Hydrate Management of Deadlegs in Oil and Gas Production Systems – Background and Development of Experimental Systems

Abstract

In the oil and gas industry, deadlegspipe sections without through-flowoften pose hydrate control challenges to gas and oil production systems. The hydrate challenges, if not properly managed, can cause severe consequences in terms of safety and cost for oil/gas production. This paper provides an overview of deadlegs in oil and gas production systems with some examples of typical challenges faced in the oil industry. Two different types of vertical deadleg experimental systems have been developed to acquire a better understanding of hydrate risks in gas-dominated deadlegs. These systems offer valuable quantitative information on hydrate deposit, such as thickness, porosity, morphology, growth rate, distribution, temperature profile, and amount of water and/or gas consumed as a factor of time in the deadleg system.

Hydrate Management in Deadlegs: Effect of Natural Convection on Hydrate Deposition

“…Instrument lines, production lines, chemical lines, and pressure safety valve lines are common examples of the deadlegs in oil and gas production. In production, due to the lack of flow through the deadlegs, the temperature in the deadlegs is often much colder than that in the main flowlines, which can lead to hydrate deposition in the deadlegs, with high risk for hydrate plugging . Thus, it is of great importance to study the characteristics of hydrate deposition in deadlegs.…”

“…The investigations of Nazeri et al only provided some preliminary results on hydrate formation and deposition in deadlegs. In order to perform more systematic and in-depth studies, Equinor (formerly Statoil) and the Phases to Flow Laboratory at the Colorado School of Mines developed and constructed a series of experimental systems to mimic gas-filled vertical deadlegs connected to a header supplying water and gas . By using the experimental systems mentioned above, many studies were conducted.…”

“…In production, due to the lack of flow through the deadlegs, the temperature in the deadlegs is often much colder than that in the main flowlines, which can lead to hydrate deposition in the deadlegs, with high risk for hydrate plugging. 12 Thus, it is of great importance to study the characteristics of hydrate deposition in deadlegs. Recently, several studies have been done to investigate hydrate formation and deposition in deadlegs.…”

“…In order to perform more systematic and in-depth studies, Equinor (formerly Statoil) and the Phases to Flow Laboratory at the Colorado School of Mines developed and constructed a series of experimental systems to mimic gas-filled vertical deadlegs connected to a header supplying water and gas. 12 By using the experimental systems mentioned above, many studies were conducted. Sa et al 15 investigated the characteristics of hydrate deposition in a 1 in.…”

Rock-Flow Cell: An Innovative Benchtop Testing Tool for Flow Assurance Studies

“…In particular, the phase changes and precipitation of solids such as gas hydrates, wax, asphaltenes, and scale are critically important, as they can even lead to catastrophic blockage in flowlines. , The resulting pressure drop and reduced production rate cause severe production losses and safety concerns. It is thus essential to have sufficient knowledge about how to properly manage such flow assurance issues for a sustainable and reliable operation of oil and gas production. − …”