Now that we Have Tortuosity Statistics, How can we Use that in Frac Design and Move Towards Production Optimization?

Abstract The previous paper in this series1 established tortuosity statistics for evaluating the quality of an unconventional lateral. This paper defines a multi-lateral, directional drilling data analysis technique to model frac interaction and effectiveness of wells in close proximity to each other. The result of this modeling is a stimulated rock volume (SRV). It is a directional drilling data metric for each well in a lease that coupled with frac metrics, can be used to develop a new cross-discipline approach to production optimization. SRV is a multi-well, directional survey methodology similar to a "traveling cylinder" calculation. Instead of calculating the distances among quasi-parallel, nearby vertical wells below an offshore platform, SRV assigns a volume to quasi-parallel nearby horizontal wells in an unconventional lease. A lease that is 5000ft wide, 10000ft long with a bench height of 1600ft has a volume of 80 billion cubic feet. This volume is parceled into 10ft by 10ft by 10ft "pixels" of rock that are 1000 cuft each. Now there are 80 million of these "sugar cubes." There may be 5-25 laterals piercing the volume. Each sugar cube is "assigned" to the closest well. If a sugar cube is more than a half frac wing length, say 800ft, it is not assigned to a well and is assumed to be not contributing to lease production. The assigned sugar cubes are added up for each lateral to obtain the SRV for each well in the lease. As with tortuosity calculations, SRV calculations on laterals can be conducted with public survey and plat data. The vertical planes can be represented graphically to give a visualization of the lease design. The results for several hundred leases are discussed. The ratio of the total SRV for the lease to the width/length/height total lease volume, a value ranging from 20 to 50%, is the quality of lease exploitation. The ratio of lease total frac sand weight to lease total SRV can be compared to the ratio of lease total production to SRV. This suggests that more production per unit volume for the same amount of frac'ing per unit volume is a higher quality lease. There currently is no published metric that calculates the proximity of unconventional laterals to each other in a lease that can be used in frac and production evaluation. Lateral spacing, a one-dimensional metric, is used. It is a design parameter usually established before drilling. The well trajectories are built around this spacing. There is currently no way to use survey data after the wells are drilled in production optimization work. SRV in this form is a first step in utilizing drilling data in this fashion.