Numerical Simulation on Coiled Tubing Erosion During Hydraulic Fracturing
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TECHNICAL ARTICLE—PEER-REVIEWED
Numerical Simulation on Coiled Tubing Erosion During Hydraulic Fracturing Peng Jia . Xiuxing Zhu . Shifeng Xue . Jun Fang
Submitted: 8 August 2020 Ó ASM International 2020
Abstract Hydraulic fracturing operation through coiled tubing is a safe, economical, and efficient well stimulation technique. During the operation, the wall of coiled tubing spooled on the reel is abraded and eroded by high-concentration proppants. Because of the high-concentration solid phase, a discrete phase model is not appropriate for erosion prediction during a hydraulic fracture operation. In this paper, the monolayer energy dissipation erosion model is used to predict the erosion of coiled tubing. The simulation results show that the sand particles accumulate at the tubing extrados to form a sliding bed and slide along the tubing wall. Therefore, the erosion of the tubing wall spooled on the reel is mainly due to the friction abrasion caused by the sliding bed of solid particles and is related to the centrifugal force of particles. Erosion rate, which is highest at the coiled tubing extrados, has a cubic relationship to the flow rate of the fracturing fluid, has a linear relationship with the sand volume fraction, and is inversely related to the reel radius. The more viscous the fluid, the more uniform the particles distribute, so the erosion rate is reduced with the increase in fluid viscosity.
P. Jia X. Zhu (&) S. Xue College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China e-mail: [email protected] P. Jia e-mail: [email protected] S. Xue e-mail: [email protected] J. Fang Key Laboratory for Petroleum Engineering of the Ministry of Education, China University of Petroleum, Beijing 102249, China e-mail: [email protected]
Keywords Coiled tubing Hydraulic fracturing Erosion Multiphase Monolayer energy dissipation
Introduction The use of coiled tubing (CT) for hydraulic fracturing operations has become a safe, economical, and efficient technique for well stimulations [1–4], as shown in Fig. 1. Sand or other proppants are conveyed through the coiled tubing into the hydraulically fractured formation to keep the fractures open after the stimulation treatment ceases. High-concentration proppants move with the fracturing fluid at a high speed and continuously erode the tubing wall [5, 6], as shown in Fig. 2. Erosion will reduce the tubing wall thickness, and the pressure rating and tensile strength of the coiled tubing will decrease as the wall thickness decreases, which can significantly reduce the service life of coiled tubing and create unsafe well site conditions. Statistics show that erosion and wear failure account for about 8.6% of coiled tubing failures [7], and it is the main failure mode for coiled tubing that delivers sand [8]. Currently, field experiments and computational fluid dynamics (CFD) simulations are the primary means of analyzing coiled tubing erosion. Gavin’s [5] field studies showed that the coiled tubing was eroded n
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