Analytical and Numerical Simulation of Asymmetric Converging Flow of Gas Under Drill Bits in Reverse Circulation Gas Drilling

Yang, Xu; Guo, Boyun; Timiyan, Tamaralayefa Ayemidi

doi:10.1115/1.4051551

Cited by 5 publications

(4 citation statements)

References 20 publications

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“…Due to unpredictable formation conditions, time-varying stress state of drilling tools, irregular borehole bottom, and wear of drill bit, simplification is introduced when drill bit simulation model is built. Firstly, since linear velocity of a drill bit is much smaller than flow velocities of the drilling fluid, drill bit rotation is not considered when constructing the model to study the flow field characteristics [21,22]. Secondly, in order to decrease the calculation time and enhance the convergence rate, the fillets, chamfers and other structures that do not affect the calculation results, are ignored.…”

Section: Fluid Domain and Meshingmentioning

confidence: 99%

Flow field simulation of a hydrogeological exploration drill bit for switching coring drilling and non-coring drilling

Shi,

2023

Preprint

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Drilling is one of the most commonly techniques in hydrogeological exploration, which is employed to obtain rock samples and build boreholes. During conventional drilling, it needs to raise all drilling tools in the borehole, when switching coring drilling and non-coring drilling, which will cause large auxiliary operation time consumption and poor drilling efficiency. According to the structure of wireline coring tools, a large diameter modular drill bit is designed to switch coring drilling and non-coring drilling without lifting the whole drilling tools. In the Comsol simulation environment, a simulation model of the modular bit is constructed using computational fluid dynamics (CFD) method. Drilling fluid velocity and pressure characteristics flowing through the modular bit were studied, with different values of flow rate at the bit inlet, clearance between external bit and internal bit for coring drilling, and layout of nozzles at the bottom of the internal bit for non-coring drilling setting respectively. According to the analysis results, velocities of drilling fluid flowing upward at the clearance between external bit and borehole wall increases linearly, and the pressure at bit inlet increases in parabola, with the flow rate increasing. With the same input flow rate, similar velocities and lower pressure loss can be obtained in the non-coring drilling compared with the coring bit, and thus drilling cuttings can be removed effectively even if there are more drilling cuttings produced in non-coring drilling than in coring drilling, when a borehole is drilled with the same diameter. When the outside diameter of the modular bit is 216mm, the recommended clearance value is 9mm or 10mm in order to obtain lower pressure loss and larger diameter core. To generate low pressure loss and ensure bit strength, the layout with 4 nozzles on the internal non-coring bit is recommended. The modular bit enables fast switching coring drilling and non-coring drilling without raising drilling tools, and the simulation model can be used for drilling parameters selection and drill bits optimization.

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Section: Fluid Domain and Meshingmentioning

confidence: 99%

Flow field simulation of a hydrogeological exploration drill bit for switching coring drilling and non-coring drilling

Shi,

2023

Preprint

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“…Han et al 14,15 found that a reasonable air velocity was conducive to discharge coal cuttings in the study of coal seam RC. Finally, Yang et al 16 studied the effect of bit structure on RC drilling performance.…”

Section: Introductionmentioning

confidence: 99%

Design optimization of a coal seam annular air reverse circulation bit

Chen

Long

et al. 2023

Energy Science & Engineering

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Reverse circulation (RC) drilling technology enables the rapid acquisition of coal seam samples, which is crucial in accurately measuring gas content. In addition, the design of the drill bit plays a key role in RC sampling. In this study, the turbulence model and simulation method applied during the RC drilling process is analyzed, and an annular jet flow bit is developed. An experimental laboratory setup is used to simulate the RC performance of the proposed drill bit, based on which an orthogonal design simulation of the structural parameters of the drilling bit studies was performed to investigate the effects of the RC drilling process. The experimental results show that annular jet flow moving up the central channel wall of the bit is conducive to the suction of annular airflow and results in the strong flow field created by the center channel of the bit generating negative pressure in the center channel of the bit, a comparison of the computational fluid dynamics data on negative pressure and suction rate shows that the annular jet flow RC bit is suitable for use in RC drilling.

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“…DTH hammer RC drilling is an innovative percussive-rotary drilling technology driven by compressed air and is a potentially effective technology for large-diameter wells [13]. It is a fast and cost-effective way to reduce the air injection rate by at least 70% and improve hole cleaning efficiency [14]. In air RC drilling, compressed air enters the annulus of the dual-wall drill pipe through a dualwall swivel.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies show that the RC drill bit is the key component to forming air reverse circulation. Most previous work on RC drilling focused on the structural design of drill bits that control cutting transport at the bottom hole [14][15][16][17]. The range of diameters of these RC drill bits studied in previous work was from 80 to 600 mm.…”

Section: Introductionmentioning

confidence: 99%

Optimum Design of Large-Diameter Reverse Circulation Drill Bit for Drilling Rescue Wells Using Orthogonal Experimental Method and CFD Simulation

Zhao

et al. 2023

Energies

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Down-the-hole (DTH) hammer drilling with reverse circulation is a novel, mobile, high-speed drilling system suitable for the specific requirements of mine rescue. This technology can be applied to shorten the rescue time during mine accidents. The performance of reverse circulation (RC) drilling depends on the structural design of the drill bit. An orthogonal experimental design is executed to investigate the effect of the structural design parameters of the large-diameter drill bit for drilling rescue wells on the cutting carrying capacity and reverse circulation performance. This study employs computational fluid dynamics (CFD) software to solve the Navier–Stokes equation for three-dimensional steady flow and calculate the flow field around the drill bit to evaluate the RC efficiency. Six key geometric parameters were proven to have a direct influence on the RC performance, including the diameter of suction nozzles Dn, the length of nozzles L, the quantity of nozzles N, the diameter of the pilot hole Dg, the inclination angle of nozzles θs, and the deflection angle of nozzles θd. The CFD simulation experiments were implemented according to the orthogonal array L18(37) and were analyzed using the range, variance, and regression analysis. A mathematical model was developed for the RC efficiency to understand the effect of the factors. The results show that the diameter of suction nozzles Dn has an essential effect on the RC performance of the drill bit. An ideal combination is Dn = 20 mm, L = 50 mm, N = 3, Dg = 50 mm, and θs = 35°, θd = 10°, which was obtained through variance analysis and validated via CFD simulation for higher efficiency. To verify its real performance, a large-diameter RC drill bit with a diameter of 1.2 m was manufactured and tested in the field. The result demonstrated that the drill bit had excellent cutting transport and reverse circulation performance.

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Analytical and Numerical Simulation of Asymmetric Converging Flow of Gas Under Drill Bits in Reverse Circulation Gas Drilling

Cited by 5 publications

References 20 publications

Flow field simulation of a hydrogeological exploration drill bit for switching coring drilling and non-coring drilling

Flow field simulation of a hydrogeological exploration drill bit for switching coring drilling and non-coring drilling

Design optimization of a coal seam annular air reverse circulation bit

Optimum Design of Large-Diameter Reverse Circulation Drill Bit for Drilling Rescue Wells Using Orthogonal Experimental Method and CFD Simulation

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