Density - neutron module МRК
The density - neutron module of the Corvette-3 LWD system includes both neutron and litho-density logging sondes, enabling reliable measurements of the following rock properties:
- Azimuthal water-saturated porosity;
- Azimuthal bulk density;
- Photoelectric absorption index (photoelectric factor);
- Borehole diameter
The litho-density logging probe was developed in collaboration with a leading Russian company in the field of radioactive methods NPP “Energia.” The device includes two gamma-gamma-ray logging sondes for measuring rock bulk density and a separate sonde for recording the gamma-ray spectrum to determine the photoelectric absorption index (photoelectric factor).
Data from both long- and short- spacing gamma-gamma-ray sondes integrated with rock bulk density provides a borehole diameter log. Water-saturated porosity results from a dual-spacing thermal-neutron logging lool.
Shielding of both neutron and density logging probes enables azimuthal density and porosity measurements and imaging. The images provide the intersection angle of the borehole with bed boundaries to clarify the location of the wellbore relative to geological objects and adjust the geosteering model in real time. A replaceable stabilizer sustains a high quality of bulk density measurements.
The outer diameter of the stabilizer depends on the diameter of the utilized drilling bit. The design of the docking adapters allows repairing the connecting thread up to five times.
The density - neutron module is available in two outer diameters: 121 mm and 172 mm. The module parts are made of high-strength non-magnetic steels and specialized erosion-resistant alloys. The design provides for the use of special vibration isolators and shock absorbers when installing all the electronic and measuring components of the module. After manufacturing, each module undergoes lengthy tests under conditions of high vibration, temperature, and pressure.
The design of the litho-density logging probe as a separate unit facilitates its maintenance and testing.
The density probe stabilizer is a single part without a cut that significantly increases its operational reliability and ease of maintenance.
|Parameter||Value / Range|
|Module O.D.||121 mm, 172 mm|
|Maximum temperature||+ 120 ° С (+ 150 ° С on request)|
|Maximum pressure||80 MPa (100 MPa on request)|
|Density measurement range||1.7 - 3.0 g / cm3|
|Density measurement accuracy||± 1.5% from 1.7 to 2.0 g / cm3
± 1.2% from 2.0 to 3.0 g / cm3
|Density Measurement Azimuthal Sectors||32|
|Water-Saturated Porosity Measurement Range||0 - 50%|
|Water-Saturated Porosity Measurement Accuracy||± 1.0% at Kp = 20%
± 4.0% at Kp = 30%
|Water-Saturated Porosity Measurement Azimuthal Sectors||16|
|Photoelectric absorption index measurement range||1.0 - 7.0|
|Photoelectric Absorption Index Measurement Accuracy||± 0.2 at Pe <2.5
± 0.25 at Pe> 2.5