Sand Production Potential and Consequences

Introduction

The sand management strategy should, as a fundamental principle, encompass all systems likely to be exposed to solids produced from the well. Consequently, the upstream and downstream battery limits for the strategy need to be clearly defined. Both passive and active means for controlling and monitoring sand production and its associated consequences should be taken into account.

Sand Production Potential

The potential for sand particles to be released and transported from formation to wellbore is determined by various complex factors requiring expert evaluation by reservoir geologists and completion engineers. Sand potential is typically assessed early in the field concept development, but this information is often limited and associated with significant uncertainty.

Different formations exhibit varying mechanical strength, characterized by the level of consolidation or how well sand grains are "cemented" together. Rock strength is determined through core-sample testing, and sand potential is assessed for the field life considering the planned recovery strategy. Core samples from exploration wells may not be representative of all subsequent production wells, introducing uncertainty. The true sand potential is also influenced by the reservoir recovery strategy, with a reduction in reservoir pore pressure increasing the potential for rock failure and sand formation, particularly in tail-end and low-pressure production.

Water enhances sand mobility to the wellbore due to reduced surface tension compared to sand and oil/gas, potentially coinciding with the onset of water production. Rapid transients in well operation may negatively impact the near-wellbore zone, leading to increased sand production and should be avoided whenever possible.

Consequences of Sand Production

Sand production can significantly impact both production and assets, with key failure modes related to erosion, sand accumulation, plugging, or contamination by sand. In most oil and gas fields, sand from the reservoir formation is an inevitable by-product. Monitoring and controlling sand production are crucial for several reasons:

• Sand may damage well components, such as sand screens, tubing, down-hole safety valves, or electrical submersible pumps (ESPs).
• Erosion in piping systems and components caused by sand may lead to undetected loss of containment.
• Sand may cause erosion in blow-down systems during emergency shutdown (ESD) depressurization or inadvertent routing of production to a knockout drum, with particular attention needed for flow restrictions and immediate piping downstream.
• Accumulation of sand in the wellbore may lead to sanding-in and well loss.
• Sand accumulation in production lines can affect corrosion rates, cause upsets during pigging operations, or increase pressure resistance during operation.
• Sand in separators may reduce separation efficiency and carry sand to downstream systems not designed for it.
• Instrumentation may be influenced, potentially affecting safety-critical systems.
• Challenges with sand volume handling and removal may cause upsets or unplanned shutdowns.
• Sand production may negatively impact produced water quality.
• Overboard disposal of produced water containing sand may cause erosion or reduced well injectivity if re-injected.
• Sand accumulation in valves may impair performance due to blockage or increased friction.
• Sand may damage rotating equipment, such as pumps and compressors.
• Even moderate sand erosion potential can affect flow accelerated corrosion (FAC), especially for non-corrosion-resistant materials.