Impact of Mineralogy on Creep Properties and Production Decline Rates Available to Purchase

Predicting production decline is important for planning and developing unconventional assets. The contribution of creep deformation to production decline is still not isolated and quantified. Mineralogy and the total organic carbon (TOC) are known to drive the creep properties of unconventional formations. High creep rates accelerate proppant embedment and can decrease the volume and conductivity of a hydraulic fracture contributing to production decline. This paper presents a multi-disciplinary workflow to model the changes in fracture surface area and conductivity at different time steps after a fracking operation based on creep and embedment rates. The workflow integrates 3 key parts: A petrophysical creep model that predicts creep and embedment rates given total porosity, mineralogy and TOC; flow simulations that provide a lower bound for changes in fracture conductivity with changing proppant concentrations; and fracture simulations that depict a fracture geometry and model proppant distribution in the subsurface after hydraulic stimulation. The workflow is applied to wells in two unconventional assets. One asset has organic-lean formations while the other has organic-rich ones. Results show that the creep effect and absolute embedment are negligible in TOC-poor formations. TOC-rich formations, on the other hand, manifests a slower decline in creep rates with time. In such formations, attention to formation depletion and changes in effective stresses are needed to better understand embedment. Fracture geometry (dimension and planar nature) and properties (proppant concentration) generated by fracture simulators can also contribute to minimizing and/or masking the effect of embedment on changing a hydraulic fracture volume and conductivity.