The role of diagenesis and depositional facies on pore system evolution in a Triassic outcrop analogue (SE Spain)
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- 作者：S. Henares ; L. Caracciolo ; G. Cultrone ; J. Fern谩ndez ; C. Viseras
- 关键词：Diagenesis ; Triassic ; Outcrop analogue ; Fluvial facies ; Pore system ; TAGI
- 刊名：Marine and Petroleum Geology
- 出版年：March, 2014
- 年：2014
- 卷：51
- 期：Complete
- 页码：136-151
- 全文大小：9390 K
文摘
This study aims at unravelling the diagenetic history and its effect on the pore system evolution of the Triassic redbeds exposed in SE Spain (TIBEM), an outcrop analogue of the TAGI (Trias Argilo-Gr茅seux Inf茅rieur) reservoir (Berkine-Ghadames Basin, Algeria). Similar climatic, base level and tectonic conditions of aforementioned alluvial formations developed analogue fluvial facies stacking patterns. Furthermore, interplay of similar detrital composition and depositional facies in both formations resulted in analogue early diagenetic features. Petrographic observations indicate lithic subarkosic (floodplain facies) and subarkosic (braidplain facies) compositions which are considered suitable frameworks for potential reservoir rocks. Primary porosity is mainly reduced during early diagenesis through moderate mechanical compaction and formation of K-feldspar overgrowth, gypsum, dolomite and phyllosilicate cements. Early mesodiagenesis is testified by low chemical compaction and quartz cementation. Telodiagenetic calcite filling fractures and K-feldspar dissolution determined the final configuration of analysed sandstones. Mercury injection-capillary pressure technique reveals overbank deposits in the floodplain as the least suitable potential reservoirs because of their lowest open porosity (OP聽<聽16%), permeability (k聽<聽5聽mD) and small dimensions. On the other hand, braidplain deposits show the highest values of such properties (OP up to 31.6% and k聽>聽95聽mD) and greater thickness and lateral continuity, so being considered the best potential reservoir. The accurate estimation of TIBEM microscale attributes can provide important input for appraisal and enhanced oil recovery performance in TAGI and in others reservoirs consisting on similar fluvial sandy facies.