Quantifying and Analyzing Relationships Between Well Log Attributes and Production for the Mississippian Play in Woods County, Ok

Abstract

This case study outlines a workflow to use older vertical well data to better understand hydrocarbon plays and help guide modern horizontal drilling. The focus of the study is Woods County, Oklahoma which lies in the heart of the Mississippian play. This county has thousands of older vertical wells, for which hundreds of digital well log files are available. Woods County also has abundant horizontal wells. The Mississippian play is a carbonate play producing at shallow depths. The relatively low horizontal drilling costs combined with existing infrastructure in place from older production make this play desirable for many operators. Despite all of the positives for drilling Mississippian wells, there is currently a lack of understanding of what causes the relatively sporadic production compared to other plays. The multiple-porosity stacked systems in carbonate reservoirs create petrophysical variability. Although this variability can lead to frustration when trying to characterize a reservoir, it can also lead to opportunities to identify localized favorable trends. The objective of this study is to quantify the relationships between well log attributes and production in the Mississippian play. By comparing older vertical well log relationships to current horizontal well log relationships, this study provides a workflow for using older well information to help guide current drilling.