Integrated open-hole data interpretation technique in tight reservoir conditions

UDK: 550.8
DOI: 10.24887/0028-2448-2019-5-40-43
Key words: well, formation, reservoir, pressure gradient, wireline formation tester, saturation, well testing, formation sample
Authors: Nguyen Lam Аnh (Vietsovpetro JV, the Socialist Republic of Vietnam, Vung Tau), D.I. Varlamov (Vietsovpetro JV, the Socialist Republic of Vietnam, Vung Tau), E.V. Kudin (Vietsovpetro JV, the Socialist Republic of Vietnam, Vung Tau)

Application of a wireline formation tester (WFT) is a widely known method of surveys during exploratory well construction. Such method allows isolating the well target area by the selective clamping sealed element and gathering fluid and gas samples from a tested reservoir zone into a special sealed container. The results of WFT surveys allow specifying saturation and hydrodynamic properties of the reservoir; reservoir pressure; position of fluid contact; reservoir fluid properties; and intervals for the subsequent cased testing and full-featured sampling. However, performing these works and studies is not always an easy task. Wireline formation testing is a complex multistage unstable process with a short-time runs that often leads to unclear results in the context of tight reservoirs, characterized by low permeability and reservoir fluid mobility aggravated by a deep zone of mud filtrate penetration. Deep penetration distorts the picture so the solution filtrate and reservoir fluid are distinguished according to chemical analysis data and additional sample studies. The article describes the method of improving the application efficiency of information that was obtained in the course of studies, by combining various data, namely, variability of carbon dioxide content in samples with the results of interpreting well survey data. Well survey based pay zones are confirmed by the reservoir samples interpretation in terms of CO2 content, which is an additional criterion for identifying the intervals that are promising for oil and gas in the well section, even in the absence of representative oil samples.

References

1. PVT laboratory study report: Block 12/11 South Con Son, Vietnam, Vung Tau: Vietsovpetro, 2017.

2. Reservoir Characterization Instrument (RCI): Pressure testing and sampling report of Vietsovpetro, Ho Chi Minh, 2017.

Application of a wireline formation tester (WFT) is a widely known method of surveys during exploratory well construction. Such method allows isolating the well target area by the selective clamping sealed element and gathering fluid and gas samples from a tested reservoir zone into a special sealed container. The results of WFT surveys allow specifying saturation and hydrodynamic properties of the reservoir; reservoir pressure; position of fluid contact; reservoir fluid properties; and intervals for the subsequent cased testing and full-featured sampling. However, performing these works and studies is not always an easy task. Wireline formation testing is a complex multistage unstable process with a short-time runs that often leads to unclear results in the context of tight reservoirs, characterized by low permeability and reservoir fluid mobility aggravated by a deep zone of mud filtrate penetration. Deep penetration distorts the picture so the solution filtrate and reservoir fluid are distinguished according to chemical analysis data and additional sample studies. The article describes the method of improving the application efficiency of information that was obtained in the course of studies, by combining various data, namely, variability of carbon dioxide content in samples with the results of interpreting well survey data. Well survey based pay zones are confirmed by the reservoir samples interpretation in terms of CO2 content, which is an additional criterion for identifying the intervals that are promising for oil and gas in the well section, even in the absence of representative oil samples.

References

1. PVT laboratory study report: Block 12/11 South Con Son, Vietnam, Vung Tau: Vietsovpetro, 2017.

2. Reservoir Characterization Instrument (RCI): Pressure testing and sampling report of Vietsovpetro, Ho Chi Minh, 2017.


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