Abstract

Coiled tubing (CT) is used as a cost-effective means of servicing wells for well intervention. Over the years, the fluid flow through CT has been discussed and theorized. Testing has been conducted to promote a better understanding of what happens inside the CT. In recent years, the use of computational fluid dynamics (CFD) software has provided greater insight into actual CT flow patterns, including fluid-flow velocity profiles, secondary flow regimes, and erosion. CFD helps to understand the CT fluid flow phenomenon, which can lead to effective tubing management. CFD has proven to be an effective alternative to full-scale testing.

This work compares the results of CFD modeling of erosion to actual field data. It compares predicted values, actual values, and computed values from the CFD solutions. CFD is used to provide correlations for the predictive model without full-scale testing, which greatly reduces the cost of development. Fluids investigated include slurry pumped from an actual job and full-scale testing.

Introduction

The CT industry has become more demanding in recent years because of deeper deployments, higher pressures, and challenging applications. The CT itself, along with managing the tubing, is an essential part in this demanding business. Understanding and having knowledge of the internal flow of fluids in the tubing can be an interesting factor.

Examining the phenomenon of erosion, pressure loss or gradient, and fluid properties are beneficial to the development of the tubing product lines. There is also the principle of secondary flow regimes and its effect. Because of the demands of the industry, all these factors can increase the potential of a successful job, reduce down time, and save money by optimizing equipment and resources. This helps the customer in their goal of increasing profits.

More and more, CFD software for fluid-flow analysis is becoming a standard practice in the CT industry. Once a base evaluation is established and confirmed, parameters can be changed very quickly. Considerable analyses can be performed without full-scale testing. This frees up resources, expedites product development, eliminates health and safety exposure associated with testing, and saves money.

Previous Work

Previous work studied the comparison of a CFD simulation of slurry flow in CT to field data (Blanco et al. 2007). The results confirmed that CFD can be used to simulate more realistic data along with modeling several layers of tubing on a reel. This study was based on three different case results from field data shown in Table 1.

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