Hi-Tech production well-logging methods for solving geological tasks in open borehole

The complex of Hi-Tech well-logging methods includes:
• STAR electrical micro-imager.
• САС-90 acoustic scanner.
• XMAC acoustic cross-dipole well-logging device.


STAR electrical micro-imager

STAR Imager electrical micro-imager allows detailed high-resolution electrical survey of formations in conductive mud. The independent six-lever structure and the power deflector ensure optimal contact of sensors with the well bore even in inclined holes. The pads of the device having 24 sensors each are mounted on each of the six linked levers, which allows 144 micro-electrical measurements with vertical and azimuthal resolution of ~ 5 mm.

 
САС-90 acoustic scanner

САС-90 well acoustic scanner was developed by Geofizika Research and Production Company and is a Russian analogue of foreign acoustic imagers. The acoustic scanner allows receiving acoustic images of the well bore walls characterized by high resolutions.

 
Tasks solved with acoustic and electrical scanners:

1. Structural analysis:
• boundary detection of formations, interlayer, superposition with azimuthal reference in the space;
• outlining stratigraphic zones;
• detection of faults.

2. Fracture analysis:
• fractures detection;
• fracture classification;
• fracture openness;
• fracture spread.

3. Secondary porosity analysis:
• detection of secondary porosity zones (mostly cavernous intervals);
• qualitative characteristics of cavernosity by intervals;
• quantitative characteristics of cavernosity by intervals (secondary porosity coefficient).

4. Discontinuity analysis:
• detection of discontinuities (anomalies of resistance, conductivity);
• facial analysis (differentiation of rocks by textural attribute);
• detection of thinly laminated interlayering.

5. Rock stress analysis:
• detection of man-caused fractures;
• detection of borehole breakout;
• direction finding of the maximum stress of rocks.

6. Well bore geometry analysis.


Broadband acoustic cross-dipole well-logging with ХМАС device

The XMAC probe combines a set of monopole and crosswise dipole receiver-transmitters, which allow obtaining high quality data on speed of P-waves, S-waves, Stoneley waves in uncompacted, slow formations, as well as azimuthal measurements of anisotropy.
 

Cross-dipole well-logging solves the following tasks:
1. Calculation of interval times of P-waves, S-waves and Stoneley waves.
2. Determination of azimuthal anisotropy of bending S- waves.
3. Calculation of dynamic mechanical properties of rocks.
4. Determination of porosity, lithology and permeability.
5. Forecasting direction of natural fractures.
6. Forecasting direction of fractures during well stimulation.


Application of this complex also allows:
• Increase of the information content of the standard complex when distinguishing reservoirs and decreasing the risks of missing permeable intervals in the carbonate section.
• Identification of thinly laminated section in the terrigenous section, which considerably influences the evaluation of effective thickness and considerably influences vertical permeability.
• Forecasting fracture development direction of hydraulic fracturing.
• Determining height and azimuth of fracture development of hydraulic fracturing.

The data obtained with the Hi-Tech complex are required for selection of the most optimal patterns of deposit development to increase oil recovery factor.

Examples of the Hi-Tech complex diagrams are provided below.
 

Example of detecting structural elements by the data of STAR electrical micro-imager

Example of natural fracturing detection in the interval of 1435.5-1442.0 m according to САС-90 acoustic scanner

Example of open conductive fracture detection according to STAR (left) and CАС-90 (right)

Example of detection of man-caused fractures and well wall breakouts according to STAR (left) and CАС-90 (right) to determine the direction of maximum horizontal stress

 

Example of determining thinly laminated interlayers according to STAR (left) and CАС-90 (right)

Example of detection of thinly laminated interlayers and cavernosity according to STAR data

 

Example of STAR (left) and XMAC (right) data comparison in the high fracturing interval of 824-840 m.

Strike direction of fractures detected according to STAR data, and anisotropy direction according to XMAC data - match.