Gas Saturation Monitoring In Heterogeneous Reservoir Using Tdt Modeling Technique

Show simple item record Hamada, G. M en_US Dahab, A.A. en_US Abdel Dayem, M. M. en_US Heikel, S. en_US
date.accessioned 2009-11-25T13:04:54Z en_US
date.available 2009-11-25T13:04:54Z en_US
date.issued 1999 en_US
identifier.citation Engineering Journal of Qatar University, 1999, Vol. 12, Pages 9-24. en_US
identifier.uri en_US
description.abstract The Zeit Bay field reservoir units consist of sandstone and carbonates, partially overlaying a tilted block of fractured basement reservoir with a complex drive mechanism. A secondary recovery scheme of gas re-injection into the original gas cap was initiated to maintain reservoir energy and to overcome pressure decline. Hence accurate detection of gas movement is very critical. Several difficulties to monitor gas-oil contacts were encountered in a considerable number of wells. Some of these difficulties were, gas channelling behind the casing, gas coning, wellbore fluid changes, porosity and lithology changes, wellbore fluid invasion into the reservoir and the presence of formation stimulation fluid. The application of conventional methods using the response of gas indicator curves could result in a false indication of formation gas-oil contacts. This paper discusses the approach adopted in order to determine the gas-oil contact in wells where such problems occur. A database was established including more than 70 TDT runs, open hole log and pressure data of 12 infill wells, and production performance records of all Zeit Bay wells. The approach follows the Polyachenko model of functional relationship between count rates and gas saturation. Several crossplots for the same range of porosity and connate water saturation, e.g. formation capture cross section (SIGM), total selected near detector counts (TSCN), total selected far detector counts (TSCF), the capture cross section of the borehole (SIBH), and inelastic far detector counts (INFD). Each crossplot gives a definite diagnostic shape around the depth of the formation gas-oil contact By using these crossplots it will be possible to calculate gas saturation from a stand alone run. The model was validated by RFT and open hole log data from infill wells. Also it was successfully applied in wells which showed an ambiguity in the detected formation gas-oil contact. The field gas-oil contact in Zeit Bay was revised using the results of the model. This revision lead to an accurate definition of the oil column and to the drilling of three additional wells in the field. The open hole log results of these wells verified the gas-oil contact determined by the model. en_US
language.iso en en_US
publisher Qatar University en_US
subject Engineering: Research Papers en_US
title Gas Saturation Monitoring In Heterogeneous Reservoir Using Tdt Modeling Technique en_US
type Article en_US
identifier.pagination 9-24 en_US
identifier.volume 12 en_US

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