Jet Drilling Research Articles

Effect of the structure of backward orifices on the jet performance of self-propelled nozzles

Self-propelled nozzle is a critical component of the radial jet drilling technology. Its backward orifice structure has a crucial influence on the propulsive force and the drilling performance. To improve the working performance of the nozzle, the numerical simulation model is built and verified by the experimental results of propulsive force. Then the theoretical model of the energy efficiency and energy coefficient of the nozzle is built to reveal the influence of the structural parameters on the jet performance of the nozzle. The results show that the energy efficiency and energy coefficient of the backward orifice increase first and then decrease with the angle increases. The energy coefficient of forward orifice is almost constant with the angle increases. With the increase in the number and diameter, energy efficiency and energy coefficient of the forward orifice gradually decrease, but the backward orifice energy coefficient first increases and then decreases. Finally, it is obtained that the nozzle has better jet performance when the angle of backward orifice is 30°, the number of backward orifice is 6, and the value range of diameter is 2–2.2 mm. This study provides a reference for the design of efficiently self-propelled nozzle for radial jet drilling technology.

Drilling Localization and Error Analysis of Radial Horizontal Jet Drilling Based on Magnetic Gradient Tensor

To obtain the real-time drilling trajectory of radial horizontal jet drilling (RHJD), a magnetized nozzle localization method based on magnetic gradient tensor (MGT) is proposed. The MGT system consisting of five tri-axial magnetometers, a tri-axial accelerometer, and a tri-axial gyroscope are installed in the casing. The magnetized nozzle is made of a strong magnetic permanent magnet whose position can be obtained by measuring the MGT generated by itself at the measurement point. The simulation and experiment of the localization method are carried out, which show that the method has high accuracy. When the detection distance is 40 m, the error is only 0.07 m, which meets the requirements of engineering practice. The accuracy of the magnetometer, the baseline distance and the magnetization strength of the nozzle are the main factors affecting the localization error. This localization method can meet the requirements of positioning accuracy in practical engineering, which greatly avoids the drilling failure of RHJD and has a wide application prospect.

High pressure jet drilling effect in chalk and alteration of local geomechanics properties surrounding the radial hole

This study presents an improved understanding of how high-velocity fluid jet affects the mechanical properties of chalk, building a solid ground for the borehole stability analysis. Our laboratory experiments on water and acid-aided water jet-drilling of chalk samples have shown that high-pressure jet drilling alters the local mechanical properties of the chalk, resulting in a significant weakening of strength properties (tensile, uniaxial/triaxial compressive and pore collapse stress) in close proximity of the jet hole. Acid-aided water has even more impact on chalk matrix as revealed by Scanning Electron Microscopy (SEM) analysis. Numerous micro-perforations are found on the surface of microsparites (calcite). However, no extensive dissolution of calcite cement was observed in the chalk matrix. Results show that mechanical properties degradation is the outcome of both dissolution of the cementation and micro-perforations created on the calcite surface.

Geometric characteristics analysis of hole making through abrasive water jet drilling

Carbon-fiber strengthened materials are creating inroads for aid in the automotive industry due to their greater properties such as high specific strength and stiffness and chemical resistance. Carbon fiber composite is a versatile material which is commonly used in many applications. The machining characteristics of such materials need attention. It is observed that abrasive water jet machining of carbon fiber composites has rarely been done, hence we propose to carry out the experimentation in abrasive water jet machining of carbon fiber composites. Abrasive water jet drilling and abrasive profile cutting are planned here. Process parameters are water pressure, stand-off distance for this study. Full factorial approach will be used for the study and all the combination of the parameters is intended to study here. The quality of the machining is planned to assess by the measurement of features such as dimensional deviation, kerfs width, circularity, roundness, surface roughness etc. The drilled profile is intended to be studied and the micro structural properties will be observed through advanced optical tools. Analysis of variance is conducted for entry hole diameter, exit hole diameter, entry hole roundness, exit hole roundness and kerf and the results have been reported.

