FORSKNINGSPROSJEKTER - Research Projects
Professor Jon Steinar Gudmundsson - Department of Petroleum Engineering and Applied Geophysics - Norwegian University of Science and Technology - Trondheim.

Roughness and Friction in Gas Pipelines

The project is based on the observation that commonly used friction factor correlations, e.g. the Colebrook-White correlation, are conservative (predict too high friction factor and hence too high pressure drop). Work started in mid-1995 and is planned to run for about 3 years in cooperation with Statoil. The work is carried out by Dr.Ing. student Elling Sletfjerding. The main aim of the work is to find a relationship between pipe roughness, friction factor and pressure drop; that is, measured roughness instead of equivalent roughness. Pipes with a range of roughness have been produced and tested for high-pressure natural gas flow at K-Lab (Statoil's calibration lab at Kårstø). Eight 6 m long pipes 150 mm ID were tested. One polished steel surface, one smooth coating and 6 with differend roughness coating. The surface roughness was measured and fractal methods are being use to characterize the roughness.

Storage and Transport of Natural Gas as Frozen Hydrate

The use of hydrate to store and transport natural gas has become feasible at atmospheric pressure. Work at NTNU has shown that natural gas hydrate is stable at atmospheric pressure provided the temperature is kept below the freezing point of water. Temperature in the range -15 to -10 C is considered appropriate. Work started in 1990 and has continued ever since. The frozen hydrat work has been carried out in close cooperation with Aker Engineering in Oslo. One of the Dr.Ing. students Aftab A. Khokhar is a visiting scholar at the Center for Hydrate Research at the Colorado School of Mines. The focus of his work is the storage of natural gas gas as structure-H. A hydrat laboratory has been built at NTNU for the purpose of obtaining data needed in the design of a commercial hydrate process. Dr.Ing. student Odd Ivar Levik started on the project in April 1996. From early-1997 a JIP (joint industry project) has been establised with the support of Aker Engineering and 6 oil companies. The JIP includes also the Hydrate Slurry to Transport Associated Gas project discussed below. The hydrate JIP has its own home page NGH at NTNU.

Hydrate Slurry to Transport Associated Gas

Work started in 1994 and continued in early-1996 by Dr.Ing. student Vibeke Andersson. A new process has been devloped to capture associated gas on offshore platforms. The gas is produced into hydrate, which is then refrigerated to -10 deg. C. The crude oil is also refrigerated to -10 deg. C. The frozen hydrate and the refrigerated crude oil are then mixted together to form a oil-hydrate slurry. This slurry is stable at atmospheric pressure. First-order cost estimates shown that the pay-back time is less than 2 years. Hydrate slurry can also be used for pipeline transport under pressure. The work is supported by the UTBYGG programme of the Research Council of Norway, Aker Engineering and since early-1997 by a JIP (Joint Industry Project) supported by 6 oil companies. The hydrate JIP has its own home page NGH at NTNU.

Gas/Liquid Flow Metering by Pulse Testing

The pressure pulse method is used to meter the gas/oil rate in oil wells and pipelines. The method is based on the water hammer equation and the Darcy-Weisbach equation. The gas/liquid mixture velocity and mixture void fraction are given directly - there is no "black box" and there is no need for calibration. The pulse test is designed for high-rate offshore wells and flowlines, but can also be used for other flow situtations, including dry gas wells and wet gas wells. The pulse test method is simple and cost effective, relative to other gas/liquid flow metering methods. Pressure pulse tests have been carried out on the Gullfaks platform in October 1995 and on the main Oseberg platform in January 1996. Read 12 viewgraphs from a presentation about the pulse test method to the European Production Engineering Association in March 1995.

Propagation of Pressure Waves in Gas/Liquid Mixtures

Work stated in late 1995 and is carried out by NFR (Research Council of Norway) supported Dr.Ing. student Kristin Falk. The project is scheduled for 3 years. The main purpose of the project is to develop a method to estimate the propagation properties of pressure waves in oil wells, similar to what is experienced in the pulse test for gas/liquid flow metering mentioned above. This to be able to give better answers (interpretations) in the pulse test method. Another way to describe the project is to say that it concerns two-phase flow water hammer effects.

Pressure Drop in Horizontal Wellbores

Work started in 1990 as a part of the PROFIT programme of the Norwegian Petroleum Directorate and several oil companies. The formal part of the project was compelted in late-1994. Work has continued in 1995 through specific tasks carried out for an oil company. Dr.Ing. student Su Ze defended his thesis on April 29, 1996. Several papers and technical reports have been published in this project. The pressure drop in horizontal wells is considered in terms of four main parts: wall friction, fluid acceleration, perforation roughness and mixing effects. It has been found that the fluid entering a wellbore through perforations, actually reduces the pressure drop, through an apparent smoothing effect.

Non-Darcy Gas Flow in Porous Media and Fractures

Work started in 1991 and was completed in late-1995 with the Dr.Ing. defence of Erik Skjetne. The work was supported by the PROPETRO programme of the Research Council of Norway (NFR). The project has been characterized by experimental work, theoretical work and computer simulation work. A number of scientific papers have been written and are being reviewed in international journals. In 1996 the project will be extended to fractures. This work will be carried out by Dr.Ing. student Trygve Kløv with support from the Nordic Energy Research Programme and Statoil.
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