NEW TECHNOLOGIES DEVELOPMENT IN THE STUDY OF PETROLEUM BASINS THERMICITY

Ziel

The aim of this project is to elaborate new reliable techniques for exploration of complex geological areas like the North Sea, from data obtained by the study of hydrocarbon bearing fluid inclusions and the comparative study of two geothermometers (Organic matter and Fission Tracks).
This program is characterized by a new approach of petroleum basin thermicity study, the achievement of which is bounded by several rules :
- the combined use of direct investigation tools
- the choice of thermal markers, the application of which is compatible with the temperature range of oil window
- the experimental calibration of these markers
This is an original and alternative way to obtain more precise time -temperature data to be introduced in computer programs designed for the genesis and migration of hydrocarbons.
The representativity of the analyses of the hydrocarbon inclusions were tested on standard inclusions, synthetized in laboratory grown salt crystals at low temperature with alkane, benzene, isobutylbenzene, toluene, and natural oils. These standard inclusions were used to calibrate the analyses achieved on natural inclusions.
Different analytical techniques were applied to standard synthetic inclusions and natural hydrocarbons inclusions from some petroleum resevoirs :
- microthermometry
- Fourier transform infrared microspectroscopy
- Raman microspectroscopy
- UV fluorescence emission
- 1H NMR : the first results obtained on synthetic and natural inclusions show the proton contribution of water, aliphatic and aromatic fractions and methane. Spectra of the standard oil, free and trapped in inclusions, are similar. The increase of the NMR sensitivity is however necessary in order to quantify the chemical informations obtained from natural inclusions.
Important improvements were obtained for the characterization of the hydrocarbon inclusion content. Different generations of hydrocabon fluids have been thus detected in the salt formation of the Gabon margin. However, the thermobarometric treatment of these data remains unprecise.
For the apatite fission track analysis, the objective was first to improve the technique for age determination and track length measurement, then to compare the track healing kinetic with the thermal evolution of the organic matter, and finally, to study the influence of the apatite chemistry on the track retention.
Different points have been developed :
- technical improvements : the calibration of the age measurement has been achieved and a semi-automatic equipment for the track length measurement has been realized. This equipment consists of an optical microscope with a drawing tube, coupled with a digitaliser linked to a computer. When the image of the lightly cursor is superimposed to the image of the fission tracks in the microscope, the length is measured and stored in the computer unit.
- comparison between two geothermometers : the kinetic of the fission track annealing in apatite has been compared to the thermal evolution of a type III organic matter. A relation between the Tmas parameter and the fission track length has been proposed.
- influence of the apatite chemistry on the track retention : the variations of the CI/F ratio within the apatite crystals modify the kinetic of the track annealing. One natural case has been described.
- modeling : a computer program for the modeling of the fission track length evolution with time-temperature conditions has been applied to different thermal history paths.
Preliminary applications have been developed about the Brent reservoirs and the Gabon margin. For the sedimentary series of the Alwyn zone, a temperature of 120 +/- 10 deg. C has been deduced for the combined use of fission tracks and fluid inclusions.
The program is divided into three stages.
Stage 1 : Physical modelling
Both simple hydrocarbon water mixtures (n-alkane, cycloalkanes, aromatics..) and crude oils will be trapped in minerals (halite , sylvite) in order to check the analytical techniques and to stimulate the natural geological systems. A pyrolysis technique allows to perform experimental simulations of organic matter maturation and fission tracks annealing under high pressures and high temperatures in a confined medium. A new device to determine routinely the length of fission track will be elaborated.
Stage 2 :Analysis
Different microprobe (microthermometry, UV and IR microspectrometry , Raman, laser-mass spectrometry...) and global techniques (N. M. R and gas chromatography will be applied in order to assess the chemistry of the trapped hydrocarbon and water mixtures in the natural fluid inclusions.
Stage 3 : All the new or improved devices and kinetic parameters obtained for organic matter and fission tracks analyses will be useful to provide new constraints for time-temperature data introduced in computer programs for basin modelling. This will be applied to a petroleum reservoir.
The study of hydrocarbon bearing fluid inclusions in common minerals of reservoirs and the numerical simulation of petroleum genesis and migration prediction from the geothermometers, will result in the production of a fast, reliable and inexpensive prospecting guide.

Programm/Programme

ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989

Thema/Themen

1.4 - GEOPHYSICS AND PROSPECTING

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

DEM - Demonstration contracts

Koordinator

CREGU

EU-Beitrag

Keine Daten

Adresse

BP 23
54501 VANDOEUVRE-LES-NANCY
Frankreich

Gesamtkosten