Abstract

Sand production may be inevitable in many fields that have a relatively lower formation strength. Sand erosion and settling predictions and sand monitoring are important elements of any effective sand production management strategy. Sand erosion predictions are used to establish tolerable sand production rates and (thus) well productivity, and to develop cost-effective inspection frequency for critical components. Prediction of critical flow rate to prevent sand settling is important for flowlines that are not designed for pigging. Quantitative sand monitoring is essential in verifying the effectiveness of sand control procedures and in generating an important input parameter for erosion and sand settling predictions. This paper presents equations for predicting sand erosion rate and sand settling flow rate, and assesses the accuracy of these equations. In addition, the paper presents an assessment of the sensitivity of commercially available non-intrusive acoustic and intrusive electrical resistance sand monitors.

Introduction

Sand production may be inevitable in many fields that have a relatively lower formation strength (< I000 psi). If sand production is expected at the early life of the field, it will be prevented by installation of downhole sand exclusion systems such as gravel packs and screens. However, as would be the case for many reservoirs, wells will not produce sand when they are first brought to production, but they will produce sand at some later point in their lives. In such a case, the operator has three options: I) complete the wells with downhole sand exclusion systems from day one, 2) re-complete the well by installing sand exclusion systems at a later date when sand production begins, or 3) do not install downhole sand exclusion systems and manage sand production by designing the facilities to handle sand if sand is produced. The last option, sand production management, is preferred in many cases because downhole sand exclusion systems can increase the risk of loss of production or even the complete well by plugging and mechanical damage.

There are three technical issues that are critical to sand production management that need to be addressed in order to maximize reservoir production while maintaining the integrity of the production facility. These are: sand erosion, sand settling, and sand monitoring. Sand erosion prediction models are necessary to establish tolerable sand production rates and to determine inspection strategy for the production facility. This will allow establishing the optimum production rate while maintaining acceptable equipment integrity and safety levels. The second technical issue which is of paramount importance in sizing and operations of infield flowlines and pipelines is sand settling. In situations where sand settling cannot be avoided and routine pigging is not feasible, which may be the case for flowlines connecting subsea wells and unmanned platforms, assessing corrosion under sand beds is an important consideration. All analyses addressing the effect of sand on reservoir management and equipment integrity require quantifying sand production rates which may be feasible using sand monitors. This paper will review sand erosion and settling prediction models and present an assessment of the quantitative accuracy of commercially available sand monitors.

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