Thermal shock assisted percussive drilling: A numerical study on the single-bit axisymmetric case

This paper presents a numerical study on thermal shock assisted percussive drilling. For this end, a finite element based numerical approach for solving the governing thermo-mechanical problem explicitly in time is presented. Rock fracture is described in the continuum sense by a damage-viscoplasticity model with separate damage variables for tensile and compressive failure types. In the numerical simulations, an axisymmetric numerical rock is dynamically indented with a spherical tool in cases of intact and heat shocked heterogeneous rocks. In realistic simulations with an initial borehole, the heat shock treatment of rock enhances the mechanical breakage, increasing especially the tensile damaging, in unconfined and confined conditions with and without down-the-hole pressure. However, according to the simulations, down-the-hole pressure effectively prevents the thermal spallation phenomenon crucial for thermal jet drilling.

Application of grey correlation-based EDAS method for parametric optimization of non-traditional machining processes

Higher dimensional accuracy along with better surface finish of various advanced engineering materials has turned out to be the prime desideratum for the present day manufacturing industries. To achieve this, non-traditional machining (NTM) processes have become quite popular because of their ability to produce intricate shape geometries on diverse difficult-to-machine materials. To allow these processes to operate at their fullest capability, it is often recommended to set their different input parameters at the optimal levels. Thus, in this paper, a new technique combining grey correlation method and evaluation based on distance from average solution is applied for simultaneous optimization of three NTM processes, i.e. photochemical machining process, laser-assisted jet electrochemical machining process and abrasive water jet drilling process. The derived optimal parametric combinations outperform those as identified by the other popular multi-objective optimization techniques with respect to the considered response values. The results of analysis of variance also identify the most influencing parameters for the said NTM processes. Finally, the developed surface plots would help the process engineers in investigating the effects of different NTM process parameters on the corresponding grey appraisal scores.

Investigation of the factors affecting the self‐propelled force in a multi‐orifice nozzle using a novel simulation method

AbstractA multi‐orifice nozzle is the primary actuator of radial jet drilling for the stimulation of unconventional and low‐permeability reservoirs. This research developed a 3D flow field simulation model to investigate the self‐propelled force of a multi‐orifice nozzle based on ANSYS‐CFX. To evaluate the self‐propelled ability of the nozzle, investigation was performed on the effects of the angle, number, the diameter of the forward and backward orifices of the multi‐orifice nozzle, and the diameter of the micro‐hole in the radial well on its self‐propelled ability by sensitivity analysis. The results revealed that the self‐propelled force slightly increased with the angle of forward orifice increasing, and decreased with the angle of backward orifice increasing; and that the self‐propelled force had a tendency to decrease significantly with the number of forward orifices increasing, and increased slightly with the number of backward orifices increasing. The self‐propelled forces for different combinations of forward and backward orifices were obtained by the simulation method, which agreed well with those obtained by the calculation method, with an average accuracy of 95.82%. It was observed that the self‐propelled force increased substantially as the value of K (d2/d1) increased, but tended to slow down when the flow rate was within a certain range. Besides, with the increase in the diameter of the micro‐hole, the self‐propelled force reduced, and increased substantially as the inlet flow rate increased, but tended to slow down as the inlet flow rate further increased. Thus, to ensure the self‐propelled ability of the jet nozzle, a set of optimal structural parameters can be used to generate the target self‐propelled ability. The research improves the working performance of multi‐orifice nozzles and provides theoretical guidance for hydraulic radial jet drilling process.

On the rock-breaking mechanism of plasma channel drilling technology

Plasma channel drilling (PCD), which is also known as high-voltage electric pulse drilling, is a highly efficient rock-breaking drilling technology with great development potential. This paper presents a method to study the rock-breaking mechanism of PCD technology. Then based on the predecessor's foundation, the factors affecting the development of plasma channels are explored using the dielectric breakdown model (DBM). Finally, a numerical rock-breaking model considering electric-thermal-mechanical three fields is established. This paper reveals the basic rock-breaking process of PCD and how the formation pressure affects the rock-breaking process of PCD technology. The main conclusions are: the formation law of plasma channel is related to the electrode structure and the inputting electrical parameters, the electrical properties of the rock and the type of rock; the plasma channel has an internal dynamic effect on the rock breaking process, and this internal dynamic effect of the plasma channel is sharply weakened after the channel is formed; shear cracks play a lead role in PCD, and the number of shear cracks is larger than that of conventional mechanical-rotary drilling; the formation pressure has little effect on the rock failure, the total volume of the chips, and the total number of cracks in the PCD, and the rock-breaking efficiency is not limited by the drilling depth. Finally, in order to improve the rock breaking-efficiency, it is recommended that the PCD technology be used in conjunction with slim hole drilling technology or jet drilling technology.

