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Prediction of mineral scale formation in wet gas condensate pipelines and in MEG (mono ethylene glycol) regeneration plants

Abstract

Gas hydrate formation is a serious problem in the oil and gas industry, since its formation can plug wells and prevent production. The gas hydrate is a crystalline solid with a natural gas molecule surrounded by a cage of water molecules. It forms at high pressures and low temperatures. This is a problem for offshore gas wells, where the temperature is low in transport lines from well to the production facilities. Mono Ethylene Glycol (MEG) is commonly used as hydrate inhibitor. Classified as a thermodynamic inhibitor, this additive functions just as antifreeze in an automotive radiator. When producing oil and gas there will in most cases also be produced some water, which can contain dissolved salts. These salts may precipitate and they tend to deposit on surfaces. Deposition of inorganic minerals from brine is called scale. Generally MEG has the adverse effect of lowering the solubility of most salts. A common method to prevent corrosion in flow lines is to increase pH by adding basic agents (e.g. NaOH, NaHCO{sub 3}) to the MEG stream. In such cases, carbonate salts are particularly troublesome since an increase in pH by one unit, will reduce the solubility by two orders of magnitude. Thus  More>>
Publication Date:
Dec 20, 2006
Product Type:
Thesis/Dissertation
Report Number:
2006:137
Reference Number:
RN07000131; TVI: 0620
Resource Relation:
Other Information: TH: Thesis (Dr.Phd); 172 refs., 86 figs., 48 tabs., 2 ills., 3 appendices; Related Information: Doctoral theses at NTNU
Subject:
36 MATERIALS SCIENCE; GAS HYDRATES; MINERALIZATION; ETHYLENE; PIPELINES; PH VALUE; CORROSION PROTECTION; CORROSION INHIBITORS; SCALE MODELS; SCALE CONTROL; EXPERIMENTAL DATA
OSTI ID:
20805442
Research Organizations:
Norges teknisk-naturvitenskapelige universitet, Trondheim (Norway)
Country of Origin:
Norway
Language:
English
Other Identifying Numbers:
Other: ISBN 82-471-8036-7; ISBN 82-471-8037-5; ISSN 1503-8181; TRN: NO0605506
Availability:
Commercial reproduction prohibited; OSTI as DE20805442
Submitting Site:
NW
Size:
209 pages
Announcement Date:
Dec 20, 2006

Citation Formats

Sandengen, Kristian. Prediction of mineral scale formation in wet gas condensate pipelines and in MEG (mono ethylene glycol) regeneration plants. Norway: N. p., 2006. Web.
Sandengen, Kristian. Prediction of mineral scale formation in wet gas condensate pipelines and in MEG (mono ethylene glycol) regeneration plants. Norway.
Sandengen, Kristian. 2006. "Prediction of mineral scale formation in wet gas condensate pipelines and in MEG (mono ethylene glycol) regeneration plants." Norway.
@misc{etde_20805442,
title = {Prediction of mineral scale formation in wet gas condensate pipelines and in MEG (mono ethylene glycol) regeneration plants}
author = {Sandengen, Kristian}
abstractNote = {Gas hydrate formation is a serious problem in the oil and gas industry, since its formation can plug wells and prevent production. The gas hydrate is a crystalline solid with a natural gas molecule surrounded by a cage of water molecules. It forms at high pressures and low temperatures. This is a problem for offshore gas wells, where the temperature is low in transport lines from well to the production facilities. Mono Ethylene Glycol (MEG) is commonly used as hydrate inhibitor. Classified as a thermodynamic inhibitor, this additive functions just as antifreeze in an automotive radiator. When producing oil and gas there will in most cases also be produced some water, which can contain dissolved salts. These salts may precipitate and they tend to deposit on surfaces. Deposition of inorganic minerals from brine is called scale. Generally MEG has the adverse effect of lowering the solubility of most salts. A common method to prevent corrosion in flow lines is to increase pH by adding basic agents (e.g. NaOH, NaHCO{sub 3}) to the MEG stream. In such cases, carbonate salts are particularly troublesome since an increase in pH by one unit, will reduce the solubility by two orders of magnitude. Thus there will be a trade off between good corrosion protection (high pH) and scale control (low pH). The aim of this work has been to develop a model that can predict mineral solubility in the presence of MEG. Experimental solubility data, together with thermodynamic data taken from literature, have been utilized to construct empirical functions for the influence of MEG on mineral scale formation. These functions enabled the expansion of an already existing aqueous scale model into a model valid for water+MEG mixed solutions. The aqueous scale model combines an equation of state (gas+oil phase) with the Pitzer ion interaction model (water phase) to describe the multiphase behaviour of gas-oil-water systems. This work summarizes the theoretical foundation and proposes how to work with pH in water+MEG solutions.}
place = {Norway}
year = {2006}
month = {Dec}
}