Oil or Fresh Water? A New Through-Tubing Measurement to Determine Water Saturation

Streeter, R.W.; Hogan, G.; Olson, Jeffrey D.

doi:10.2118/27646-ms

Cited by 6 publications

References 4 publications

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Simulation on the Method of Determining Remaining Oil Saturation by Measuring Dual Pulsed Neutron Parameters

et al. 2011

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The parameters of C/O ratio and Sigma based on pulsed neutron source can be obtained at the same time in one logging, which utilizes a special pulse and measurement timing design to record inelastic, capture gamma ray spectra and gamma ray time spectrum at the far and near detector. By combining dual parameters for determining oil, water and gas saturation, it can resolve the problem no way to distinguish gas and water only using C/O, oil and fresh water only using Sigma, in addition, it can determine saturation under the condition of unknown borehole porosity information. By theoretical analysis and Monte Carlo simulation method, the gamma ray time spectrum after repetitive pulse of neutron emission can still meet the exponential decay law, and repetitive pulse before neutron lifetime measuring can raise gamma count rate of time spectrum 3 to 5 times, therefore, the dual parameters measured simultaneously in one logging are feasible. Through dual parameters of C/O ratio and Sigma, the C/O data is cross plotted against Sigma data and then to determine oil, water and gas saturation. By using Monte Carlo method to set up computation model, inelastic gamma spectrum, capture gamma spectrum and time spectrum under certain borehole and formation conditions can be simulated, and the logging response is given when determining oil, water and gas saturation by using cross plot technique of C/O and Sigma. In addition, the influence of lithology, porosity, shale content, borehole size, formation water salinity and gas density on determining saturation were simulated, and it will provide response relation for determining oil saturation by dual parameters of C/O ratio and Sigma.

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Simulation on the Method of Determining Remaining Oil Saturation by Measuring Dual Pulsed Neutron Parameters

et al. 2011

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Novel Approach to Estimate Water Saturation Behind Casing Using Carbon Oxygen Data: Challenges and a Case Study in Abu-Dhabi Onshore Reservoirs

Aziz

Wazeer²,

Odom³

et al. 2020

Day 1 Mon, November 09, 2020

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Carbon-Oxygen ratio measurements are advantageous for calculation of water saturation behind casing in situations where the normal pulsed neutron sigma log fails to do so. Examples include reservoirs stimulated by acids or those having fresh water. Carbon steel casing commonly used to inhibit corrosion processes. In most cases, the carbon content in the steel material is an unknown parameter that can contaminate the accuracy of the C/O measurement. Another challenge, particularly in Abu Dhabi National Oil Company (ADNOC) reservoirs, is the high salinity of the formation water (typically 200 Kppm NaCl) where Chlorine makes more gamma rays per neutron compared to other elements and can interfere with the oxygen accuracy. In this paper, we propose methods and workflows to assure the accuracy of oil saturation from C/O measurements. To lower the dependence on carbon, examples of a process that uses the ratio of the Oxygen window to the total inelastic gamma counts are demonstrated. The responses of other inelastic data including the total inelastic count rate and the ratio of inelastic to capture can be scaled as water saturation as a secondary quality control method. Examples of C/O processing with chlorine corrections are also demonstrated. Data from two wells with consistent reservoir parameters (porosity, rock, wellbore, etc.) are used to demonstrate the proposed techniques. This data is augmented with computer models and analysis to understand the various steps in the workflow. The proposed technique has been applied with acceptable saturation results behind carbon steel in acid stimulated reservoirs, with high salinity water. This paper provides a solution to estimate water saturation behind carbon steel casings in acid stimulated reservoirs and with high salinity water. We have developed workflows as best practices to assure the accuracy of Carbon/Oxygen oil saturation measurements.

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Cased Hole Exploration: Modern Pulsed Neutron Techniques for Locating By-Passed Hydrocarbons in Old Wells

Streeter¹,

Hogan²,

Rogers³

et al. 1996

Permian Basin Oil and Gas Recovery Conference

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Many Permian Basin fields are considered "mature", with some of these fields almost depleted and/or undergoing water or CO2: flooding. Operators are being faced with decisions to P&A or to recomplete in other zones, often with inadequate data. Unfortunately, many of these wells were logged before modem porosity logs were available. In other wells, for various reasons, the entire well was not logged. The integration of modem pulsed neutron technologies1 can. however, provide the operator with reservoir parameters from inside casing. For porosity, pulsed neutron systems can make a thermal neutron ratio porosity' (RPHI) similar in response to the compensated neutron. Pulse neutron systems can also be used to make a new type of porosity (IPHI) derived from gamma rays created by inelastic scattering of fast neutrons. IPHI is similar in response to an open hole density and can be crossplotted with RPHI to help identify lithology changes and differentiate tight zones from gas. The crossplotted porosity also helps compensate for lithology and gas effects, and to some extent for some variations in near wellbore environment. The crossplotted porosity can then be used with sigma and/or CATO2 to determine water saturation.

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Oil or Fresh Water? A New Through-Tubing Measurement to Determine Water Saturation

Cited by 6 publications

References 4 publications

Simulation on the Method of Determining Remaining Oil Saturation by Measuring Dual Pulsed Neutron Parameters

Simulation on the Method of Determining Remaining Oil Saturation by Measuring Dual Pulsed Neutron Parameters

Novel Approach to Estimate Water Saturation Behind Casing Using Carbon Oxygen Data: Challenges and a Case Study in Abu-Dhabi Onshore Reservoirs

Cased Hole Exploration: Modern Pulsed Neutron Techniques for Locating By-Passed Hydrocarbons in Old Wells

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