has been attracting increasing attention. An experimental investigation carried out on carbon fiber reinforced plastics laminates using diamond core drill. Diamond core drills are simultaneously drilling and grinding fiber reinforced plastics therefore improve hole quality. To this end, a proper ultrasonic system for a core drill designed and fabricated. The effects of process parameters including cutting velocity, feed rate, thickness and ultrasonic vibration on thrust force and delamination studied. Analysis of variance (ANOVA) established to examine single and multiple effects of variables on delamination and determine their contribution rate. Subsequently, Regression models in order to predict delamination through machining parameters introduced and optimized condition evaluated. The lowest delamination is observed in lower cutting velocity and feed rate by applying ultrasonic vibration on the thinner CFRP. Machining force in rotary ultrasonic drilling method compared to conventional drilling reduced. Moreover, by statistical evaluation, resulted that thickness influence on delamination is more than other variables.

Design and numerical analysis of a large‐diameter air reverse circulation drill bit for reverse circulation down‐the‐hole air hammer drilling

AbstractReverse circulation down‐the‐hole (RC‐DTH) air hammer drilling is a fast and cost‐effective method for hard rock drilling. As the air RC drill bit is the heart for RC‐DTH air hammer drilling system to form the reverse circulation, a large‐diameter RC drill bit was innovatively designed and numerically optimized with respect to the suction ability. Results show that increasing the suction‐nozzle elevation angle and deflection angle can improve the drill bit suction ability. The drill bit performance reaches its optimal state when the air flow rate was about 1.205 kg/s, thereafter it exhibits a reverse variation trend with the increase in air mass flow rate. The optimum diameter of the suction nozzles is 20 mm for the drill bit studied in this work. The RC drill bit with outer diameter of 665 mm and RC‐DTH air hammer with outer diameter of 400 mm were manufactured and a field trial was conducted. Field test results show that the penetration rate using the RC‐DTH air hammer drilling method is more than twice the conventional rotary drilling method. This drilling approach poses a great potential for the large‐diameter hard rock drilling applied in the upper portions of a well bore above the potential producing reservoir formation for land oil and gas drilling, geothermal drilling and relevant field drilling operations.

RESEARCH OF AXIAL FORCE AND THE TORQUE ACTION ON A DRILL STRING AT ROTARY AND COMBINED DRILLING METHODS

The estimation approach of the work performed by the main force factors acting on the drill string, rotary and combined drilling methods, was proposed. The problem of obtaining analytical functions of force factors action for a mechanical system with distributed parameters was formulated. 
 To solve the problem, the axial load and torque functions of the drill string analysis was performed, depending on the alternating parameter - the well depth. By integrating these functions, analytical dependencies were established for determining the axial load and torque acting on the drill string in sections of directional and S-shaped wells. Relying on industrial data, numerical calculations of the size of work on sections of such wells were carried out. The obtained research results can be further used to find energy-saving modes of the drill string.

Characteristics of Gravelly Granite Residual Soil in Bored Pile Design: An In Situ Test in Shenzhen

Granite residual soil is widely distributed in south China and is treated as a special soil. Its design parameters in rotary drilling bored piles are a matter of debate due to lack of in‐situ pile load tests. Back‐analysis of test piles is a reliable means of studying the geotechnical capacity of granite residual soil for pile design. In this study, a series of in situ tests was conducted comprising six full‐scale instrumented test piles in gravelly granite residual soil in Shenzhen to consider the effects of different construction methods. The six piles were constructed with three different rotary drilling methods. Two commonly used design methods were investigated in the back‐analysis: the SPT and effective stress methods. The results of the loading tests and strain gauges were used to obtain the back‐analyzed parameters of the ultimate shaft resistance and ultimate base resistance for gravelly granite residual soil with these two design methods.

Drilling, sampling, and sample-handling system for China's asteroid exploration mission

Asteroid exploration has a significant importance in promoting our understanding of the solar system and the origin of life on Earth. A unique opportunity to study near-Earth asteroid 99942 Apophis will occur in 2029 because it will be at its perigee. In the current work, a drilling, sampling, and sample-handling system (DSSHS) is proposed to penetrate the asteroid regolith, collect regolith samples at different depths, and distribute the samples to different scientific instruments for in situ analysis. In this system, a rotary-drilling method is employed for the penetration, and an inner sampling tube is utilized to collect and discharge the regolith samples. The sampling tube can deliver samples up to a maximum volume of 84mm3 at a maximum penetration depth of 300mm to 17 different ovens. To activate the release of volatile substances, the samples will be heated up to a temperature of 600°C by the ovens, and these substances will be analyzed by scientific instruments such as a mass spectrometer, an isotopic analyzer, and micro-cameras, among other instruments. The DSSHS is capable of penetrating rocks with a hardness value of six, and it can be used for China's asteroid exploration mission in the foreseeable future.

