Advanced Desander Removes Solids Without Deferring Well Production
- Colin Sherwood (Stork Technical Services)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- August 2012
- Document Type
- Journal Paper
- 28 - 31
- 2012. Copyright is retained by the author. This document is distributed by SPE with the permission of the author. Contact the author for permission to use material from this document.
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As oil and gas fields mature, production of sand and other reservoir solids can become an increasing and sometimes major impediment to hydrocarbon production and facility operations. These solids can move through the wellbore into process facilities, causing flow assurance problems that affect system integrity, export line transportation, cleaning, and disposal. As operators seek to optimize production from mature assets, solids management is likely to take on additional importance. Sand and solids production can also be a problem on some new wells.
To address these issues, Stork Technical Services developed an advanced online desander (AOD) for managing separator solids, providing thermographic determination of sand accumulation, and enabling clean sand discharge to the sea, with no deferred production (Fig. 1). The system has been used successfully in eight deployments on the Hummingbird floating production, storage, and offloading system (FPSO), which supports Centrica’s Chestnut field, operated by Wood Group, in the United Kingdom North Sea.
Risks of Sand in Production Vessels
The presence of sand in production vessels reduces capacity and affects separation performance, which leads to deteriorating produced water quality and the carry-over of water in the oil phase. If not controlled, the sand can cause a separator to be taken offline and manually cleaned. This exposes facility crew members to process hazards and may damage downstream equipment.
Conventional sand management techniques require a shutdown of 10 to 14 days for manual sand removal, resulting in a significant delay and additional expense. Following this, oil-on-sand discharge rules may limit disposal options and compel storage of some or all of the sand.
The Online Desanding Technology
The desander is designed to allow more operator uptime and to reduce costs, compared with traditional vessel entry cleanout methods. With the new technology, there is no need to shut down production, and the elimination of manual cleaning improves safety. In addition, the technology enables operators to change their approach to planned shutdown periods. Because the system allows a high degree of cleaning to take place before shutdown, the team of technical experts needed for a shutdown can be smaller and planning for it simpler.
The system comprises a number of purpose-designed, integrated components including solids extraction, solids separation, and solids conditioning packages. A high-flow jetting unit with a recovered-liquid package recycles the separator water. The system complies with European Union hazardous area safety requirements and can be used in Zone 2 hazardous offshore environments.
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