Basin-scale resource assessment has long been used to identify focus areas and evaluate acreage. The continuous nature of unconventional reservoirs makes them well suited to this type of assessment. The approach presented here is based on geologic assessment of the basin. Productivity analyses are linked to geologic and operational factors to produce an integrated assessment that enables estimation of technically recoverable resources, evaluation of economic scenarios and projections of future production.

Our approach to basin-scale resource assessment begins with structural and stratigraphic analysis, including simple wireline facies models to map lithologic variations across the basin. Petrophysical analysis uses a multi-mineral solver approach that is calibrated to core data to estimate mineral volumes, porosity, S_W, and TOC. Petrophysical analyses are also used to calculate pore pressure, mechanical properties, and the effect of clay-sourced water on salinity.

The results of these studies are used to construct 3D geologic models that are granular for basin-scale models, for example an average of 1500 x 1500 feet laterally. Results from engineering analyses (e.g. gas-oil ratio and formation volume factors) are also incorporated into the model. The initial stage of modeling ends with hydrocarbons-in-place.

Production data is used to develop type decline curves from horizontal wells within the basin/formations of interest. Rock and fluid attributes from the geologic model are extracted along the laterals of horizontal wells and combined with completion and production data to evaluate controls on productivity. These results are used to estimate technically recoverable resources (TRR) for individual reservoirs. TRR estimates become the input to economic analyses and future production estimation.

Resource assessments have been completed for multiple shale plays in the US. Hydrocarbon-in-place estimates range from 12.5 BBOE for the Fayetteville to ~7,800 BBOE for the Delaware Basin. Estimates of technically recoverable resource (TRR) range from ~3.8 BBOE for the Fayetteville, to 844 BBOE for the Delaware Basin. Produced volumes range from 1.25% of TRR in the Delaware Basin to 43% of TRR in the Fayetteville.

Our approach to basin/play-scale resource assessment yields an integrated product incorporating inputs from multiple disciplines to not only provide critical geologic understanding of the basin, and estimate resources, but to highlight areas that may have greater potential and to forecast how economic conditions may impact future development.