Abstract
Using geologic attributes that include total organic carbon, porosity, brittleness, natural fracture density, and oil saturation, we develop the Shale Capacity for the Bakken reservoir. First, the seismic data are frequency enhanced through a broadband spectral inversion. From the enhanced seismic data we generate seismic curvature, spectral attributes, post-stack acoustic impedance, and pre-stack elastic parameters. These result in 50+ seismic attributes that we use with the log data in a neural network to model geologic and petrophysical properties. These properties are built into a 3D Shale Capacity model. We then measure a well’s Shale Capacity with the Relative Intercepted Shale Capacity (RISC) to relate the Shale Capacity to engineering data (i.e. 90-day Initial Production). RISC is the percentage of a wellbore’s horizontal length that intercepts low to zero Shale Capacity.
Shale Capacity is applied to an area producing from wells drilled mainly in the Middle Bakken formation. The survey area is 30 square miles and includes 3D seismic data, well logs from three vertical wells, and geosteering (depth control) points. We calculate the Bakken Shale Capacity in two parts (1) Upper/Lower Bakken Shale Capacity and (2) Middle Bakken Shale Capacity. We determine RISC for six of the twelve horizontal wells and derive a correlation between RISC and 90-day Initial Production (IP). This correlation has an R2 coefficient of 0.94. For the remaining six wells, we predict the 90-day IP using the derived correlation. The prediction gives an R2 coefficient of 0.90 between the predicted and measured 90-day IP’s. In this example, Shale Capacity correlates with the microseismic data. Near the heel of the well where the Shale Capacity is low or zero, the microseismic event density is lowest. Similarly, where the Shale Capacity is highest, the microseismic event density is the greatest.
