# Experimental Analysis of Shale Cuttings Migration in Horizontal Wells
## 2 Experimental Methods  
### Experimental Device  
To simulate the migration of cuttings in horizontal wells under various operational conditions, an experimental apparatus was developed. The total length of the device was 20.8 m, with an annular inner diameter of 220 mm, a drill tool outer diameter of 127 mm, and a connection outer diameter of 170 mm (Figures 1 and 2). The experimental system was composed of the following key components:  
(1) Drilling fluid system.  
The drilling fluid system functions as the principal medium for the transportation of cuttings and is integral to the process of cuttings migration. This system employs a pump, regulated by a frequency converter, to circulate fluid from a storage tank into the horizontal annulus. A flowmeter is utilized to measure the fluid flow rate, thereby simulating the circulation of drilling fluid within the horizontal section of the wellbore (Figure 3). This system allows for the investigation of how varying flow rates impact the transport of cuttings.  
Cuttings injection system.  
This system is designed to replicate the generation of cuttings during drilling operations. A control valve regulates the injection of cuttings from a storage tank into the annulus according to predefined parameters. The system also records the injection data, allowing for precise control over the amount and timing of cuttings injected into the wellbore.  
Figure 1: Schematic diagram of cuttings migration simulator.  
Figure 3: Drilling fluid flowmeter.  
Figure 2: Physical diagram of cuttings migration simulator.  
(3)  
Simulated wellbore system.  
The lower section of the simulated wellbore is made from a combination of cement and transparent tempered glass, forming a sealed environment. The transparent glass provides visibility for observing the real-time migration of cuttings, while the rough cement surface mimics the texture of an actual wellbore, allowing for a more realistic simulation of the cutting transport process in the annulus.  
(4) Rotation and eccentricity system.  
The drill pipe's rotation and eccentricity have a significant impact on the flow of drilling fluid and the migration of cuttings. This system uses a real drill pipe and an adjustable motor to control the rotation speed and eccentricity of the drill tool (Figure 4). It is equipped with sensors to monitor and record parameters such as rotation speed and eccentricity during the simulation.  
(5) Control and data acquisition system.  
To facilitate the precise control of experimental parameters and to ensure accurate data collection, the control system is integrated with a computer. This setup enables the automated control of the experimental apparatus and the real-time acquisition of operational data, making it easy to monitor and adjust parameters during experiments.  
(6) Cuttings separation system.  
The cuttings separation system (Figure 5) is used to measure the volume of cuttings that have been returned through the annulus. By separating the cuttings from the circulating drilling fluid, the system allows for accurate quantification of the amount of cuttings being transported. The cuttings separation system separates cuttings from the drilling fluid using a sieve mesh, where the cuttings are removed through physical filtration. The separated  
Figure 4: Speed control device.  
cuttings are collected in a dedicated container equipped with a volumetric measurement device that accurately records both the volume and weight of the cuttings. In this way, the cuttings are efficiently separated, while the treated drilling fluid is recirculated for further use.