Factors Controlling Stylolite Distribution in Upper Kharaib Formation Limestones (Lower Cretaceous), Onshore Abu Dhabi

Stylolites are ubiquitous in petroleum reservoirs and are important as potential sources of ions for cementation and as heterogeneities affecting fluid flow. The factors controlling the initiation and morphology of stylolites have been discussed in many previous studies, but a significant problem for such interpretation is that the original rock before the stylolites formed is generally not available for study, having been highly altered by dissolution, especially along and immediately adjacent to the locations of key interest. The present study addresses this problem by comparing cores from the water-filled flanks of a giant oilfield, where stylolites are abundant, with cores from the oil-filled crest, where stylolite formation was inhibited by the earlier emplacement of oil.. Because the investigated reservoir zone shows a high degree of lateral stratigraphic continuity over large distances, crest and flank locations appear to be closely similar in depositional character. Comparison of these locations is thus used for a sort of geological time-travel; to be able to see the more chemically compacted and cemented flank sections as they were before the oil arrived and abundant, high-amplitude stylolites formed along the flanks. The results are interpreted to discuss the relative timing of different stylolites, the factors controlling stylolite formation, and the relationship between stylolites and the porosity of the enclosing limestones.