Abstract

Literature data on the influence of magnetic fields on organic deposition process are most oriented to charged species, e.g., calcium carbonate scale. It has also been claimed that the use of magnetic tools can mitigate paraffin deposition in flow lines. If this technique can be applied to subsea flowlines the benefits are potentially high. However, magnetic tool manufacturers do not provide the necessary level of information to make the customer feel comfortable to rely on such devices. Therefore, a research project has been established to shed some light to this yet controversial subject. The paraffin crystallization process under the influence of magnetic fields and paraffin inhibitors (PIs) has been investigated with the aid of Microscopy. The objective of this study was three-folded - to provide a laboratory evidence to recommend - or not - the use of magnetic tool in the field, - to verify the Microscopy usefulness to study non-isotropic paraffin crystallization process and, - to provide an additional tool to help in selecting PIs. To our best knowledge the technical contributions of this study are- to confirm that magnetic field do alter paraffin crystallization process, - to establish a relationship between PIs and the paraffin crystallization process and, - the development of experimental analytical procedures to investigate paraffin deposition-related processes.

Introduction

Paraffin deposition is a well-known phenomenon that plagues the oil industry all over the world. As a rule paraffin problems can been solved in onshore fields with inexpensive physical and chemical methods. However, as the oil industry is continually moving to deep water scenarios where paraffin deposition takes place in difficult-to-reach subsea flow lines, manifolds and wet Xmas trees, no inexpensive solutions are known. Conversely, operators are concerned to paraffin deposition problems in deepwater production facilities for they are costly, time-consuming and means a serious menace to the economical feasibility of their enterprises. To cope with operational problems associated to organic deposition in deep waters, Petrobras has been funding an integrated research program - the so-called Petrobras Flow Assurance Program (PROCAP) - aimed at forecasting organic deposition and preventing and/or solving the problem in offshore wells. A set of preventive and remedial solutions were either in-house- or jointly-developed. The major products that arose from this research effort are briefly described as follows:

Pigging A jointly industrial project on pipeline pigging simulation was launched by Petrobras in 1996. More than one hundred successful pigging operations have been conducted in subsea flow lines in Campos Basin so far.

Nitrogen Generating System (SGN) The SGN method comprises the controlled reaction between two nitrogen-containing chemicals which is capable of generating a large amount of nitrogen gas and heat. The method has been successfully used in more than one hundred operations in Campos Basin area.

Paraffin Inhibitors The use of paraffin inhibitor (PI) is another approach to solve paraffin deposition problems in offshore fields. The technology which also includes the correct application of these chemicals in the field has been used in a long-term test in the Albacora field, Campos Basin. On-going research on this subject has been oriented toward finding more cost-effective PI's and understanding how these chemicals prevent paraffin crystals from growing. Magnetic devices

A study to investigate the potential of the so-called magnetic fluid conditioners (MFCs) to inhibit paraffin deposition is being carried out at Petrobras Research Center.

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