Active Heated Pipe Technologies for Field Development Optimisation

Abstract

Active heated pipe technologies are enabling solutions for field developments allowing cost effective management of flow assurance to overcome specific challenges like longer distance tie-backs and greater water depths. This paper introduces wax and hydrate issues and conventional approaches to manage them. It highlights the need for other approaches, such as active heating technologies, to reach longer tie-back distances and greater water depths. It reviews Direct Electrical Heating (DEH), Electrically Heat-Traced Flowline (EHTF), and active heated flowline bundles comprising Hot Water Circulation (HWC) and EHTF in bundle. A general presentation of these systems is given, including design, fabrication and installation methods, as well as the maturity of the technology. Typical field architecture is proposed to illustrate the benefits of each active heating technology in terms of field development optimisation. This paper provides global information and an understanding of different available solutions for active heating pipeline systems, with technical and economic perspectives, and concludes with elements for selection of optimised field architecture. Wet DEH is a field proven technology with large track record that has already been installed on a 43km pipeline in 1070m water depth. It fits production fields not requiring high thermal insulation performances and thus allowing wet insulated pipe (U-Value =2W/m2.K). The system presents high electrical power requirement (50-150W/m). Therefore, infrastructure capacities in terms of footprint and power supply available have to be checked against specific project power requirements. EHTF fits production fields requiring high thermal insulation performance provided by Pipe-in-pipe (down to U-Value < 0.5W/m2.K). Thanks to its high efficiency, the system has low power requirement (typically below 50W/m). Therefore, it can also be an alternative to DEH when topsides capacities cannot meet footprint and power supply requirements. Pipeline heat tracing is a known technology for onshore plants and by extension applicable for subsea applications. The implementation of EHTF is completing qualification of this technology for deepwater applications. HWC within bundle is a field proven technology. It fits production fields requiring high thermal insulation performance provided by bundle arrangement (down to U-Value < 0.5W/m2.K). The technology requires power and equipment to heat water thus impacting topsides space. These requirements vary considering project specific needs and selection of direct or indirect heating. For example, re-use of the produced water as an indirect heating medium can highly limit required power generation.

Field Development Cost Optimization: a SURF Contractor's Experience and Perspective

“…Active heated pipe technologies represent technical enablers for challenging field developments as well as opportunities for cost reductions, as described in [7].…”

“…A conventional production loop system can thus be replaced by a single heated production line (illustrated in Figure 14), what represents significant cost savings associated with a reduction by half of the flowlines length and the removal of one riser. The active heating technology may be based on direct heating (Direct Electrical Heating -DEH, see [7]) or trace heating (see next paragraph).…”

An Overview of Flow Assurance Heat Management Systems in Subsea Flowlines

“…Flow assurance issues are part of these risks and with most of the conventional fields already being produced, operators are facing in the past 15 years increasing issues in developing fields that have changed from stand-alone host structures and largely concentrated resources to scattered ones with tie architectures to existing facilities or shores [160]. In the last 10 years [161], the numbers of long tie-backs doubled [162]. Truly, long tie-backs to existing infrastructures (higher than 10 miles for oil fields and 30 miles for gas fields) are planned, from a cost perspective, as they give entry to far reserves circumventing new topside installation [161].…”

“…In the last 10 years [161], the numbers of long tie-backs doubled [162]. Truly, long tie-backs to existing infrastructures (higher than 10 miles for oil fields and 30 miles for gas fields) are planned, from a cost perspective, as they give entry to far reserves circumventing new topside installation [161]. By venturing further and into deeper subsea, together with growing flow assurance issues associated with fluid characteristics (hydrates, wax, high viscosity, pour point) as well as flowing conditions (temperature, pressure, flow rate), have expanded conventional flow assurance methods wax and hydrate prevention which included passive insulation to its limits, forcing the use of conventional or hybrid loop architecture (e.g., depressurization, dead oil circulations, and chemical injection to its limits) at elevated costs [160].…”

Electrical Power Infrastructure and Control Solutions for Subsea Electrically Heat-Traced Flowline Pipe-in-Pipe EHTF PiP System

“…1), has been well described and documented in previous papers (Cherkaoui 2016, McDermott 2014, Louvet 2016 and in very basic terms comprises a Pipe-in-Pipe (PiP), high performance thermal insulation, specifically designed electrical heating wires and various dual barrier connecting methods (to gain electrical access to the enclosed heating wires within the PiP annulus) typically forming a low power EHTF system as developed by Subsea 7 and ITP InTerPipe. The EHTF system presented ( Fig.…”