EFFECT OF THE MINERALOGICAL COMPOSITION ON THE PETROPHYSICS AND RESERVOIR ROCK QUALITY OF ABU MADI FORMATION IN BALTIM GAS FIELDS, NILE DELTA, EGYPT | ||
| Journal of Egyptian Geophysical Society | ||
| Volume 13, Issue 1, 2015, Pages 153-161 PDF (2.22 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jegs.2015.385049 | ||
| Authors | ||
| M.Y. Zein El Din1; A.S. Salah2; I.H. Ali2 | ||
| 1(1) Geology Dept. Faculty of Science, Al Azhar University, Egypt. | ||
| 2(2) Belaiym Petroleum Company (Petrobel), Egypt. | ||
| Abstract | ||
| Upper Messinian Abu Madi Formation in Baltim Fields has been penetrated by wells targeting reservoirs levels during the last decade. Production and well log data in this area suggest that significant volumes of gas are still present in reservoirs levels of this formation. Upper Messinian Abu Madi Formation in Baltim Fields consists of fluvial sandstones filling incised valleys. The valley infills are made up of sandstones with a complex mineralogy. The matrix of these sandstones is made up of various amounts of quartz, feldspars, clay minerals and rock fragments. They were subjected to a complex diagenetic history and the resulting paragenesis influenced the present reservoir properties. Consequently, heterogeneities in the petrophysical properties result in significant reservoir rock quality and production issue. This study represented the results of a diagenetic analysis, performed within a well constrained sedimentological facies that aims at understanding the impact of mineralogy and diagenesis on reservoir quality evolution. Thirty core samples from eight wells were collected to perform a petrographic analysis, and to propose an effect of mineralogical composition on petrophysical reservoir rock quality. Four main diagenetic events were identified that occurred during burial through petrographic analysis, namely clay coating around the grains, compaction/dissolution of matrix grains, quartz and feldspars dissolution, and carbonate cementation in the remaining pore space. Clay minerals (in shape of ferroan chlorite) content and carbonate cementation are the main factors that control the reservoir quality of these sandstones. The reservoir quality is influenced by the presence of ferroan calcite cementation, while high porosity value is associated with low cementation content and vice versa. Presence of feldspars, especially when it’s highly altreated and desolated, leads to increasing porosity values by creating secondary porosity (microporosity). The characterization of both mineralogy and petrophysical properties gives useful keys to locate the diagenetic phases laterally and vertically, and to predict the petrophysical properties distribution in the subsurface reservoir | ||
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