An experimental system for coiled tubing partial underbalanced drilling (CT-PUBD) technique

Shi, Huaizhong; Ji, Zhaosheng; Zhao, Haifeng; Chen, Z. L.; Zhang, H. Z.

doi:10.1063/1.5029303

Cited by 2 publications

(1 citation statement)

References 17 publications

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“…Although all the three techniques discussed above play important roles in improving the drilling speed, there are still some problems such as poor hole cleaning, low wellbore safety and high drilling cost. To solve these problems, a new drilling technique called coiled tubing partial underbalanced drilling (CT-PUBD) is proposed here (Shi et al 2018). It uses a dual-wall pipe system by inserting coiled tubing into the traditional drill pipe to achieve an underbalanced drilling condition near the bit.…”

Section: Introductionmentioning

confidence: 99%

Investigations into the coiled tubing partial underbalanced drilling (CT-PUBD) technique for drilling hard formations

Shi

Zhao

et al. 2018

Pet. Sci.

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To improve the rate of penetration (ROP) in drilling deep and hard formations, this paper proposes a new drilling method called coiled tubing partial underbalanced drilling (CT-PUBD). As a preliminary investigation into the new drilling method, this paper presents predictions of hole cleaning efficiency, drilling speed, cuttings migration and pressure loss in the drilling process with CT-PUBD. Based on numerical simulation and full-scale experimental studies, we conclude that using CT-PUBD, an underbalanced drilling condition can be achieved near the bit while maintaining wellbore safety at the same time. This condition can be achieved using a cuttings discharge device, a rotary packer and a backflow controller. According to the numerical simulations performed in this study, CT-PUBD can achieve high efficiency of hole cleaning. Along the cuttings migration process, the fluid velocities can reach the maximum values in the backflow holes. A full-scale laboratory experimental system was used to test the hydraulic characteristics and obtain the drilling performance of the new technology. The result shows that CT-PUBD significantly improves the ROP compared to the conventional drilling method. Keywords Partial underbalanced drilling Á Coiled tubing Á Flow fields Á Cuttings removal Á Rate of penetration (ROP)

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Section: Introductionmentioning

confidence: 99%

Investigations into the coiled tubing partial underbalanced drilling (CT-PUBD) technique for drilling hard formations

Shi

Zhao

et al. 2018

Pet. Sci.

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Numerical Simulation and Experimental Study of Cuttings Transport in Narrow Annulus

Shi

Zhao

et al. 2019

Journal of Energy Resources Technology

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With the development of petroleum industry, it needs an efficient drill method such as under balanced drilling (UBD) to enhance the rate of penetration (ROP). However, borehole instability is a problem that UBD must face. The coiled tubing partial underbalanced drilling (CT-PUBD) is proposed to try to solve this problem while keeping an underbalanced condition with high ROP. This paper analyzes the laws of cuttings transport in the narrow annulus focus on this new technique through the simulations and experiments. From the results of simulations, it obtains that the particle velocity declines with the increase of rotational speed and increases with the increase of flow rate. The particles become concentrated as the flow rate increases, and the high flow rate limits particles in a small area. The particle distribution undergoes a process of concentration, dispersion, and concentration as the rotational speed increases. The high rotational speed makes particles deviate from the high fluid velocity area, which causes low particle velocity. The relationships between particle velocity and rotational speed and between particle velocity and flow rate are fitted through the equations, respectively. The phenomenon of collision of particles, sinking and rising of particles, and variation of particle velocity are observed in the experiments. The error between the particle velocity in the experiment and numerical simulation is less than 8.5%. This paper is an exploratory study conducted for the cuttings transport in narrow annulus.

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An experimental system for coiled tubing partial underbalanced drilling (CT-PUBD) technique

Cited by 2 publications

References 17 publications

Investigations into the coiled tubing partial underbalanced drilling (CT-PUBD) technique for drilling hard formations

Investigations into the coiled tubing partial underbalanced drilling (CT-PUBD) technique for drilling hard formations

Numerical Simulation and Experimental Study of Cuttings Transport in Narrow Annulus

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