Kundu, Balaram¹, K.K. Prasad¹, Chatar Singh¹ 
(1) ONGC, Baroda, India

ABSTRACT: Performance of High Resolution Induction Tool (HRI) in WRBC

High-resolution induction tool (HRI) along with state of art logging unit EXCELL - 2000 was inducted into the suite of in-house logging tools in early 1997. Fourteen wells have been logged with this tool so far, which have been studied herein to assess the performance of this tool in the area under Ankleshwar project e.g. Gandhar, Kosamba, Kim etc., vis-a-vis environment under which recording was done. This study brings out that for generating resistivity data of reliable quality from HRI tool, it should be run against the zones where Rm is above 0.1 ohm.m at formation temperature. This is corroborating with limit of Rm as suggested by the manufacturer. It has been observed that not only the limit of Rm value at formation temperature but the ratio Rmf/Rw also has a bearing on the performance of this tool. Preferable value of this ratio should exceed 0.3. This limit of Rmf/Rw is the out come of this study. The wells where Rm < 0.1 ohm.m. at F.T. and Rmf/Rw < 0.3 HDRS responses become spiky which is not corroborated by porosity response and shows poor repeatability. The spikes do not appear to relate to the formation attributes. It has also been observed that the HDRS value appears to outstrip RLLD value on both low and high end of resistivity in some of the wells.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.