Title

Determining reservoir- and basin-scale stratigraphic architectures of the Bartlesville Sandstone from well log data

Presentation Type

Poster

Abstract

The Bartlesville Sandstone in Oklahoma has been reported to represent the clastic sedimentary filling of a Pennsylvanian-aged incised valley. Since drilling began in 1897, this formation has been perforated with thousands of oil wells, from which many electronic well logs and initial production documents still exist. By compiling, correlating, and analyzing this geophysical data, this project aims to better understand the regional and local stratigraphic architecture of the Bartlesville Sandstone. Results from this work can be used as an analog for predicting the sedimentary characteristics of incised valley sequences elsewhere. The large-scale heterogeneity of incised valleys is controlled by changes in accommodation and sediment supply. Establishing a regional sequence stratigraphic framework for the Bartlesville Sandstone is the best way to study these changes. Characteristic gamma ray, bulk density, and resistivity signals in well logs were used to correlate and define erosional and flooding surfaces throughout the study area. These surfaces were interpreted to represent the lower and upper bounds of the formation. Between these two markers, the slightly more inconspicuous boundary separating the upper and lower Bartlesville was identified by interpreting further trends in these well logs.

After defining the upper and lower boundaries of the Bartlesville, the total thickness of the formation was examined by creating an isopach map for the study area. This map shows that the Bartlesville has a thick axis and thin margins, which is evidence supporting its interpretation as an incised valley.

In addition to defining the overall thickness and extent of this formation, smaller-scale features were also explored. The upper Bartlesville was interpreted to consist mainly of isolated sand bodies. Using the electrical logs and driller's documents, individual sand bodies were located and correlated when possible to further understand the evolution of the valley system.

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Determining reservoir- and basin-scale stratigraphic architectures of the Bartlesville Sandstone from well log data

UC Ballroom

The Bartlesville Sandstone in Oklahoma has been reported to represent the clastic sedimentary filling of a Pennsylvanian-aged incised valley. Since drilling began in 1897, this formation has been perforated with thousands of oil wells, from which many electronic well logs and initial production documents still exist. By compiling, correlating, and analyzing this geophysical data, this project aims to better understand the regional and local stratigraphic architecture of the Bartlesville Sandstone. Results from this work can be used as an analog for predicting the sedimentary characteristics of incised valley sequences elsewhere. The large-scale heterogeneity of incised valleys is controlled by changes in accommodation and sediment supply. Establishing a regional sequence stratigraphic framework for the Bartlesville Sandstone is the best way to study these changes. Characteristic gamma ray, bulk density, and resistivity signals in well logs were used to correlate and define erosional and flooding surfaces throughout the study area. These surfaces were interpreted to represent the lower and upper bounds of the formation. Between these two markers, the slightly more inconspicuous boundary separating the upper and lower Bartlesville was identified by interpreting further trends in these well logs.

After defining the upper and lower boundaries of the Bartlesville, the total thickness of the formation was examined by creating an isopach map for the study area. This map shows that the Bartlesville has a thick axis and thin margins, which is evidence supporting its interpretation as an incised valley.

In addition to defining the overall thickness and extent of this formation, smaller-scale features were also explored. The upper Bartlesville was interpreted to consist mainly of isolated sand bodies. Using the electrical logs and driller's documents, individual sand bodies were located and correlated when possible to further understand the evolution of the valley system.