As unconventional plays in the US L48 have been exploited and developed over the past 10 years there has been a continuing push to identify optimized production. Much of this conversation is built around stacking patterns and which array is optimum to achieve the right balance between maximizing production, while minimizing infrastructure and development costs. Most methods used by operators for assessing the number of potential production units, and therefore well spacing, rely on indirect measurements. However, the availability of rock samples, whether that be core or cuttings, and produced fluids from both legacy and new production wells offer direct insight into compartmentalization and when in production the range of the stimulated rock volume (SRV) and the drained rock volume (DRV) between those defined units. Combining this data, during both the initial appraisal and later production phases, with operator workflows and context allows detailed assessment and understanding of subsurface drainage patterns, what they indicate about the optimization of the stacking pattern and how they will impact longevity of production wells. These data can also indicate viability for ‘infill’ wells between the already producing flow units and the potential effectiveness of stacking patterns in future development acreage. This paper will discuss the application and utility of geochemical data across a number of unconventional case study examples and how these results drive decision making and development, with the goal of these examples being to educate operators in both the value of geochemical data, legacy and new production, and how it can be used to optimize their own production.