Abstract

Sand production is a problem that is often encountered in unconventional oil and gas exploitation and that is difficult to effectively solve. Accurate online monitoring of sand production is one of the keys to ensuring the safety and long-term production of oil wells as well as efficient production throughout the life cycle of production wells. This paper proposes a method for monitoring sand production in offshore oil wells that is based on the vibration response characteristics of sand-carrying fluid flow impinging on the pipe wall. This method uses acceleration sensors to obtain the weak vibration response characteristics of sand particles impinging on the pipe wall on a two-dimensional time-frequency plane. The time-frequency parameters are further optimized, and the ability to identify weakly excited vibration signals of sand particles in the fluid stream is enhanced. The difference between the impact response of the sand particles and the impact response of the fluid flow to the pipe wall is identified, and corresponding indoor verification experiments are carried out. Under different sand contents, particle sizes, and flow rates (sand content 0-2‰, sand particle size 96-212 μm, and flow velocity 1-3 m/s), the impact response frequency of sand particles to the pipe wall exhibits good consistency. The characteristic frequency band of sand impacting the pipe wall is 30-50 kHz. A statistical method is used to establish the response law of the noise signal of the fluid. Based on this knowledge, a real-time calculation model of sand production in offshore oil wells is constructed, and the effectiveness of this model is verified. Finally, a field test is carried out with a self-developed sand production signal dynamic time-frequency response software system on 4 wells of an oil production platform in the Bohai Sea. This system can effectively distinguish sand-producing wells from non-sand-producing wells. The dynamic time-frequency response, field test results, and actual laboratory results are consistent, verifying the effectiveness of the method proposed in this paper and further providing a theory for improving the effectiveness of the sand production monitoring method under complex multiphase flow conditions. This study also provides technical guidance for the industrial application of sand production monitoring devices in offshore oil wells.

Highlights

  • Unconventional oil and gas fields are currently a focus of oil and gas exploration and development in the petroleum industry

  • To study the vibration signal characteristics of sand-carrying fluid impacting the pipe wall, the influence of different sand contents on the signal characteristics of sand production was first studied through experiment 1

  • This frequency band was the vibration signal excited by the fluid flow impacting the pipe wall, and most frequencies were mainly concentrated in the low-frequency band below 20 kHz

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Summary

Introduction

Unconventional oil and gas fields are currently a focus of oil and gas exploration and development in the petroleum industry. Through the research and application of online monitoring systems for sand production in production wells, real-time information on sand production in oil wells can be continuously and effectively obtained These data can be used to guide the formulation of moderate sand production strategies and sand control plans for sand production wells and to provide real-time data for informing intelligent oilfield production management. This approach extends the life of oil wells, improves the production efficiency of oil wells, and extends the economic development cycle of oil fields

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