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Contenido archivado el 2022-12-27

ACOUSTIC MEASUREMENTS ON RESERVOIR ROCK

Objetivo

The objective of the research is to determine more rock properties from the microseismogram obtained via borehole measurements with the Sonic tool.
- An atmospheric acoustic measurement set-up has been constructed consisting of : XYZ system, programmable waveform generator, oscilloscope, transducers and amplifiers. The equipment is controled by an IBM PC and allows the storage, plotting and calculation of the data. Both refraction and transmission measurements can be performed.
- A borehole simulator (triaxial cell) has been designed and built allowing acousting refraction measurements at 435 bar and 150 degrees C at conditions corresponding to 4000 m depth. The sample size is 400 mm in diameter with a height of 600 mm.
- Establishing a relation of rock properties with acoustic properties from field microseismograms is extremely difficult because too many unknown factors are present.
- Reservoir samples can be constructed in the laboratory with the silica-lock process or with araldite in which one rock property can be changed keeping the other properties constant. The rock behaves as real subsurface reservoir rock.
- The software developed for this project gives theoretical estimates that highly improves the interpretation of the experiments. The computer models are based on the Biot theory and Biot theory with a frequency limit.
- Using the transmission measurements with Plona's method the attenuation constants of the rock are determined with three methods. The methods compare very well. It is therefore advised to use the highest amplitude method.
-The computer program using the 'Biot theory with frequency limit' is very fast and gives accurate wave mode velocitites. The attenuation of shear and fast compressional are predicted accurately. The attenuation of the slow compressional mode is not correct.
During the field applications new evaluation methods have been developed:
1. The shale fraction present in a reservoir can consist of a varying mixture of different clay minerals. Each mixture is characterized by its own shale point, resulting in a range of five shale points valid for the reservoir interval in our shaly sandstone example.
2. A method is proposed to obtain the five shale points from the logs.
3. As a result the hydrocarbon conten of the reservoir is determined more accurately.
Microseismograms are measured under atmospheric pressure and room temperature on artificially created rock. The synthetic rock closely resembles "natural" sandstone but it has the advantage that all rock parameters are known exactly and can be changed independently. Thus by changing one rock parameter it is attempted to establish a correlation between that particular parameter and the received microseismogram. To investigate the influence of pressure and temperature on the recorded wave train the acoustic measurements will also be performed in a triaxial cell under conditions of up to 400 bar pressure and 150 deg. C.

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

COLLEGE VAN BESTUUR DELFT UNIVERSITY OF TECHNOLO
Aportación de la UE
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Dirección
BUREAU HOGESCHOOL COLLEGE VAN BESTUUR P.O. BOX 5
2600 AA DELFT
Países Bajos

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Coste total
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