Advanced Petrophysical Evaluation of a Low-Resistivity Laminated Shaly Sand Formation Showed Significant Increase in Reserves Calculations

2017 ◽  
Author(s):  
Alisa Kukharchuk ◽  
An XiaoXuan ◽  
Eric Doss
Keyword(s):  
Low Resistivity ◽  
Shaly Sand ◽  
Petrophysical Evaluation

The Application of Maine Petrophysical Method; Adding Resources by Explore the Opportunity in Low Resistivity Pay Reservoir

2021 ◽  
Author(s):  
Mohammad Reza ◽  
Riezal Arieffiandhany ◽  
Debby Irawan ◽  
S Shofiyuddin ◽  
Darmawan Budi Prihanto
Keyword(s):  
High Resolution ◽  
Transition Zone ◽  
Water Saturation ◽  
Electrical Parameter ◽  
Parameter Determination ◽  
Type Curve ◽  
Petrophysical Analysis ◽  
Low Resistivity ◽  
Resistivity Logs ◽  
Shaly Sand

Abstract Manifestation of Low Resistivity Pay (LRP) Existences in ONWJ Area because of Fine Grained, Superficial Microporosity, Laminated Shaly Sand and Electronic Conduction. Water saturation petrophysical analysis for LRP Case due to those reason above can be solved by electrical parameter determination with Type Curve. But to overcome the LRP caused by Laminated Shaly Sand, the use of high resolution resistivity logs that are close to the resolution of thin bed reservoir is a must. Alternative solutions, conventional high resolution resistivity logs, namely Micro Spherical Focused Log (MSFL) are used to interpret thin bed reservoirs that have the hydrocarbon potential. This intergrated petrophysical analysis is called MAINE Petrophysical Method The Petrophysical MAINE method is the development of the TECWAL (Type Curve, Core and Water Analysis) method which leaves question marks on Laminated Shaly Sand Reservoir and the possibility of variations in the Electrical Parameter and Water Saturation Irreducible (SWIRR) dependent on Rocktype. The Basis of the MAINE Method is the Worthington Type Curve with some assumptions such as Each rocktype has a different value of Bulk Volume of Water (BVW) and BVW can be used to determine the SWIRR value of each rocktype and Each rocktype has different electrical parameter m and n. In the process, the use of J-Function and Buckles Plot is applied to help determinet Rocktype and BVW values. The rocktype will be the media in distributing the value of Electrical Parameter generated by the Type Curve and the value will be used in water saturation calculation. In Laminated Shaly Sand Reservoir, Rocktyping will be analyzed more detail using the High Resolution Conventional Log, Micro Spherical Focused Log (MSFL). The expected final result of this analysis is the more reliable Water Saturation (SW) and the integration of water saturation values in the Buckles Plot which can help in determining the transition zone in order to avoid mistakes in determining the perforation zone. Through the MAINE Petrophysical Method, there is a decrease in water saturation from an average value 86% to 66% or a decrease 23%. This result is quite significant for the calculation of reserves in the LRP zone. By integrating this method with the Buckles Plot, it can help the interpreter to determine the perforation interval in order to avoid water contact or the transition zone

Identifying the Potential Upside of Hydrocarbon Saturation from Electric Logs

2009 ◽  
Vol 12 (01) ◽  
pp. 53-67 ◽  
Author(s):  
Paul F. Worthington
Keyword(s):  
Reservoir Rock ◽  
Log Analysis ◽  
Well Log ◽  
Screening Process ◽  
Type Curves ◽  
Hydrocarbon Saturation ◽  
Shaly Sand ◽  
Well Log Analysis ◽  
Formation Water Salinity ◽  
Petrophysical Evaluation

Summary Validated electrical type curves, which collectively describe a continuum of conductivity behavior of fluid-saturated rocks, allow the petrophysical evaluation of hydrocarbon saturation to be set within a generic reference framework. As part of this process, the type curves permit pre-existing data from other reservoirs to be examined as potential analogs. Through the type curves, a reservoir rock can be classified in terms of its electrical character, specifically adherence to, or departures from, classical clean-sand (Archie) conditions and, by corollary, the degree of any shale (non-Archie) effects. The classification guides the approach to future core-data acquisition and to well-log analysis. In particular, in non-Archie reservoirs the type curves indicate whether the formation-water salinity is sufficiently high for the application of shaly-sand equations for the evaluation of hydrocarbon saturation or whether recourse should be made to a (customized) pseudo-Archie approach. Thus, the type curves are used to ensure that interpretative algorithms are appropriate to the petrophysical task at hand. The application of the type curves, using initializing log data from seven shaly hydrocarbon reservoirs containing relatively fresh formation waters, has illustrated how petrophysical interpretations away from the key intervals can be screened with minimal supporting information through a pseudo-Archie approach. Comparisons of best estimates of hydrocarbon-filled porosity with previously reported values have indicated a potential volumetric upside in all cases, with hydrocarbon saturations being up to 30 saturation units higher for these complex reservoirs. This outcome is attributed to the generic nature of the screening process, which takes account of the electrical character of a reservoir without any of the procedural constraints that are associated with conventional well-log analysis. To reduce further the risk of underestimating hydrocarbon volumes, a set of equivalence charts has been constructed using basic petrophysical properties. The equivalence charts allow a quick-look recognition of any departures from Archie conditions and thence whether the type curves are likely to be required. The screening process has been synthesized into pragmatic workflows, whose adoption should impart additional quality assurance to the petrophysical evaluation of hydrocarbon volumes.

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