Correlation and sequence stratigraphic interpretation of the lithostratigraphic Snake Cave Interval: Implications for hydrocarbon reservoir prospectivity between the southeast Blantyre and northwestern Neckarboo Sub-basins, Darling Basin, southeastern Australia
Introduction
Adequate knowledge and understanding of sequence stratigraphy has developed as a key and commonly used method of stratigraphic analysis within sedimentary basins to help in hydrocarbon exploration and exploitation. Data presented here are based upon a detailed subsurface sequence stratigraphic analysis, involving lithology and a wireline log with synthetic seismogram available from one well only. The context of this research contains terms and name abbreviations found in Table 1 used throughout this paper. The focal of this study encompasses new documentation of the subsurface sequence stratigraphic framework of the upper Lower Devonian through upper Middle Devonian Snake Cave Interval (uL-uM Dev SCI) in the lower part of the Mulga Downs Group (MDG) for prospective sandstone reservoir potential in the southeast Darling Basin (DB). A summary of the regional setting of Upper Cambrian to Devonian stratigraphy of non-marine sediments in the DB is presented by Brown et al. (1982), Byrnes (1985), Mullard (1995); Alder et al. (1998), Willcox et al. (2003), Mills and David (2003), Cooney and Mantaring (2007), Khalifa and Mills, 2010, Khalifa and Mills, 2014, Khalifa et al. (2016),Khalifa et al. (2017) and Khalifa et al. (2019) and an overview of several studies by various researchers, especially for regional stratigraphy and paleogeography of the Snake Cave Interval (SCI) have been published in recent years (e.g. Neef and Bottrill, 1996, Bembrick, 1997a, 1997b; Blevin et al., 2007; Khalifa and Ward, 2009; Khalifa, 2010; Neef, 2011, 2012). Despite these scientific investigations, the internal lithostratigraphic controls of the highly variable sedimentological analysis relationships paleo-environments of the rates of the SCI, in several areas of the DB (cf. Khalifa and Ward, 2009; Khalifa et al., 2015; Khalifa and Mills, 2020) are poorly understood. Herein are presented the stratigraphic facies and their regional correlation based on core/cutting data and wireline log responses to assist this understanding.
Several studies have described the evolution of sequence stratigraphy, which is extensively regarded as a valuable tool to recognize and predict facies relations and sedimentary environment distributions (e.g. Van Wagoner et al., 1988; Galloway, 1989a, 1989b; Mitchum and Van Wagoner, 1991; Van Wagoner, 1995; Catuneanu, 2006). Furthermore, instituting a completely integrated sedimentological feature and sequence stratigraphic unit configuration has long been acknowledged to strengthen effective petroleum exploration by assisting sedimentary basin analysis and stratigraphy (Payenberg and Lang, 2003; Frohlich et al., 2010; Vakarelov and Ainsworth, 2013; Zhou et al., 2014; Njoku, 2020). Evaluation and interpretation of sequence stratigraphic unit and key sequence stratigraphic surfaces with a combination of lithologic or other nonstandard attributes play a critical role in the predication of geological modelling of hydrocarbon reservoir, source, and seal occurrence and correlation (Galloway, 1989a, 1989b, 1989b; Ainsworth, 2005; Catuneanu, 2002, 2006, 2006; Catuneanu et al., 2011; Graham et al., 2015; Neal et al., 2016).
This research article presents the subsurface geology and discusses the implications of developing an internal sequence stratigraphic framework for the SCI by describing and correlating cores and cuttings data, together with wireline logs from petroleum exploration wells and synthetic seismogram profiles within the southeast Blantyre (BLE) and northwestern Neckarboo (NKO) sub-basins (Fig. 1). The results from this research will fill a long-standing gap in the knowledge of the sequence stratigraphic units’ significance for the southeast BLE and northwestern NKO sub-basins. It will also improve our understanding of how the regional configuration and integration of wireline logs and lithology data have been used to divide the SCI succession of siliciclastic into key sequence stratigraphic surfaces in contrast with systems tract and depositional sequences, and may provide indications of hydrocarbon oil and gas reservoir potential for future exploration.
Section snippets
Lithostratigraphic nomenclature and general depositional facies
A regional lithostratigraphic framework for the upper Lower through upper Middle Devonian (uL-uM Dev) SCI was developed, building on extensive previous work (e.g. Ward et al., 1969; Glen, 1982; Neef et al., 1995; Neef and Bottrill, 1996, 2001; Bembrick, 1997a, 1997b; Alder et al., 1998; Wilcox et al., 2003; Khalifa and Ward, 2010; Khalifa et al., 2016; Khalifa and Mills, 2020), which contains the subsurface and outcrop data based lithostratigraphic nomenclature units and parallels of the SCI
Materials and methodology
The subsurface materials for this study were obtained from the Geological Survey of New South Wales (GSNSW), as shown in Fig. 1, the two sub-basins, southeast Blantyre [NY-1 exploration well completion report by Orion Petroleum Limited (2008) and ME-1 exploration well completion report by Haskell and Wiltshire (1970)] and northwestern Neckarboo [KE-1 stratigraphic well completion report by Clark et al. (2001)]. The three wells include wireline logs (e.g. gamma ray, density and resistivity) and
Interpretation and results of sequence stratigraphic units
Sequence stratigraphic unit analysis of wireline logs has been discussed and demonstrated by several researchers. For example, Posamentier and Vail (1988), Posamentier et al. (1988) Van Wagoner et al. (1990), Emery and Myers (1996), Galloway (1989a, 1989b) and Catuneanu (2002, 2006) provided an outstanding source of information for those unacquainted with such interpretations of similar lithostratigraphy of the Snake Cave Interval in the literature, as defined in the present work.
Facies association relationships and systems tracts within depositional sequences
New facies scheme relationship and sequence stratigraphic unit analysis of the lithostratigraphy of SCI in the studied areas show that it represents a well-preserved example of the MFFA-A and BFFA-B with minor FSLCFA-C (Fig. 7, Fig. 8, Fig. 9 and Table 3). Furthermore, this sequence stratigraphic unit subdivision has given an improved understanding of accommodation and sediments supply development. The accompanying changes in depositional characteristics of lithotype pattern analysis have been
Conclusions
The new knowledge of the delineation and correlation of sequence stratigraphy in the non-marine upper Lower through upper Middle Devonian of the Snake Cave succession reality is based on the subsurface data, which has enhanced the hydrocarbon potential of sandstone reservoir prospectivity in the studied areas. Over all, three conclusions have been drawn from this study as outlined below:
Sequence stratigraphic units are based on the wireline-logs signatures, lithologic, synthetic seismogram and
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
The authors hope that the Geological Survey of New South Wales (GSNSW) in Australia would benefit from the results of this research article which presents part of a more correlation and sequence stratigraphy synthesis of the upper Lower through upper Middle Devonian of the Snake Cave Interval sedimentary succession and implications for hydrocarbon prospectivity of central part of the Darling Basin. The authors thank the GSNSW, and the Director of Mines, Tasmania, who authorized the publication
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