Caries Removal by Chemomechanical (Carisolv™) vs. Rotary Drill: A Systematic Review.

Background:Chemomechanical caries removal is an effective alternative to the traditional rotary drilling method. The advantages of chemomechanical techniques in terms of the need for anesthesia, pain perception and patient preference are systematically reviewed and a meta-analysis of the time required for caries removal is reported.Method:Randomized controlled studies of comparison of chemomechanical techniques with conventional rotary drill were selected from a systematic search of standard biomedical databases, including the PubMed and Cochrane clinical trials. Non-repeated search results were screened for relevance and risk of bias assessment, followed by methodology assessment. Statistical models were applied to the outcome parameters - time required, pain perception, need of anesthesia and patient preference - extracted from the studies. Results:Out of the 111 non-repeated search results, 26 studies receiving a low bias score were selected for the review, and 16 randomized clinical trials of rotary and Carisolv techniques were considered for meta-analysis. Meta-analysis by fixed effect as well as random effect models indicate that Carisolv takes more time (3.65 ± 0.05 and 4.09 ± 0.29 min) than rotary drill (8.65 ± 0.09 and 8.97 ± 0.66 min) method. Advantages of reduced pain (14.67 for Carisolv vs. 6.76 for rotary drill), need for anesthesia (1.59% vs. 10.52%) outweigh the longer time requirement and make it the preferred (18.68% vs. 4.69%) method.Conclusion:Chemomechanical techniques stand out as a minimally invasive and preferred method based on the meta-analyses. Evaluation of pain experienced using robust methods is needed to strengthen the evidence for their use.

Study on Vibration Frequency and Rock Fragmentation Effect of Sonic Drill Rig

Sonic drill rig can obtain good drilling and sampling effects in sand gravel layer with high-frequency vibration and low speed rotation of the power head. The drilling speed of sonic drill is five times than traditional rotary drilling method. Meanwhile, it does not need slurry to protect wall of borehole during drilling, so it has the following advantages: good fidelity of rock and soil samples and less environmental pollution. As a consequence, it has a good application prospect in the exploration of hydropower station, environmental protection drilling and other fields. In the paper, combining drilling experiment of domestic sonic drill rig YGL-S100 in Xiangjiaba hydropower station, the influence of sonic drill's vibration frequency on rock fragmentation effect and the reasonable choice of drilling technology had been researched and analyzed. Further, improving the sonic drill properties and optimizing drilling technology parameter were carried out.

DETERMINATION OF PENETRATION RATE WHEN USING VIBRATION IN DRILLING OIL WELLS

The subject of oil as a source of energy occupies the main priority all over the world. Facts and statistics indicate that the average consumption of oil product exhausts half the world oil reserve in the last 150 years. The consumption average reaches 1300 billion barrel yearly. In the beginning of the nineteenth century exploring and getting the oil was not a main challenge as it is now. Since the main goal is still finding new oil traps even at deep depths where it reaches sometimes thousands of meters. This requires developing the well drilling techniques and huge equipments to increase the rate of penetration and decrease the digging cost. In the last years, the efforts of professionals and those who are concerned in oil industry concentrate mainly in digging bit. While increasing the drills efficiency through developing the classic ways of drilling (the most popular all over the world is rotary drilling method) may be the most suitable way to achieve the mentioned goals. This paper represents the results of practical study to determine the penetration rate using vibration. A group of cement samples with various compressive strengths were deducted. The results show that the penetration rate for these samples is higher than the values achieved by the rotary drilling method. Also the study shows that we can achieve a good penetration rate (more than 15m/h) with low level frequency.

Microwave Drilling of Bones

This paper presents a feasibility study of drilling in fresh wet bone tissue in vitro using the microwave drill method [Jerby et al, 2002], toward testing its applicability in orthopaedic surgery. The microwave drill uses a near-field focused energy (typically, power under approximately 200 W at 2.45-GHz frequency) in order to penetrate bone in a drilling speed of approximately 1 mm/s. The effect of microwave drilling on mechanical properties of whole ovine tibial and chicken femoral bones drilled in vitro was studied using three-point-bending strength and fatigue tests. Properties were compared to those of geometrically similar bones that were equivalently drilled using the currently accepted mechanical rotary drilling method. Strength of mid-shaft, elastic moduli, and cycles to failure in fatigue were statistically indistinguishable between specimen groups assigned for microwave and mechanical drilling. Carbonized margins around the microwave-drilled hole were approximately 15% the hole diameter. Optical and scanning electron microscopy studies showed that the microwave drill produces substantially smoother holes in cortical bone than those produced by a mechanical drill. The hot spot produced by the microwave drill has the potential for overcoming two major problems presently associated with mechanical drilling in cortical and trabecular bone during orthopaedic surgeries: formation of debris and rupture of bone vasculature during drilling.

