In Shale plays, EUR relies almost exclusively on "primary" production with practically no account for Enhanced Oil Recovery (EOR) practices. However, many remarkable facts are sometimes considered as "anecdotic" or pointed out as outliers, rather than including them as part of a coherent explicative model. Both, included in the literature and commented by the operators, we have repeatedly found many cases reporting such "anomalous" facts such as: (i) Low liquid recoveries during flow back periods, (ii) Rapid salinization of flow back water, (iii) Higher productivities correlating with lower percent of flow back recoveries, (iv) Early oil production right after flowback starts, (v) Shales described as "thirsty" or "dehydrated" (meaning lower water saturation than expected due to its pore geometry) and (vi) the evidence of huge capillary pressures, developed and supported by well documented overpressures.

After accepting these "anomalies" as an intimate part of the behavior of these non-conventional scenarios, we get many major consequences in the way we could develop and exploit them. Thus, we propose a new methodology that consists on a novel operative sequence to enhance oil production in multi stage frac Shale Oil scenarios.

The main mechanism involves countercurrent water imbibition processes, and consists of a cyclic scheme of (i) water injection, (ii) soaking and (iii) production periods that could be repeated until capillary effects fade out. This methodology, if proven successful, means a complete shift of the current exploitation practices, probably leading to a new paradigm in the way these unconventional resources could be developed and produced.

This proposal, if proved successful, should have a paramount impact in the appraisal and economics of these types of resources development, not only improving recoveries with low cost operations to transform resources into reserves, but also leveraging operational issues such as paraffin deposition, pressure maintenance, potential acid treatments, etc.

The approach involves a de risking process in three stages (i) conceptual, (ii) theoretical and (iii) experimental (lab and field tests). This paper describes the status of development of the analysis and the findings so far, which show encouraging results to continue imrproving the technique and perform additional field testing.

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