ABSTRACT

Sand management technology has become more prevalent in the petroleum industry to increase well production. Sand may deposit on pipeline walls, causing problems such as pipe blockage, reduced flow area, structural pipe issues, abrasion, corrosion, and low production in wells.

This paper explores the multiphase model and computation algorithms used to simulate multiphase flow with sand particles through a subsea pipeline to predict the pressure gradient, transport velocity, and sand deposition. Being able to predict sand accumulation and understanding real-time sand velocity in a pipeline can help define design criteria for subsea pipelines and help pipeline operators maximize production while minimizing well and pipeline downtime.

INTRODUCTION

Sandstone reservoirs are the source for most of the world's hydrocarbons; however, sand is a common by-product of oil and gas production, especially when producing from reservoirs with low formation strength. When rock around the well perforations is weak, the reservoir fluids can push sand or solid material into the wellbore. Sand in the produced oil and gas enters the pipeline network, which can increase frictional pressure loss, pipeline damage due to erosion, potential equipment failure, and sand deposition (causing flow assurance problems and pressure changes).

The traditional sand management method involves preliminary sand extraction from the produced fluid before it is released into the main pipeline. Unfortunately, this method is expensive and not applicable in all cases, such as deep, subsea pipelines. As a result, newer sand management methods focus on tracking the amount of sand in the pipeline and operating the pipeline at conditions that minimize the risks.

With these new sand management methods, pipeline simulations become an even more powerful tool for pipeline operators to identify the influence sand has on pressure and temperature changes in the pipeline, detecting erosion and sand deposition, and understanding the impact different operating conditions have on the pipeline performance and safety.

This paper discusses a set of sand management modeling and simulation algorithms and approach to detect sand deposition and erosional velocity. The approach was applied to a cluster of offshore platforms and wells connected by a subsea pipeline; in the case described, these simulated sand deposition and erosional velocity events were compared to real-time pipeline data—including theoretical and actual pipeline pressure loss—and verified, allowing the pipeline operator to take appropriate mitigation actions and reduce lost production opportunity.

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