Hydraulic extension ability of radial jet drilling with multi-nozzles jet bit

Radial jet drilling technology, which utilizes hydraulic energy of jet to create multiple radial micro-laterals in different layers from the main borehole, has been used widely as an effective approach to enhance the oil recovery, and the extreme extension length of radial micro-laterals affects the effect of simulation directly. However, the prediction model for hydraulic extreme extension ability of RJD has been rarely studied. In this study, a modified model for hydraulic extreme extension ability is proposed based on the force analysis of RJD system and related calculation models for frictions are developed by theoretical and experimental methods. In order to obtain the maximum extension length, the influential factors including flow rate of drilling fluid, specifications of flexible hose, and structure parameters of jet bit are investigated. The results indicate that the hydraulic extension ability of RJD presents a significant positive correlation with the flow rate of drilling fluid and the inner diameter of flexile hose. Although an increase of the number of backward nozzles or its diameter can improve the extreme extension ability of RJD, there is still an optimal value for both the number and diameter of backward nozzles. Without sacrificing the rock-breaking and expanding ability of jet bit, the number of forward nozzles and the angle of backward nozzles should be minimized. Furthermore, a field case of RJD proves the prediction model is favourable for drilling engineering, with a model error of less than 8.5%.

Experimental Investigation of Drilling Lateral Boreholes in Chalk Rocks with High-Pressure Jets

Increasing reservoir connectivity to the wellbore and bypassing the damaged area is crucial in improving the productivity of the wells and enhancing the swept area. This has become feasible by a new technology called radial jet drilling (RJD), in which relatively long, small-diameter laterals can be drilled radially from the main wellbore. In this study, the authors attempt to gain a better understanding of the efficiency of a high-velocity jet drilling on chalk destruction, and also identify parameters controlling the jet drilling. For this purpose, two distinct outcrop chalks from Austin, Texas (US) and Northern Province, Welton (UK) are used in this study, which are analogs to the reservoir chalk in the North Sea. In conjunction with the jet drilling experiments, basic rock mechanics testing is carried out in order to correlate the rock strength and stiffness properties to the jet drilling performance. Jet drilling of boreholes is evaluated not only by varying the fluid and nozzle type and the fluid pressure at the nozzle, but also varying the jet drilling setup under unconfined and also confined stress fields resembling reservoir condition. Results of our study show a clear correlation of the rock strength (and stiffness) on the threshold pressure and specific energy required to break the rock. Tight chalk requires more than 30% higher pump pressure than used in soft chalk for breaking the chalk, having more than twice the strength properties. Soft chalk presents larger borehole size and better rate of penetration, both with water and acid-aided fluid, owing to its higher matrix permeability value, as well as lower mechanical properties that favor diffusion of the jet drilling fluid into the rock and faster erosion/breakage compared with tight chalk. Static nozzles create a larger surface area compared with rotating nozzles. The penetration rate of the nozzle is improved significantly under stress confinement. In addition, jet drilling in the direction of minimum principal stress (σ3) appears to be faster owing to localization of shear failure around the drilled hole induced by the differential stresses compared with the jet drilling in the direction of maximum principal stress (σ1) under isotropic stress or ambient conditions.

Optimization of machining parameters for kerf angle and roundness error in abrasive water jet drilling of CFRP composites with different fiber orientation angles

In this study, carbon fiber-reinforced polymer (CFRP) composites with three different fiber orientation angles (M1: [0°/90°]s, M2: [+ 45°/− 45°]s, and M3: [0°/45°/90°/− 45°]s) were drilled (with and without pilot holes) on an abrasive water jet (AWJ) machine and the effect of the drilling parameters on the kerf angle (K) and roundness error (Re) of selected holes was investigated to determine quality characteristics. The first aim of the study was the single-objective optimization of drilling parameters for minimum K and Re individually. The second aim was the multi-objective optimization of drilling parameters for the simultaneous minimization of both K and Re. The Taguchi method was applied for single-objective optimization, while all steps of the Taguchi-based gray relational analysis were used for multi-objective optimization. Drilling experiments were performed using the L16 (44) orthogonal array. Four levels each for water pressure, stand-off distance, traverse feed rate, and hole diameter were selected as control factors. Analysis of experimental findings revealed that pilot drilling improved the kerf angle of the hole by 12.4% and the roundness error by 22.87%. Minimum kerf angle and roundness error were realized in the AWJ drilling of the M3 CFRP. The most effective parameter on kerf angle and roundness error in AWJ drilling of M1, M2, and M3 CFRP materials was water pressure (80.6%, 76.9%, and 73.8%, respectively), followed by stand-off distance (11.7%, 12.0%, and 13.5%),while other drilling parameters remained below 10%. The statistical evaluation and optimization results in this study can contribute to the evaluation of the AWJ machinability of CFRP composites.

