Numerical investigation and optimization of structural and operating parameters for cuttings transport in a bidirectional eccentric micro-underreamer.

Xu Zhang, Mengyu Cao, Li Liu, Yuqi Sun, Wei Li, Qiang Zhang, Fulu Chen, Chaoyu Li

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Article in Scientific reports, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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8 authors.

Xu ZhangSchool of Mechanical Science and Engineering, Northeast Petroleum University, Daqing, 163318, China.

Mengyu CaoSchool of Mechanical Science and Engineering, Northeast Petroleum University, Daqing, 163318, China.

Li LiuCNPC Engineering Technology R&D Company Limited, Beijing, China. 13195316035@163.com.

Yuqi SunCNPC Engineering Technology R&D Company Limited, Beijing, China.

Wei LiCollege of Petroleum Engineering, Northeast Petroleum University, Daqing, 163318, China.

Qiang ZhangSchool of Mechanical Science and Engineering, Northeast Petroleum University, Daqing, 163318, China.

Fulu ChenCollege of Petroleum Engineering, Northeast Petroleum University, Daqing, 163318, China.

Chaoyu LiSchool of Mechanical and Electrical Engineering, Sanming University, Sanming, 365004, China. 20240104@fjsmu.edu.cn.

Funding

CNPC Applied Research Project 2023ZZ16-5CNPC Key Core Technology Research Project 2024ZG39National Science and Technology Major Project for New Oil and Gas Exploration and Development 2025ZD1401206National Science and Technology Major Project for New Oil and Gas Exploration and Development 2025ZD1404205

6 · The paper itself

Abstract

Cuttings transport behavior plays a crucial role in downhole safety, drilling efficiency, and wellbore cleaning during underreaming operations. Because of the complex local flow passage and eccentric structural characteristics of a bidirectional eccentric micro-underreamer, cuttings migration and discharge are highly sensitive to downhole operating conditions. In this study, a three-dimensional solid-liquid two-phase flow model was established for a bidirectional eccentric micro-underreamer, and an Eulerian-Lagrangian approach was employed to describe the two-way coupling between the drilling fluid and cuttings particles. After the blade structural parameters were optimized, the effects of drill string rotational speed, weight on bit, drilling fluid density, and drilling fluid viscosity on cuttings transport behavior were systematically investigated. The results indicate that drill string rotational speed and weight on bit both exert non-monotonic effects on cuttings discharge efficiency, and relatively favorable cuttings-carrying performance was achieved at 50 r/min and 100 kN, respectively. By contrast, increasing drilling fluid density weakened cuttings transport performance, whereas increasing drilling fluid viscosity enhanced the drag and suspension capacities of the fluid for cuttings particles. Within the investigated range, a drilling fluid density of 1.6 g/cm

Indexed as

Bidirectional eccentric micro-underreamerCuttings transportDrilling fluid propertiesEulerian–Lagrangian method

Identifiers

PMID42575919

DOI10.1038/s41598-026-64085-8

PMCPMC13458523

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.