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Challenges Exploring Unconventionals in Emerging Areas, North Africa Case Study

Abstract

Shale plays are moving from the well-known and explored USA ones to those belonging to not so mature areas. Such new areas are offering us a more frontier objectives in terms of exploration.

A regional screening has been conducted by REPSOL in Europe and North Africa in order to identify favorable geologic areas for unconventional targets in onshore basins.

Due to the special characteristics of unconventional resources the most important geological elements to explore, evaluate and develop a successful project are leaded by the quality, maturity, thickness and distribution of the source rock in a preserved basin. Four basic geological parameters have been used in these regional evaluations: TOC, Ro, Thickness and Depth. All these parameters have been plotted and compared in GIS maps (figure 1). From this exercise, additionally to the classical basins, a cluster of unexpected non-productive areas with some potential were identified.

On top of that, we could differentiate in terms of exploration maturity among mature basins, with not only a proven petroleum system but also surface facilities already developed; those that are fairly mature, with a proven petroleum system, but still in development in terms of surface facilities, and those that are immature basins, as is the case of many of the onshore basins poorly explored in North Africa.

So, the exploration of unconventionals in areas that are not the “classical” ones is closer to a frontier exploration methodology than a development process, as the ones applied in USA and other producer basins. In this way surface geology, geochemical sampling, core drilling, basin modelling and analogy are sometimes more important tools than a “speculative” EUR.

The challenge was how to face these differences and build a methodology that allow us to properly explore and evaluate (above and below surface) the unconventional potential in North Africa, applying afterward this methodology worldwide.