Mechanisms of enhancing the machining performance in micro abrasive waterjet drilling of hard and brittle materials by vibration assistance

A study of the effect of vibration assistance on the machining performance in the micro slurry jet drilling of hard and brittle materials typified by single crystal 4H-SiC wafers is presented. It shows that this technology provides benefits to the machining process by improving both material removal rate and surface finish, and such improvements are more profound by increasing the vibration amplitude. Ductile-like mode deformation is noticed to be dominant on the surfaces processed with vibration assistance for this highly brittle material. It is found that major material removal is achieved through brittle fractures of the material by the direct impact of the jet. A smoothening process following the jet impact through a crossflow-driven motion of the particles over the brittle-fractured surface at an engaging depth below the critical value for the cleavage fracture of the material improves the processed surface quality. A finite element (FE) analysis of the particle impact reveals that the vibration applied to the target surface adds no energy to the impacting process, but makes the transfer and application of jet energy more effective by promoting a sweeping effect. This effect clears the surface from the accumulation of the after-impact particles, allowing the subsequent particles from the jet to impact directly onto the surface. The FE study also shows that the applied vibration does not change the engaging depth made by the after-impact particles, but raises the crossflow velocity through the sweeping effect. This enables the smoothening process to extend beyond the restriction imposed by a repeating action of dull particles, and results in the brittle-fractured surface to be flattened and smoothened.

Abrasive Jet Drilling Of Glass using Normal-bed and Fluidized-bed AJM Setup

Abrasive Jet Machining (AJM) is a promising unconventional modern machining process used to machine hard and brittle materials. This paper focuses on machining of borosilicate-glass work piece with various grits of zircon abrasives using normal and fluidised bed mixing chamber based AJM setups.The normal AJM setup is first designed and fabricated to conduct the experiments according to the Box-Behnken design of response surface methodology. Again, some modifications are made in the existing normal mixed chamber to fabricate the fluidized bed mixing chamber based AJM setup and experiments are carried out with the same input parameters on both the AJM setups. The SEM micrograph analysis is performed to study the impact-mechanism and crack-propagation due to AJM.

Analyses of particle size and abrasive water jet drilling of synthesized chromel metal matrix

The chromel was one type of nickel-based metal matrix (MMC) and it was fabricated through stir casting technique. The titanium carbide (TiC) was used as a reinforcement material. The particles were analyzed through Atomic Force Microscopy (AFM) and Dynamic Light Scattering (DLS). Abrasive Water Jet Drilling (AWJD) was mechanical energy based non-traditional process that was applied to pierce the stir casted chromel MMC. During the drilling process, jet pressure, traverse speed, and standoff distance were pointed as the main input factors. The Material Subtraction Rate (MSR) and Surface Finish (SF) have been chosen as the response factors. The effect of factors and their correlation were validated through variance test and interface plots.

Genetic algorithm model for abrasive water jet machining of Inconel 617

This article details the methodology for the development of a multi objective optimization model for the abrasive water jet machining of Inconel 617. Genetic algorithm is the tool used for the optimization process. Abrasive water jet drilling of Inconel 617 is conducted using the Taguchi design of experiments. The various input factors considered are water pressure, abrasive flow volume and standoff distance. The responses selected for this study are overcut, circularity and drill rate. A simultaneous multi optimization model is developed using genetic algorithm. The optimization is done with four stages where in different weightages are added to the input factors and the results have been reported.

Simulated Annealing as a Simultaneous Optimization Tool for Abrasive Water Jet Drilling of Inconel 617

This article details the methodology for the development of a multi objective optimization model for the abrasive water jet machining of Inconel 617. Simulated annealing is the tool used for the optimization process. Abrasive water jet drilling of Inconel 617 is conducted using the Taguchi design of experiments. The various input factors considered are water pressure, abrasive flow volume and standoff distance. The responses selected for this study are overcut, circularity and drill rate. A simultaneous multi optimization model is developed using simulated annealing. The optimization is done with four stages where in different weightages are added to the input factors and the results have been reported.

