DETECTION METHOD OF INDUSTRIAL GAS ACCUMULATIONS IN OVERPRODUCTIVE DEPOSITS Russian patent published in 2008 - IPC G01V5/04 

FIELD: mining engineering.

SUBSTANCE: geophysical investigations are performed by means of impulse neutron-neutron logging (INNL) and analysis of time distribution of the thermal neutrons density. For this purpose, time delay t₁ and t₂ as well as measuring windows Δt describing neutron properties of the cement environment and the bed, are selected so that to exclude interference. The neutron density J₁ and J₂ is measured in the specified time windows throughout the studied interval of the well. The obtained curves J₁ and J₂ are normalised by the marker bed characterised by absence of gas accumulation and a good cementing quality. In addition, gas accumulation zones are discovered in a differentiated manner behind the column in the cement stone for increasing the neutron density by 6-10 times at a virtually constant damping decrement of the neutrons in the collector layers, and in the collector layers gas accumulation zones are discovered by a spontaneous increase in the neutron density by more than 10 times with a damping decrement of the neutrons being close to "0".

EFFECT: enhanced accuracy and reliability of detection of the zones of migration and secondary gas accumulation behind the casing column.

2 dwg