New Trend in Oilfield Flow-Assurance Management: A Review of Thermal Insulating Fluids

Abstract

Flow assurance has been one of the major considerations in deepwater completion design, in which undesired heat loss from production tubing contributes to the formation of gas hydrates and causes the deposition of paraffin and asphaltene materials. Traditionally, controlling annular heat loss has been achieved with the injection of steam, the application of silicate foam, the pressurization of the annulus with inert gas, the use of gelled oil as an insulating packer fluid, and the use of vacuum insulated tubing (VIT). Each of these applications, however, has drawbacks because of either its working mechanism or the higher cost associated with the technology.To secure the insulation of the wellbore and to reduce heat transfer from the production tubing to the surrounding areas, various aqueous insulating fluid systems with superior thermal properties have been developed in recent years. Field applications of these fluids have demonstrated significant reduction in heat loss by reducing conduction and minimizing convection. These thermal insulating fluids have been implemented with great success in more than 75 deepwater riser and packer applications in the Gulf of Mexico (GOM) over the last several years. Case histories have demonstrated that installation of these water-based insulating fluids is an effective alternative to conventional insulation options and is becoming the preferred insulation method in many deepwater projects. This paper will highlight the evolution of different insulating fluid systems and the field experience with each system. Proper testing methods relevant to oilfield flow assurance will be discussed and testing results for these fluids will be detailed. Field cases in the GOM will be summarized, and the effectiveness of these fluid systems will be demonstrated.

An Overview of Flow Assurance Heat Management Systems in Subsea Flowlines

“…VIT is a remodeled PIP design system with an annulus at vacuum conditions that reduce the transfer of heat from the crude oil to the environment [50,126]. The VITs are regarded as expensive when compared to other passive insulation systems [50,126,[131][132][133] but are favorable in regions where crude oil has a high cloud point [50]. The advantage of the insulation modules for flow line applications is geometry modifications to suit both riser and additional lines [85].…”

“…The Norman and Alaska production fields deployed the VIT techniques to control the issues of flow assurance [50,126,[129][130][131]. They are seen as expensive when compared to other passive insulation techniques [50,126,[131][132][133] but might be favorable in areas like the Gulf of Mexico with a high cloud-point temperature [50,127]. Table 3 provides the vacuum insulation properties.…”

Fluid-fluid and fluid-solid phase equilibria in carbon dioxide + waxy systems 1. CO + n-C

“…The deposition and buildup of solid waxes on the inner surface of the cold pipe wall decreases the pipeline cross-sectional area and increases the surface roughness of pipes causing a restriction of oil flow and ultimately plugs the production equipments. Mitigation and remediation of waxy solid requires use of various techniques which includes mechanical cleaning (pigging) [2], chemical injection (inhibitors, dispersants or solvent) [3], thermal method (insulation, heating) [4,5] and surface treatment (anti-wax coating) [6]. Most of these techniques are costly and must be expanded in right place upon in an adequate manner.…”

Safer Dual-Functional Gas Hydrate Dissolver and Inhibitor to Replace Methanol

“…This solution may not be practical especially when production takes place from deep-water horizons . Another step is to increase the temperature of the conduit, either by insulating the conduit or by heating above the gas hydrate equilibrium temperature. − Other methods intend to either remove the free water from the gas or oil stream through a dehydration process, or add another gas (such as nitrogen, N 2 ) to modify the gas composition in a way that prevents the formation of the stable gas hydrate crystals. , …”