Coiled Tube Turbodrilling: A proposed technology to optimise drilling deep hard rocks for mineral exploration

The need to drill deep boreholes more efficiently for mineral exploration has raised the attention to investigate the feasibility of recent drilling technologies for such applications. The two principal methods of Reverse Circulation (RC) and diamond core drilling are usually used in combination by mine operators are subjected to certain limitations and inefficiencies. Considering that delivering large volume of reliable samples from deep zones to the surface in shortest possible time is of paramount importance in mineral exploration, then drilling small size holes as fast as possible and delivering the small chip samples to the surface would be a good alternative with several advantages over conventional drilling methods. As a result, the Coiled Tube (CT) turbodrilling technology is proposed here followed by presenting detailed calculations for the system required power and hydraulics and also Bottom Hole Assembly (BHA) selection suitable for hardrocks mineral exploration applications

Design of a slurry loop for cuttings transport studies in hard rock drilling applications

Transportation of the fluid and slurry (fluid and solid particles mixture) in the pipe and annulus space has been the focus of numerous studies. There are different parameters to be considered when studying slurry transportation. These include slurry velocity or flow rates; fluid properties such as density and rheology; and solid particles properties including concentration, density, shape and size. Also the angle of the flow conduit, rotation of the pipe and possible eccentricity of the annulus are other factors which influence slurry transport characteristics. Although a number of analytical, numerical and empirical equations as well as numerical simulations have been developed for studying the flow and slurry transport, the results need to be validated against either field or lab data. As performing field tests is costly and time consuming conducting simulations at laboratory scale appears as a good alternative. Different flow loops have been designed to study the slurry transport in different science and engineering disciplines including oil and gas and mining. However, few of these consider in particular cuttings transportation in small size annulus space. The flow characteristics appear to be very different when it travels within a small size annulus, in particular when the fluid velocity is high. In this study, a review of some of the existing slurry flow loops will be conducted. Then the details of a slurry loop which has been designed and commissioned for the purpose of studying cuttings transport in a small size annulus space for applications in drilling mineral exploration wells using coil tube technology will be presented

A drifting impact oscillator with periodic impulsive loading: Application to percussive drilling

Peer reviewe

Utilizing Coiled tube rig for mineral exploration application

Mineral exploration is in a race to employ drilling technology that can perform the exploration and drilling investigation in a fast and inexpensive manner. After an extensive study of the available drilling technologies in the market, coiled tubing was chosen as a tool to be employed for mineral exploration due to its flexible mobility and ease of operation with minimum number of personnel. Since coiled tubing technology is primarily used in oil and gas industry, it was important to re-design the coiled tube rig to drill hard rocks in a fast and feasible manner. The main requirements were to drill the smallest feasible hole diameter and go as deep in the ground as possible, in the shortest reasonable time. The drilled rock particles, cuttings, are to be collected and analysed at the surface for their metal mineral contents. The process also needs to be repeated multiple times at different locations for mapping, without the need to change the tube on the rig due to failure or potential failure. The focus of the new designed coiled tube, for drilling and mineral exploration, is three fold. First is to increase the rate of penetration (ROP) in drilling by designing a small high speed turbo motor. Second is to determine the controlling parameters of cuttings transport to effectively lift the cuttings to the surface for analysis and third is to minimize the overall weight of the rig for manoeuvring and to prolong the life span of the coiled tube string. In this paper, a small downhole turbo motor, 5cm outer diameter, is designed to achieve a rotation speed of up to 10,000 rpm to fit on a small bit, coiled tube drilling assembly. The motor design utilised multiple finite volume and finite element analysis software for fluid flow study and fluid structural interaction analysis.The paper is also introducing the concept of flow slurry loop that is designed to lift the cutting particles to the surface for mineralisation analysis. The controlling parameters of the cuttings transportation are the particles physical properties such as size, density, concentration and shape, as well as the rheological properties of the carrying fluid, drilled hole angle, as well as the fluid flow rate and flow dynamics within the annulus gap between the coiled tube and drilled hole. Such parameters are addressed via experimental work as well as numerical analysis. The paper is also presenting the selection and testing procedure of the material type for the coiled tube string. The tube needs to be light in weight for rig transportation and to drill few dozens of drill investigations holes before failing due to fatigue. A fatigue bending machine is designed to test the endurance limit of candidate materials for coiled tube string and performance index methodology is followed for material selection of the optimum material. The coiled tube rig is designed to be light in weight for transportation and relocation. It is also required to speed the drilling operation with the minimum foot print and will reclaim the drilled rock particles for mineral composition analysis at the surface

Turbodrill Design and Performance Analysis

Turbodrill (turbine down hole motor) has been recently proposed by the authors as the preferred drive mechanism with high rotation speed for hard rocks drilling for deep mineral exploration applications.Turbodrill is a type of hydraulic axial turbomachinery in which turbine motor section has multistage of rotors and stators that convert the hydraulic power provided by the drilling fluid to mechanical power with diverting the fluid flow through the stator vanes to rotor vanes. This paper presents a methodology for designing multistage turbodrills with asymmetric rotor and stator blades configurations. The numerical simulation approach and the simulations results carried out using computational fluid dynamics (CFD) code for the proposed small size model of turbodrill stage with different drilling fluid (mud) types and various mass flow rates are presented. As a result optimum operational parameters are proposed for gaining the required rotation speed and torque for hard rocks drilling

Millers' Breakdown

An unidentified man plays in a fiddle competition at the Clyde Fiddler's Convention

Character Strengths and Generalised Anxiety Disorder: Investigating the Role of Overuse, Underuse, and Optimal Use.

Positive psychology research has extensively explored the relationship between character strengths and well-being. While research has begun to examine the impact of optimal strength use, the role of under-overusing strengths in mental health, particularly Generalised Anxiety Disorder (GAD), remains uninvestigated. This study aims to address this gap by examining the potential contribution of under- or overuse of character strengths to GAD symptomatology/diagnosis

Prototype gauges for measuring detonation temperature and pressure of commercial explosives

A better understanding of the detonation performance of an explosive charge can be gained by directly measuring pressure, temperature and velocity of detonation (VOD). This is particularly important with commercial explosives because their performance is directly influenced by the degree of confinement given by the borehole diameter and the surrounding rock mass. A project funded by the Australian Coal Association Research Program (ACARP) was initiated in early 2009 with the view to design and build cost effective prototype instrumentation to measure the relative differences in detonation pressures and temperatures of commercial mining explosives. The project’s primary focus was on low density explosives. Low density (also referred to as low shock) explosives have been available in various forms for nearly 20 years. Identifying the pressure release patterns of both conventional and low density explosives under different geotechnical conditions should provide the necessary information to both validate detonation codes and better define input parameters for breakage and fragmentation models. This paper gives a general description of the prototype instrumentation developed and reports on the results obtained to date in testing the proposed instrumentation in laboratory scale conditions