Numerical and Laboratory Investigations for Maximization of Production from Tight/Shale Oil Reservoirs: From Fundamental Studies to Technology Development and Evaluation
Sample of Eagle Ford oil shale with a propped (quartz sand) fracture.
Gas production from tight gas/shale gas reservoirs over the last decade has met with spectacular success with the advent of advanced reservoir stimulation techniques (mainly hydraulic fracturing), to the extent that shale gas is now among the main contributors to US hydrocarbon production. This remarkable success has not been matched by similar progress in the production of (relatively) low-viscosity liquid hydrocarbons (including condensates) because of the significant challenges to liquid flow posed by the ultra-low permeability (and the correspondingly high capillary pressures and irreducible liquids saturations) of such reservoirs. These difficulties have limited liquids production to a very low fraction (usually <5%) of the resources-in-place. Increasing the recovery of liquids from these ultra-low permeability systems even by 50-100% over its current very low levels (to a level that is still low in absolute terms, but very significant in relative, hence economic, terms) not only will increase production and earnings, but will have considerable wider economic implications, as the enhanced recovery will affect reserves and the valuation of companies.
The overall objective of this project is to investigate (with a focus on quantification) at multiple scales the most promising processes that enhance production from tight/shale oil reservoirs, using LBNL’s unique set of parallel lab, micro-imaging, and reservoir simulation capabilities. The research is divided into two areas that address pressing questions about the micro- and macro-scale processes that control the mobility of fluids in fractured and unfractured shales. The first area is proppant transport, including the movement and distribution of proppants in propagating fractures, the effect of proppants on the fracture permeability during injection and production, and their long-term fate, including crushing or embedment during fracture closure. The second area is production enhancement, which includes lab- and reservoir-scale investigations of processes (separate and in combination) that enhance permeability, decrease viscosity or irreducible saturations of reservoir fluids, and result in the greatest recovery of desirable hydrocarbons. Coordination between simulations, lab-scale tests, and micro-scale visualization (validation through comparisons to ground-truth data) will provide some of the first direct observations of proppant behavior and develop enhanced simulation capabilities for reservoir-scale modeling.
If successful in identifying interactions, processes and methods that can increase production by as little as 50-100 percent over the current low recovery rates (usually 5% or less), the impact in the industry will be significant and potentially dramatic (despite a recovery that may remain low in absolute terms) not only because of an increase in hydrocarbon recovery, but also because this will allow an increase in reserve estimation and company valuation, with considerable economic consequences.