Session: 04-04-01 Flow Assurance & Subsea Equipment

Paper Number: 79513

79513 - Technical and Environmental Evaluation of a Hydrate Cold Flow Technique to Produce an Oil Reservoir Using a Long Tie-Back and Comparison Against Traditional Development Concepts 

In Norway, most of the future offshore oil and gas field developments are expected to be developed through tie-back solutions. Here, the produced reservoir streams are transported over very long distances on irregular terrain and cold ambient temperatures to processing facilities offshore or onshore. These conditions of high pressure and low temperature are likely to cause the formation of hydrate and wax particles that can lead to increased pressure drop and gradual or sudden plugging. Traditional measures to address hydrate and wax formation often involve the injection of chemicals, costly thermal insulation, or heating that have a high environmental footprint. An alternative measure less costly and more environmentally friendly is cold flow. Cold flow consists of inducing in a controlled manner the formation of hydrate and wax particles and the subsequent formation of a stable liquid slurry that does not agglomerate and plug the pipe downstream. This process is performed in a unit that consists of a reactor and a cooler.

This study presents a technical and environmental evaluation of a hydrate cold flow technique as a flow assurance method to produce an oil reservoir using a long tie-back and comparison against traditional development concepts. The case study is a synthetic field located on the Norwegian Continental Shelf. Several development alternatives were considered and compared:  1. production to an FPSO, 2. tie-back production over a distance of 100 km to an existing offshore platform using chemical injection and pipeline heating and 3. tie-back production over a distance of 100 km to an existing offshore platform using cold flow. Two reservoir recovery methods were considered: gas injection and water injection. A commercial transient multiphase simulator was employed to model the subsea system for the tie-back solutions. An analytical model was developed to compute the carbon emissions for each concept.

Results show that hydrate cold flow (case 3) can successfully be used to produce the reservoir. Some operational parameters are calculated and discussed such as: required length, branches and size of the cooler, boosting requirements, pressure drop in the pipeline. Advantages and limitations of the concept were identified and discussed, and a comparison is made against cases 1 and 2, considering costs, energy consumption, emissions during operation, and footprint.  

Keywords: Flow assurance, Hydrate formation, Carbon emissions, Cold Flow technology

 

Presenting Author: Leila Eyni Norwegian University of Science and Technology

Authors:

Leila Eyni Norwegian University of Science and Technology
Mostafa Fattahi Politecnico Di Torino
Heiner Schumann Sintef Industry
Fredrik Lund EMPIG
Milan Stanko Norwegian University of Science and Technology
Lars Strømmegjerde EMPIG