Plasma Channel Miniature Hole Drilling Technology

With growing economic and environmental pressures, oil companies seek ways to increase the oil recovery from every well. Re-entry drilling of horizontal sidetracks from existing wells and multilateral drilling for new wells are techniques which help to achieve that increase. However, new approaches are needed to reduce the cost and to improve efficiency of rotary drilling methods used for these purposes. A new nonrotary plasma channel drilling (PCD) method for drilling of small diameter holes (3.5-15 cm) in oilfields for sidetrack creation and multilateral drilling is described in this paper. The method relies upon the use of the energy of impulse spark discharges which are formed inside the rock formation ahead of the drill position. Repeated formation of the plasma channel results in an effective and controlled drilling action. Plasma channel drills developed at Strathclyde University are able to cut clearly defined circular holes in medium hard sandstone with speeds of up to 16 cm/min using specific energies as low as 400 J/cm/sup 3/. Plasma channel drilling has the potential to increase the lifetime of oil wells and would significantly reduce the cost of exploration drilling and subsurface data acquisition. PCD technology can also be a cost-effective and practical solution for other applications such as mineral mining, water boring and scale removal where micro-hole drilling is essential.

An Overview of Top-Drive Drilling System Applications and Experiences

Summary Top-drive drilling has become one of the new technologies of the 1980's. Application of this seemingly old concept is now widespread in most offshore areas of the world. Top-drive drilling may be one of the biggest changes made to the rotary-drilling method since the development of the rotary table. This paper analyzes why the concept of drilling with top drive, similar to the very old concept of a power swivel, has suddenly become so successful. Applications and locations are presented to show the system's worldwide use. Results of more than 50 systems currently in operation are analyzed to present benefits and trends. The results show surprising benefits for almost any type of well, and overall time savings generally exceed 20%. Benefits from the extended-reach potential associated with top drives are enormous. These results explain the primary motivation for most applications of the system.

ボルトセッタについて

In the Coal Mining Reserch Centre, Japan, we developed five “Bolt Setters” for the purpose of preventing emergency and improving efficiency at Bolting works.First one has tracks and two hydraulic rotation moters for drilling and Bolting, which is operated by electric moter.Second one has a percussion drill which is installed on the simple wheel. It is operated by human power. Third one hastracks and hydraulic rotary percussion drill, which is operated by air motor (4kg/cm2 pressure).Fourth one has tracks and hydraulic rotary percussion drill, which is operated by electric moter.Last one has tracks, hydraulic rotary percussion or rotary drill and special mechanism which is able to choice rotary or rotary percussion drilling methods. It is operated by air moter (4kg/cm2 pressure).

エチオピアの地下水

The writer has engaged in hydrogeological survey and technical services for ETHI-OPIA A. I. D. BANK Undeground Water Resources Development Project.This project was started on Novemder 1974, ultilizing six Japanese drilling rigs (four percussion type and two rotary type) for the purpose of solving the drought problem.Based on the data odtained from this project the writer classifies the ground water types into five classes, and are listed as follows:1. Abyssinia plateau type2. Rift valley type3. Dire Dawa fan type4. Ogaden desert type5. Awash valley typeThe discharge rate is expected 100-300 1/min. with drawdown 10-40m, except the Ogaden desert in which the successful drilling depth are from 50m upto 120m.Most of the water in the survey area has a conductivity around 500ppm with hith hardness. In the Ogaden area, water from the wells shows high chlorine contents of 2000ppm and up.The water of some wells in the Rift valley, contains as high as 6ppm Fluorine.In the Awash valley the water of the wells shows high water temperature of above 30°C.As for the drilling method, rotary drilling method, with the exception of few wells by air rotary drilling method, was used in the Abyssinia platau. Cable tool method was used in the Rift valley area. Either cable tool or rotary method was used in the other areas.

Development of Nonpneumatic Caisson Engineering

The open well method of manually digging foundations down to bedrock and filling the resulting shaft with concrete or stone was developed in Chicago in the 1890s. Mechanical driling was also used at this time, a large steam-powered auger being used in Kansis City; but it was not rapidly adopted due to the cheapness of the open well process. In the 1920s, well-drilling techniques were adopted, enabling foundation piers to be drilled into soft ground to greater depths than were previously possible. Subsequently engine-driven augers were used and in 1926 a hydraulic rotary drilling method was patented by Powell and a dry method by Hunt and Ropp. These two processes were widely implemented. Mobile augers, both truck mounted and crane mounted were also developed and used. Recent developments to advance pier drilling techniques include the Benoto Deep Caisson Excavator (1957) and the use of bentonite when drilling in water-bearing soils.

Choice of rotary drilling methods and drill characteristics

Choice of rotary drilling methods and drill characteristics