TRIPHASE FLOW AND PIPELINE/RISER COUPLING

Objectif

The project consists in the production of crude oil or gas in wells and in the transport via flowlines and pipelines under polyphasic flowing conditions of such hydrocarbons towards processing units.
The general purpose is to finalize the development of a number of computing methods for these polyphasics flows : these include various flowing patterns which are still poorly known in spite of the increasing research in this domain in the past years i.e. transport of multiphase effluents. These models will allow production cost reductions and development of new production configurations.
Usually based on correlations restricted to a small validity domain, traditional computing methods are not accurate enough ; optimization of production equipment and operating techniques.
PHASE 1 : TRIPHASIC FLOWS
A thorough databank including 96 measuring points among which 45 under triphasic conditions and 51 under diphasic conditions water/air and oil/air has been developed at the I.M.F.T. and completed by measuring points obtained on the diphasic test loop of Boussens in diameters of 3" and 6" with the oil/gas and water/gas system.
Results have shown that the creep relative to these two phases is very low, and that the triphasic flow gas-oil-water can be assimilated to a diphasic flow gas-liquid, in which the liquid presents particular rheological properties. Interpretation of the overall test data has allowed the adaptation of the gas-oil diphasic computation model developed within the scope of a previous contract, so to cover precisely the overall gas-liquid polyphasic flows. The WELLSIM programme, incorporating this model, has been tested on operational data deriving from oil and water production wells: the average error is more satisfactory than the resultsof similar comparisons, with conventional computing methods.
PHASE 2 : PIPELINE-RISER COUPLING
Mechanisms that govern the formation of instabilities and their frequency have been recognised during specific experiments run under stable flow (high speeds) and instable flow (low speeds) conditions. This enabled us to set-up an equation system which translates the movement mass and quantity balance in an unsteady pattern. However, difficulties were encountered while carrying out the numerical resolution of the system comprising a minimum of simplifying hypotheses. A simplified model called voluminal with numerical resolution of equations through the method of finite differences has allowed to recover in a qualitative manner the aspect of pressure or flowrate fluctuations measured at the riser foot but the accuracy, which depends on the time pitch, proved to be insufficient. Hence, a second model including a smaller number of simplifying hypotheses has been set-up using as an equations resolution mode the method of characteristics. Difficulties of numerical order were then encountered and additional studies are presently undertaken in view of finalisation so to run the overall validation tests required. This is being performed beyond the scope of this project.
PHASE 3 : TRANSIENT DIPHASIC FLOWS
The preliminary studies on transient diphasic flows have been carried out. Tests and modelling studies have been untertaken in view of setting up a computation method within the scope of other projects.
The project is to be developed in three phases :
Phase 1 : Study of triphasic flows in tubings.
The instrumentation and data processing system on a triphasic flow test loop have been improved and finalized. The tests were started under diphasic gas-oil and gas-water conditions in order gradually to introduce the new triphasic flow parameters and to examine more in detail the part played by each of the liquid phases. An initial campaign of tests under triphasic conditions was then undertaken with an oil content of 70 % in the liquid mixture. In addition, a test campaign under petroleum conditions with a natural gas-water system was performed on the Boussens diphasic loop in order to study problems of water carryover in natural gas wells.
Phase 2 : Study of the instabilities causes by pipeline-riser coupling in diphasic flows.
The coupling between pipeline and riser was covered by a campaign of systematic tests so as to recognize the flow conditions in two horizontal and vertical lines, coupled or not coupled. The limit between stable and unstable flow conditions was specified. A simple model was developed to take into account the phenomena of instability : the initial results are encouraging.
Phase 3 : Transient diphasic flows in transport pipelines : analysis of the present data and definition of an experimental and modelling programme (preliminary study). Transient diphasic flows underwent preliminary study. This study has enabled a specific research programme on these flow conditions to be defined.

Programme(s)

ENG-HYDROCARB 1C - Programme (EEC) of Community projects in the hydrocarbons sector, 1973-1985

Thème(s)

1.12 - TRANSPORT

Appel à propositions

Data not available

Régime de financement

DEM - Demonstration contracts

Coordinateur

GERTH

Contribution de l’UE

Aucune donnée

Adresse

232 AV. NAPOLEON BONAPARTE
92500 Rueil Malmaison
France

Coût total