This paper demonstrates how geochemical production allocations can be used to calibrate reservoir simulation models and improve the optimization of well spacing and hydraulic fracture design in unconventional assets. Geochemical analyses provide quantitative assessments of flow by layer over time. This allows numerical models to be fine-tuned to realistically capture the productive fracture height for wells landed in different stratigraphic layers.

This paper presents a calibration and optimization workflow using a fully coupled hydraulic fracturing, reservoir, and geomechanics simulator, as applied to the HFTS-2 dataset in the Delaware Basin, Texas, USA. Modeling began with building a geomechanical stress profile using the viscoelastic stress relaxation (VSR) method. The model was then calibrated to key observations from the field diagnostic data, which included: horizontal and vertical well DAS/DTS/DSS fiber, downhole microseismic arrays, pressure gauges, core-through data, image logs, DFITs, proppant-in-cuttings analysis, interference tests, and production data. Finally, the calibrated model was used to perform an economic optimization of design parameters by running hundreds of variations and comparing their performance.

The problem of a plane strain hydraulic fracture propagating in a layered formation is considered. Fracture toughness, in-situ stress, and leak-off coefficient are assumed to vary by layer, while the elastic properties are kept constant throughout the domain for simplicity. The purpose of this study is to develop a numerical algorithm based on a fixed mesh approach, which is able to solve the above problem accurately using elements that can even be larger than the layer size.

This study describes an automated history matching and optimization workflow using an integrated hydraulic fracturing reservoir simulator and applies the workflow in four cases. The automated workflow solves a formal mathematical optimization problem to minimize misfit with observations from any point in the lifecycle of a hydraulically fractured well, or to maximize a quantity of interest, such as net present value.

Multistage hydraulic stimulation has the potential to greatly expand the production of geothermal in the United States and worldwide. Zonal isolation and limited-entry completion overcome the problem of flow localization and generate hundreds or thousands of conductive fractures throughout a large volume of rock. In contrast, conventional geothermal stimulation designs are bullheaded as a single stage into a vertical or deviated wellbore, resulting in a small number of dominant flow-pathways.

Parent/child interactions pose a critical challenge for oil and gas shale producers. The industry has progressed significantly in its understanding of causes and mitigation. However, important uncertainties remain. Fracture-driven interactions or more commonly, “frac hits”, exhibit varied behaviors in different basins.

The stimulation design of hydraulically fractured wells has always pitted the engineer’s capability to maximize the fracture extent (or fracture half-length within the formation) versus the conductivity of the fracture pack generated by the deposited proppant material. In essence, the area of productive reservoir rock contacted by the hydraulic fracture treatment needs to be appropriately engineered to remain connected to the wellbore over the life of the well to maximize reservoir recovery.