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Zawartość zarchiwizowana w dniu 2022-12-27

IMPROVED METHOD OF MEASUREMENT AND CHARACTERIZATION OF THE POROUS MICROSTRUCTURE OF OIL RESERVOIR ROCKS

Cel

The main objectives of the project are the following :
a) Development of a laboratory apparatus and technique for the serial microtoming of double pore casts of reservoir rocks and data processing with image analysis.
b) Development of a computer-aided simulator of mercury intrusion and retraction in a network of chambers and throats.
c) Development of a code for microcomputers, which will give the characteristics of the pore microstructure of reservoir rocks based on data from serial microtoming and mercury intrusion-retraction.
d) Demonstration of the system through application to core samples from Greek oil reservoirs.
Stage 1: The experimental technique was developed to the point that production and serial microtoming of pore casts is done on a routine basis.
We also developed a computer code that converts data from serial microtoming and image analysis into information concerning the chamber size distribution, the specific genus (genus per unit volume), and the coordination number. The computer code is in a user-friendly form.
Stage 2: We developed an experimental apparatus for the visual and quantitative study of mercury intrusion-retraction in planar pore networks. We also developed a simulator for this process. The objective of this work is to study mercury porosimetry under well defined conditions.
We developed a simulator of mercury intrusion-retraction in a three dimensional chamber-and-throat network, see ref. (3). Special emphasis was given in the development of simple rules for the advancement of menisci, the rupture of mercury threads, and the entrapment of mercury, which reflect thephysics of the process correctly. A systematic study of the effects of various geometric, topological and statistical parameters on the mercury porosimetry curves was made.
We completed a parametric experimental study of immiscible displacement in model porous media. This work reveals the mechanisms of immiscible displacement, and thus it acts as a guide for the development of theoretical simulators. We also developed a network-type computer simulator of immiscible imbibition which takes into account the role of the precursor wetting film in the disconnection of the non-wetting fluid, and also a network type computer simulator of the motion of note-wetting ganglia in porous media (see ref (1) and of collision and coalescence of ganglia (see ref. (2).
Stage 3: We developed a computer code that predicts mercury intrusion and retraction curves, if the pore structure is known. We also developed an interactive computer aided procedure for solving the reverse problem.
Stage 4: Over a two hundred core samples from Greek drilling sites have been analyzed to the extent permissible by the current state of advancement of out technique.
The project is divided in four stages :
Stage 1
Task : Development of the apparatus and technique described in objective A.
Method : The equipment consists of : (i) a specially designed apparatus for the preparation of pore casts, using epoxy resins; (ii) a microtome; (iii) microscope with high resolution TV camera; (iv) image analyzer. Pore casts are subjected to serial microtoming at 7.5 um intervals. The image analyzer is used to digitize and store the images of the section faces.
A computer code, especially developed for purpose, is used to analyze these data in order to obtain information about the pore (chamber and throat) size distribution, the skeleton of the pore network, the genus per unit volume, and the coordination number distribution.
Stage 2
Task : Development of the simulator of mercury porosimetry described in objective B.
Method : Information about the throat size distribution can by obtained by deconvolving the intrusion-retraction curves. To this end, a reliable mercury intrusion-retraction simulator for three dimensional chamber and throat networks was developed. This simulator takes into account the mechanisms with which mercury menisci move in pores and stop at entrances to throats or (in certain cases) chambers. It also takes into the mechanism of snap-off, which lads to the disconnection and entrapment of mercury in the form of ganglia, during retraction as well as the sequence with which mercury menisci move and threads rupture.
Finally, the microroughness of the pore walls is taken into account by modelling it as a fractal surface.
Stage 3
Task : Development of a computer code for the determination of the characteristics of the pore microstructure of reservoir rocks, as described in objective C.
Method : A computer code (compatible with the IBM PC-AT, or similar microcomputer) was developed, which is able to determine the throat size distribution that gives the best fit to the mercury intrusion-retraction data. To this end the code will accept as input the following; (i) chamber size distribution; (ii) porosity (from maximum mercury intrusion); (iii) the range of the throat-to-chamber coordination number and genus per unit volume ( from stage 1); (iv) digitized data from mercury porosimetry curves (the initial drainage and imbibition curves).
A suitable parametrized throat size distribution is assumed, and the optimal values of the parameters are determined.
Stage 4
Task : Realization of objective D.
Method : The practicability of the method consisting of the results of stages 1. 2 and 3 was demonstrated by applying the technique to core samples from Greek reservoirs and drilling sites. A systematic analysis of samples from Greek reservoirs was performed, in close cooperation with the Public Petroleum Corp. of Greece, and a library of results was established.

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Koordynator

INSTITUTE OF CHEMICAL ENGINEERING AND HIGH TEMP.
Wkład UE
Brak danych
Adres
PO BOX 1239
26110 Patras
Grecja

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