(67e) Advancements in Laboratory Testing for Effective Gas Hydrates Management in the Flow Assurance of Oil and Gas Production

Gas hydrates is a significant part in the portfolio of topics covered in the flow assurance of oil and gas production. Major advances have been made in understanding hydrates formation in multiphase system, which has enabled a gradual shift in practice to hydrate management from avoidance. In hydrate management, a solid understanding is required from the formation conditions (thermodynamics) to the formation process (kinetics) to the transportability (multiphase flow) in flowlines. As such, it is important for laboratory testing to provide the essential information needed to develop quantifiable metrics for the risks associated with hydrate management.

A number of testing equipment are typically used for testing of hydrate formation in the laboratory. The conventional testing tools include high pressure autoclave, high pressure rheometer, and rocking cells, in addition to fluid characterization such as wetting index, emulsion stability, and chemical composition. More recently, we have developed a number of different tools and techniques to broaden our insight and reliability of the knowledge to be translated from the laboratory to the field. The tools developed include a single methodology for accurate hydrate equilibrium boundary measurements and predictions in inhibited systems, an innovative setup for hydrate transportability in multiphase flow systems with a simple metric for flow risk, and a novel approach for modeling hydrates formation accounting for kinetics and agglomeration.

The tool for hydrate equilibrium for inhibited systems is based on the simple concept of depression temperature, which can be easily determined from water activity. We will demonstrate how this methodology works for simple and complex systems alike, eliminating the need for time-consuming and expensive measurements. The second tool is the rock-flow cell for hydrate formation under multiphase flow conditions, which is a setup capable of providing information to assess the agglomeration, deposition, and bedding of hydrates. Together, these results can be summarized and understood in terms of a hydrate flow risk index, which is a measure of the transportability of hydrate slurries. Finally, a new concept for hydrate formation based on dry vs wet is introduced to explain the actual mechanism for hydrate slurry transportability. Models for the hydrate kinetics and agglomeration using this concept are proposed with promising results.

The ideas and results presented will highlight both the simplicity and complexity of hydrates management in flow assurance. The goal of this presentation is to expose the community to recent developments in hydrate research that can significantly impact the understanding and implementation of management strategies that are technically effective and lower the risk in the decision making of flow assurance practices.