Environmental challenges of gas and oil shale stimulation

Abstract

The unconventional oil and gas reservoirs have been playing a significantly increasing role in US. The drilling and hydraulic fracturing technologies that unconventional resource developments comprehensively depend on are under increased scrutiny due to the uncertainties involved on their potential contamination to groundwater as well as their contributions to air and other pollutions. The potential distortion to natural habitat by the required infrastructure also one of the consequences of large developments in most often nearby wildlife preserves as well as highly populated urban areas. The missing fundamental technical knowledge on the stimulated reservoir volume and drained gas slows down the implementation and enhanced recovery effort costing oil and gas companies significant revenues and reserve recovery. Moreover, the heterogeneities and high level of anisotropy contained in unconventional resources make it impossible to use the existing conventional techniques for many applications due to higher precision information required in nano/micro scale and core scale. On contrary, the production history match and reservoir simulation effort uses averaged effective reservoir parameters as input for drainage patterns, gas —in‐place, production rate and field design which does not take into consideration these anisotropy and heterogeneity in the models. The corresponding predictive modeling effort give several decades off from what happens in unconventional reservoirs and require immediate attention not only from characterization perspective, but also having a better understanding on the fundamentals of fracturing operations in unconventional reservoirs and its impact on environment and groundwater.