Тип бассейна: Платформ
Подтип бассейна: Внутриплатформенный (интракратонный)
Класс бассейна: Синеклизный
Возраст бассейна: Древний - Палеозойский
Тип полезных ископаемых:
Геологический возраст начало:
Геологический возраст конец:
Площадь: 232231.31 км²
Oued Mya Basin
The Oued Mya Basin is an elongated Paleozoic cratonic depression in the northeastern Algerian Saharan platform. The basin is bounded by the Hassi Messaoud Arch and Amguid Arch in the east, Allal High, Tilrhemt High, and Idjerane Arch in the west (Fig. 1). Touggourt saddle is situated in the north, while a structural terrace separates the Oued Mya Basin from the Mouydir Basin in the south. The basin has witnessed multiple compression and extension phases of the Pan-African (590 Ma) as well as Alpine orogeny (65 Ma; Benayad et al., 2011). The basin is characterized by vertical N-S, NNE, and NNW-oriented Pan-African basement faults (English et al., 2017). The long-lived vertical strike-slip faults have been reactivated multiple times during the geological evolution through the transtensional and transpressional episodes (Galeazzi et al., 2010). The basin hosts a cumulative of 4500-5000 m of sedimentary succession (Benamrane et al., 1993; Yahi and Khatir, 1995). Most of the oil and gas accumulations in the Oued Mya Basin are located on the low-relief structures along the flank of the Tilrhemt Arch (Klett, 2000).
Fig. 1. Location map of the Oued Mya Basin situated at the northeastern Algerian Saharan platform, together with the nearby basins, structural features, and studied well locations. The base map is adapted from KeyFacts Energy (2016)
Researchers have interpreted that these accumulations are majorly within the anticlines, faulted anticlines, or fault blocks developed during the Hercynian and Austrian deformation (Petroconsultants, 1996; Boote et al., 1998; Klett, 2000). A regional lithostratigraphic section is provided in Fig. 2 (Klett, 2000). Primary hydrocarbon reservoirs of the Oued Mya Basin belong to the R1 sandstones and Hamra Quartzites of the Cambrian and Ordovician ages respectively (Benayad et al., 2011).
Fig. 2. Representation of a regional lithostratigraphic section of the Oued Mya Basin (Klett, 2000).
The Cambrian reservoirs correspond to braided fluvial units being unconformably deposited above the pre-Cambrian metamorphic basement (Carr, 2002; Lang et al., 2012). This was followed by the deposition of the Early Paleozoic transgressive shales, namely El Gassi Shale, which separates the Cambrian reservoir from the glaciogenic Ordovician reservoir. The base of the Ordovician Hamra quartzite Formation marks a sequence boundary between preglacial and glacial deposits. Benayad et al. (2013, 2014) studied the petrographic characteristics of the Ordovician reservoirs and inferred that the principal diagenetic factors controlling the reservoir quality are quartz overgrowths and pore-filling illites which reduced the reservoir porosity and permeability. Chlorites have been reported within the Cambrian reservoirs produced by the illite transformation. The post-glacial sea-level increase deposited organic-rich marine shales during Silurian (McDougall et al., 2003; Eschard et al., 2005). Both the Lower Silurian and Ordovician shales are the established source rocks, with high total organic carbon content (∼6%-14%; Benamrane et al., 1993). The Jurassic evaporites formed the regional seal to the petroleum system
The well locations are presented in Table 1 and plotted in Fig. 1. All the wells were drilled through the Cambrian reservoir.
All the wells were drilled through the Cambrian reservoir. Routine core analysis (RCA) was accomplished on the core samples covering reservoir pay zones, as obtained from the four studied wells (Well-B, E, F, and I). Wireline geophysical logs were recorded in all the wells, which were the primary input parameters in the geomechanical analyses. Six wells (Well-A, C, D, E, G, and K) had acoustic image log data set. Downhole measurements of formation pressure and minifrac were available from one well (Well-K), used for the calibration and validation of various calculated parameters.
A well-log correlation panel is presented in Fig. 3, which represents the distribution of the Ordovician and Cambrian reservoirs. The Ordovician reservoir is approximately 100-150 m thick, while 200 m+ thickness is encountered in the Cambrian interval.
Fig. 3. Presents the well-log correlations the Oued Mya field, flattened at the top of the Silurian shale (top seal for the Ordovician reservoir). The map in the inset (left bottom) represents the structural contour map of the Ordovician reservoir top.
Data source:Assessment of reservoir stress state and its implications for Paleozoic tight oil reservoir development in the Oued Mya Basin, northeastern Algerian Sahara. Rafik Baouche, Shib Sankar Ganguli, Souvik Sen, Ahmed E. Radwan. Geosystems and Geoenvironment 2 (2023)
Следующий Бассейн: North - Central Gregory Rift