Developments of non-conventional drilling methods—a review

Demand for drilled micro-holes on difficult to machine materials have increased over the past years and non-traditional drilling processes are commonly used to fabricate such micro-holes on difficult to machine materials. This research investigates different non-traditional drilling processes, such as electro discharge, laser beam, abrasive water jet, electrochemical and electrochemical discharge drilling methods. Drilling mechanism, material removal rate/machining speed and surface finish have been analysed for every process. These analyses clearly show that vaporisation, melting, chemical dissolution and mechanical erosion are dominant material removal mechanism during non-traditional drilling. The understanding on electro discharge, laser beam and abrasive water jet drilling are more developed than that of electrochemical, electrochemical discharge and hybrid drilling processes.

Rock-Breaking Properties Under the Rotatory Impact of Water Jets in Water Jet Drilling

Water jet drilling is widely used to develop coalbed methane reservoirs. The water jet drill bit is the core component, and a self-rotating bit is an economical bit because of its high rock-breaking efficiency and low energy consumption. Because the important parameters concerning the rock-breaking efficiency of these drill bits are unclear, this study carried out rock-breaking experiments on water jet rotation under different conditions of drill bit rotation speed, jet pressure, and jet impact angle. How the rock was fractured and eroded under these different conditions was analyzed. The results show that the volume of rock broken under rotary jet erosion increases exponentially with increasing jet pressure. The rock-breaking depth is the most important factor that influences the volume of rock broken, whereas the diameter of the area broken is a secondary factor. There is an optimum water jet rotation speed for the most efficient rock breakage, and this rotation speed is positively correlated with jet pressure. There is also an optimum water jet impact angle for rock breaking, and, in our experiments, this angle was 10°. The rotary impact of the water jet causes the rock to be in a three-way tension state, and this reduces the water cushion effect and jet reflection. This study can be used as a reference and guide for optimizing the design of self-rotating water jet bits and the determination of reasonable drilling parameters.

Abrasive water jet drilling of float glass and characterization of hole profile

The applications of glass are tremendous since prehistoric period. Glass being brittle, amorphous material, it is highly difficult to carry out its machining using conventional methods. As abrasive water jet is a versatile non-traditional machining process, the current study uses Abrasive Water Jet (AWJ) for drilling glass. Among the various types of glass, most fragile glass type—float glass is used for study. Appropriate process parameters are used for machining based on the results and observations from preliminary experimentation. Also the Taguchi design is selected to carry out experimentation for all the possible combinations. The evaluation process of the drilled hole is carried out using optical profile projectors—to view the hole profile; Coordinate Measuring Machine (CMM)—to measure circularity and cylindricity; and Scanning Electron Microscopy (SEM) to observe the chipping and cracks developed during machining. Based on the deviation in hole profile, kerf analysis is carried out. Based on all the input and output parameters quantified, Analysis of Variance (ANOVA) is carried out to determine the most influential parameters. Finally based on the results obtained, for the experimented conditions and equipment used, Abrasive water jet drilling process is not recommended for drilling smaller diameter holes in float glass.

Flow structure and rock-breaking feature of the self-rotating nozzle for radial jet drilling

For improving the hole-enlarging capability, roundness and rock-breaking efficiency of the nozzle in radial jet drilling, a new structure of self-rotating nozzle was put forward. The flow structure and rock-breaking features of the self-rotating nozzle were investigated with sliding mesh model and labortary tests and also compared with the straight and the swirling integrated nozzle and multi-orifice nozzle which have been applied in radial jet drilling. The results show that the self-rotating jet is energy concentrated, has longer effective distance, better hole-enlarging capability and roundness and impacts larger circular area at the bottom of the drilling hole, compared with the other two nozzles. Forward jet flow generated from the nozzle is peak shaped, and the jet velocity attenuates slowly at the outer edge. Due to periodic rotary percussion, the pressure fluctuates periodically on rock surface, improving shear and tensile failures on the rock matrix and thereby enhancing rock-breaking efficiency. The numerical simulation results of the flow structure of the nozzle are consistent with the experiments. This study provides an innovative approach for radial jet drilling technology in the petroleum industry.