Method of investigation of oil and gas-producing wells

Abstract

A method of determination of oil- and gas-productive layers in a well, includes performing a first logging in a well having a casing over a potentially promising depth of a well from a space inside the casing radially outwardly through the casing by sending transmitting signals into layers near the well and receiving reflected signals, with perforations in the casing and in the layers in condition of presence of a filtrate in the layers in the near-well zone, insulating the perforations in the layers from an interior of the well, maintaining the perforations of the layers insulated from the interior of the well over a time sufficient for migration of the filtrate away from the near-well zone and accumulating in the near-well zone of the layers oil or gas, performing a second logging in condition when the near-well zone of the layers no longer contains the filtrate but can contain oil or gas, and comparing the reflected signals obtained from the second logging with the reflected signals obtained from the first logging to determine the presence or absence of oil or gas in the layers within the potentially promising depths.

1 . A method of determination of oil- and gas-productive layers in a well, comprising the steps of performing a first logging in a well having a casing over a potentially promising depth of a well from a space inside the casing radially outwardly through the casing by sending transmitting signals into layers near the well and receiving reflected signals, with perforations in the casing and in the layers in condition of presence of a filtrate in the layers in the near-well zone; insulating the perforations in the layers from an interior of the well; maintaining the perforations of the layers insulated from the interior of the well over a time sufficient for migration of the filtrate away from the near-well zone and accumulating in the near-well zone of the layers oil or gas; performing a second logging in condition when the near-well zone of the layers no longer contains the filtrate but can contain oil or gas; and comparing the reflected signals obtained from the second logging with the reflected signals obtained from the first logging to determine the presence or absence of oil or gas in the layers within the potentially promising depths. 
     
     
         2 . A method as defined in  claim 1 , wherein said first and second logging includes using a neutron logging determining neutron properties of the near-well zone of the layers for obtaining the reflected signals in the first neutron logging and obtaining the reflected signals in the second neutron logging and comparing the signals of the second neutron logging with the signals of the first neutron logging. 
     
     
         3 . A method as defined in  claim 1 , wherein said insulating includes introducing a cement solution between the casing and the layers for closing the perforations in the layers so as to interrupt a hydrodynamic communication between the layers and the well. 
     
     
         4 . A method as defined in  claim 1 , wherein said maintaining includes maintaining the perforations of the layers insulated for a period of 1-3 months.