|
Wax Control in the Presence of Hydrates RPSEA 1201
Overview
Wax precipitation in flow lines is a serious problem. Unique challenges are associated with transporting fluids through long subsea pipelines. One way of preventing wax precipitation in long subsea lines is to insulate them – an expensive solution. One idea that has been tested recently, but not been implemented commercially, is cold flow. The idea is to use a non-heated, uninsulated pipeline to transport oil-water mixtures in cold, subsea environments where both hydrates and waxes are likely to form. The concept in cold flow is to create slurry of hydrate and/or wax particles and transport the oil-water mixture in the presence of this slurry. The seed particles in the slurry act as nucleation sites and prevent or minimize further wax deposition...
A number of other wax control technologies have been proposed, some of which are being commercially used. These include mechanical methods such as pigging, chemical injection technologies and thermal management strategies, which focus on preventing the problem. In previous studies, no single strategy has proven to be completely effective in preventing and/or remediating the problem. There is a necessity to carefully evaluate all available technologies, and select one or two for further evaluation.
This project uses a two-phase approach to identify the most promising technologies and forwarding them for further testing toward commercial maturity. First a comprehensive literature survey will be undertaken on this subject, and all the possible options for wax control in cold-flow subsea pipelines will beconsidered. This review and analysis will yield two technologies for further evaluation. These technologies will be selected based on our analysis coupled with interaction and feedback from the industrial board and from RPSEA. Testing of deep-sea flow assurance technologies will require good understanding of oil and chemical characterization, properties measurement, fluid rheology (including slurry hydrodynamics) and interfacial and surface properties. The University of Utah is uniquely positioned to undertake this project because of existing facilities and knowledge and experience in all the aspects described above. Comprehensive projects on wax precipitation in the trans-Alaskan pipeline, high-pressure carbon dioxide induced asphaltene precipitation studies, fluid compatibilities with respect of asphaltenes and waxes and chemometric methods development have all been performed at the University in the last ten years. Laboratories at the University are equipped with oil and gas characterization analytical equipment (gas chromatographs, mass spectrometers, liquid chromatographs, elemental analyzers, etc.), rheometers (including constant stress and equipment necessary for slurry characterization), instrumented flow loops and laser and particle-imaging velocimetry (PIV) visualization tools. The team at the University will assemble a high-pressure flow loop capable of PIV and a high-pressure rheometer for Phase 2 of the project.
The team of principal investigators at the University (Deo – characterization, precipitation and flow, Magda – rheology and Mclennan – slurry transport), will be complemented by Dr. Rich Roehner, a consultant with significant experience in all aspects of wax control in pipelines. Potential benefits of the project include identification and testing of two of the most promising subsea wax control technologies for further evaluation.
Objectives
The objective of this project is to develop a fundamental understanding of preventing wax formation in deep uninsulated subsea pipelines. Two major tasks to accomplish this objective would be:
- A comprehensive literature review concerning flow in subsea pipelines, hydrate and wax formation, and methods to prevent deposition.
- An experimental program to evaluate two of the most promising technologies for preventing wax formation.
Approach
Phase 1: Literature Search and Wax Management Screening
This work will document and:
- Identify new wax management technologies
- Determine Technology Readiness Level (TRL) for all options (compatible with cold flow)
- Identify wax management technical gaps and areas for future improvement
- Report summarized findings from current technology evaluation
- Determine the testing methods of oil samples to determine predict wax deposition issues
- Determine the state-of-the-art in wax deposition simulation models
Phase 2: Proof of Concept Screening
This work will document:
- The definition, performance and data analysis for promising technologies proof-of-concept testing.
- Development of a qualification plan for promising technologies to be evaluated in a future RPSEA program.
Project Results
Literature Analysis (Login Required)
|