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Inflatable or Temporary sleeve around logging instrument to improve tool response in gas- or air-filled borehole

IP.com Disclosure Number: IPCOM000249399D
Publication Date: 2017-Feb-23
Document File: 2 page(s) / 133K

Publishing Venue

The IP.com Prior Art Database

Abstract

The formation sensitivity of certain wireline logging instrument (e.g. pulsed neutron instrument) reduces due to presence of air or gas in the borehole, whereas they perform optimally when the borehole is filled with liquid (water, brine, oil or mixture). A sleeve can be designed for such instruments which stays deflated on surface and is inflated downhole temporarily for logging purposes. Once logging has been completed, the sleeve can be returned back to the original shape for pulling out of hole. This way, the minimum restriction through which the tool is deployed may not have any changes.

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Title:  Inflatable or Temporary sleeve around logging instrument to improve tool response in gas- or air-filled borehole

Abstract:  The formation sensitivity of certain wireline logging instrument (e.g. pulsed neutron instrument) reduces due to presence of air or gas in the borehole, whereas they perform optimally when the borehole is filled with liquid (water, brine, oil or mixture). A sleeve can be designed for such instruments which stays deflated on surface and is inflated downhole temporarily for logging purposes. Once logging has been completed, the sleeve can be returned back to the original shape for pulling out of hole. This way, the minimum restriction through which the tool is deployed may not have any changes.

Description:  The formation sensitivity of certain wireline logging tools, e.g. Pulsed neutron tool, significantly reduces if the borehole is filled with air or gas. Hence, we recommend to fill the borehole with water, brine or oil, which gives higher sensitivity to the formation. The drop in formation sensitivity, in case of air- or gas-filled borehole, is primarily due to the low hydrogen index of the air or gas in the borehole. To work around this issue, a sleeve has been designed which is installed on the detector section of the pulsed neutron instrument. The sleeve has similar hydrogen index as that of water and helps in restoring the sensitivity of pulsed neutron tool towards formation. But, since the sleeve is of bigger diameter, the minimum restriction through which the tool needs to go through increases, which limits the wells on which the system can be deployed. As a solution to this issue, a sleeve can be designed for the instrument, which stays in deflated condition during deployment from surface, so that the tool can go across the minimum restriction. This may increase the diameter of the tool marginally and will still go through the minimum restrictions. Once downhole, the sleeve can be inflated (e.g. by carrying water in an additional chamber and then pumping it to the sleeve) for data acquisition purposes. Once data acquisition is complete,...