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Gamma-ray logging, compensated (dual) neutron logging and active casing collar locator slim tool (combination logging tool) SRK-42-220

The tool has the following modifications by max operating temperature T max and upper value of borehole hydrostatic pressure Pmax :
  by temperature: 120°C,
  by pressure: 80 MPa.

Designed to measure exposure rate (ER) of natural gamma radiation (gamma-ray logging – GR), water-filled porosity by compensated thermal neutron-neutron logging (2NNLth) and casing collar location. Scattered thermal neutron-flux density is measured while logging; counting rates in the channels of near and far sondes and technological parameters (temperature inside the tool, supply voltage etc.) are recorded while logging

Used for logging of open and cased oil and gas wells filled with any mud.

Applications:
 determination of porosity;
 detailed lithological identification;
 gas-bearing formations identification, gas-liquid and oil-water contact identification;
 gas saturation coefficient determination.

The measuring equipment of compensated neutron-neutron logging contains chamber for fast neutron encapsulated source (Pu+Be with 0.3÷1.4 CU output) and two thermal neutron helium detectors (9.6 Íå – 3/760/25ÍÕ, 25 Íå – 3/760/25ÍÕ). GR measuring equipment contains one scintillation gamma-ray detector (NaJ(Tl) or CsJ(Na) 30×170 mm).

Measured parameters Range Error
ER of rock’s natural gamma radiation 0÷250 mR/h ±15 %
Water-filled porosity by 2NNLth 1÷40 % 4.2+2.3(40/phi-1)%

General specifications
Tool length, mm 3385 not more than
Tool diameter, mm 43 not more than
Tool weight, kg 20 not more than
Power supply
supply voltage, V
frequency, Hz
±10%
±1%
 
Borehole diameter, mm 180  

Logging speed, m/hr

in terrigenous section
in carbonate section


250÷400
400÷800
 
Records frequency, pollings per 1 m 10÷20  
Combinability feed-through  
Location in the borehole free