This paper demonstrates an integrated approach to measuring and quantifying stimulated rock area, productive frac area, and their impact on optimum completions and well spacing in the Permian Basin. A diagnostic pilot was planned to reduce key uncertainties in pore pressure differences in a stacked play, variability in reservoir quality, and interaction of wetted/productive fractures between benches in a tightly spaced Drilling Spacing Unit (DSU). Technologies used in this study include frac diagnostics with fiber and pressure gauges, well interference tests, time-lapse geochemistry, chemical tracers, and integration of all surveillance data into fracture and reservoir modeling workflows.

A vertical dedicated monitor well was drilled and instrumented with pressure gauges and optical fiber. These pressure gauges were monitored to build a pore-pressure gradient profile for the entire stack and capture any local changes in pressures. A horizontal well was also equipped with permanent fiber to assess fracture growth from neighboring benches. Strain data from the fiber installed in the vertical monitor well was measured during hydraulic fracturing. The put-on-production schedule enabled measurement of inter-bench and intra-bench production interference between wells. Time-lapse geochemistry analysis helped evaluate contribution from each bench for a given well. Completion and spacing sensitivities were run to optimize development planning decisions.

Extensive overlap was seen in wetted fracture geometries. Fractures in most benches were observed propagating predominantly in height relative to length. Productive fracture geometries indicated significant overlap in drainage area in most benches at the spacing tested. Time-lapse geochemistry showed wells in multiple benches competing for the same resources. Calibrated fracture and reservoir models also suggested the need to increase hypotenusal distances between wells to mitigate interference and maximize capital efficiency.

This integrated project clearly established the value of running diagnostic pilots and collecting high resolution data before, during, and after completions to quantify the size and shape of the fractures created and propped extent of the stimulated rock. The experimental pad was setup with a tightly spaced well configuration and helped accelerate subsurface learnings to move towards a more optimal development plan in a short time frame. Combining surveillance data with integrated modeling workflows resulted in significant improvement in value accretion to the business unit.

The diagnostic pilot presented in this paper required a multi-disciplinary effort from team members with a wide variety of skill sets – drilling, completions, geology, reservoir, facilities, and instrumentation. The team members from across the organization worked together to ensure near-perfect set-up, collection, analysis, and interpretation of the rich diagnostic data collected to make business recommendations.

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